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Multicenter study nets new lung tumor-suppressor gene

BOSTON–Collaborating scientists in Boston and North Carolina have found that a particular gene can block key steps of the lung cancer process in mice. The researchers report in the journal Nature that LKB1 is not only a “tumor-suppressor” gene for non-small cell lung cancer in mice, it also may be more powerful than other, better-known suppressors. The study will be published on the journal’s Web site on Aug. 5 and later in a print version.

If further research shows LKB1 has a similar effect in human lung cells, it could influence the way non-small cell lung cancer is diagnosed and treated, says the study’s senior author, Kwok-Kin Wong, MD, PhD, of Dana-Farber, one of three institutions, along with Massachusetts General Hospital and the University of North Carolina School of Medicine, leading the work. If tumors with LKB1 mutations are found to be especially fast-growing, for example, patients with such tumors might be candidates for more aggressive therapy.

People born with defective versions of LKB1 often develop Peutz-Jeghers syndrome, which is marked by intestinal growths and an increased risk for certain cancers. Non-inherited mutations of the gene have been found in some lung cancers. This suggested that LKB1 normally thwarts tumors from forming. Mutated versions may be unable to act as a brake on cancer.

To find out, the investigators ran a series of experiments in mice with a defective form of a gene called Kras, which drives the formation and growth of lung cancer. They tracked the development of lung cancer in animals with mutated LKB1 and compared it to the experience of animals with abnormalities in either of two well-known tumor-suppressor genes.

They found that while Kras “cooperated” with the mutated tumor-suppressor genes to produce lung cancer, it cooperated even more strongly with mutated LKB1. “The LKB1-deficient tumors grew more rapidly and spread more frequently than the others, and comprised all three types of non-small cell lung cancer — squamous cell carcinoma, large-cell carcinoma, and adenocarcinoma — rather than just one or two,” Wong says. “This suggests that LKB1 plays a role at major stages of the tumors’ development: initiation, differentiation of normal lung cells into cancer cells, and metastasis.”

An examination of human non-small-cell lung tissue suggests LKB1 mutations play a role there as well. Of 144 samples analyzed, 34 percent of the lung adenocarcinomas and 19 percent of the squamous cell carcinomas contained abnormal versions of the gene, researchers report.

“We were surprised at how significant a role LKB1 mutations play in non-small cell lung cancer development in mice,” say Wong, who is also an assistant professor of medicine at Harvard Medical School. “This suggests there may be additional lung tumor-suppressor genes yet to be discovered. We’re currently examining whether these results apply to human lung cancers as well and, if so, how such information can improve treatment.”

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The lead author of the study was Hongbin Ji, PhD, of Dana-Farber. Other Dana-Farber co-authors include Dongpo Cai, PhD, Liang Chen, PhD, Pasi Janne, MD, PhD, Bruce Johnson, MD, Jussi Koivunen, MD, PhD, Danan Li, Mei-Chih Liang, PhD, Kate McNamara, Matthew Meyerson, MD, PhD, Samanthi Perera, PhD, Geoffrey Shapiro, MD, PhD, and Takeshi Shimamura, PhD. Other authors were based at Children’s Hospital Boston, Brigham and Women’s Hospital, Broad Institute of Harvard University and Massachusetts Institute of Technology, University of Tennessee Health Science Center, and the University of Texas Southwestern Medical Center.

The research was supported by the National Institutes of Health, the Sidney Kimmel Foundation for Cancer Research, the American Federation of Aging, the Joan Scarangello Foundation to Conquer Lung Cancer, the Flight Attendant Medical Research Institute, the Waxman Foundation, the Harvard Stem Cell Institute, and the Linda Verville Foundation.

Dana-Farber Cancer Institute (www.dana-farber.org) is a principal teaching affiliate of the Harvard Medical School and is among the leading cancer research and care centers in the United States. It is a founding member of the Dana-Farber/Harvard Cancer Center (DF/HCC), designated a comprehensive cancer center by the National Cancer Institute.

