Cancer researchers at Georgetown University Medical Center have taken a step towards understanding how and why a widely used chemotherapy drug works in patients with breast cancer.
In laboratory studies, the researchers isolated a protein, caveolin-1, showing that in breast cancer cells this protein can enhance cell death in response to the use of Taxol, one of two taxane chemotherapy drugs used to treat advanced breast and ovarian cancer. But in order to work, they found the protein needs to be "switched on," or phosphorylated. The results were reported in the Journal of Biological Chemistry.
Their finding suggests it may eventually be possible to test individual breast cancer patients for the status of such molecular markers as caveolin-1 in their tumors to determine the efficacy-to-toxicity ratio for Taxol, said the study's first author, postdoctoral fellow Ayesha Shajahan, Ph.D., of Lombardi Comprehensive Cancer Center at Georgetown.
"Because breast tumors are not all the same, it is important to know the cancer's molecular makeup in order to increase the efficiency, and lower the toxicity, of chemotherapy drugs, and this work takes us some steps forward in this goal," she said. "It also offers insights into why some breast cancer cells can become resistant to therapeutic drugs."
Additionally, the study identifies caveolin-1 as a new molecular target for increasing the efficacy of taxanes, according to the study's lead investigator, Robert Clarke, Ph.D., D.Sc., a Professor of Oncology and Physiology & Biophysics. "This is important because the taxanes are active drugs in breast cancer, so now that we know caveolin-1 is a new mechanism to explain how these drugs kill breast cancer cells, we can potentially take advantage of that fact to improve these agents."
The taxanes are Taxol (also known as paclitaxel) and Taxotere (docetaxel). Taxol was originally derived from the Pacific yew tree, and Taxotere is a semi-synthetic version of Taxol with slight chemical changes. These drugs stabilize a cell's "microtubules," the road-like protein structures that send chemical signals to all parts of the cell, and which must be flexible if a cell is to divide. Taxanes lock these structures into place, not allowing them to change when the cell begins to divide - which is necessary for tumor growth. Research has also indicated that the drugs induce programmed cell death (apoptosis) in cancer cells by inactivating an "apoptosis stopping protein" called BCL2, thus stopping it from inhibiting cell death.
Caveolin-1 is a protein that is found in most cells under normal conditions and it is involved in an array of cellular events that ranges from vesicle trafficking to cell migration. It is, therefore, as a key regulator of multiple events within the cell.
In cancer, the expression level of caveolin-1 can vary depending on cell type. However, the precise role of caveolin-1 in cancer has been controversial: whether it acts as a suppressor or facilitator of tumor formation depends on the cell type. In human breast cancer, caveolin-1 has been known to act as a tumor suppressor since caveolin-1 expression is down-regulated during the primary stages of breast cancer. More recent studies indicate that that caveolin-1 expression is increased in more aggressive types of breast cancer.
Under the mentorship of Clarke, Shajahan sought to determine factors that regulate expression and function of caveolin-1 in the breast. In this study, the researchers show that in their breast cancer cell model that phosphorylated caveolin-1 increased cell death by activating other key regulators vital to both breast cancer progression and cell death, including BCL2, the same protein that Taxol works on; p21, which controls cell cycle progression; and the tumor suppressor p53.
If caveolin-1 isn't phosphorylated, breast cancer cells appear to be resistant to Taxol treatment, the researchers conclude. "Thus, this study opens an area of investigation in our lab that will concentrate on understanding how this multi-tasking protein can serve as a marker for chemotherapeutic drug efficacy," Shajahan said.
The study was supported by grants from the National Institute of Health, and the Department of Defense to Clarke and a postdoctoral fellowship award from Susan G. Komen Breast Cancer Foundation to Shajahan. The other co-authors for this study were Aifen Wang, M.Sc., Markus Decker, B.Sc., and . Minetta C. Liu, M.D. from Georgetown University Medical Center, and Richard D. Minshall, Ph.D. from the University of Illinois at Chicago.
About Georgetown University Medical Center
Georgetown University Medical Center is an internationally recognized academic medical center with a three-part mission of research, teaching and patient care (through our partnership with MedStar Health). Our mission is carried out with a strong emphasis on public service and a dedication to the Catholic, Jesuit principle of cura personalis -- or "care of the whole person." The Medical Center includes the School of Medicine and the School of Nursing & Health Studies, both nationally ranked, the world-renowned Lombardi Comprehensive Cancer Center and the Biomedical Graduate Research Organization (BGRO).
Contact: Laura Cavender
Georgetown University Medical Center
View drug information on Taxol; Taxotere.
среда, 31 августа 2011 г.
воскресенье, 28 августа 2011 г.
Easily Blocked Protein May Help Stop Parasites
Researchers at Washington University School of Medicine in St. Louis have identified a parasite protein that has all the makings of a microbial glass jaw: it's essential, it's vulnerable and humans have nothing like it, meaning scientists can take pharmacological swings at it with minimal fear of collateral damage.
The protein, calcium dependent protein kinase 1 (CDPK1), is made by Toxoplasma gondii, the toxoplasmosis parasite; cryptosporidium, which causes diarrhea; plasmodium, which causes malaria; and other similar parasites known as apicomplexans.
In the May 20 issue of Nature, researchers report that genetically suppressing CDPK1 blocks the signals that toxoplasma parasites use to control their movement, preventing them from moving in and out of host cells. They also found that toxoplasma's version of CDPK1 is easier to disable than expected and identified a compound that effectively blocks its signaling ability.
"Kinases are proteins that are common throughout biology, but the structures of CDPKs in apicomplexans much more closely resemble those found in plants than they do those of animals," says senior author L. David Sibley, PhD, professor of molecular microbiology. "We showed that these differences can be exploited to identify potent and specific inhibitors that may provide new interventions against disease."
Infection with toxoplasma is most familiar to the general public from the recommendation that pregnant women avoid changing cat litter. Cats are commonly infected with the parasite, as are many livestock and wildlife. Humans also can become infected by eating undercooked meat or by drinking water contaminated with spores shed by cats.
Epidemiologists estimate that as many as one in every four humans worldwide is infected with toxoplasma. Infections are typically asymptomatic, only causing serious disease in patients with weakened immune systems. In some rare cases, though, infection in patients with healthy immune systems leads to serious eye or central nervous system disease, or congenital defects in the fetuses of pregnant women.
Sibley studies toxoplasma both to find ways to reduce human infection rates and as a model for learning about other apicomplexans, such as plasmodium, that are more significant sources of disease and death.
The new study, led by graduate student Sebastian Lourido, began as an effort to determine what CDPK1 does for toxoplasma. Researchers genetically modified the parasite, eliminating its normal copy of CDPK1 and replacing it with a version of the gene that they could turn on and off. When they turned the new gene off, they found that they had paralyzed the parasite, preventing it from moving and from breaking into and out of host cells. Turning the gene back on restored these abilities.
Further tests revealed that CDPK1 controls toxoplasma's ability to secrete microneme proteins, sticky proteins that act as handholds and allow the parasites to move about their environment and pass through host cell membranes.
In a separate collaborative paper published earlier this month in Nature Structural and Molecular Biology, scientists in the laboratory of co-author Raymond Hui, PhD, principal investigator of parasitology at the Structural Genomics Consortium of the University of Toronto, determined the three dimensional structure of the CDPK1 protein. Researchers found that the area drugs would normally bind in order to disable the protein was more accessible than in virtually all other kinases, including those that control signaling in humans.
"To our surprise, CDPK1 just has a naturally large keyhole for inhibitors to slide into," Lourido says. "This good fortune allowed us to exploit bulky kinase inhibitors that had been previously pioneered by the laboratory of Kevan Shokat, PhD, professor of cellular and molecular pharmacology at the University of California, San Francisco, and a Howard Hughes Medical Institute investigator."
When tested on parasites, the bulky inhibitors successfully blocked CDPK1 function and parasite infectivity without affecting human cells.
Lourido suspects CDPK1 may play a similar role in plasmodium, but its version of the protein is predicted to be harder to selectively target with inhibitors. Little is known about what CDPK1 does in cryptosporidium, but since it shares close similarity to toxoplasma, it may also be essential and susceptible to inhibition by similar compounds.
Sibley and Lourido plan to learn more of the details of how CDPK1 controls microneme secretion, using toxoplasma as a model to study the functions of parasites and how they differ from human cells. The successful toxoplasma inhibitor is now undergoing further testing in animals to see if it can eventually be adapted for clinical use to prevent infection in humans.
Lourido S, Shuman J, Zhang C, Shokat KM, Hui R, Sibley LD. Calcium-dependent protein kinase 1 is an essential regulator of exocytosis in Toxoplasma. Nature, May 20, 2010.
Funding from the American Heart Association and the National Institutes of Health supported this research.
