New Form of Human Cell Division Discovered

Scientists at the University of Wisconsin Carbone Cancer Center report the discovery of a novel type of cell division in human cells. They believe it serves as a natural back-up mechanism during faulty cell division.
"If we could promote this new form of cell division, which we call klerokinesis, we may be able to prevent some cancers from developing," says lead researcher Mark Burkard, M.D., Ph.D., an assistant professor of hematology-oncology in the department of medicine at the UW School of Medicine and Public Health. He presented the finding yesterday at the American Society for Cell Biology’s annual conference in San Francisco.
Dr. Burkhard, a physician investigator who treats breast cancer patients, also studies polyploidy. About 14% of breast cancers and 35% of pancreatic cancers have three or more sets of chromosomes, instead of the usual two sets. Many other cancers have cells containing defective chromosomes rather than too many or too few.
"Our goal in the laboratory has been to find ways to develop new treatment strategies for breast cancers with too many chromosome sets," continued Dr. Burkhard.
The original goal of the current study was to make human cells that have extra chromosomes sets. But after following the accepted recipe, the researchers unexpectedly observed the new form of cell division. Until now, Dr. Burkard and most cell biologists today accepted a century-old hypothesis developed by German biologist Theodor Boveri, who studied sea urchin eggs. Boveri surmised that faulty cell division led to cells with abnormal chromosome sets, and then to the unchecked cell growth that defines cancer. With accumulated evidence over the years, most scientists have come to accept the hypothesis.
Normal cell division is at the heart of an organism's ability to grow from a single fertilized egg into a fully developed individual. More than a million-million rounds of division must take place for this to occur. In each division, one mother cell becomes two daughter cells. Even in a fully grown adult, many kinds of cells are routinely remade through cell division.
Dr/ Burkard and his team were making cells with too many chromosomes to mimic cancer. The scientists blocked cytokinesis with a chemical and waited to see what happened. "We expected to recover a number of cells with abnormal sets of chromosomes," explained Dr. Burkard.
The researchers found that, rather than appearing abnormal, daughter cells ended up looking normal most of the time. Contrary to Boveri's hypothesis, abnormal cell division rarely had long-term negative effects in human cells. So the group decided to see how the human cells recovered normal sets of chromosomes by watching with a microscope that had the ability to take video images.
"We started with two nuclei in one cell," continued Dr. Burkard. "To our great surprise, we saw the cell pop apart into two cells without going through mitosis."
Each of the two new cells inherited an intact nucleus enveloping a complete set of chromosomes. The splitting occurred, unpredictably, during a delayed growth phase rather than at the end of mitosis. The scientists did a number of additional experiments to carefully make sure that the division they observed was different than cytokinesis.
"We had a hard time convincing ourselves because this type of division does not appear in any textbook," noted Dr. Burkard.
Over time, they found that only 90% of daughter cells had recovered a normal complement of chromosomes. Dr. Burkard would like to leverage that statistic up to 99%. "If we could push the cell toward this new type of division, we might be able to keep cells normal and lower the incidence of cancer," he said.
Dr. Burkard now thinks that among all those rounds of cell division an organism goes through, every once in a while cytokinesis can fail. And that this new division is a back-up mechanism that allows cells to recover from the breakdown and grow normally. The group has dubbed the new type of division klerokinesis to distinguish it from cytokinesis.
In addition to his work on klerokinesis, Dr. Burkhard’s lab seeks to advance cancer therapy by two approaches—candidate evaluation (“bottom-up”) and therapeutic strategy (“top-down”). In the first approach, his team interrogates the function of specific kinases such as Plk1 to determine how these control human cell division and evaluate the potential worth as a cancer drug target. Using chemical genetics, Dr. Burkhard says they dispense with the “arduous task of up-front drug discovery” and simply mutate the target kinase to prepare for chemical interrogation of function.
In contrast, the top-down approach seeks to selectively target a unique characteristic of cancer cells that sensitize them to specific drugs. For example, Dr. Burkhard’s group has identified compounds that specifically block the proliferation of cells which harbor excess number of chromosomes; such polyploid cells are commonly found in cancer. “Using the combination of these two approaches, we hope to identify new drug targets or allow improved selection of patients likely to benefit from existing treatments,” he says.

Courtesy: GEN: genetic engineering and biotechnology news

Video link: http://blogs.nature.com/spoonful/2012/12/video-newly-discovered-form-of-cell-division-may-help-ward-off-cancer.html#wpn-more-4171

Genomic 'Hotspots' Offer Clues to Causes of Autism, Other Disorders

An international team, led by researchers from the University of California, San Diego School of Medicine, has discovered that "random" mutations in the genome are not quite so random after all. Their study, to be published in the journal Cell on December 21, shows that the DNA sequence in some regions of the human genome is quite volatile and can mutate ten times more frequently than the rest of the genome. Genes that are linked to autism and a variety of other disorders have a particularly strong tendency to mutate.

Clusters of mutations or "hotspots" are not unique to the autism genome but instead are an intrinsic characteristic of the human genome, according to principal investigator Jonathan Sebat, PhD, professor of psychiatry and cellular and molecule medicine, and chief of the Beyster Center for Molecular Genomics of Neuropsychiatric Diseases at UC San Diego.

"Our findings provide some insights into the underlying basis of autism -- that, surprisingly, the genome is not shy about tinkering with its important genes" said Sebat. "To the contrary, disease-causing genes tend to be hypermutable."

Sebat and collaborators from Rady Children's Hospital-San Diego and BGI genome center in China sequenced the complete genomes of identical twins with autism spectrum disorder and their parents. When they compared the genomes of the twins to the genomes of their parents, the scientists identified many "germline" mutations (genetic variants that were present in both twins but not present in their mother or father).

Nearly 600 germline mutations -- out of a total of 6 billion base pairs -- were detected in the 10 pairs of identical twins sequenced in the study. An average of 60 mutations was detected in each child.

"The total number of mutations that we found was not surprising," said Sebat, "it's exactly what we would expect based on the normal human mutation rate." What the authors did find surprising was that mutations tended to cluster in certain regions of the genome. When the scientists looked carefully at the sites of mutation, they were able to determine the reasons why some genomic regions are "hot" while other regions are cold.

"Mutability could be explained by intrinsic properties of the genome," said UC San Diego postdoctoral researcher Jacob Michaelson, lead author of the study. "We could accurately predict the mutation rate of a gene based on the local DNA sequence and its chromatin structure, meaning the way that the DNA is packaged."

The researchers also observed some remarkable examples of mutation clustering in an individual child, where a shower of mutations occurred all at once. "When multiple mutations occur in the same place, such an event has a greater chance of disrupting a gene," said Michaelson.

The researchers surmised that hypermutable genes could be relevant to disease. When they predicted the mutation rates for genes, the authors found that genes that have been linked to autism were more mutable than the average gene, suggesting that some of the genetic culprits that contribute to autism are mutation hotspots.

The authors observed a similar trend for other disease genes. Genes associated with dominant disorders tended to be highly mutable, while mutation rates were lower for genes associated with complex traits.

"We plan to focus on these mutation hotspots in our future studies," said Sebat. "Sequencing these regions in larger numbers of patients could enable us to identify more of the genetic risk factors for autism."

Journal Reference:

1. Jacob J. Michaelson, Yujian Shi, Madhusudan Gujral, Hancheng Zheng, Dheeraj Malhotra, Xin Jin, Minghan Jian, Guangming Liu, Douglas Greer, Abhishek Bhandari, Wenting Wu, Roser Corominas, Áine Peoples, Amnon Koren, Athurva Gore, Shuli Kang, Guan Ning Lin, Jasper Estabillo, Therese Gadomski, Balvindar Singh, Kun Zhang, Natacha Akshoomoff, Christina Corsello, Steven McCarroll, Lilia M. Iakoucheva, Yingrui Li, Jun Wang, Jonathan Sebat. Whole-Genome Sequencing in Autism Identifies Hot Spots for De Novo Germline Mutation. Cell, 2012; 151 (7): 1431 DOI: 10.1016/j.cell.2012.11.019

Courtesy: ScienceDaily

Bats May Hold Clues to Long Life and Disease Resistance

Bats are amazing creatures. They've been around for at least 65 million years, and in that time have become one of the most abundant and widespread mammals on Earth.

The Bat Pack, a team of researchers at the Australian Animal Health Laboratory (AAHL) in Geelong, conduct a wide range of research into bats and bat borne viruses, and their potential effects on the human population, as part of the effort to safeguard Australia from exotic and emerging pests and diseases.

Their paper, published today in the journal Science, provides an insight into the evolution of the bat's flight, resistance to viruses, and relatively long life.

The Bat Pack, in collaboration with the Beijing Genome Institute, led a team that sequenced the genomes of two bat species -- the Black Flying Fox, an Australian mega bat, and the David's Myotis, a Chinese micro bat.