Contact: Bill Schaller
william_schaller@dfci.harvard.edu
617-632-5357
Dana-Farber Cancer Institute

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August 5, 2007 Posted by | Baltimore, Barcelona, Bethesda, Biological Sciences, Calgary, Canada, Cancer, Cancer Biology, France, Genes, Genetic, Genetic Link, Genetics, Genome, Genomic, Germany, Global, Global Health Vision, Global News, Health Canada, Human Genome, LKB1, Lung Cancer, Medical History, Medical Journals, Newfoundland, News, News Australia, News Canada, News Israel, News Italy, News Jerusalem, News Switzerland, News UK, News US, News USA, NIH, Peutz-Jeghers syndrome, University of North Carolina, World News | 2 Comments

Identifying the mechanism behind a genetic susceptibility to type 2 diabetes

Type 2 diabetes is reaching epidemic proportions in the developed world. Determining if and how certain genes predispose individuals to type 2 diabetes is likely to lead to the development of new treatment strategies for individuals with the disease.

In a study appearing in the August issue of the Journal of Clinical Investigation Valeriya Lyssenko and colleagues from Lund University in Sweden show that certain variants of the gene TCF7L2 make individuals more susceptible to type 2 diabetes. The susceptibility variants were associated with increased expression of TCF7L2 in pancreatic islet cells and decreased islet cell secretion of insulin. Consistent with this, ectopic overexpression of TCF7L2 in human islet cells decreased insulin secretion in response to exposure to glucose. This study identifies TCF7L2 type 2 diabetes susceptibility variants and provides a mechanism by which these genetic variants might cause susceptibility to the disease. As discussed by the authors and in the accompanying commentary by Andrew Hattersley from Peninsula Medical School in the United Kingdom, future studies are likely to investigate the potential for manipulating the signaling pathways controlled by TCF7L2 for the development of new therapeutics for type 2 diabetes.

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TITLE: Mechanisms by which common variants in the TCF7L2 gene increase risk of type 2 diabetes

AUTHOR CONTACT:
Valeriya Lyssenko
Lund University, University Hospital Malma, Malma, Sweden.
Phone: 46-40-391214; Fax: 46-40-391222; E-mail: Valeri.Lyssenko@med.lu.se.

View the PDF of this article at: https://www.the-jci.org/article.php?id=30706

ACCOMPANYING COMMENTARY
TITLE: Prime suspect: the TCF7L2 gene and type 2 diabetes risk

AUTHOR CONTACT:
Andrew T. Hattersley
Institute of Biomedical and Clinical Sciences, Peninsula Medical School, Exeter, United Kingdom.
Phone: 44-1392-406806; Fax: 44-1392-406767; E-mail: Andrew.Hattersley@pms.ac.uk.

View the PDF of this article at: https://www.the-jci.org/article.php?id=33077

Contact: Karen Honey
press_releases@the-jci.org
215-573-1850
Journal of Clinical Investigation

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August 2, 2007 Posted by | Alberta, Baltimore, Barcelona, Bethesda, Biological Sciences, Calgary, Canada, Diabetes, France, Genes, Genetic, Genetic Link, Genetics, Genome, Genomic, Germany, Global, Global Health Vision, Global News, Health Canada, Human Genome, Irvine, Italy, Japan, Journal of Clinical Investigation, Medical Journals, Newfoundland, News, News Australia, News Canada, News Israel, News Italy, News Jerusalem, News Switzerland, News UK, News US, News USA, Nova Scotia, Nunavut, Osaka, Ottawa, Pennsylvania, Prince Edward Island, Public Health, Quebec, Research, RSS, RSS Feed, Slovakia, Spain, Toronto, Type 2 Diabetes, US, Virginia, Washington DC, Washington DC City Feed, World News | Leave a comment

U-M researchers find family of ‘on switches’ that cause prostate cancer

Gene fusions trigger cancer growth, could impact treatment choices

ANN ARBOR, Mich. — Researchers at the University of Michigan Comprehensive Cancer Center have discovered how genes turn on the switch that leads to prostate cancer.