Washington University School of Medicine's 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children's hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked fourth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children's hospitals, the School of Medicine is linked to BJC HealthCare.
Source: Washington University in St. Louis
The protein, calcium dependent protein kinase 1 (CDPK1), is made by Toxoplasma gondii, the toxoplasmosis parasite; cryptosporidium, which causes diarrhea; plasmodium, which causes malaria; and other similar parasites known as apicomplexans.
In the May 20 issue of Nature, researchers report that genetically suppressing CDPK1 blocks the signals that toxoplasma parasites use to control their movement, preventing them from moving in and out of host cells. They also found that toxoplasma's version of CDPK1 is easier to disable than expected and identified a compound that effectively blocks its signaling ability.
"Kinases are proteins that are common throughout biology, but the structures of CDPKs in apicomplexans much more closely resemble those found in plants than they do those of animals," says senior author L. David Sibley, PhD, professor of molecular microbiology. "We showed that these differences can be exploited to identify potent and specific inhibitors that may provide new interventions against disease."
Infection with toxoplasma is most familiar to the general public from the recommendation that pregnant women avoid changing cat litter. Cats are commonly infected with the parasite, as are many livestock and wildlife. Humans also can become infected by eating undercooked meat or by drinking water contaminated with spores shed by cats.
Epidemiologists estimate that as many as one in every four humans worldwide is infected with toxoplasma. Infections are typically asymptomatic, only causing serious disease in patients with weakened immune systems. In some rare cases, though, infection in patients with healthy immune systems leads to serious eye or central nervous system disease, or congenital defects in the fetuses of pregnant women.
Sibley studies toxoplasma both to find ways to reduce human infection rates and as a model for learning about other apicomplexans, such as plasmodium, that are more significant sources of disease and death.
The new study, led by graduate student Sebastian Lourido, began as an effort to determine what CDPK1 does for toxoplasma. Researchers genetically modified the parasite, eliminating its normal copy of CDPK1 and replacing it with a version of the gene that they could turn on and off. When they turned the new gene off, they found that they had paralyzed the parasite, preventing it from moving and from breaking into and out of host cells. Turning the gene back on restored these abilities.
Further tests revealed that CDPK1 controls toxoplasma's ability to secrete microneme proteins, sticky proteins that act as handholds and allow the parasites to move about their environment and pass through host cell membranes.
In a separate collaborative paper published earlier this month in Nature Structural and Molecular Biology, scientists in the laboratory of co-author Raymond Hui, PhD, principal investigator of parasitology at the Structural Genomics Consortium of the University of Toronto, determined the three dimensional structure of the CDPK1 protein. Researchers found that the area drugs would normally bind in order to disable the protein was more accessible than in virtually all other kinases, including those that control signaling in humans.
"To our surprise, CDPK1 just has a naturally large keyhole for inhibitors to slide into," Lourido says. "This good fortune allowed us to exploit bulky kinase inhibitors that had been previously pioneered by the laboratory of Kevan Shokat, PhD, professor of cellular and molecular pharmacology at the University of California, San Francisco, and a Howard Hughes Medical Institute investigator."
When tested on parasites, the bulky inhibitors successfully blocked CDPK1 function and parasite infectivity without affecting human cells.
Lourido suspects CDPK1 may play a similar role in plasmodium, but its version of the protein is predicted to be harder to selectively target with inhibitors. Little is known about what CDPK1 does in cryptosporidium, but since it shares close similarity to toxoplasma, it may also be essential and susceptible to inhibition by similar compounds.
Sibley and Lourido plan to learn more of the details of how CDPK1 controls microneme secretion, using toxoplasma as a model to study the functions of parasites and how they differ from human cells. The successful toxoplasma inhibitor is now undergoing further testing in animals to see if it can eventually be adapted for clinical use to prevent infection in humans.
Lourido S, Shuman J, Zhang C, Shokat KM, Hui R, Sibley LD. Calcium-dependent protein kinase 1 is an essential regulator of exocytosis in Toxoplasma. Nature, May 20, 2010.
Funding from the American Heart Association and the National Institutes of Health supported this research.
Washington University School of Medicine's 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children's hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked fourth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children's hospitals, the School of Medicine is linked to BJC HealthCare.
Source: Washington University in St. Louis
четверг, 25 августа 2011 г.
Medical Evacuation Procedures Targeted By US Air Force Grant
University of Cincinnati (UC) researchers have received a grant in excess of $2 million from the U.S. Air Force School of Aerospace Medicine to determine the ideal time to fly that minimizes health complications to injured soldiers due to the rush to move them from the battlefield into a safe zone.
"There is a sense of urgency about getting these wounded soldiers to a cleaner, safer environment," explains Col. Warren Dorlac, MD, co-principal investigator on the UC study. "Our overriding goal is to protect patients from anything that could potentially lead to a cascade of medical complications that will jeopardize survival. But the reality is that evacuation is happening at a time when they are most prone to a secondary hit."
According to U.S. military reports, about 30 to 50 soldiers are critically wounded each month and require medical evacuation out of a war zone. Most are in transit to a full-service hospital within 48 hours.
Avoiding this "second hit" - such as a serious infection or pneumonia - improves survival dramatically. Doing so is challenging, however, in the middle of a war zone where medical troops are being cared for in maze of canvas and plywood hospital tents.
Dorlac and his colleagues believe there may be a direct link between inflammatory changes in the body and the timing of strategic medical evacuation movements.
For this study, UC researchers will investigate how early evacuation of combat casualties affects the body's inflammatory response, possibly predisposing already critically wounded people to death from related complications.
"We need to understand the biological effects of the hypobaric environment so we can minimize the risk for additional injuries," says Dorlac, associate professor of surgery at UC and director of the Cincinnati Center for Sustainment and Readiness Skills (C-STARS) program housed in University Hospital.
Currently, no data exists on the impact of the hypobaric environment - characterized by reduced oxygen levels - and altitude on patients recovering from traumatic injuries.
"Determining the ideal time to fly could reduce infection, minimize hospital stays and result in fewer amputations and deaths for the soldiers defending our country," adds Dorlac.
Because of the nature of a combat zone, the average medical evaluation plane quickly ascends 8,000 feet within 10 minutes. The plane is very different than a hospital intensive care unit - 90 decibels of noise, lots of vibration and a pressurized environment that results in less oxygen to revive tissues and relieve stress on the body's systems.
This, says Dorlac, is far from the ideal setting for a traumatic brain-injured or other severely injured patient.
"When we send a patient up in an airplane, we're essentially putting them into an environment we know can't be good for them in an effort to move them to safety," he adds. "A dark, quiet intensive care unit with very little stimulation or distraction is preferable. Even minor movements can cause a change in intracranial pressure."
For this two-phase study, the UC team will create three animal models representative of traumatic military combat injuries: controlled hemorrhage, hepatic ischemia reperfusion and scald/burn.
The controlled hemorrhage model, characterized by a low but sustainable level of blood pressure, is meant to reflect a soldier who has experienced a heavy-bleeding wound but doesn't reach a field hospital to receive fluids for several hours.
Hepatic ischemia reperfusion model represents a patient who needs serious abdominal surgery that requires re-establishing blood flow to a major organ.
The scald/burn model corresponds to a blast burn wound from weapon fire.
"Each model has a different inflammatory response, all of them severe and relevant to injuries our soldiers are experiences during war," explains Alex Lentsch, PhD, co-principal investigator of the study and director of UC's surgical research unit.
"By understanding how the inflammatory response evolves over the course of different injuries, flight times and altitudes," he adds, "we will be able to better target care for patients who have been severely injured and need to be moved across country."
After taking baseline biological measurements, researchers will test whether moving to an altitude of 8,000 feet increases the body's inflammatory response. This information is necessary to determine an ideal to time to fly that minimizes the risk for additional medical complications.
Cellular inflammation markers in the blood will be measured before and after flight to determine how different altitudes affect the body's inflammatory response after injury.
"When a person experiences trauma and loses a lot of blood, the body sends warning signals and stimulates certain cells that will try to fix or repair the problem, causing inflammation," explains Lentsch. "But this storm of cellular response is unselective. This all eventually leads to multiple organ dysfunction."
The study's second phase will focus on a more complex brain injury model using concepts learned in the initial research. Researchers will continue to look at the effect of flight timing and altitude on the patient's inflammatory response but also monitor blood oxygenation levels and intracranial pressure.
Three areas have been shown to increase brain tissue loss and increase mortality in head injured patients: lack of oxygen (hypoxia); low blood pressure (hypotension); and increased intracranial pressure, which can be brought on by a low oxygen environment characteristic of a medical evacuation plane.
"There is nothing known beyond anecdotal evidence about inflammation's affects on the survival of patients with traumatic injuries, so we have a great opportunity to learn more about this problem and make an impact on the real world."