Once the genomes were sequenced, they compared them to the genomes of other mammals, including humans, to find where the similarities and differences lay.

Chris Cowled, post-doctoral fellow at AAHL says the research may eventually lead to strategies to treat, or even prevent disease in humans.

"A deeper understanding of these evolutionary adaptations in bats may lead to better treatments for human diseases, and may eventually enable us to predict or perhaps even prevent outbreaks of emerging bat viruses," Dr Cowled said.

"Bats are a natural reservoir for several lethal viruses, such as Hendra, Ebola and SARS, but they often don't succumb to disease from these viruses. They're also the only mammal that can fly, and they live a long time compared to animals similar in size."

Flying is a very energy intensive activity that also produces toxic by-products, and bats have developed some novel genes to deal with the toxins. Some of these genes, including P53, are implicated in the development of cancer or the detection and repair of damaged DNA.

"What we found intriguing was that some of these genes also have secondary roles in the immune system," Dr Cowled said.

"We're proposing that the evolution of flight led to a sort of spill over effect, influencing not only the immune system, but also things like ageing and cancer."

The research was a global effort involving the Beijing Genome Institute in Shenzhen, China; Australia's national science research agency, the CSIRO; the University of Copenhagen; Wuhan Institute of Virology at the Chinese Academy of Sciences; the Naval Medical Research Center and Henry M. Jackson Foundation in the USA; Uniformed Services University, USA; and the Graduate Medical School at the Duke-National University of Singapore.

Journal Reference:

1. G. Zhang, C. Cowled, Z. Shi, Z. Huang, K. A. Bishop-Lilly, X. Fang, J. W. Wynne, Z. Xiong, M. L. Baker, W. Zhao, M. Tachedjian, Y. Zhu, P. Zhou, X. Jiang, J. Ng, L. Yang, L. Wu, J. Xiao, Y. Feng, Y. Chen, X. Sun, Y. Zhang, G. A. Marsh, G. Crameri, C. C. Broder, K. G. Frey, L.-F. Wang, J. Wang. Comparative Analysis of Bat Genomes Provides Insight into the Evolution of Flight and Immunity. Science, 2012; DOI: 10.1126/science.1230835

Courtesy: ScienceDaily

New Window On Parkinson's Disease: Metallic Probe Proves Able to Detect Fibrils from Misfolded Proteins in Real Time

Rice University scientists have discovered a new way to look inside living cells and see the insoluble fibrillar deposits associated with Parkinson's disease.

The combined talents of two Rice laboratories -- one that studies the misfolded proteins that cause neurodegenerative diseases and another that specializes in photoluminescent probes -- led to the spectroscopic technique that could become a valuable tool for scientists and pharmaceutical companies.

The research by the Rice labs of Angel Martí and Laura Segatori appeared online this month in the Journal of the American Chemical Society.

The researchers designed a molecular probe based on the metallic element ruthenium. Testing inside live neuroglioma cells, they found the probe binds with the misfolded alpha-synuclein proteins that clump together and form fibrils and disrupt the cell's functions. The ruthenium complex lit up when triggered by a laser -- but only when attached to the fibril, which allowed aggregation to be tracked using photoluminescence spectroscopy.

Researchers trying to understand molecular mechanisms of protein misfolding have had limited alternatives to monitor protein aggregation in cells, Martí said. A probe that can monitor the formation of aggregates should be of great value in the search for drugs that break up fibrils or prevent them from ever forming.

Two years ago, Martí, an assistant professor of chemistry and bioengineering, and Rice graduate student Nathan Cook revealed their metallic compounds that switch on like a light bulb when they attach to misfolded proteins; that study involved the beta amyloids that form plaques in the brains of Alzheimer's sufferers.

At about the same time, Cook approached Segatori, the T.N. Law Assistant Professor of Chemical and Biomolecular Engineering and assistant professor of biochemistry and cell biology, to ask if she would serve on his dissertation committee. They started talking about his work with Martí, and Segatori quickly saw the potential of a partnership.

Segatori has made important strides in the study of diseases caused by proteins that misfold and clump together. Alzheimer's, Parkinson's and Gaucher diseases are examples, all the result of genetic mutations or conditions that disrupt the way proteins fold and keep them from performing their functions.

"There are a few compounds you can use to detect the presence of these types of protein aggregates, but none of them have been reported to work in cells," Segatori said. "When you're thinking about developing a therapeutic strategy, you want to be able to detect the presence of fibril aggregates in living cells, or even in animals. It's been very nice to collaborate with someone with the expertise to do this."

"The connection between Parkinson's and Alzheimer's is natural, although they are very different diseases because Alzheimer's beta amyloid peptides are extracellular, while the onset of Parkinson's is associated with alpha-synuclein protein inside cells," Martí said. "We always thought we could apply the same techniques we used for beta amyloids to probe the aggregation of other proteins.

"When we learned that Laura has cells that overexpress alpha-synuclein, we thought, 'That's perfect.' She had the system and we had the probes," he said.

Segatori pointed out the ruthenium complex has no therapeutic benefit for Parkinson's sufferers, but "is a step toward understanding the chemistry, which obviously will help in the development of drugs."

They see the possibility that metallic complexes can be tailored to tag aggregates implicated in other degenerative diseases. "Metal complexes are like Legos, in the sense that you can attach whatever you want to them," Cook said.

As a proof of principle, the researchers created an in vitro cell model of Parkinson's disease and found their ruthenium complexes clearly labeled fibrillar alpha-synuclein proteins in cells.

"We can use it to test our strategies to prevent misfolding of proteins or to increase their degradation, so they will be eliminated," Segatori said. "It will be an easy tool to use for a lot of experiments."

Kiri Kilpatrick, a graduate student in Segatori's lab, co-authored the paper.

The National Science Foundation and the Welch Foundation supported the research.

Journal Reference:

1. Nathan P. Cook, Kiri Kilpatrick, Laura Segatori, Angel A. Mart. Detection of α-Synuclein Amyloidogenic Aggregatesin Vitroand in Cells using Light-Switching Dipyridophenazine Ruthenium(II) Complexes. Journal of the American Chemical Society, 2012; 121214074651005 DOI: 10.1021/ja3100287

Courtesy: ScienceDaily

Combating Alzheimer's and Parkinson's Disease With Novel Antibodies

Antibodies developed by researchers at Rensselaer Polytechnic Institute are unusually effective at preventing the formation of toxic protein particles linked to Alzheimer's disease and Parkinson's disease, as well as Type 2 diabetes, according to a new study.

The onset of these devastating diseases is associated with the inappropriate clumping of proteins into particles that are harmful to cells in the brain (Alzheimer's disease and Parkinson's disease) and pancreas (Type 2 diabetes). Antibodies, which are commonly used by the immune system to target foreign invaders such as bacteria and viruses, are promising weapons for preventing the formation of toxic protein particles. A limitation of conventional antibodies, however, is that high concentrations are required to completely inhibit the formation of toxic protein particles in Alzheimer's, Parkinson's, and other disorders.

To address this limitation, a team of researchers led by Rensselaer Professor Peter Tessier has developed a new process for creating antibodies that potently inhibit formation of toxic protein particles. Conventional antibodies typically bind to one or two target proteins per antibody. Antibodies created using Tessier's method, however, bind to 10 proteins per antibody. The increased potency enables the novel antibodies to prevent the formation of toxic protein particles at unusually low concentrations. This is an important step toward creating new therapeutic molecules for preventing diseases such as Alzheimer's and Parkinson's.

"It is extremely difficult to get antibodies into the brain. Less than 5 percent of an injection of antibodies into a patient's blood stream will enter the brain. Therefore, we need to make antibodies as potent as possible so the small fraction that does enter the brain will completely prevent formation of toxic protein particles linked to Alzheimer's and Parkinson's disease," said Tessier, assistant professor in the Howard P. Isermann Department of Chemical and Biological Engineering at Rensselaer. "Our strategy for designing antibody inhibitors exploits the same molecular interactions that cause toxic particle formation, and the resulting antibodies are more potent inhibitors than antibodies generated by the immune system."

Results of the new study were published online last week by the journal Proceedings of the National Academy of Sciences (PNAS).

This research was conducted in the laboratories of the Center for Biotechnology and Interdisciplinary Studies at Rensselaer.

Tessier's research represents a new way of generating therapeutic antibodies. Currently, most antibodies are obtained by exploiting the immune system of rodents. Mice are injected with a target protein, for example the Alzheimer's protein, and the animal's immune system generates an antibody specific for the target protein. Tessier's method is radically different as it relies on rational design approaches to create antibodies based on properties of the target proteins.

Along with Tessier, co-authors of the paper are Rensselaer graduate students Ali Reza Ladiwala, Moumita Bhattacharya, Joseph Perchiaccaa; Ping Cao and Daniel Raleigh of the Department of Chemistry at Stony Brook University; Andisheh Abedini and Ann Marie Schmidt of the Diabetes Research Program at New York University School of Medicine; and Jobin Varkey and Ralf Langen of the Zilkha Neurogenetic Institute at the University of Southern California, Los Angeles.