The team discovered that pieces of two chromosomes can trade places with each other and cause two genes to fuse together. The fused genes then override the “off” switch that keeps cells from growing uncontrollably, causing prostate cancer to develop.

By testing these gene fusions in mice and in cell cultures, the researchers showed that the fusions are what cause prostate cancer to develop. But it’s not just one set of genes that fuse. The researchers found that any one of several in a family of genes can become scrambled and fuse. Results of the study appear in the Aug. 2 issue of Nature.

“Each of these switches, or gene fusions, represent different molecular subtypes. This tells us there’s not just one type of prostate cancer. It’s a more complex disease and potentially needs to be treated differently in each patient,” says lead study author Arul Chinnaiyan, M.D., Ph.D., director of the Michigan Center for Translational Pathology, a new U-M center whose goal is to translate research into real world practice.

The gene fusion research is the centerpiece project of the new center. In the current study, researchers found one of several abnormal gene fusions in the prostate cancer tissue samples they tested. In 2005, the researchers identified a prostate-specific gene called TMPRSS2, which fuses with either ERG or ETV1, two genes known to be involved in several types of cancer.

The Nature paper reports on five additional genes that fuse with ERG or ETV1 to cause prostate cancer. Gene fusions were involved in 60 percent to 70 percent of the prostate cancer cell lines the researchers looked at. The genes involved are all controlled by a different mechanism. For example, four of the genes are regulated by androgen, a male sex hormone known to fuel prostate cancer. Androgen deprivation is a common therapy for prostate cancer.

Knowing which gene fusion is involved in an individual patient’s tumor could impact treatment options. If an androgen-regulated gene is involved, androgen therapy would be appropriate. But if the gene fusion involves a gene that represses androgen, the anti-androgen therapy could encourage the cancer’s growth. This may also explain why androgen treatment is not effective for some prostate cancers.

“Typing someone’s prostate cancer by gene fusion can affect the treatment given. We would not want to give androgen to someone whose prostate cancer gene fusion is not regulated by androgen,” says Chinnaiyan, who is the S.P. Hicks Collegiate Professor of Pathology at the U-M Medical School.

Rearrangements in chromosomes and fused genes are known to play a role in blood cell cancers like leukemia and lymphoma, and in Ewing’s sarcoma. A fused gene combination that plays a role in chronic myelogenous leukemia led researchers to develop the drug Gleevec, which has dramatically improved survival rates for that disease.

Chinnaiyan believes the prostate gene fusions will eventually lead to similar treatments for prostate cancer.

“More immediately, we hope to develop tests for diagnosis or prognosis. But long-term, we hope this will lead to better therapies to treat prostate cancer. The key challenge is to find a drug that would go after this gene fusion,” Chinnaiyan says.

The gene fusion technology has been licensed to San Diego-based Gen-Probe Inc., which is working on a screening tool to detect gene fusions in urine. The tool could one day supplement or replace the prostate specific antigen, or PSA, test currently used to screen for prostate cancer.

The idea of translating laboratory research findings into a test or treatment that will impact patients is central to the new Michigan Center for Translational Pathology. The center brings together experts in genomics, proteomics and bioinformatics to look at common patterns and potential targets in cancer and other diseases. This is the first center of its kind in the nation in that it is associated with one of 39 National Cancer Institute-designated “comprehensive” cancer centers, a premier medical school and a large health system with both clinicians and patients.

The center’s goal is to study the genes, proteins and other markers on cells to develop new diagnostic tests or screening tools as well as targeted treatments for cancer and other diseases, with the key being to translate these laboratory discoveries into clinical applications.