Timothy Pritts, MD, PhD, and Lt. Col. Gina Dorlac, MD, are co-investigators in this study. Maj Stephen Barnes, MD, previously of CSTARS Cincinnati will also stay involved. Testing will take place both at UC and Brooks Air Force Base in San Antonio, Texas.
Source: Amanda Harper
University of Cincinnati
"There is a sense of urgency about getting these wounded soldiers to a cleaner, safer environment," explains Col. Warren Dorlac, MD, co-principal investigator on the UC study. "Our overriding goal is to protect patients from anything that could potentially lead to a cascade of medical complications that will jeopardize survival. But the reality is that evacuation is happening at a time when they are most prone to a secondary hit."
According to U.S. military reports, about 30 to 50 soldiers are critically wounded each month and require medical evacuation out of a war zone. Most are in transit to a full-service hospital within 48 hours.
Avoiding this "second hit" - such as a serious infection or pneumonia - improves survival dramatically. Doing so is challenging, however, in the middle of a war zone where medical troops are being cared for in maze of canvas and plywood hospital tents.
Dorlac and his colleagues believe there may be a direct link between inflammatory changes in the body and the timing of strategic medical evacuation movements.
For this study, UC researchers will investigate how early evacuation of combat casualties affects the body's inflammatory response, possibly predisposing already critically wounded people to death from related complications.
"We need to understand the biological effects of the hypobaric environment so we can minimize the risk for additional injuries," says Dorlac, associate professor of surgery at UC and director of the Cincinnati Center for Sustainment and Readiness Skills (C-STARS) program housed in University Hospital.
Currently, no data exists on the impact of the hypobaric environment - characterized by reduced oxygen levels - and altitude on patients recovering from traumatic injuries.
"Determining the ideal time to fly could reduce infection, minimize hospital stays and result in fewer amputations and deaths for the soldiers defending our country," adds Dorlac.
Because of the nature of a combat zone, the average medical evaluation plane quickly ascends 8,000 feet within 10 minutes. The plane is very different than a hospital intensive care unit - 90 decibels of noise, lots of vibration and a pressurized environment that results in less oxygen to revive tissues and relieve stress on the body's systems.
This, says Dorlac, is far from the ideal setting for a traumatic brain-injured or other severely injured patient.
"When we send a patient up in an airplane, we're essentially putting them into an environment we know can't be good for them in an effort to move them to safety," he adds. "A dark, quiet intensive care unit with very little stimulation or distraction is preferable. Even minor movements can cause a change in intracranial pressure."
For this two-phase study, the UC team will create three animal models representative of traumatic military combat injuries: controlled hemorrhage, hepatic ischemia reperfusion and scald/burn.
The controlled hemorrhage model, characterized by a low but sustainable level of blood pressure, is meant to reflect a soldier who has experienced a heavy-bleeding wound but doesn't reach a field hospital to receive fluids for several hours.
Hepatic ischemia reperfusion model represents a patient who needs serious abdominal surgery that requires re-establishing blood flow to a major organ.
The scald/burn model corresponds to a blast burn wound from weapon fire.
"Each model has a different inflammatory response, all of them severe and relevant to injuries our soldiers are experiences during war," explains Alex Lentsch, PhD, co-principal investigator of the study and director of UC's surgical research unit.
"By understanding how the inflammatory response evolves over the course of different injuries, flight times and altitudes," he adds, "we will be able to better target care for patients who have been severely injured and need to be moved across country."
After taking baseline biological measurements, researchers will test whether moving to an altitude of 8,000 feet increases the body's inflammatory response. This information is necessary to determine an ideal to time to fly that minimizes the risk for additional medical complications.
Cellular inflammation markers in the blood will be measured before and after flight to determine how different altitudes affect the body's inflammatory response after injury.
"When a person experiences trauma and loses a lot of blood, the body sends warning signals and stimulates certain cells that will try to fix or repair the problem, causing inflammation," explains Lentsch. "But this storm of cellular response is unselective. This all eventually leads to multiple organ dysfunction."
The study's second phase will focus on a more complex brain injury model using concepts learned in the initial research. Researchers will continue to look at the effect of flight timing and altitude on the patient's inflammatory response but also monitor blood oxygenation levels and intracranial pressure.
Three areas have been shown to increase brain tissue loss and increase mortality in head injured patients: lack of oxygen (hypoxia); low blood pressure (hypotension); and increased intracranial pressure, which can be brought on by a low oxygen environment characteristic of a medical evacuation plane.
"There is nothing known beyond anecdotal evidence about inflammation's affects on the survival of patients with traumatic injuries, so we have a great opportunity to learn more about this problem and make an impact on the real world."
Timothy Pritts, MD, PhD, and Lt. Col. Gina Dorlac, MD, are co-investigators in this study. Maj Stephen Barnes, MD, previously of CSTARS Cincinnati will also stay involved. Testing will take place both at UC and Brooks Air Force Base in San Antonio, Texas.
Source: Amanda Harper
University of Cincinnati
понедельник, 22 августа 2011 г.
Flies Show Link Between Sleep And Immune System
Go a few nights without enough sleep and you're more likely to get sick, but scientists have no real explanation for how sleep is related to the immune system. Now, researchers at the Stanford University School of Medicine are finding that fruit flies can point to the answers.
What they have learned thus far is that illness and sleep disruption may be a two-way street: sick flies can't sleep, and losing sleep makes them more susceptible to infection.
"When flies get sick, they stop sleeping," said David Schneider, PhD, assistant professor of microbiology and immunology. "Disrupting sleep in turn disrupts the immune system, which makes them even more infected and it's downhill from there in a 'spiral of death." Schneider is the senior author of a study on the sleep patterns of flies, published in Current Biology.
Schneider worked with postdoctoral scholar Mimi Shirasu-Hiza, PhD, who is the study's first author, to examine the connection between illness and sleep patterns by infecting fruit flies with one of two bacteria - Streptococcus pneumoniae or Listeria monocytogenes.
The infected flies lost their "day" and "night" patterns of activity, which are part of the regular changes that occur in the course of a day, called circadian rhythm. Uninfected flies alternate between 12 hours of high activity and 12 hours of low activity. The researchers found the sick flies had fewer sleep sessions and shorter periods of continuous sleep than did healthy flies. They basically just didn't sleep well, concluded the researchers.
The researchers can't say for sure whether a disruption of the brain's central clock, which is the area of the fly brain that exhibits circadian gene activity, was responsible for the changes seen in the sick flies; but the behavior of the ill flies looked a lot like that of flies known to have disruptions in their genes controlling circadian rhythm.
So the next step, after confirming that flies lost sleep when infected, was to ask the converse: when sleep is disrupted, does that affect immunity"
The challenge was how to disrupt the flies' sleep. Schneider tried building a machine that jostled the flies randomly. "All it was really good at doing was throwing the tubes around the room," said Schneider. "Also it was too regular, the flies got used to it so they could nap."
Another option was to keep the flies in continuous light. But Schneider and Shirasu-Hiza decided that an even better way would be to turn to established fly strains isolated decades ago that possess disruptions in their genes controlling circadian rhythm. In this case, these mutant flies could be kept under exactly the same light and temperature conditions as the normal flies.
They looked at flies that were defective in one of two genes, called "timeless" and "period". They found that the loss of either gene's function made the flies more sensitive to bacterial infections and these sick flies died significantly faster than control flies, which lived two to four times as long as the sick ones.
"We want to know how the internal clock knows the animal is infected, and how does the immune system know that you are not sleeping properly" said Schneider. "How do those messages get sent back and forth"
Their findings also raise the question of why the flies have a change in their sleep pattern when infected. The researchers speculate that from an evolutionary standpoint, there may be some microbes that are fought better when sleep is disrupted, although clearly not the two microbes they tested in the current study. "We think that is the reason flies do this," said Schneider, "but sometimes it's a good thing, sometimes it's a bad thing."
Building on their findings, they can begin to answer these questions. Shirasu-Hiza will be testing mutant flies with other circadian rhythm genes missing.
They hope their work inspires researchers who work on vertebrates to explore the molecular underpinnings of the interaction between sleep and immunity.
"The cool thing is that many of the clock genes are conserved between flies and vertebrates; we have 'period' and we have 'timeless'," said Schneider. "As usual, it doesn't work in exactly the same way, but what the fly does is let us find genes that are involved in the process, and then go figure out exactly how they are rewired to work in the human. The fly is really good for prospecting."
This work was funded by the National Institutes of Health, the Irvington Institution and the National Science Foundation. Other Stanford researchers who contributed to this study are: postdoctoral scholar Marc Dionne, PhD, graduate student Linh Pham, and graduate student Janelle Ayres.