This study was funded with support from the American Health Assistance Foundation, the National Science Foundation, the Pew Charitable Trust, and the National Institutes of Health.

Journal Reference:

1. A. R. A. Ladiwala, M. Bhattacharya, J. M. Perchiacca, P. Cao, D. P. Raleigh, A. Abedini, A. M. Schmidt, J. Varkey, R. Langen, P. M. Tessier. Rational design of potent domain antibody inhibitors of amyloid fibril assembly. Proceedings of the National Academy of Sciences, 2012; DOI: 10.1073/pnas.1208797109

Courtesy: ScienceDaily

Steroid Hormone Receptor Prefers Working Alone to Shut Off Immune System Genes

Researchers at Emory University School of Medicine have obtained a detailed molecular picture that shows how glucocorticoid hormones shut off key immune system genes.

The finding could help guide drug discovery efforts aimed at finding new anti-inflammatory drugs with fewer side effects.

The results are scheduled for publication Dec. 9 by the journal Nature Structural & Molecular Biology.

Synthetic glucocorticoid hormones -- for example, prednisone and dexamethasone -- are widely used to treat conditions such as allergies, asthma, autoimmune diseases and cancer. They mimic the action of the natural hormone cortisol, which is involved in the response to stress and in regulating metabolism and the immune system. For this reason, synthetic glucocorticoids have a variety of severe side effects such as increased blood sugar and reduced bone density.

Both cortisol and synthetic hormones act by binding the glucocorticoid receptor, a protein that binds DNA and turns some genes on and others off. The hormone is required for the glucocorticoid receptor (GR) to enter the nucleus, giving it access to DNA.

For GR-targeting therapeutics, the desired anti-inflammatory effects are thought to come mainly from turning off inflammatory and immune system genes, while the side effects result from turning on genes involved in processes such as metabolism and bone growth.

The mechanism driving GR anti-inflammatory action has been debated, since was no GR binding site identified near these anti-inflammatory genes. Thus, GRs immunosupression was thought to occur indirectly, whereby GR blocks the ability of other critical DNA-binding proteins to stimulate gene expression. Last year French scientists discovered that the GR turns some immune system genes off directly by recognizing a distinct DNA sequence used only in gene repression.

Eric Ortlund, PhD, Emory assistant professor of biochemistry, and first author William Hudson, a Molecular and Systems Pharmacology graduate student, used X-rays to probe crystals of GR bound to a stretch of DNA where it acts "repressively" to shut down the transcription of immune genes.

When the GR turns genes on, two GR molecules grasp each other while binding to DNA. However, the mode of binding to DNA at repressive sequences had remained unknown. Their analysis demonstrated that GR binds to repressive sites in pairs, but with two monomeric GR molecules located on opposite sides of the DNA helix.

"This unexpected geometry was still a surprise because GR has never been crystallized as a monomer bound to DNA, though previous studies proposed that GR monomers repress genes as opposed to GR dimers, which activate genes," says Ortlund.

In addition, the two GR molecules bind to different DNA sequences within the repressive DNA element, Hudson and Ortlund found. They also analyzed how mutations affected the ability of GR to bind repressive sites, showing that binding of the first GR molecule inhibits the binding of a second GR molecule. This "negative cooperativity" may play a role in ensuring that only GR monomers bind to DNA.

The study suggests that a drug preventing GR from interacting with other GR molecules while still allowing them to bind DNA and turn genes off may have anti-inflammatory effects with fewer side effects. One such plant-based compound, "compound A," has been under investigation by several laboratories.

"Our structural data could help scientists design synthetic hormones that separate these two aspects of GR function, potentially leading to improved steroid hormones for diseases ranging from asthma to autoimmune disorders," says Ortlund.

Journal Reference:

1. William H Hudson, Christine Youn, Eric A Ortlund. The structural basis of direct glucocorticoid-mediated transrepression. Nature Structural & Molecular Biology, 2012; DOI: 10.1038/nsmb.2456

Courtesy: ScienceDaily

Existing Drugs May Help More Breast Cancer Patients

More patients can benefit from highly effective breast cancer drugs that are already available, according to DNA sequencing studies by researchers at Washington University School of Medicine in St. Louis and other institutions.
The investigators found that some women with the HER2 negative subtype may benefit from anti-HER2 drugs even though standard tests don't indicate they are candidates for the drugs.
"These patients are going to be missed by our routine testing for HER2 positive breast cancer," says Ron Bose, MD, PhD, assistant professor of medicine. "Currently they're not going to receive a HER2 targeted drug because we don't have a way to identify them. And we predict they are going to have a more aggressive form of breast cancer."
Bose, who treats patients at Washington University's Siteman Cancer Center at Barnes-Jewish Hospital, will present the data Dec. 7 at the San Antonio Breast Cancer Symposium.
Today, a type of breast cancer known as HER2 positive is treated with drugs that inhibit the function of the HER2 protein. To be classified as HER2 positive, a patient must have more than the normal two copies of the HER2 gene. Too much HER2 drives tumor growth and some HER2 positive patients may have as many as 20 copies of the gene. Doctors test for this gene "amplification" in every patient diagnosed with breast cancer. It must be present for a woman to receive anti-HER2 drugs.
But instead of multiple copies of the gene churning out too much HER2, some patients deemed HER2 negative based on standard testing may have mistakes in just a few "letters" of the DNA in their two gene copies that result in excess activity of the protein. Bose and his colleagues estimate that these undetected HER2 mutations -- rather than the HER2 amplification -- may be driving tumor growth in 1.5 to 2 percent of all breast cancer patients. With about 230,000 new cases of breast cancer diagnosed in the United States each year, even this modest percentage translates into more than 4,000 patients per year.
The study, led by senior author Matthew J. Ellis, MD, PhD, of Washington University, and published online Dec. 7 in the journal Cancer Discovery, analyzed data from eight DNA sequencing studies, which together included about 1,500 patients. Two of the sequencing studies were conducted by The Genome Institute at Washington University, in collaboration with study co-author Elaine R. Mardis, PhD, co-director of the genome institute.
Of the 1,500 patients, 25 were found to have HER2 mutations without gene amplification. Not all mutations appeared to have the same effect, however. After analyzing 13 of the mutations, seven were found to drive cancer growth. In the laboratory analysis, most of these mutations responded well to the anti-HER2 drugs lapatinib and trastuzumab, both approved by the U.S. Food and Drug Administration. Although two of the mutations were resistant to lapatinib in lab tests, they responded well to neratinib, a newer anti-HER2 drug that is currently in phase II clinical trials.
Bose also cautions that some mutations were found to be "silent," meaning they did not drive the tumor's growth and therefore would likely not respond to anti-HER2 drugs.
The study's findings have led directly to the launching of a phase II clinical trial to test whether patients with HER2 mutations (but not the amplification) will benefit from anti-HER2 drugs. The trial will include patients with stage IV breast cancer classified as HER2 negative. Their HER2 genes will be sequenced to look for mutations. If mutations are present, they will be treated with neratinib in addition to the standard treatment they would otherwise receive.
At Washington University, the trial will be led by Cynthia X. Ma, MD, PhD, associate professor of medicine. The other centers participating in the study are the Dana-Farber Cancer Institute, Memorial Sloan-Kettering Cancer Center and the University of North Carolina, Chapel Hill.
Bose points to this study as an example of the potential value in sequencing the DNA of cancer patients, even when limited to a single gene of interest such as HER2.
"If we can identify mutations that we can act on, that information will help us better guide treatment," Bose says. "In this case, we don't even have to develop new drugs against HER2 mutations. It's just a matter of finding the patients."
This work was supported by grants from the National Institutes of Health (NIH grant numbers R01CA095614, U01HG00651701, and U54HG003079), the Edward Mallinckrodt, Jr. Foundation, the 'Ohana Breast Cancer Research Fund, and the Foundation for Barnes-Jewish Hospital/Siteman Cancer Center Cancer Frontier Fund. Data access was provided by the Cancer Genome Atlas Network.

Journal Reference:

1. Ron Bose, Shyam M. Kavuri, Adam C. Searleman, Wei Shen, Dong Shen, Daniel C. Koboldt, John Monsey, Nicholas Goel, Adam B. Aronson, Shunqiang Li, Cynthia X. Ma, Li Ding, Elaine R. Mardis, and Matthew J. Ellis. Activating HER2 Mutations in HER2 Gene Amplification Negative Breast Cancer. Cancer Discovery, 2012; DOI: 10.1158/2159-8290.CD-12-0349

Courtesy: ScienceDaily

Mice With Fluorescent Replicating Cells Could Help Cancer and Regenerative Medicine Research

A newly-engineered strain of mice whose dividing cells express a fluorescent protein could open the door to new methods of regulating cell proliferation in humans. Cell proliferation plays a key role in degenerative diseases, in which specific cells do not replicate enough, and in cancers, in which cells replicate too much.