Chinnaiyan and his team have received numerous awards and honors, including the American Association for Cancer Research Team Science Award for their previously published work on gene fusions, and the Specialized Program of Research Excellence Outstanding Investigator award. The new Center for Translational Pathology supported in part by the Prostate Cancer Foundation, which has offered to match up to $1 million dollars in donations to support work related to developing therapies against prostate cancer gene fusions at the university.

“Mapping of the human genome was only the beginning. Equipped with the comprehensive analysis of the human genome, we can now systematically examine the blueprint of disease at the molecular level. This essential knowledge may lead to better diagnostic tests and promising new treatments for cancer, cardiovascular disease, diabetes and other illnesses,” Chinnaiyan says.

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For information about the Michigan Center for Translational Pathology, go to http://www.med.umich.edu/mctp.

About 218,890 men will be diagnosed with prostate cancer this year, and 27,050 will die from the disease, according to the American Cancer Society. The gene fusion work is not currently available for treatment or diagnosis, and no clinical trials are currently recruiting. For information about prostate cancer and currently available treatments, go to http://www.mcancer.org or call the U-M Cancer AnswerLine at 800-865-1125.

In addition to Chinnaiyan, U-M study authors were Scott Tomlins; Saravana Dhanasekaran, Ph.D.; Bharathi Laxman; Qi Cao; Beth Helgeson; Xuhong Cao; David Morris, M.D.; Anjana Menon; Xiaojun Jing; Bo Han; James Montie, M.D.; Kenneth Pienta, M.D.; Diane Roulston; Rajal Shah, M.D.; Sooryanarayana Varambally, Ph.D.; and Rohit Mehra, M.D. Mark Rubin, M.D., from Brigham and Women’s Hospital, Dana-Farber Cancer Institute and Harvard Medical School is also a study author.

Funding for the study came from the U.S. Department of Defense, the National Institutes of Health, the Early Detection Research Network, the Prostate Cancer Foundation and Gen-Probe Inc.

The University of Michigan has filed for a patent on the detection of gene fusions in prostate cancer, on which Tomlins, Mehra, Rubin and Chinnaiyan are co-inventors. The diagnostic field of use has been licensed to Gen-Probe Inc. Chinnaiyan also has a sponsored research agreement with Gen-Probe; however, GenProbe has had no role in the design or experimentation of this study, nor has it participated in the writing of the manuscript.

Reference: Nature, Vol. 448, No. 7153, Aug. 2, 2007

Contact: Nicole Fawcett
nfawcett@umich.edu
734-764-2220
University of Michigan Health System

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August 1, 2007 Posted by | acute lymphoblastic leukemia, Alberta, Baltimore, Barcelona, Bethesda, Calgary, Canada, Cancer, Cancer Biology, Cancer Biology and Therapy, Chemotherapy, Childhood Lukemia, France, Genes, Genetic, Genetic Link, Genetics, Genome, Genomic, Germany, Global, Global Health Vision, Global News, Health Canada, Human Genome, Irvine, Italy, Japan, journal Nature Genetics, Leukemia, Lung Cancer, Medical Journals, Nature Genetics, Newfoundland, News, News Australia, News Canada, News Israel, News Italy, News Jerusalem, News Switzerland, News UK, News US, News USA, non-Hodgkin's lymphoma, Nova Scotia, Oncology, Osaka, Ottawa, Prince Edward Island, Public Health, Quebec, Research, RSS, RSS Feed, Slovakia, Spain, Toronto, UK, University of Michigan, US, Virginia, Washington DC, Washington DC City Feed, World News | 3 Comments

Huntington’s disease study shows animal models on target

This release is available in French.

An international team of researchers has published a benchmark study showing that gene expression in several animal models of Huntington’s Disease (HD) closely resembles that of human HD patients.

The results, published August 1, 2007, in the , validate the applicability of using animal models to study human disease and will have important consequences for the pertinence of these models in preclinical drug testing.