Stanford University Medical Center integrates research, medical education and patient care at its three institutions - Stanford University School of Medicine, Stanford Hospital & Clinics and Lucile Packard Children's Hospital at Stanford. For more information, please visit the Web site of the medical center's Office of Communication & Public Affairs at mednews.stanford/.
Contact: Mitzi Baker
Stanford University Medical Center
What they have learned thus far is that illness and sleep disruption may be a two-way street: sick flies can't sleep, and losing sleep makes them more susceptible to infection.
"When flies get sick, they stop sleeping," said David Schneider, PhD, assistant professor of microbiology and immunology. "Disrupting sleep in turn disrupts the immune system, which makes them even more infected and it's downhill from there in a 'spiral of death." Schneider is the senior author of a study on the sleep patterns of flies, published in Current Biology.
Schneider worked with postdoctoral scholar Mimi Shirasu-Hiza, PhD, who is the study's first author, to examine the connection between illness and sleep patterns by infecting fruit flies with one of two bacteria - Streptococcus pneumoniae or Listeria monocytogenes.
The infected flies lost their "day" and "night" patterns of activity, which are part of the regular changes that occur in the course of a day, called circadian rhythm. Uninfected flies alternate between 12 hours of high activity and 12 hours of low activity. The researchers found the sick flies had fewer sleep sessions and shorter periods of continuous sleep than did healthy flies. They basically just didn't sleep well, concluded the researchers.
The researchers can't say for sure whether a disruption of the brain's central clock, which is the area of the fly brain that exhibits circadian gene activity, was responsible for the changes seen in the sick flies; but the behavior of the ill flies looked a lot like that of flies known to have disruptions in their genes controlling circadian rhythm.
So the next step, after confirming that flies lost sleep when infected, was to ask the converse: when sleep is disrupted, does that affect immunity"
The challenge was how to disrupt the flies' sleep. Schneider tried building a machine that jostled the flies randomly. "All it was really good at doing was throwing the tubes around the room," said Schneider. "Also it was too regular, the flies got used to it so they could nap."
Another option was to keep the flies in continuous light. But Schneider and Shirasu-Hiza decided that an even better way would be to turn to established fly strains isolated decades ago that possess disruptions in their genes controlling circadian rhythm. In this case, these mutant flies could be kept under exactly the same light and temperature conditions as the normal flies.
They looked at flies that were defective in one of two genes, called "timeless" and "period". They found that the loss of either gene's function made the flies more sensitive to bacterial infections and these sick flies died significantly faster than control flies, which lived two to four times as long as the sick ones.
"We want to know how the internal clock knows the animal is infected, and how does the immune system know that you are not sleeping properly" said Schneider. "How do those messages get sent back and forth"
Their findings also raise the question of why the flies have a change in their sleep pattern when infected. The researchers speculate that from an evolutionary standpoint, there may be some microbes that are fought better when sleep is disrupted, although clearly not the two microbes they tested in the current study. "We think that is the reason flies do this," said Schneider, "but sometimes it's a good thing, sometimes it's a bad thing."
Building on their findings, they can begin to answer these questions. Shirasu-Hiza will be testing mutant flies with other circadian rhythm genes missing.
They hope their work inspires researchers who work on vertebrates to explore the molecular underpinnings of the interaction between sleep and immunity.
"The cool thing is that many of the clock genes are conserved between flies and vertebrates; we have 'period' and we have 'timeless'," said Schneider. "As usual, it doesn't work in exactly the same way, but what the fly does is let us find genes that are involved in the process, and then go figure out exactly how they are rewired to work in the human. The fly is really good for prospecting."
This work was funded by the National Institutes of Health, the Irvington Institution and the National Science Foundation. Other Stanford researchers who contributed to this study are: postdoctoral scholar Marc Dionne, PhD, graduate student Linh Pham, and graduate student Janelle Ayres.
Stanford University Medical Center integrates research, medical education and patient care at its three institutions - Stanford University School of Medicine, Stanford Hospital & Clinics and Lucile Packard Children's Hospital at Stanford. For more information, please visit the Web site of the medical center's Office of Communication & Public Affairs at mednews.stanford/.
Contact: Mitzi Baker
Stanford University Medical Center
пятница, 19 августа 2011 г.
Researchers Determine How Mosquitoes Survive Dengue Virus Infection
Colorado State University researchers have discovered that mosquitoes that transmit deadly viruses such as dengue avoid becoming ill by mounting an
immediate, potent immune response. Because their immune system does not eliminate the virus, however, they are able to pass it on to a new victim. In
a study published February 13 in the open-access journal PLoS Pathogens, the researchers show that RNA interference - the mosquito immune response
-- is initiated immediately after they ingest blood containing dengue virus, but the virus multiplies in the mosquitoes nevertheless.
Dengue fever and dengue hemorrhagic fever are major global public health burdens, with up to 100 million cases occurring annually, yet no vaccines or
specific preventative medicines are currently available. The Aedes aegypti mosquito transmits dengue virus. Determining how the virus evades the
mosquito's defense is an important next step in research that aims to fight disease by interrupting the growth of dengue virus within the mosquito
before it can be transmitted.
RNA interference is an evolutionarily ancient antiviral defense used by mosquitoes and other invertebrates to destroy the RNA of many invading
arthropod-borne viruses. This team of researchers previously showed that ramping up the RNA interference response in mosquitoes prevented dengue
infection, and now they show that temporarily impairing this immune response increased virus transmission.
The investigators analyzed RNA from adult mosquitoes, finding that both the trigger and initiator molecules for RNA interference were formed after
infection, yet viral RNA could readily be detected in the same mosquitoes. They also measured infectious virus rates in the mosquitoes' saliva,
which revealed levels whereby the mosquitoes could transmit the disease to humans.
These findings indicate that genetic manipulation of RNA interference could be a significant weapon in stopping dengue virus transmission by Aedes
aegypti.
CITATION:
"Dengue Virus Type 2 Infections of Aedes aegypti
Are Modulated by the Mosquito's RNA Interference Pathway."
PLoS Pathog 5(2): e1000299. doi:10.1371/journal.ppat.1000299
dx.plos/10.1371/journal.ppat.1000299
About PLoS Pathogens
PLoS Pathogens publishes outstanding original articles that significantly advance the understanding of pathogens and how they
interact with their host organisms. All works published in PLoS Pathogens are open access. Everything is immediately available subject only to the
condition that the original authorship and source are properly attributed. Copyright is retained by the authors. The Public Library of Science uses
the Creative Commons Attribution License.
plospathogens
About the Public Library of Science
The Public Library of Science (PLoS) is a non-profit organization of scientists and physicians committed to making the world's scientific and medical
literature a freely available public resource.
Public Library of Science
immediate, potent immune response. Because their immune system does not eliminate the virus, however, they are able to pass it on to a new victim. In
a study published February 13 in the open-access journal PLoS Pathogens, the researchers show that RNA interference - the mosquito immune response
-- is initiated immediately after they ingest blood containing dengue virus, but the virus multiplies in the mosquitoes nevertheless.
Dengue fever and dengue hemorrhagic fever are major global public health burdens, with up to 100 million cases occurring annually, yet no vaccines or
specific preventative medicines are currently available. The Aedes aegypti mosquito transmits dengue virus. Determining how the virus evades the
mosquito's defense is an important next step in research that aims to fight disease by interrupting the growth of dengue virus within the mosquito
before it can be transmitted.
RNA interference is an evolutionarily ancient antiviral defense used by mosquitoes and other invertebrates to destroy the RNA of many invading
arthropod-borne viruses. This team of researchers previously showed that ramping up the RNA interference response in mosquitoes prevented dengue
infection, and now they show that temporarily impairing this immune response increased virus transmission.
The investigators analyzed RNA from adult mosquitoes, finding that both the trigger and initiator molecules for RNA interference were formed after
infection, yet viral RNA could readily be detected in the same mosquitoes. They also measured infectious virus rates in the mosquitoes' saliva,
which revealed levels whereby the mosquitoes could transmit the disease to humans.
These findings indicate that genetic manipulation of RNA interference could be a significant weapon in stopping dengue virus transmission by Aedes
aegypti.
CITATION:
"Dengue Virus Type 2 Infections of Aedes aegypti
Are Modulated by the Mosquito's RNA Interference Pathway."
PLoS Pathog 5(2): e1000299. doi:10.1371/journal.ppat.1000299
dx.plos/10.1371/journal.ppat.1000299
About PLoS Pathogens
PLoS Pathogens publishes outstanding original articles that significantly advance the understanding of pathogens and how they
interact with their host organisms. All works published in PLoS Pathogens are open access. Everything is immediately available subject only to the
condition that the original authorship and source are properly attributed. Copyright is retained by the authors. The Public Library of Science uses
the Creative Commons Attribution License.
plospathogens
About the Public Library of Science
The Public Library of Science (PLoS) is a non-profit organization of scientists and physicians committed to making the world's scientific and medical
literature a freely available public resource.