Cells in the human body grow and multiply during body growth or during tissue regeneration after damage. However most mature tissues require only rare cell divisions. Scientists who wish to study these rare populations of replicating cells face a serious obstacle: most current methods for labeling and identifying replicating cells involve procedures that kill the cells and destroy sensitive biological material. This limits the ability of scientists to examine important functions of these cells, for example the genes active in such cells.

To address this problem, two Hebrew University of Jerusalem researchers -- Prof. Yuval Dor from the Institute for Medical Research Israel-Canada (IMRIC) and Dr. Amir Eden from the Alexander Silberman Institute of Life Sciences -- together with colleagues in Denmark and the U.S., created a mouse strain in which replicating cells express a fluorescent protein which is destroyed once cell division is completed. In all tissues of these mice, replicating cells are labeled by green fluorescence, which allows identification and isolation of live, replicating cells directly from healthy or diseased tissue.

Using this system, research associate Dr. Agnes Klochendler and PhD student Noa Weinberg-Corem at the Hebrew University were able to isolate a rare population of replicating cells from the livers of mice, and study the genes that they express compared with resting liver cells. Interestingly, they found that in replicating liver cells there is a significant decrease in the expression of genes responsible for key liver functions such as fatty acid and amino acid metabolism.

The research results indicate that when differentiated cells divide, they temporarily shift to a less differentiated state. This finding is important to our understanding of the difference between the two fundamental states of differentiation and proliferation in normal cells. It is also relevant for the situation in cancer, where cells are proliferating and often less differentiated.

In the future, the researchers hope to develop methods for regulating cell proliferation. For example, isolation and study of the rare replicating cells in the pancreas could lead to development of approaches to promote the proliferation and expansion of insulin-producing cells, whose loss is the hallmark of diabetes.

This could also be useful in other areas such as cancer and regenerative biology. By distinguishing between abnormally expressed genes in tumors and the genes associated with normal cell divisions, researchers may be able to identify cancer-specific replication markers with a potential to become new drug targets. Similarly, scientists could analyze the effects of specific drugs on the biology of replicating cells, providing important clues for regenerative medicine.

Journal Reference:

1. Agnes Klochendler, Noa Weinberg-Corem, Maya Moran, Avital Swisa, Nathalie Pochet, Virginia Savova, Jonas Vikeså, Yves Van de Peer, Michael Brandeis, Aviv Regev, Finn Cilius Nielsen, Yuval Dor, Amir Eden. A Transgenic Mouse Marking Live Replicating Cells Reveals In Vivo Transcriptional Program of Proliferation. Developmental Cell, 2012; 23 (4): 681 DOI: 10.1016/j.devcel.2012.08.009

Courtesy: ScienceDaily

Happy Face Tattoo Does Serious Work

A medical sensor that attaches to the skin like a temporary tattoo could make it easier for doctors to detect metabolic problems in patients and for coaches to fine-tune athletes' training routines. And the entire sensor comes in a thin, flexible package shaped like a smiley face.

"We wanted a design that could conceal the electrodes," says Vinci Hung, a PhD candidate in the Department of Physical & Environmental Sciences at UTSC, who helped create the new sensor. "We also wanted to showcase the variety of designs that can be accomplished with this fabrication technique."

The new tattoo-based solid-contact ion-selective electrode (ISE) is made using standard screen printing techniques and commercially available transfer tattoo paper, the same kind of paper that usually carries tattoos of Spiderman or Disney princesses. In the case of the sensor, the "eyes" function as the working and reference electrodes, and the "ears" are contacts for a measurement device to connect to.

Hung contributed to the work while in the lab of Joseph Wang, a distinguished professor at the University of California San Diego. She worked there for six months earlier this year under the Michael Smith Foreign Study supplement from NSERC.

"It was a wonderful opportunity," Hung said. She worked directly with Wang, who is well-known for his innovations in the field of nanoengineering and is a pioneer in biosensor technology.

The sensor she helped make can detect changes in the skin's pH levels in response to metabolic stress from exertion. Similar devices, called ion-selective electrodes (ISEs), are already used by medical researchers and athletic trainers. They can give clues to underlying metabolic diseases such as Addison's disease, or simply signal whether an athlete is fatigued or dehydrated during training. The devices are also useful in the cosmetics industry for monitoring skin secretions.

But existing devices can be bulky, or hard to keep adhered to sweating skin. The new tattoo-based sensor stayed in place during tests, and continued to work even when the people wearing them were exercising and sweating extensively. The tattoos were applied in a similar way to regular transfer tattoos, right down to using a paper towel soaked in warm water to remove the base paper.

To make the sensors, Hung and her colleagues used a standard screen printer to lay down consecutive layers of silver, carbon fiber-modified carbon and insulator inks, followed by electropolymerization of aniline to complete the sensing surface.

By using different sensing materials, the tattoos can also be modified to detect other components of sweat, such as sodium, potassium or magnesium, all of which are of potential interest to researchers in medicine and cosmetology.

Journal Reference:

1. Amay J. Bandodkar, Vinci W. S. Hung, Wenzhao Jia, Gabriela Valdés-Ramírez, Joshua R. Windmiller, Alexandra G. Martinez, Julian Ramírez, Garrett Chan, Kagan Kerman, Joseph Wang. Tattoo-based potentiometric ion-selective sensors for epidermal pH monitoring. The Analyst, 2013; 138 (1): 123 DOI: 10.1039/C2AN36422K

Courtesy: ScienceDaily

Multitasking Plasmonic Nanobubbles Kill Diseased Cells, Modify Others

Researchers at Rice University have found a way to kill some diseased cells and treat others in the same sample at the same time. The process activated by a pulse of laser light leaves neighboring healthy cells untouched.

The unique use for tunable plasmonic nanobubbles developed in the Rice lab of Dmitri Lapotko shows promise to replace several difficult processes now used to treat cancer patients, among others, with a fast, simple, multifunctional procedure.

The research is the focus of a paper published online this week by the American Chemical Society journal ACS Nano and was carried out at Rice by biochemist Lapotko, research scientist and lead author Ekaterina Lukianova-Hleb and undergraduate student Martin Mutonga, with assistance from the Center for Cell and Gene Therapy at Baylor College of Medicine (BCM), Texas Children's Hospital and the University of Texas MD Anderson Cancer Center.

Plasmonic nanobubbles that are 10,000 times smaller than a human hair cause tiny explosions. The bubbles form around plasmonic gold nanoparticles that heat up when excited by an outside energy source -- in this case, a short laser pulse -- and vaporize a thin layer of liquid near the particle's surface. The vapor bubble quickly expands and collapses. Lapotko and his colleagues had already found that plasmonic nanobubbles kill cancer cells by literally exploding them without damage to healthy neighbors, a process that showed much higher precision and selectivity compared with those mediated by gold nanoparticles alone, he said.

The new project takes that remarkable ability a few steps further. A series of experiments proved a single laser pulse creates large plasmonic nanobubbles around hollow gold nanoshells, and these large nanobubbles selectively destroy unwanted cells. The same laser pulse creates smaller nanobubbles around solid gold nanospheres that punch a tiny, temporary pore in the wall of a cell and create an inbound nanojet that rapidly "injects" drugs or genes into the other cells.

In their experiments, Lapotko and his team placed 60-nanometer-wide hollow nanoshells in model cancer cells and stained them red. In a separate batch, they put 60-nanometer-wide nanospheres into the same type of cells and stained them blue.

After suspending the cells together in a green fluorescent dye, they fired a single wide laser pulse at the combined sample, washed the green stain out and checked the cells under a microscope. The red cells with the hollow shells were blasted apart by large plasmonic nanobubbles. The blue cells were intact, but green-stained liquid from outside had been pulled into the cells where smaller plasmonic nanobubbles around the solid spheres temporarily pried open the walls.

Because all of this happens in a fraction of a second, as many as 10 billion cells per minute could be selectively processed in a flow-through system like that under development at Rice, said Lapotko, a faculty fellow in biochemistry and cell biology and in physics and astronomy. That has potential to advance cell and gene therapy and bone marrow transplantation, he said.

Most disease-fightingand gene therapies require "ex vivo" -- outside the body -- processing of human cell grafts to eliminate unwanted (like cancerous) cells and to genetically modify other cells to increase their therapeutic efficiency, Lapotko said. "Current cell processing is often slow, expensive and labor intensive and suffers from high cell losses and poor selectivity. Ideally both elimination and transfection (the introduction of materials into cells) should be highly efficient, selective, fast and safe."

Plasmonic nanobubble technology promises "a method of doing multiple things to a cell population at the same time," said Malcolm Brenner, a professor of medicine and of pediatrics at BCM and director of BCM's Center for Cell and Gene Therapy, who collaborates with the Rice team. "For example, if I want to put something into a stem cell to make it turn into another type of cell, and at the same time kill surrounding cells that have the potential to do harm when they go back into a patient -- or into another patient -- these very tunable plasmonic nanobubbles have the potential to do that."

