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