Huntington’s disease is an incurable and fatal hereditary neurodegenerative disorder caused by a mutation in the gene that encodes the huntingtin protein. Neurons in certain regions of the brain succumb to the effects of the altered protein, leading to severe motor, psychiatric, and cognitive decline. Several recent studies have shown that the mutant huntingtin protein modifies the transcriptional activity of genes in affected neurons. This disease mechanism is a promising new avenue for research into the causes of neuronal death and a novel potential approach for treatment.

Led by EPFL professor Ruth Luthi-Carter, and involving collaborators from six countries, the current study found a marked resemblance between the molecular etiology of neurons in animal models and neurons in patients with HD. This implies that animal models are relevant for studying human HD and testing potential treatments.

To come to this conclusion, the scientists measured the gene expression profile of seven different transgenic mouse models of HD, representing different conditions and disease stages. These profiles clarified the role of different forms and dosages of the protein hungtintin in the transcriptional activity of neurons. They then designed and implemented novel computational methods for quantifying similarities between RNA profiles that would allow for comparisons between the gene expression in mice and in human patients. “Interestingly, results of different testing strategies converged to show that several available models accurately recapitulate the molecular changes observed in human HD,” explains Luthi-Carter. “It underlines the suitability of these animal models for preclinical testing of drugs that affect gene transcription in Huntington’s Disease.”

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More Information:

EPFL Laboratory of functional neurogenomics, http://lngf.epfl.ch/

Alexandre Kuhn ; +41 21 693 1731
alexandre.kuhn@epfl.ch

Professor Ruth Luthi-Carter; +41 21 693 9533
ruth.luthi-carter@epfl.ch

Contact: Alexandre Kuhn
alexandre.kuhn@epfl.ch
41-216-931-731
Ecole Polytechnique Fédérale de Lausanne

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July 31, 2007 Posted by | Alberta, Baltimore, Barcelona, Bethesda, Calgary, Canada, DNA, France, Genes, Genetic, Genetic Link, Genetics, Genome, Genomic, Germany, Global, Global Health Vision, Global News, Health Canada, Human Genome, Huntington's disease, Italy, Japan, Neurodegenerative Diseases, Newfoundland, News, News Australia, News Canada, News Israel, News Italy, News Jerusalem, News Switzerland, News UK, News US, News USA, Nova Scotia, Nunavut, Ottawa, Prince Edward Island, Proteins, Quebec, Research, RSS, RSS Feed, Spain, Toronto, UK, US, Virginia, Washington DC, Washington DC City Feed, World News | Leave a comment

Flip of genetic switch causes cancers in mice to self-destruct, Stanford researchers find

STANFORD, Calif. – Killing cancerous tumors isn’t easy, as anyone who has suffered through chemotherapy can attest. But a new study in mice shows that switching off a single malfunctioning gene can halt the limitless division of tumor cells and turn them back to the path of their own planned obsolescence.

The surprising possibility that a cell’s own natural mechanism for ensuring its mortality could be used to vanquish tumors opens the door to a new approach to developing drugs to treat cancer patients, according to Dean Felsher, MD, PhD, associate professor of medicine (oncology) and of pathology at the Stanford University School of Medicine. Felsher is the senior author of the study to be published July 30 in the advance online version of the Proceedings of the National Academy of Sciences.

“Our research implies that by shutting off a critical cancer gene, tumor cells can realize that they are broken and restore this physiologic fail-safe program,” said Felsher.

Cancer can be notoriously resistant to medical treatment. Not only do cancer cells proliferate uncontrollably, they somehow circumvent the mechanism that causes normal cells to die when they get old or malfunction. That makes cancer cells effectively immortal unless doctors manage to squelch them.

The gene Felsher’s team studied produces a protein called Myc (pronounced “mick”), which promotes cell division. A mutation of the gene causes cells to overproduce the protein, prompting perpetual cell division and tumor growth. By turning off the mutated gene, the researchers found that not only did uncontrolled cell division cease, but the cells also reactivated a normal physiological mechanism, called senescence, which makes it possible for a cell to eventually die.