The long-term objective of a collaborative effort among Rice, BCM, Texas Children's Hospital and MD Anderson is to improve the outcome for patients with diseases whose treatment requires ex vivo cell processing, Lapotko said.

Lapotko plans to build a prototype of the technology with an eye toward testing with human cells in the near future. "We'd like for this to be a universal platform for cell and gene therapy and for stem cell transplantation," he said.

The work was supported by the National Institutes of Health.

Journal Reference:

1. Ekaterina Y. Lukianova-Hleb, Martin B. G. Mutonga, Dmitri O. Lapotko. Cell-Specific Multifunctional Processing of Heterogeneous Cell Systems in a Single Laser Pulse Treatment. ACS Nano, 2012; : 121128105005009 DOI: 10.1021/nn3045243

Courtesy: ScienceDaily

'Obese but Happy Gene' Challenges the Common Perception of Link Between Depression and Obesity

Researchers at McMaster University have discovered new genetic evidence about why some people are happier than others.

McMaster scientists have uncovered evidence that the gene FTO -- the major genetic contributor to obesity -- is associated with an eight per cent reduction in the risk of depression. In other words, it's not just an obesity gene but a "happy gene" as well.

The research appears in a study recently published in the journal Molecular Psychiatry. The paper was produced by senior author David Meyre, associate professor in clinical epidemiology and biostatistics at the Michael G. DeGroote School of Medicine and a Canada Research Chair in genetic epidemiology; first author Dr. Zena Samaan, assistant professor, Department of Psychiatry and Behavioural Neurosciences, and members of the Population Health Research Institute of McMaster University and Hamilton Health Sciences.

"The difference of eight per cent is modest and it won't make a big difference in the day-to-day care of patients," Meyre said. "But, we have discovered a novel molecular basis for depression."

In the past, family studies on twins, and brothers and sisters, have shown a 40 per cent genetic component in depression. However, scientific studies attempting to associate genes with depression have been "surprisingly unsuccessful" and produced no convincing evidence so far, Samaan said.

The McMaster discovery challenges the common perception of a reciprocal link between depression and obesity: That obese people become depressed because of their appearance and social and economic discrimination; depressed individuals may lead less active lifestyles and change eating habits to cope with depression that causes them to become obese.

"We set out to follow a different path, starting from the hypothesis that both depression and obesity deal with brain activity. We hypothesized that obesity genes may be linked to depression," Meyre said.

The McMaster researchers investigated the genetic and psychiatric status of patients enrolled in the EpiDREAM study led by the Population Health Research Institute, which analyzed 17,200 DNA samples from participants in 21 countries.

In these patients, they found the previously identified obesity predisposing genetic variant in FTO was associated with an eight per cent reduction in the risk of depression. They confirmed this finding by analyzing the genetic status of patients in three additional large international studies.

Meyre said the fact the obesity gene's same protective trend on depression was found in four different studies supports their conclusion. It is the "first evidence" that an FTO obesity gene is associated with protection against major depression, independent of its effect on body mass index, he said.

Journal Reference:

1. Z Samaan, S Anand, X Zhang, D Desai, M Rivera, G Pare, L Thabane, C Xie, H Gerstein, J C Engert, I Craig, S Cohen-Woods, V Mohan, R Diaz, X Wang, L Liu, T Corre, M Preisig, Z Kutalik, S Bergmann, P Vollenweider, G Waeber, S Yusuf, D Meyre. The protective effect of the obesity-associated rs9939609 A variant in fat mass- and obesity-associated gene on depression. Molecular Psychiatry, 2012; DOI: 10.1038/mp.2012.160

Courtesy: ScienceDaily

Alzheimer's Disease in Mice Alleviated: Promising Therapeutic Approach for Humans

Pathological changes typical of Alzheimer's disease were significantly reduced in mice by blockade of an immune system transmitter. A research team from Charité -- Universitätsmedizin Berlin and the University of Zurich has just published a new therapeutic approach in fighting Alzheimer's disease in the current issue of Nature Medicine. This approach promises potential in prevention, as well as in cases where the disease has already set in.

Alzheimer's disease is one of the most common causes of dementia. In Germany and Switzerland alone, around 1.5 million people are affected, and forecasts predict a doubling of the number of patients worldwide within the next 20 years. The accumulation of particular abnormal proteins, including amyloid-ß (Aβ) among others, in patients' brains plays a central role in this disease. Prof. Frank Heppner from the Department of Neuropathology at Charité and his colleague Prof. Burkhard Becher from the Institute for Experimental Immunology at the University of Zurich were able to show that turning off particular cytokines (immune system signal transmitters) reduced the Alzheimer's typical amyloid-ß deposits in mice with the disease. As a result, the strongest effects were demonstrated after reducing amyloid-ß by approximately 65 percent, when the immune molecule p40 was affected, which is a component of the cytokines interleukin (IL)-12 and -23.

Relevant for human therapy

Follow-up experiments also relevant for humans showed that substantial improvements in behavioral testing resulted when mice were given the antibody blocking the immune molecule p40. This effect was also achieved when the mice were already showing symptoms of the disease. Based on the current study by Prof. Heppner's and Prof. Becher's team, the level of p40 molecules is higher in Alzheimer's patients' brain fluid, which is in agreement with a recently published study by American colleagues demonstrating increased p40 levels in blood plasma of subjects with Alzheimer's disease, thus showing obvious relevance for human therapy.

The significance of the immune system in Alzheimer's research is the focus of current efforts. Prof. Heppner and Prof. Becher suspect that cytokines IL-12 and IL-23 themselves are not causative in the pathology, and that the mechanism of the immune molecule p40 in Alzheimer's requires additional clarification. However, they are convinced that the results of their six-years of research work justify the step toward clinical studies in humans, for which they plan to collaborate with a suitable industrial partner.

IIn the context of other illnesses, such as psoriasis, a medication that suppresses p40 in humans has already been applied. "Based on the safety data in patients," comment Profs. Heppner and Becher, "clinical studies could now be implemented without delay. Now, the goal is to bring the new therapeutic approach to Alzheimer patients quickly."

Journal Reference:

1. Johannes vom Berg, Stefan Prokop, Kelly R Miller, Juliane Obst, Roland E Kälin, Ileana Lopategui-Cabezas, Anja Wegner, Florian Mair, Carola G Schipke, Oliver Peters, York Winter, Burkhard Becher, Frank L Heppner. Inhibition of IL-12/IL-23 signaling reduces Alzheimer's disease–like pathology and cognitive decline. Nature Medicine, 2012; DOI: 10.1038/nm.2965

Courtesy: ScienceDaily

Use of Stem Cells in Personalized Medicine

Johns Hopkins researchers report concrete steps in the use of human stem cells to test how diseased cells respond to drugs. Their success highlights a pathway toward faster, cheaper drug development for some genetic illnesses, as well as the ability to pre-test a therapy's safety and effectiveness on cultured clones of a patient's own cells.

he project, described in an article published November 25 on the website of the journal Nature Biotechnology, began several years ago, when Gabsang Lee, D.V.M., Ph.D., an assistant professor at the Johns Hopkins University School of Medicine's Institute for Cell Engineering, was a postdoctoral fellow at Sloan-Kettering Institute in New York. To see if induced pluripotent stem cells (iPSCs) could be used to make specialized disease cells for quick and easy drug testing, Lee and his colleagues extracted cells from the skin of a person with a rare genetic disease called Riley-Day syndrome, chosen because it affects only one type of nerve cell that is difficult if not impossible to extract directly from a traditional biopsy. These traits made Riley-Day an ideal candidate for alternative ways of generating cells for study.

In a so-called "proof of concept" experiment, the researchers biochemically reprogrammed the skin cells from the patient to form iPSCs, which can grow into any cell type in the body. The team then induced the iPSCs to grow into nerve cells. "Because we could study the nerve cells directly, we could for the first time see exactly what was going wrong in this disease," says Lee. Some symptoms of Riley-Day syndrome are insensitivity to pain, episodes of vomiting, poor coordination and seizures; only about half of affected patients reach age 30.

In the recent research at Johns Hopkins and Memorial Sloan-Kettering, Lee and his co-workers used these same lab-grown Riley-Day nerve cells to screen about 7,000 drugs for their effects on the diseased cells. With the aid of a robot programmed to analyze the effects, the researchers quickly identified eight compounds for further testing, of which one -- SKF-86466 -- ultimately showed promise for stopping or reversing the disease process at the cellular level.

Lee says a clinical trial with SKF-86466 might not be feasible because of the small number of Riley-Day patients worldwide, but suggests that a closely related version of the compound, one that has already been approved by the U.S. Food and Drug Administration for another use, could be employed for the patients after a few tests.