Public Library of Science
вторник, 16 августа 2011 г.
Brain Research Poised To Dramatically Advance Global Society
World-renowned scientists convened at George Mason University on May 21 and 22 to call for a 10-year intellectual revolution - the "decade of the mind." The proceedings that will be published after this historic gathering will make the case for a $4 billion public research initiative dedicated to reaching the next level of understanding the human brain--the yet-to-be-discovered inner workings of the mind. The symposium also outlined the dramatic implications the decade will have on the global economy and health care.
"We are at the 'tipping point' of making enormous advances in public health, particularly in managing diseases that affect the mind, such as Alzheimer's disease, Parkinson's disease, autism and schizophrenia," said Jim Olds, director of Mason's Krasnow Institute for Advanced Study. "We at Mason are honored to be hosting this gathering of the world's leading researchers in brain study who together will outline the vision for the 'Decade of the Mind' that we will present to federal policymakers."
The two-day symposium included nine sessions, each featuring one aspect of brain research, and was moderated by scientists from the Krasnow Institute for Advanced Study. The symposium was anchored by a plenary session including the nine panelists. Moderated by New York Times science writer George Johnson, the session provided an open forum for the scientists to discuss their groundbreaking research in areas such as neuroscience, neurobiology, computer science, psychology, robotics and economics. The panel also explained the urgency to continue the study of the human mind and the benefits this research could bring to society.
"It is our intention to cover a lot of ground in two days because we need to capture the magnitude of the impact of what we are proposing to Congress," said Olds. "A 10-year focus to bring the enormous promise of brain research will launch an intellectual revolution here and throughout the world, with lasting impacts on society."
In the United States today, more than five million people are living with Alzheimer's disease according to the Alzheimer's Association. The number of people affected by this ultimately fatal disease will only increase over the next decade as early onset Alzheimer's begins to affect the baby boomer generation.
Today, one in 17 Americans suffer from a serious mental illness, the leading cause of disability in the U.S. for people 15 to 44 years old, according to the National Institute on Mental Health. New brain research during the initiative, coupled with advances in MRI technology and other non-invasive research tools, will allow scientists to better understand what causes these illnesses and how to manage or cure them.
This initiative also could help thousands of soldiers, sailors and airmen who have served in Afghanistan and Iraq more quickly and easily recover from brain injuries caused during combat, especially by improvised explosive devices.
Further research could allow advances in robotics and artificial intelligence that would make most future military vehicles - and aircraft - operate unmanned and autonomously, thereby saving thousands of lives during combat operations.
"The economic impact of the 'Decade of the Mind' will be felt in all levels of society," said Olds. "By translating our knowledge of the human mind to building more intelligent machines and computer applications, we can improve the welfare of millions of people worldwide."
The groundwork for this initiative was laid during the "Decade of the Brain," declared by President George H.W. Bush in 1990. It produced immense advances in brain research, including the development of MRI scanners and progress in the understanding of Alzheimer's disease and mental illness. Using these advances as a basis for further exploration into the human mind, this new decade would provide the nation's scientific community the opportunity to understand more about the mind than ever before and tackle some of society's most pressing challenges.
Decade of the Mind symposium presenters included: Marcus Raichle, MD, Washington University (St. Louis) School of Medicine; Nancy Kanwisher, PhD, Massachusetts Institute of Technology; John Holland, PhD, University of Michigan; Dharmendra Modha, PhD, IBM; Giulio Tononi, MD, PhD, University of Wisconsin; George A. Bekey, PhD, University of Southern California; Gordon Shepherd, PhD, Yale University; Vernon Smith, PhD, George Mason University, Nobel Laureate; and George Johnson, New York Times science writer, plenary session moderator.
For more information about the Decade of the Mind symposium, visit krasnow.gmu/decade.
About the Krasnow Institute for Advanced Study
The Krasnow Institute for Advanced Study seeks to expand understanding of mind, brain and intelligence by conducting research at the intersection of the separate fields of cognitive psychology, neurobiology and the computer-driven study of artificial intelligence and complex adaptive systems. These separate disciplines increasingly overlap and promise progressively deeper insight into human thought processes. The institute also examines how new insights from cognitive science research can be applied for human benefit in the areas of mental health, neurological disease, education and computer design.
About George Mason University
George Mason University, located in the heart of Northern Virginia's technology corridor near Washington, D.C., is an innovative, entrepreneurial institution with national distinction in a range of academic fields. With strong undergraduate and graduate degree programs in engineering, information technology, biotechnology and health care, Mason prepares its alumni to succeed in the workforce and meet the needs of the region and the world. Mason professors conduct groundbreaking research in areas such as cancer, climate change, information technology and the biosciences, and Mason's Center for the Arts brings world-renowned artists, musicians and actors to its stage. Its School of Law is recognized by U.S. News and World Report as one of the top 50 law schools in the United States.
Contact: Jim Greif
George Mason University
"We are at the 'tipping point' of making enormous advances in public health, particularly in managing diseases that affect the mind, such as Alzheimer's disease, Parkinson's disease, autism and schizophrenia," said Jim Olds, director of Mason's Krasnow Institute for Advanced Study. "We at Mason are honored to be hosting this gathering of the world's leading researchers in brain study who together will outline the vision for the 'Decade of the Mind' that we will present to federal policymakers."
The two-day symposium included nine sessions, each featuring one aspect of brain research, and was moderated by scientists from the Krasnow Institute for Advanced Study. The symposium was anchored by a plenary session including the nine panelists. Moderated by New York Times science writer George Johnson, the session provided an open forum for the scientists to discuss their groundbreaking research in areas such as neuroscience, neurobiology, computer science, psychology, robotics and economics. The panel also explained the urgency to continue the study of the human mind and the benefits this research could bring to society.
"It is our intention to cover a lot of ground in two days because we need to capture the magnitude of the impact of what we are proposing to Congress," said Olds. "A 10-year focus to bring the enormous promise of brain research will launch an intellectual revolution here and throughout the world, with lasting impacts on society."
In the United States today, more than five million people are living with Alzheimer's disease according to the Alzheimer's Association. The number of people affected by this ultimately fatal disease will only increase over the next decade as early onset Alzheimer's begins to affect the baby boomer generation.
Today, one in 17 Americans suffer from a serious mental illness, the leading cause of disability in the U.S. for people 15 to 44 years old, according to the National Institute on Mental Health. New brain research during the initiative, coupled with advances in MRI technology and other non-invasive research tools, will allow scientists to better understand what causes these illnesses and how to manage or cure them.
This initiative also could help thousands of soldiers, sailors and airmen who have served in Afghanistan and Iraq more quickly and easily recover from brain injuries caused during combat, especially by improvised explosive devices.
Further research could allow advances in robotics and artificial intelligence that would make most future military vehicles - and aircraft - operate unmanned and autonomously, thereby saving thousands of lives during combat operations.
"The economic impact of the 'Decade of the Mind' will be felt in all levels of society," said Olds. "By translating our knowledge of the human mind to building more intelligent machines and computer applications, we can improve the welfare of millions of people worldwide."
The groundwork for this initiative was laid during the "Decade of the Brain," declared by President George H.W. Bush in 1990. It produced immense advances in brain research, including the development of MRI scanners and progress in the understanding of Alzheimer's disease and mental illness. Using these advances as a basis for further exploration into the human mind, this new decade would provide the nation's scientific community the opportunity to understand more about the mind than ever before and tackle some of society's most pressing challenges.
Decade of the Mind symposium presenters included: Marcus Raichle, MD, Washington University (St. Louis) School of Medicine; Nancy Kanwisher, PhD, Massachusetts Institute of Technology; John Holland, PhD, University of Michigan; Dharmendra Modha, PhD, IBM; Giulio Tononi, MD, PhD, University of Wisconsin; George A. Bekey, PhD, University of Southern California; Gordon Shepherd, PhD, Yale University; Vernon Smith, PhD, George Mason University, Nobel Laureate; and George Johnson, New York Times science writer, plenary session moderator.
For more information about the Decade of the Mind symposium, visit krasnow.gmu/decade.
About the Krasnow Institute for Advanced Study
The Krasnow Institute for Advanced Study seeks to expand understanding of mind, brain and intelligence by conducting research at the intersection of the separate fields of cognitive psychology, neurobiology and the computer-driven study of artificial intelligence and complex adaptive systems. These separate disciplines increasingly overlap and promise progressively deeper insight into human thought processes. The institute also examines how new insights from cognitive science research can be applied for human benefit in the areas of mental health, neurological disease, education and computer design.