“What was unexpected was just the fact that cancer cells had retained the ability to undergo senescence at all,” said Felsher. Cancer researchers had long thought the senescence process had to be irreversibly disrupted for a tumor to develop.

The researchers worked with a series of mice engineered to have Myc-triggered cancers of either the liver, blood or bones, along with a specially constructed version of the Myc gene that they could switch off by feeding the mice antibiotics. When the mice dined on doses of the drugs, invariably, the tumors ceased growing and then diminished, with some disappearing over the course of just a few days.

Although Felsher’s lab had previously shown that mouse tumors diminished and disappeared when Myc was switched off, they hadn’t been sure how the process actually worked. Historically, most research involving genetic methods of battling cancer cells has focused on reactivating genes called tumor-suppressor genes, which are generally overcome by a proliferating cancer. No one had explored the idea that senescence might play a key role in diminishing tumors.

Felsher described senescence as acting like a fail-safe mechanism to stop cancer. When a cell detects a deleterious mutation, it launches the senescence process, resulting in the permanent loss of the cell’s ability to proliferate, thus halting any cancer.

“In order to become tumor cells, those cells have to overcome senescence,” said Chi-Hwa Wu, PhD, postdoctoral researcher in Felsher’s lab and first author of the study. Wu had the inspiration to explore whether the sudden diminishment they had observed in the tumors might be due to the reactivation of some latent remnant of the trigger for senescence.

Through a series of experiments looking at enzymes associated with the senescence process, as well as some molecular markers, Wu confirmed her suspicion. And not only was senescence occurring in cells that had been thought to be incapable of it, the process was reactivated in all the different tumors they studied.

Consider it a cell version of the Jekyll-and-Hyde transformation. “It’s sort of like Mr. Hyde realizing that there’s something wrong with him and then being able to put himself back into his normal state as Dr. Jekyll,” Felsher said.

In addition to the deepened understanding of how the process of senescence works, Felsher and Wu see a lot of potential for new approaches to treating cancer, beyond the traditional tactic of trying to kill cancer cells directly. “This work implies that maybe part of the strategy should involve figuring out how to get the cancer cells to just be allowed to do what they originally wanted to do anyway, which is to not be proliferating endlessly and growing uncontrolled,” said Felsher.

The next step for the team is to see how well the approach works in human cancer cells. “And we’re also trying to figure out what the mechanism is,” Felsher said. “What are the molecular mechanisms of this, so that we can figure out how to better treat cancer””

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Other authors on the research paper are Jan van Riggelen, PhD, postdoctoral researcher; Alper Yetil, graduate student in cancer biology; Alice Fan, MD, instructor in medicine (oncology), and medical student Pavan Bachireddy.

The study was funded by the National Cancer Institute, the National Institutes of Health, the Leukemia and Lymphoma Society, the Burroughs Wellcome Fund, the Damon Runyon Lilly Clinical Investigator Award, the Lymphoma Research Foundation and the Howard Hughes Medical Institute.

Stanford University Medical Center integrates research, medical education and patient care at its three institutions – Stanford University School of Medicine, Stanford Hospital & Clinics and Lucile Packard Children’s Hospital at Stanford. For more information, please visit the Web site of the medical center’s Office of Communication & Public Affairs at http://mednews.stanford.edu.

Contact: Lou Bergeron
louisb3@stanford.edu
650-723-3900
Stanford University Medical Center

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July 31, 2007 Posted by | acute lymphoblastic leukemia, Alberta, Baltimore, Barcelona, Bethesda, Biological Sciences, Calgary, Canada, Cancer, Cancer Biology, Cancer Biology and Therapy, Childhood Lukemia, France, Genes, Genetic, Genetic Link, Genetics, Genome, Genomic, Germany, Global, Global Health Vision, Global News, Health Canada, Howard Hughes Medical Institute, Human Genome, Italy, Japan, Leukemia, Medical Journals, Molecular Biology, National Cancer Institute, National Institutes of Health, Newfoundland, News, News Australia, News Canada, News Israel, News Italy, News Jerusalem, News Switzerland, News UK, News US, News USA, NIH, non-Hodgkin's lymphoma, Nova Scotia, Nunavut, Osaka, Ottawa, Prince Edward Island, Public Health, Quebec, Research, RSS, RSS Feed, Toronto, UK, US, Virginia, Washington DC, Washington DC City Feed, Wellcome Trust, World News | Leave a comment