The implications of the experiment reach beyond Riley-Day syndrome, however. "There are many rare, 'orphan' genetic diseases that will never be addressed through the costly current model of drug development," Lee explains. "We've shown that there may be another way forward to treat these illnesses."

Another application of the new stem cell process could be treatments tailored not only to an illness, but also to an individual patient, Lee says. That is, iPSCs could be made for a patient, then used to create a laboratory culture of, for example, pancreatic cells, in the case of a patient with type 1 diabetes. The efficacy and safety of various drugs could then be tested on the cultured cells, and doctors could use the results to help determine the best treatment. "This approach could move much of the trial-and-error process of beginning a new treatment from the patient to the petri dish, and help people to get better faster," says Lee.

Other authors of the paper are Christina N. Ramirez, Ph.D., Nadja Zeltner, Ph.D., Becky Liu, Constantin Radu, M.S., Bhavneet Bhinder, Hakim Djaballah, Ph.D., and Lorenz Studer, Ph.D., of the Sloan-Kettering Institute; and Hyesoo Kim, Ph.D., Young Jun Kim, M.D., Ph.D., InYoung Choi, Ph.D., and Bipasha Mukherjee-Clavin of the Johns Hopkins University School of Medicine.

The work was supported by funds from New York State Stem Cell Science (NYSTEM), the New York Stem Cell Foundation (NYSCF), the state of Maryland (TEDCO, MSCRF), the Commonwealth Foundation for Cancer Research, the Experimental Therapeutics Center at Memorial Sloan-Kettering Cancer Center, the William Randolph Hearst Fund in Experimental Therapeutics, the L.S. Wells Foundation, and the National Cancer Institute (grant number 5 P30 CA008748-44).

Journal Reference:

1. Gabsang Lee, Christina N Ramirez, Hyesoo Kim, Nadja Zeltner, Becky Liu, Constantin Radu, Bhavneet Bhinder, Yong Jun Kim, In Young Choi, Bipasha Mukherjee-Clavin, Hakim Djaballah, Lorenz Studer. Large-scale screening using familial dysautonomia induced pluripotent stem cells identifies compounds that rescue IKBKAP expression. Nature Biotechnology, 2012; DOI: 10.1038/nbt.2435

Courtesy: ScienceDaily

Watermelon Genome Decoded: Scientists Find Clues to Disease Resistant Watermelons

Are juicier, sweeter, more disease-resistant watermelons on the way? An international consortium of more than 60 scientists from the United States, China, and Europe has published the genome sequence of watermelon (Citrullus lanatus) -- information that could dramatically accelerate watermelon breeding toward production of a more nutritious, tastier and more resistant fruit. The watermelon genome sequence was published in the Nov. 25 online version of the journal Nature Genetics.

The researchers discovered that a large portion of disease resistance genes were lost in the domestication of watermelon. With the high-quality watermelon sequence now complete, it is hoped that breeders can now use the information to recover some of these natural disease defenses.

The authors reported that the genome of the domesticated watermelon contained 23,440 genes, roughly the same number of genes as in humans. The group compared the genomes of 20 different watermelons and developed a first-generation genetic variation map for watermelon. This information allowed them to identify genomic regions that have been under human selection, including those associated with fruit color, taste and size.

"Watermelons are an important cash crop and among the top five most consumed fresh fruits; however, cultivated watermelons have a very narrow genetic base, which presents a major bottleneck to its breeding. Decoding the complete genome of the watermelon and resequencing watermelons from different subspecies provided a wealth of information and toolkits to facilitate research and breeding," said Zhangjun Fei, a scientist at the Boyce Thompson Institute for Plant Research at Cornell University, and one of the leaders of this project.

Fei worked with BTI scientists on different aspects of the research, including James Giovannoni, to generate the gene expression data through RNA-sequencing and Lukas Mueller to provide additional analysis to confirm the quality of the genome assembly. Fei also collaborated with Amnon Levi, a research geneticist at the USDA-ARS, U.S. Vegetable Laboratory, Charleston, S.C., on genetic mapping and identifying candidate genes that might be useful to enhance disease resistance in watermelon. The genome sequences of the watermelon are publicly available at the Cucurbit Genomics Database, which is created and maintained by Fei's group.

Believed to have originated in Africa, watermelons were cultivated by Egyptians more than 4,000 years ago, where the fruit was a source of water in dry, desert conditions. They are now consumed throughout the world -- with over 400 varieties in global commercial production. China leads in global production of the fruit, and the United States ranks fourth with more than 40 states involved in the industry. Despite being over 90 percent water, watermelons do contain important nutrients such as vitamins A and C, and lycopene, a compound that gives some fruits and vegetables their red color and appears to reduce the risk of certain types of cancer. Watermelon is also a natural source of citrulline, a non-essential amino acid with various health and athletic performance benefits.

Journal Reference:

1. Shaogui Guo, Jianguo Zhang, Honghe Sun, Jerome Salse, William J Lucas, Haiying Zhang, Yi Zheng, Linyong Mao, Yi Ren, Zhiwen Wang, Jiumeng Min, Xiaosen Guo, Florent Murat, Byung-Kook Ham, Zhaoliang Zhang, Shan Gao, Mingyun Huang, Yimin Xu, Silin Zhong, Aureliano Bombarely, Lukas A Mueller, Hong Zhao, Hongju He, Yan Zhang, Zhonghua Zhang, Sanwen Huang, Tao Tan, Erli Pang, Kui Lin, Qun Hu, Hanhui Kuang, Peixiang Ni, Bo Wang, Jingan Liu, Qinghe Kou, Wenju Hou, Xiaohua Zou, Jiao Jiang, Guoyi Gong, Kathrin Klee, Heiko Schoof, Ying Huang, Xuesong Hu, Shanshan Dong, Dequan Liang, Juan Wang, Kui Wu, Yang Xia, Xiang Zhao, Zequn Zheng, Miao Xing, Xinming Liang, Bangqing Huang, Tian Lv, Junyi Wang, Ye Yin, Hongping Yi, Ruiqiang Li, Mingzhu Wu, Amnon Levi, Xingping Zhang, James J Giovannoni, Jun Wang, Yunfu Li, Zhangjun Fei, Yong Xu. The draft genome of watermelon (Citrullus lanatus) and resequencing of 20 diverse accessions. Nature Genetics, 2012; DOI: 10.1038/ng.2470

Courtesy: ScienceDaily

Brain Imaging Alone Cannot Diagnose Autism

In a column appearing in the current issue of the journal Nature, McLean Hospital biostatistician Nicholas Lange, ScD, cautions against heralding the use of brain imaging scans to diagnose autism and urges greater focus on conducting large, long-term multicenter studies to identify the biological basis of the disorder.
"Several studies in the past two years have claimed that brain scans can diagnose autism, but this assertion is deeply flawed," said Lange, an associate professor of Psychiatry and Biostatistics at Harvard Medical School. "To diagnose autism reliably, we need to better understand what goes awry in people with the disorder. Until its solid biological basis is found, any attempt to use brain imaging to diagnose autism will be futile."
While cautioning against current use of brain imaging as a diagnostic tool, he is a strong proponent of using this technology to help scientists better understand autism. Through the use of various brain imaging techniques, including functional magnetic resonance imaging (MRI), positron emission tomography (PET), and volumetric MRI, Lange points out that researchers have made important discoveries related to early brain enlargement in the disorder, how those with autism focus during social interaction and the role of serotonin in someone with autism.
"Brain scans have led to these extremely valuable advances, and, with each discovery, we are getting closer to solving the autism pathology puzzle," said Lange. "What individuals with autism and their parents urgently need is for us to carry out large-scale studies that lead us to find reliable, sensitive and specific biological markers of autism with high predictive value that allow clinicians to identify interventions that will improve the lives of people with the disorder."
Autism and autism spectrum disorder (ASD) are terms regularly used to describe a group of complex disorders of brain development. This spectrum characterized, in varying degrees, by difficulties in social interaction, verbal and nonverbal communication, and repetitive behaviors, whose criteria have been revised in the newly proposed Diagnostic and Statistical Manual of Mental Disorders (DSM-5). The prevalence of ASD in the United States has increased 78 percent in the last decade, with the Centers for Disease Control estimating that one in 88 children has ASD.'

Journal Reference:

1. Nicholas Lange. Perspective: Imaging autism. Nature, 2012; DOI: 10.1038/491S17a

Courtesy: ScienceDaily

New Therapeutic Target for Alzheimer's Disease Identified

Research led by Chu Chen, PhD, Associate Professor of Neuroscience at LSU Health Sciences Center New Orleans, has identified an enzyme called Monoacylglycerol lipase (MAGL) as a new therapeutic target to treat or prevent Alzheimer's disease.

The study was published online November 1, 2012 in the Online Now section of the journal Cell Reports.