About George Mason University
George Mason University, located in the heart of Northern Virginia's technology corridor near Washington, D.C., is an innovative, entrepreneurial institution with national distinction in a range of academic fields. With strong undergraduate and graduate degree programs in engineering, information technology, biotechnology and health care, Mason prepares its alumni to succeed in the workforce and meet the needs of the region and the world. Mason professors conduct groundbreaking research in areas such as cancer, climate change, information technology and the biosciences, and Mason's Center for the Arts brings world-renowned artists, musicians and actors to its stage. Its School of Law is recognized by U.S. News and World Report as one of the top 50 law schools in the United States.
Contact: Jim Greif
George Mason University
суббота, 13 августа 2011 г.
Autophagy Is The Key To Survival And Virulence For A Fungal Pathogen
Autophagy is a process whereby cells recycle material during stress situations, such as when nutrients are scarce. Some cells also use this process as an immune defense mechanism to eliminate pathogens. However, new data, generated in mice by Peter Williamson and colleagues, at the University of Illinois at Chicago, has identified autophagy as a new virulence-associated trait and survival mechanism for Cryptococcus neoformans - a fungal pathogen that commonly infects immunocompromised individuals, such as those with HIV.
In the study, a mutant form of C. neoformans that lacked the protein Vps34 PI3K (known as the vps34D mutant) was found to be less able to form autophagy-related 8-labeled (Atg8-labeled) vesicles than normal C. neoformans. Furthermore, the vps34D mutant was less virulent in mice than normal C. neoformans. Consistent with a crucial role for autophagy in determining the extent of the disease caused by infection with C. neoformans, a strain of C. neoformans in which Atg8 expression was knocked down showed reduced virulence in mice. The authors therefore suggested that more detailed understanding of this virulence pathway might lead to new drugs for treating individuals who become infected with C. neoformans.
TITLE: PI3K signaling of autophagy is required for starvation tolerance and virulence of Cryptococcal neoformans
AUTHOR CONTACT:
Peter R. Williamson
University of Illinois at Chicago, Chicago, Illinois, USA.
Source: Karen Honey
Journal of Clinical Investigation
In the study, a mutant form of C. neoformans that lacked the protein Vps34 PI3K (known as the vps34D mutant) was found to be less able to form autophagy-related 8-labeled (Atg8-labeled) vesicles than normal C. neoformans. Furthermore, the vps34D mutant was less virulent in mice than normal C. neoformans. Consistent with a crucial role for autophagy in determining the extent of the disease caused by infection with C. neoformans, a strain of C. neoformans in which Atg8 expression was knocked down showed reduced virulence in mice. The authors therefore suggested that more detailed understanding of this virulence pathway might lead to new drugs for treating individuals who become infected with C. neoformans.
TITLE: PI3K signaling of autophagy is required for starvation tolerance and virulence of Cryptococcal neoformans
AUTHOR CONTACT:
Peter R. Williamson
University of Illinois at Chicago, Chicago, Illinois, USA.
Source: Karen Honey
Journal of Clinical Investigation
среда, 10 августа 2011 г.
Discovery Explains How Cold Sore Virus Hides During Inactive Phase
Now that Duke University Medical Center scientists have figured out how the virus that causes cold sores hides out, they may have a way to wake it up and kill it.
Cold sores, painful, unsightly blemishes around the mouth, have so far evaded a cure or even prevention. They're known to be caused by the herpes simplex virus 1 (HSV1), which lies dormant in the trigeminal nerve of the face until triggered to reawaken by excessive sunlight, fever, or other stresses.
"We have provided a molecular understanding of how HSV1 hides and then switches back and forth between the latent (hidden) and active phases," said Bryan Cullen, Duke professor of molecular genetics and microbiology.
His group's findings, published in Nature, also provide a framework for studying other latent viruses, such as the chicken pox virus, which can return later in life as a case of shingles, and herpes simplex 2 virus, a genitally transmitted virus that also causes painful sores, Cullen said.
Most of the time, HSV1 lives quietly for years, out of reach of any therapy we have against it. It does not replicate itself during this time and only produces one molecular product, called latency associated transcript RNA or LAT RNA.
"It has always been a mystery what this product, LAT RNA, does," Cullen said. "Usually viral RNAs exist to make proteins that are of use to the virus, but this LAT RNA is extremely unstable and does not make any proteins."
In studies of mice, the team showed that the LAT RNA is processed into smaller strands, called microRNAs, that block production of the proteins that make the virus turn on active replication. As long as the supply of microRNAs is sufficient, the virus stays dormant.
After a larger stress, however, the virus starts making more messenger RNA than the supply of microRNAs can block, and protein manufacturing begins again. This tips the balance, and the virus ultimately makes proteins that begin active viral replication.
The new supply of viruses then travels back down the trigeminal nerve, to the site of the initial infection at the mouth. A cold sore always erupts in the same place and is the source of viruses that might infect another person, either from direct contact, or sharing eating utensils or towels, Cullen said.
The approach to curing this nuisance would be a combination therapy, Cullen said. "Inactive virus is completely untouchable by any treatment we have. Unless you activate the virus, you can't kill it," he said.
Cullen and his team are testing a new drug designed to very precisely bind to the microRNAs that keep the virus dormant. If it works, the virus would become activated and start replicating.
Once the virus is active, a patient would then take acyclovir, a drug that effectively kills replicating HSV1.
"In principle, you could activate and then kill all of the virus in a patient," Cullen said. "This would completely cure a person, and you would never get another cold sore."
He and the team are working with drug development companies in animal trials to begin to answer questions about how to deliver this drug most effectively.
Co-authors included Jennifer Lin Umbach, Ph.D., and Heather W. Karnowski, B.S., of the Duke Department of Molecular Genetics and Microbiology and Center for Virology, and Martha F. Kramer, Igor Jurak, and Prof. Donald M. Coen of the Department of Biological Chemistry and Molecular Pharmacology at Harvard Medical School. This work was supported by two NIH grants.
Source: Mary Jane Gore
Duke University Medical Center
View drug information on Acyclovir Capsules.
Cold sores, painful, unsightly blemishes around the mouth, have so far evaded a cure or even prevention. They're known to be caused by the herpes simplex virus 1 (HSV1), which lies dormant in the trigeminal nerve of the face until triggered to reawaken by excessive sunlight, fever, or other stresses.
"We have provided a molecular understanding of how HSV1 hides and then switches back and forth between the latent (hidden) and active phases," said Bryan Cullen, Duke professor of molecular genetics and microbiology.
His group's findings, published in Nature, also provide a framework for studying other latent viruses, such as the chicken pox virus, which can return later in life as a case of shingles, and herpes simplex 2 virus, a genitally transmitted virus that also causes painful sores, Cullen said.
Most of the time, HSV1 lives quietly for years, out of reach of any therapy we have against it. It does not replicate itself during this time and only produces one molecular product, called latency associated transcript RNA or LAT RNA.
"It has always been a mystery what this product, LAT RNA, does," Cullen said. "Usually viral RNAs exist to make proteins that are of use to the virus, but this LAT RNA is extremely unstable and does not make any proteins."
In studies of mice, the team showed that the LAT RNA is processed into smaller strands, called microRNAs, that block production of the proteins that make the virus turn on active replication. As long as the supply of microRNAs is sufficient, the virus stays dormant.
After a larger stress, however, the virus starts making more messenger RNA than the supply of microRNAs can block, and protein manufacturing begins again. This tips the balance, and the virus ultimately makes proteins that begin active viral replication.
The new supply of viruses then travels back down the trigeminal nerve, to the site of the initial infection at the mouth. A cold sore always erupts in the same place and is the source of viruses that might infect another person, either from direct contact, or sharing eating utensils or towels, Cullen said.
The approach to curing this nuisance would be a combination therapy, Cullen said. "Inactive virus is completely untouchable by any treatment we have. Unless you activate the virus, you can't kill it," he said.
Cullen and his team are testing a new drug designed to very precisely bind to the microRNAs that keep the virus dormant. If it works, the virus would become activated and start replicating.
Once the virus is active, a patient would then take acyclovir, a drug that effectively kills replicating HSV1.
"In principle, you could activate and then kill all of the virus in a patient," Cullen said. "This would completely cure a person, and you would never get another cold sore."
He and the team are working with drug development companies in animal trials to begin to answer questions about how to deliver this drug most effectively.
Co-authors included Jennifer Lin Umbach, Ph.D., and Heather W. Karnowski, B.S., of the Duke Department of Molecular Genetics and Microbiology and Center for Virology, and Martha F. Kramer, Igor Jurak, and Prof. Donald M. Coen of the Department of Biological Chemistry and Molecular Pharmacology at Harvard Medical School. This work was supported by two NIH grants.
Source: Mary Jane Gore
Duke University Medical Center
View drug information on Acyclovir Capsules.
воскресенье, 7 августа 2011 г.