Research links genetic mutations to lupus

WINSTON-SALEM, N.C. – A gene discovered by scientists at Wake Forest University School of Medicine has been linked to lupus and related autoimmune diseases. The finding, reported in the current issue of Nature Genetics, is the latest in a series of revelations that shed new light on what goes wrong in human cells to cause the diseases.

“This research is a huge leap toward understanding the cause of lupus and related autoimmune diseases,” said Fred Perrino, Ph.D., a co-author on the paper and a professor of biochemistry at Wake Forest. “There had been few clues before now.”

Perrino, who discovered the gene in 1998, said he suspected it was involved in human disease, but it took a group of researchers from around the world collaborating to put the puzzle together.

“We’ve known that lupus was a complex disease, but now we have a specific protein and a particular cellular process that appears to be one of the causes,” said Perrino. “We’re connecting the dots to understand the biology of what’s going on with the disease.”

In Nature Genetics, lead author Min Ae Lee-Kirsch, M.D., from the Technische Universität Dresden in Dresden, Germany, and colleagues report finding variations of the TREX1 gene discovered by Perrino in patients with systemic lupus erythematosus. The study involved 417 lupus patients from the United Kingdom and Germany. Mutations were found in nine patients with lupus and were absent in 1,712 people without lupus.

“Our data identify a stronger risk for developing lupus in patients that carry variants of the gene,” said Lee-Kirsch.

In recent years, the gene was also linked to Aicardi-Goutieres syndrome, a rare neurological disease that causes death in infants, and to chilblain lupus, an inherited disease associated with painful bluish-red skin lesions that occur during cold weather and usually improve in summer. The current research also links it to Sjogren’s syndrome, a form of lupus.

The diseases are all autoimmuine diseases, which means that the body makes antibodies against itself. In lupus, these antibodies cause pain and inflammation in various parts of the body, including the skin, joints, heart, lungs, blood, kidneys and brain. The disease is characterized by pain, heat, redness, swelling and loss of function.

Perrino began studying the protein made by the gene more than 14 years ago.

“We basically cracked open cells to locate the protein and find the gene,” said Perrino. “In the 14 years since, we’ve learned a lot about the protein and how it functions.”

The gene manufactures a protein, also known as TREX1, whose function is to “disassemble” or “unravel” DNA, the strand of genetic material that controls processes within cells. The “unraveling” occurs during the natural process of cells dying and being replaced by new cells. If a cell’s DNA isn’t degraded or unraveled during cell death, the body develops antibodies against it.

“If the TREX1 protein isn’t working to disassemble the DNA, you make antibodies to your own DNA and can end up with a disease like lupus,” said Perrino.

Perrino and colleagues at Wake Forest have been studying the gene and its protein since 1993. Thomas Hollis, Ph.D., an assistant professor of biochemistry at Wake Forest, is credited with solving the structure of both TREX1 and a similar protein, TREX2. Perrino has also developed a way to measure the function of the proteins.

In a study reported in April in the Journal of Biological Chemistry, Hollis and Perrino found that three variations of the gene reduced the activity of the protein by four- to 35,000-fold.

“Now that we have the structure, we can understand how it disassembles DNA and how mutations in the gene may affect that process,” said Hollis.

The researchers hope that understanding more about the gene’s mutations and the structure of the protein may lead to drug treatments to help ensure that mutant copies of the gene are inactive.

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Media Contacts: Karen Richardson, krchrdsn@wfubmc.edu; Shannon Koontz, shkoontz@wfubmc.edu; at 336-716-4587.