The research team found that inactivation of MAGL, best known for its role in degrading a cannabinoid produced in the brain, reduced the production and accumulation of beta amyloid plaques, a pathological hallmark of Alzheimer's disease. Inhibition of this enzyme also decreased neuroinflammation and neurodegeneration, and improved plasticity of the brain, learning and memory.

"Our results suggest that MAGL contributes to the cause and development of Alzheimer's disease and that blocking MAGL represents a promising therapeutic target," notes Dr. Chu Chen, who is also a member of the Department of Otolaryngology at LSU Health Sciences Center New Orleans.

The researchers blocked MAGL with a highly selective and potent inhibitor in mice using different dosing regimens and found that inactivation of MAGL for eight weeks was sufficient to decrease production and deposition of beta amyloid plaques and the function of a gene involved in making beta amyloid toxic to brain cells. They also measured indicators of neuroinflammation and neurodegeneration and found them suppressed when MAGL was inhibited. The team discovered that not only did the integrity of the structure and function of synapses associated with cognition remain intact in treated mice, but MAGL inactivation appeared to promote spatial learning and memory, measured with behavioral testing.

Alzheimer's disease is a neurodegenerative disorder characterized by accumulation and deposition of amyloid plaques and neurofibrillary tangles, neuroinflammation, synaptic dysfunction, progressive deterioration of cognitive function and loss of memory in association with widespread nerve cell death. The most common cause of dementia among older people, more than 5.4 million people in the United States and 36 million people worldwide suffer with Alzheimer's disease in its various stages. Unfortunately, the few drugs that are currently approved by the Food and Drug Administration have demonstrated only modest effects in modifying the clinical symptoms for relatively short periods, and none has shown a clear effect on disease progression or prevention.

"There is a great public health need to discover new therapies to prevent and treat this devastating disorder," Dr. Chen concludes. The research was supported by grants from the National Institutes of Health. In addition to scientists from LSU Health Sciences Center New Orleans, the research team also included investigators from the Massachusetts Institute of Technology.

Journal Reference:

1. Rongqing Chen, Jian Zhang, Yan Wu, Dongqing Wang, Guoping Feng, Ya-Ping Tang, Zhaoqian Teng, Chu Chen. Monoacylglycerol Lipase Is a Therapeutic Target for Alzheimer's Disease. Cell Reports, 01 November 2012 DOI: 10.1016/j.celrep.2012.09.030 .
2. Courtesy: ScienceDaily

New Finding Gives Clues for Overcoming Tamoxifen-Resistant Breast Cancer

A University of Cincinnati (UC) cancer biology team reports breakthrough findings about specific cellular mechanisms that may help overcome endocrine (hormone) therapy-resistance in patients with estrogen-positive breast cancers, combating a widespread problem in effective medical management of the disease.

Xiaoting Zhang, PhD, and his colleagues have identified a specific estrogen receptor co-activator -- known as MED1 -- as playing a central role in mediating tamoxifen resistance in human breast cancer. The team reports its findings in the Nov. 1, 2012, issue of Cancer Research, a scientific journal of the American Association for Cancer Research.

According to the National Cancer Institute, nearly 227,000 women are diagnosed with breast cancer annually in the United States. About 75 percent have estrogen-positive tumors and require adjuvant hormone therapy such as tamoxifen, a drug that works by interfering with estrogen's ability to stimulate breast cancer cell growth.

Despite advances in hormone therapy drugs, cancer surveillance research has shown that 50 percent of patients will develop resistance to the drug and experience a cancer relapse.

The hormones estrogen and progesterone can stimulate the growth of some breast cancers. Hormone therapy is used to stop or slow the growth of these tumors. Hormone-sensitive (i.e., positive) breast cancer cells contain specific proteins known as hormone receptors that become activated once hormones bind to them, leading to cancer growth.

Based on new findings, UC Cancer Institute scientists believe that tamoxifen resistance may be driven by a novel molecular "crosstalk" point between the estrogen and HER2 (human epidermal growth factor receptor 2) signaling pathways.

Testing in both pre-clinical models and human breast cancer tissue samples showed that MED1 co-amplifies and co-expresses with HER2, a gene that has an increased presence in 20-30 percent of invasive human breast cancer and plays a major role in tamoxifen resistance.

HER2 over-expression led to MED1 activation while reduction of MED1 caused breast cancer cells that were otherwise tamoxifen-resistant to respond and stop dividing. Further mechanistic studies showed that HER2 activation of MED1 resulted in the recruitment of co-activators instead of co-repressors by tamoxifen-bound estrogen receptor. This, explains Zhang, drives expression of not only traditional estrogen receptor-positive cancer target genes, but also HER2 and those estrogen receptor target genes abnormally activated by HER2.

"Together, these findings suggest this 'crosstalk' could play a central role in mediating tamoxifen resistance in human breast cancer, especially because recent published data also indicated that high MED1 expression levels correlate with poor treatment outcome and disease-free survival of patients who underwent endocrine therapy," explains Zhang, an assistant professor of cancer biology at the UC College of Medicine and breast cancer researcher with the UC Cancer Institute.

"We are currently utilizing RNA-based nanotechnology to target MED1 in an effort to simultaneously block both estrogen and HER2 pathways to overcome endocrine-resistant breast cancer."

UC study collaborators include cancer biologists Jiajun Cui, PhD, Katherine Germer, MD, Shao-chun Wang, PhD; environmental health researcher Tianying Wu, PhD; and pathologist Jiang Wang, MD. Qianben Wang, PhD of the Ohio State University College of Medicine, and Jia Luo, PhD, of the University of Kentucky, also contributed to this study.

The study was supported with start-up funding from the UC Cancer Institute, Ride Cincinnati/Marlene Harris Pilot Grant, Susan G. Komen for the Cure Foundation and the Center for Clinical and Translational Science and Training -- home to UC's institutional Clinical and Translational Science Award program grant from the National Institutes of Health.

Journal Reference:

1. J. Cui, K. Germer, T. Wu, J. Wang, J. Luo, S.-c. Wang, Q. Wang, X. Zhang. Cross-talk between HER2 and MED1 Regulates Tamoxifen Resistance of Human Breast Cancer Cells. Cancer Research, 2012; 72 (21): 5625 DOI: 10.1158/0008-5472.CAN-12-1305

 Courtesy: ScienceDaily

Complex Logic Circuit Made from Bacterial Genes

By force of habit we tend to assume computers are made of silicon, but there is actually no necessary connection between the machine and the material. All that an engineer needs to do to make a computer is to find a way to build logic gates -- the elementary building blocks of digital computers -- in whatever material is handy.

So logic gates could theoretically be made of pipes of water, channels for billiard balls or even mazes for soldier crabs.

By comparison Tae Seok Moon's ambition, which is to build logic gates out of genes, seems eminently practical. As a postdoctoral fellow in the lab of Christopher Voigt, PhD, a synthetic biologist at the Massachusetts Institute of Technology, he recently made the largest gene (or genetic) circuit yet reported.

Moon, PhD, now an assistant professor of energy, environmental and chemical engineering in the School of Engineering & Applied Science at Washington University in St. Louis is the lead author of an article describing the project in the Oct. 7 issue of Nature. Voigt is the senior author.

The tiny circuits constructed from these gene gates and others like them may one day be components of engineered cells that will monitor and respond to their environments.

The number of tasks they could undertake is limited only by evolution and human ingenuity. Janitor bacteria might clean up pollutants, chemical-engineer bacteria pump out biofuels and miniature infection-control bacteria might bustle about killing pathogens.

How to make an AND gate out of genes

The basis of modern computers is the logic gate, a device that makes simple comparisons between the bits, the 1s and 0s, in which computers encode information. Each logic gate has multiple inputs and one output. The output of the gate depends on the inputs and the operation the gate performs.

An AND gate, for example, turns on only if all of its inputs are on. An OR gate turns on if any of its inputs are on.

Suggestively, genes are turned on or off when a transcription factor binds to a region of DNA adjacent to the gene called a promotor.

To make an AND gate out of genes, however, Moon had to find a gene whose activation is controlled by at least two molecules, not one. So only if both molecule 1 AND molecule 2 are present will the gene be turned on and translated into protein.

Such a genetic circuit had been identified in Salmonella typhimurium, the bacterium that causes food poisoning. In this circuit, the transcription factor can bind to the promotor of a gene only if a molecule called a chaperone is present. This meant the genetic circuit could form the basis of a two-input AND gate.

The circuit Moon eventually built consisted of four sensors for four different molecules that fed into three two-input AND gates. If all four molecules were present, all three AND gates turned on and the last one produced a reporter protein that fluoresced red, so that the operation of the circuit could be easily monitored.

In the future, Moon says, a synthetic bacterium with this circuit might sense four different cancer indicators and, in the presence of all four, release a tumor-killing factor.

Crosstalk and timing faults

There are huge differences, of course, between the floppy molecules that embody biological logic gates and the diodes and transistors that embody electronic ones.