'LEGO-Like' Building Blocks To Halt Cell Growth Wins Hebrew University Prize
A method for delivery of drugs to targeted cells through the design of specific molecular structures called SIB (Small Integrated Building Blocks) has won a prestigious scientific prize for a Ph.D. student in organic chemistry at the Hebrew University of Jerusalem
Jerusalemite Nir Qvit, 34, will be one of those receiving the Kaye Innovation Award on June 13, during the 69th meeting of the Hebrew university Board of Governors.
Qvit has shown through his research that it is possible to greatly increase drug delivery efficiency by designing specific molecular structures made up of known pharmaceutically effective peptides (small protein molecules) that are attached to tailor-made, geometric-like structures called "scaffolding."
Each scaffold is specifically designed to combine the peptides in such a way that they will form an effective medicinal combination and so that they will bind to the receptors of specific targeted cells. Qvit refers to his process as somewhat analogous to building different kinds of structures through the use of LEGO.
Qvit, a student of Prof. Chaim Gilon of the Department of Organic Chemistry, has shown, for example, that with a particular combination of peptides and scaffold design, it is possible to create a synthetic molecule that will bind to the IGF-1 (insulin-like growth factor-1) receptor. IGF-1 is a protein that plays a critical role in the proliferation of many cancers, including prostate, lung, breast, colon and brain cancers. The binding action of the molecule to the receptor inhibits the activation of the IGF-1 protein in the cells, thus halting the cancerous growth.
Through this process of "combinational chemistry," involving peptides and scaffold design, Qvit says that many different types of molecules can be built that will reach specifically targeted cells, offering hope for treatment of not only cancer, but other diseases as well, without harming healthy cells.
The Kaye Innovation Awards have been given annually since 1994. Isaac Kaye of England, a prominent industrialist in the pharmaceutical industry, established the awards to encourage faculty, staff, and students of the Hebrew University to develop innovative methods and inventions with good commercial potential which will benefit the university and society.
Contact: Jerry Barach
The Hebrew University of Jerusalem
Jerusalemite Nir Qvit, 34, will be one of those receiving the Kaye Innovation Award on June 13, during the 69th meeting of the Hebrew university Board of Governors.
Qvit has shown through his research that it is possible to greatly increase drug delivery efficiency by designing specific molecular structures made up of known pharmaceutically effective peptides (small protein molecules) that are attached to tailor-made, geometric-like structures called "scaffolding."
Each scaffold is specifically designed to combine the peptides in such a way that they will form an effective medicinal combination and so that they will bind to the receptors of specific targeted cells. Qvit refers to his process as somewhat analogous to building different kinds of structures through the use of LEGO.
Qvit, a student of Prof. Chaim Gilon of the Department of Organic Chemistry, has shown, for example, that with a particular combination of peptides and scaffold design, it is possible to create a synthetic molecule that will bind to the IGF-1 (insulin-like growth factor-1) receptor. IGF-1 is a protein that plays a critical role in the proliferation of many cancers, including prostate, lung, breast, colon and brain cancers. The binding action of the molecule to the receptor inhibits the activation of the IGF-1 protein in the cells, thus halting the cancerous growth.
Through this process of "combinational chemistry," involving peptides and scaffold design, Qvit says that many different types of molecules can be built that will reach specifically targeted cells, offering hope for treatment of not only cancer, but other diseases as well, without harming healthy cells.
The Kaye Innovation Awards have been given annually since 1994. Isaac Kaye of England, a prominent industrialist in the pharmaceutical industry, established the awards to encourage faculty, staff, and students of the Hebrew University to develop innovative methods and inventions with good commercial potential which will benefit the university and society.
Contact: Jerry Barach
The Hebrew University of Jerusalem
четверг, 4 августа 2011 г.
Assembly Of Molecules Critical To Protein Function Witnessed By Researchers
A Virginia Tech research group lead by two biochemistry graduate students has isolated proteins responsible for the iron-sulfur cluster assembly process and witnessed the necessary protein interactions in vivo - within a cell. They have captured pathway intermediates and observed protein interactions between the two major players in iron-sulfur cluster assembly.
Iron-sulfur clusters are critical to life on earth. They are necessary for protein function in cellular processes, such as respiration in humans and other organisms and photosynthesis by plants. "But we do not understand how Fe-S molecules are made or the specifics of how they bond," said Callie Raulfs of Christiansburg, Va. "It does not happen spontaneously. It has to be regulated."
Diseases such as Friedrich's ataxia and several types of anemia are a result of iron-sulfur cluster (ISC) assembly malfunctions.
Using genetic and biochemical techniques, Ph.D. students Raulfs and Ina P. O'Carroll, of Tirana, Albania, have isolated components of the ISC machinery in the process of making iron-sulfur clusters. "This work provides insight into the sequential steps of the iron-sulfur cluster assembly process, helping to explain how molecules of iron and sulfur are synthesized and distributed in cells," said O'Carroll.
The work, "In vivo iron-sulfur cluster formation," by Raulfs, O'Carroll, Virginia Tech post-doctoral associates Patricia C. Dos Santos of Brazil and Mihaela-Carmen Unciuleac of Romania, and Dennis R. Dean of Blacksburg, professor of biochemistry and director of the Fralin Biotechnology Center at Virginia Tech, has been published in the Proceedings of the National Academy of Science (PNAS) Online Early Edition the week of June 16-20, 2008.
Previous studies by Dean and others have demonstrated that proteins can assemble clusters from components in vitro systems - that is, outside of an organism. Ten years ago, working with nitrogen-fixation systems, Dean's lab was the first to discover ISC proteins. Now Dean's students, Raulfs and O'Carroll, are the first to witness the assembly process in vivo - within a cell.
"The cool thing is we've come up with a way to observe ISC proteins from their native host with a cluster attached," said O'Carroll. "The system also allows us to capture different phases of the process."
The students have isolated three different intermediates of the ISC proteins involved in intercellular biosynthesis - or the cluster assembly process.
Rather than multiplying the proteins by placing them in E. coli, the Virginia Tech team used Azotobacter vinelandii, an aerobic, soil microbe that fixes nitrogen from the atmosphere, to obtain natural levels of the ISC proteins. "A vinelandii grows quickly and keeps the interior of the cell free of oxygen, which is important, since oxygen can destroy Fe-S clusters," said Raulfs, who first isolated a protein complex with a cluster attached, providing in vivo evidence that the two proteins get together and form a cluster.
"Because we are isolating proteins from the cell, we are also able to observe interactions between different Fe-S cluster asembly proteins," said O'Carroll. "We have been able to isolate a complex between the two major players in iron-sulfur assembly, the cluster assembly scaffold (IscU) and the sulfur-delivery protein (IscS)."
The methodology is to add a histidine amino acid tag to the ISC proteins "so we can fish the proteins out of the cell," said O'Carroll.
"Because we are fishing the cluster-containing protein out of the cell that has all of the other assembly proteins present at physiological levels, we are able to observe what else comes with the protein. What was really exciting in this case was that we saw large amounts of one of the other iron sulfur cluster assembly protein, IscS." said O'Carroll.
The work marks the first time researchers have been able to observe ISC proteins from the balanced environment of the native cell.
Next, they plan to determine the role of the individual genes in the set that produces ISC proteins in order to determine the effect of each gene on the assembly process. "The goal is to determine the events and the order in the ISC assembly process so we can figure out how cells make clusters and deliver them to specific target proteins," said O'Carroll.
The researchers are now developing a system that others can use to study proteins.
Raulfs received her undergraduate degree from the College of William and Mary. She has been a fellow in the Exploring Interfaces through Graduate Education and Research (EIGER) project, a National Science Foundation Integrative Graduate Education and Research Traineeship (IGERT) program at Virginia Tech.
O'Carroll received her undergraduate degree from McDaniel College. Dos Santos is the senior postdoc in the Dean lab. Unciuleac is now a post-doctoral fellow with the Molecular Biology Program at the Sloan-Kettering Institute.
The research is supported by the National Science Foundation.
Source: Susan Trulove
Virginia Tech
Iron-sulfur clusters are critical to life on earth. They are necessary for protein function in cellular processes, such as respiration in humans and other organisms and photosynthesis by plants. "But we do not understand how Fe-S molecules are made or the specifics of how they bond," said Callie Raulfs of Christiansburg, Va. "It does not happen spontaneously. It has to be regulated."
Diseases such as Friedrich's ataxia and several types of anemia are a result of iron-sulfur cluster (ISC) assembly malfunctions.
Using genetic and biochemical techniques, Ph.D. students Raulfs and Ina P. O'Carroll, of Tirana, Albania, have isolated components of the ISC machinery in the process of making iron-sulfur clusters. "This work provides insight into the sequential steps of the iron-sulfur cluster assembly process, helping to explain how molecules of iron and sulfur are synthesized and distributed in cells," said O'Carroll.