Engineers designing biological circuits worry a great deal about crosstalk, or interference. If a circuit is to work properly, the molecules that make up one gate cannot bind to molecules that are part of another gate.

This is much more of a problem in a biological circuit than in an electronic circuit because the interior of a cell is a kind of soup where molecules mingle freely.

To ensure that there wouldn't be crosstalk among his AND gates, Moon mined parts for his gates from three different strains of bacteria: Shigella flexneri and Pseudomonas aeruginosa, as well as Salmonella.

Although the parts from the three different strains were already quite dissimilar, he made them even more so by subjecting them to error-prone copying cycles and screening the copies for ones that were even less prone to crosstalk (but still functional).

Another problem Moon faced is that biological circuits, unlike electronic ones, don't have internal clocks that keep the bits moving through the logic gates in lockstep. If signals progress through layers of gates at different speeds, the output of the entire circuit may be wrong, a problem called a timing fault.

Experiments designed to detect such faults in the synthetic circuit showed that they didn't occur, probably because the chaperones for one layer of logic gates degrades before the transcription factors for the next layer are generated, and this forces a kind of rhythm on the circuit.

Hijacking a bacterium's controller

"We're not trying to build a computer out of biological logic gates," Moon says. "You can't build a computer this way. Instead we're trying to make controllers that will allow us to access all the things biological organisms do in simple, programmable ways."

"I see the cell as a system that consists of a sensor, a controller (the logic circuit), and an actuator," he says. "This paper covers work on the controller, but eventually the controller's output will drive an actuator, something that will do work on the cell's surroundings. "

An synthetic bacterium designed by a friend of Moon's at Nanyang Technological University in Singapore senses signaling molecules released by the pathogen Pseudomonas aeruginosa. When the molecules reach a high enough concentration, the bacterium generates a toxin and a protein that causes it to burst, releasing the toxin, and killing nearby P. aeruginosa.

"Silicon cannot do that," Moon says.

Journal Reference:

1. Tae Seok Moon, Chunbo Lou, Alvin Tamsir, Brynne C. Stanton, Christopher A. Voigt. Genetic programs constructed from layered logic gates in single cells. Nature, 2012; DOI: 10.1038/nature11516

Courtesy: ScienceDaily

New Light Shed On Cancer Risks Associated With Night Work

Night work can increase cancer risk in men, according to a new study published in the American Journal of Epidemiology by a research team from Centre INRS-Institut Armand-Frappier and Centre de recherche du Centre hospitalier de l'Université de Montréal. The study is one of the first in the world to provide evidence among men of a possible association between night work and the risk of prostate, colon, lung, bladder, rectal, and pancreatic cancer and non-Hodgkin's lymphoma.

"Exposure to light at night can lead to a reduced production of the sleep hormone melatonin, inducing physiological changes that may provoke the development of tumours. This hormone, habitually released in the middle of the night in response to absence of light, plays a pivotal role in hormonal functions and in the immune system," explained Professor Marie-Élise Parent of Centre INRS-Institut Armand-Frappier, the study's lead investigator.

Despite finding that night work increases the risk of a number of cancers, the researchers are intrigued by the absence of a relationship between duration of night work and cancer risk found in the study. In theory, an increasing duration in the period of night work would be expected to be accompanied by an increase in the risk of cancer, but the results obtained did not confirm such a tendency. As well as opening up new research avenues, this finding raises questions about the factors that might influence people`s adaptation to night work. Other more targeted research, including Dr. Parent's current research on prostate cancer, will also allow for a more detailed study of the consequences of night work on health.

For this research, Dr. Parent and her team analyzed data from a study on occupational exposure and cancer that was conducted between 1970 and 1985, involving 3,137 men aged 35 to 70 years who had been diagnosed with a cancer at 18 hospitals in the Montreal metropolitan area, compared to a control group of 512 cancer-free individuals from the general population.

The epidemiological study by Marie-Élise Parent, Mariam El-Zein, and Marie-Claude Rousseau of Centre INRS-Institut Armand-Frappier and Javier Pintos and Jack Siemiatycki of Centre de recherche du Centre hospitalier de l'Université de Montréal and Université de Montréal was funded by Health Canada, the National Cancer Institute of Canada , Quebec's Institut de recherche Robert-Sauvé en santé et sécurité au travail, and Fonds de recherche du Québec -- Santé (FRQS).

Journal Reference:

1. M.-E. Parent, M. El-Zein, M.-C. Rousseau, J. Pintos, J. Siemiatycki. Night Work and the Risk of Cancer Among Men. American Journal of Epidemiology, 2012; DOI: 10.1093/aje/kws318

Courtesy: ScienceDaily

 

Early-Earth Cells Modeled to Show How First Life Forms Might Have Packaged RNA

Researchers at Penn State University have developed a chemical model that mimics a possible step in the formation of cellular life on Earth four-billion years ago. Using large "macromolecules" called polymers, the scientists created primitive cell-like structures that they infused with RNA -- the genetic coding material that is thought to precede the appearance of DNA on Earth -- and demonstrated how the molecules would react chemically under conditions that might have been present on the early Earth.

 

The journal Nature Chemistry is posting the research as an Advance Online Publication on 14 October 2012.

In modern biology, all life, with the exception of some viruses, uses DNA as its genetic storage mechanism. According to the "RNA-world" hypothesis, RNA appeared on Earth first, serving as both the genetic-storage material and the functional molecules for catalyzing chemical reactions, then DNA and proteins evolved much later. Unlike DNA, RNA can adopt many different molecular conformations and so it is functionally interactive on the molecular level. In the soon-to-be-published research paper, two professors of chemistry, Christine Keating and Philip Bevilacqua, and two graduate students, Christopher Strulson and Rosalynn Molden, probe one of the nagging mysteries of the RNA-world hypothesis.

"A missing piece of the RNA-world puzzle is compartmentalization," Bevilacqua said. "It's not enough to have the necessary molecules that make up RNA floating around; they need to be compartmentalized and they need to stay together without diffusing away. This packaging needs to happen in a small-enough space -- something analogous to a modern cell -- because a simple fact of chemistry is that molecules need to find each other for a chemical reaction to occur."

To test how early cell-like structures could have formed and acted to compartmentalize RNA molecules even in the absence of lipid-like molecules that make up modern cellular membranes, Strulson and Molden generated simple, non-living model "cells" in the laboratory. "Our team prepared compartments using solutions of two polymers called polyethylene glycol (PEG) and dextran," Keating explained. "These solutions form distinct polymer-rich aqueous compartments, into which molecules like RNA can become locally concentrated."

The team members found that, once the RNA was packed into the dextran-rich compartments, the molecules were able to associate physically, resulting in chemical reactions. "Interestingly, the more densely the RNA was packed, the more quickly the reactions occurred," Bevilacqua explained. "We noted an increase in the rate of chemical reactions of up to about 70-fold. Most importantly, we showed that for RNA to 'do something' -- to react chemically -- it has to be compartmentalized tightly into something like a cell. Our experiments with aqueous two-phase systems (ATPS) have shown that some compartmentalization mechanism may have provided catalysis in an early-Earth environment."

Keating added that, although the team members do not suggest that PEG and dextran were the specific polymers present on the early Earth, they provide a clue to a plausible route to compartmentalization -- phase separation. "Phase separation occurs when different types of polymers are present in solution at relatively high concentrations. Instead of mixing, the sample separates to form two distinct liquids, similar to how oil and water separate." Keating explained. "The aqueous-phase compartments we manufactured using dextran and PEG can drive biochemical reactions by increasing local reactant concentrations. So, it's possible that some other sorts of polymers might have been the molecules that drove compartmentalization on the early Earth." Strulson added that, "In addition to the RNA-world hypothesis, these results may be relevant to RNA localization and function in non-membrane compartments in modern biology."

The team members also found that the longer the string of RNA, the more densely it would be packed into the dextran compartment of the ATPS, while the shorter strings tended to be left out. "We hypothesize that this research result might indicate some kind of primitive sorting method," Bevilacqua said. "As RNA gets shorter, it tends to have less enzyme activity. So, in an early-Earth system similar to our dextran-PEG model system, the full-length, functional RNA would have been sorted and concentrated into one phase, while the shorter RNA that is not only less functional, but also threatens to inhibit important chemical reactions, would not have been included."

The scientists hope to continue their investigations by testing their model-cell method with other polymers. Keating added, "We are interested in looking at compartmentalization in polymer systems that are more closely related to those that may have been present on the early Earth, and also those that may be present in contemporary biological cells, where RNA compartmentalization remains important for a wide range of cellular processes."

This research was funded by the National Science Foundation (grant CHE-0750196).

Journal Reference:

1. Christopher A. Strulson, Rosalynn C. Molden, Christine D. Keating, Philip C. Bevilacqua. RNA catalysis through compartmentalization. Nature Chemistry, 2012; DOI: 10.1038/nchem.1466C

Courtesy: ScienceDaily