The work, "In vivo iron-sulfur cluster formation," by Raulfs, O'Carroll, Virginia Tech post-doctoral associates Patricia C. Dos Santos of Brazil and Mihaela-Carmen Unciuleac of Romania, and Dennis R. Dean of Blacksburg, professor of biochemistry and director of the Fralin Biotechnology Center at Virginia Tech, has been published in the Proceedings of the National Academy of Science (PNAS) Online Early Edition the week of June 16-20, 2008.
Previous studies by Dean and others have demonstrated that proteins can assemble clusters from components in vitro systems - that is, outside of an organism. Ten years ago, working with nitrogen-fixation systems, Dean's lab was the first to discover ISC proteins. Now Dean's students, Raulfs and O'Carroll, are the first to witness the assembly process in vivo - within a cell.
"The cool thing is we've come up with a way to observe ISC proteins from their native host with a cluster attached," said O'Carroll. "The system also allows us to capture different phases of the process."
The students have isolated three different intermediates of the ISC proteins involved in intercellular biosynthesis - or the cluster assembly process.
Rather than multiplying the proteins by placing them in E. coli, the Virginia Tech team used Azotobacter vinelandii, an aerobic, soil microbe that fixes nitrogen from the atmosphere, to obtain natural levels of the ISC proteins. "A vinelandii grows quickly and keeps the interior of the cell free of oxygen, which is important, since oxygen can destroy Fe-S clusters," said Raulfs, who first isolated a protein complex with a cluster attached, providing in vivo evidence that the two proteins get together and form a cluster.
"Because we are isolating proteins from the cell, we are also able to observe interactions between different Fe-S cluster asembly proteins," said O'Carroll. "We have been able to isolate a complex between the two major players in iron-sulfur assembly, the cluster assembly scaffold (IscU) and the sulfur-delivery protein (IscS)."
The methodology is to add a histidine amino acid tag to the ISC proteins "so we can fish the proteins out of the cell," said O'Carroll.
"Because we are fishing the cluster-containing protein out of the cell that has all of the other assembly proteins present at physiological levels, we are able to observe what else comes with the protein. What was really exciting in this case was that we saw large amounts of one of the other iron sulfur cluster assembly protein, IscS." said O'Carroll.
The work marks the first time researchers have been able to observe ISC proteins from the balanced environment of the native cell.
Next, they plan to determine the role of the individual genes in the set that produces ISC proteins in order to determine the effect of each gene on the assembly process. "The goal is to determine the events and the order in the ISC assembly process so we can figure out how cells make clusters and deliver them to specific target proteins," said O'Carroll.
The researchers are now developing a system that others can use to study proteins.
Raulfs received her undergraduate degree from the College of William and Mary. She has been a fellow in the Exploring Interfaces through Graduate Education and Research (EIGER) project, a National Science Foundation Integrative Graduate Education and Research Traineeship (IGERT) program at Virginia Tech.
O'Carroll received her undergraduate degree from McDaniel College. Dos Santos is the senior postdoc in the Dean lab. Unciuleac is now a post-doctoral fellow with the Molecular Biology Program at the Sloan-Kettering Institute.
The research is supported by the National Science Foundation.
Source: Susan Trulove
Virginia Tech
понедельник, 1 августа 2011 г.
Evolution's Steps Revealed By Structure Of 450 Million Year Old Protein
A detailed map that pinpoints the location of every atom in a 450-million-yeard-old resurrected protein reveals the precise evolutionary steps needed to create the molecule's modern version, according to researchers from the University of North Carolina at Chapel Hill and the University of Oregon.
Until now, scientists trying to unravel the evolution of the proteins and other molecules necessary for life have worked backwards, making educated guesses based on modern human body chemistry. By moving forward from an ancient protein, the team laid out the step-by-step progression required to reach its current form and function.
The study appears in the journal Science.
"We were able to see exactly how mutations in the ancient structure led to the modern receptor," said lead author Eric Ortlund, who carried out the research as a UNC-Chapel Hill postdoctoral fellow. Ortlund is now an assistant professor of biochemistry in the Emory University School of Medicine.
In the current study, Ortlund and Matt Redinbo, a professor of chemistry, biochemistry and biophysics at UNC-Chapel Hill, generated a three-dimensional picture of the ancient receptor with an imaging technique called X-ray crystallography. The nanoscale image revealed the receptor's structure, down to the placement of every atom. With the structure in place, Ortlund and his colleagues retraced evolution's path.
The researchers examined the precursor to a modern protein known as a glucocorticoid receptor. In humans, the receptor plays a crucial role, responding to the hormone cortisol and regulating the body's stress response. The two -- receptor and hormone -- fit together as precisely as a lock and key. The precursor preferred a different hormone, so several mutations were necessary before the lock could fit the cortisol key.
The University of Oregon team, which included postdoctoral scientist Jamie Bridgham, resurrected the ancient protein via a large database of modern receptor genes. This earlier work, which compared the genetic similarities and differences among two of these modern genes, found the receptor descended from a single common genetic ancestor 450 million years ago. The researchers then recreated the ancient receptor in the laboratory.
Only seven mutations were needed to bridge the 450-million-year gulf, the researchers found. However, not every mutation changed the protein's function. These "permissive" mutations appear to pave the way for future, more significant changes. "It's like they prepared for opportunity to knock in the form of a new hormone," Ortlund said.
The permissive mutations bolstered the receptor's structure, like contractors reinforce a historic home's foundation before making renovations. After these changes took place, a more extreme mutation repositioned an entire group of atoms, bringing them closer to fitting the cortisol hormone. Another created the tight new fit with cortisol.
"These permissive mutations are chance events. If they hadn't happened first, then the path to the new function could have become an evolutionary road not taken," said co-author Joe Thornton, a professor of evolutionary biology at the University of Oregon.
The researchers worked out which mutations came first by synthesizing different versions of the mutated protein in the laboratory. Had the radical mutations come first, the receptor protein would have lost its function entirely, they found.
The research was funded by the National Institutes of Health, the National Science Foundation, a UNC Lineberger Comprehensive Cancer Center fellowship to Ortlund and an Alfred P. Sloan research fellowship to Thornton.
Source: Becky Oskin
University of North Carolina at Chapel Hill
Until now, scientists trying to unravel the evolution of the proteins and other molecules necessary for life have worked backwards, making educated guesses based on modern human body chemistry. By moving forward from an ancient protein, the team laid out the step-by-step progression required to reach its current form and function.
The study appears in the journal Science.
"We were able to see exactly how mutations in the ancient structure led to the modern receptor," said lead author Eric Ortlund, who carried out the research as a UNC-Chapel Hill postdoctoral fellow. Ortlund is now an assistant professor of biochemistry in the Emory University School of Medicine.
In the current study, Ortlund and Matt Redinbo, a professor of chemistry, biochemistry and biophysics at UNC-Chapel Hill, generated a three-dimensional picture of the ancient receptor with an imaging technique called X-ray crystallography. The nanoscale image revealed the receptor's structure, down to the placement of every atom. With the structure in place, Ortlund and his colleagues retraced evolution's path.
The researchers examined the precursor to a modern protein known as a glucocorticoid receptor. In humans, the receptor plays a crucial role, responding to the hormone cortisol and regulating the body's stress response. The two -- receptor and hormone -- fit together as precisely as a lock and key. The precursor preferred a different hormone, so several mutations were necessary before the lock could fit the cortisol key.
The University of Oregon team, which included postdoctoral scientist Jamie Bridgham, resurrected the ancient protein via a large database of modern receptor genes. This earlier work, which compared the genetic similarities and differences among two of these modern genes, found the receptor descended from a single common genetic ancestor 450 million years ago. The researchers then recreated the ancient receptor in the laboratory.
Only seven mutations were needed to bridge the 450-million-year gulf, the researchers found. However, not every mutation changed the protein's function. These "permissive" mutations appear to pave the way for future, more significant changes. "It's like they prepared for opportunity to knock in the form of a new hormone," Ortlund said.
The permissive mutations bolstered the receptor's structure, like contractors reinforce a historic home's foundation before making renovations. After these changes took place, a more extreme mutation repositioned an entire group of atoms, bringing them closer to fitting the cortisol hormone. Another created the tight new fit with cortisol.
"These permissive mutations are chance events. If they hadn't happened first, then the path to the new function could have become an evolutionary road not taken," said co-author Joe Thornton, a professor of evolutionary biology at the University of Oregon.
The researchers worked out which mutations came first by synthesizing different versions of the mutated protein in the laboratory. Had the radical mutations come first, the receptor protein would have lost its function entirely, they found.
The research was funded by the National Institutes of Health, the National Science Foundation, a UNC Lineberger Comprehensive Cancer Center fellowship to Ortlund and an Alfred P. Sloan research fellowship to Thornton.
Source: Becky Oskin
University of North Carolina at Chapel Hill
Подписаться на:
Сообщения (Atom)