Wake Forest University Baptist Medical Center is an academic health system comprised of North Carolina Baptist Hospital and Wake Forest University Health Sciences, which operates the university’s School of Medicine. U.S. News & World Report ranks Wake Forest University School of Medicine 18th in primary care and 44th in research among the nation’s medical schools. It ranks 35th in research funding by the National Institutes of Health. Almost 150 members of the medical school faculty are listed in Best Doctors in America.

Contact: Karen Richardson
krchrdsn@wfubmc.edu
336-716-4453
Wake Forest University Baptist Medical Center

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July 29, 2007 Posted by | Alberta, Baltimore, Barcelona, Bethesda, Biological Sciences, Calgary, Canada, Clinical Trials, France, Genes, Genetic, Genetic Link, Genetic Marker C allele of rs10505477, Genetics, Genome, Genomic, Global, Global Health Vision, Global News, Health Canada, Human Genome, Italy, Japan, Lupus, Nature Genetics, Newfoundland, News, News Australia, News Canada, News Israel, News Italy, News Jerusalem, News Switzerland, News UK, News US, News USA, NIH, Nova Scotia, Nunavut, Osaka, Ottawa, Prince Edward Island, Public Health, Quebec, Research, RSS, RSS Feed, Slovakia, Spain, Toronto, UK, US, Virginia, Wake Forest University Baptist Medical Center, WASHINGTON, Washington DC, Washington DC City Feed, World Health Organisation, World News | 1 Comment

One man’s junk may be a genomic treasure

Scientists have only recently begun to speculate that what’s referred to as “junk” DNA – the 96 percent of the human genome that doesn’t encode for proteins and previously seemed to have no useful purpose – is present in the genome for an important reason. But it wasn’t clear what the reason was. Now, researchers at the University of California, San Diego (UCSD) School of Medicine have discovered one important function of so-called junk DNA.

Genes, which make up about four percent of the genome, encode for proteins, “the building blocks of life.” An international collaboration of scientists led by Michael G. Rosenfeld, M.D., Howard Hughes Medical Investigator and UCSD professor of medicine, found that some of the remaining 96 percent of genomic material might be important in the formation of boundaries that help properly organize these building blocks. Their work will be published in the July 13 issue of the journal Science.

“Some of the ‘junk’ DNA might be considered ‘punctuation marks’ – commas and periods that help make sense of the coding portion of the genome,” said first author Victoria Lunyak, Ph.D., assistant research scientist at UCSD.

In mice, as in humans, only about 4 percent of the genome encodes for protein function; the remainder, or “junk” DNA, represents repetitive and non-coding sequences. The research team studied a repeated genomic sequence called SINE B2, which is located on the growth hormone gene locus, the gene related to the aging process and longevity. The scientists were surprised to find that SINE B2 sequence is critical to formation of the functional domain boundaries for this locus.

Functional domains are stretches of DNA within the genome that contain all the regulatory signals and other information necessary to activate or repress a particular gene. Each domain is an entity unto itself that is defined, or bracketed, by a boundary, much as words in a sentence are bracketed by punctuation marks. The researchers’ data suggest that repeated genomic sequences might be a widely used strategy used in mammals to organize functional domains.

“Without boundary elements, the coding portion of the genome is like a long, run-on sequence of words without punctuation,” said Rosenfeld.

Decoding the information written in “junk” DNA could open new areas of medical research, particularly in the area of gene therapy. Scientists may find that transferring encoding genes into a patient, without also transferring the surrounding genomic sequences which give structure or meaning to these genes, would render gene therapy ineffective.

Contributors to the paper include Lluis Montoliu, Rosa Roy and Angel Garcia-Díaz of the Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología in Madrid, Spain; Christopher K. Glass, M.D., Ph.D., UCSD Department of Cellular and Molecular Medicine; Esperanza Núñez, Gratien G. Prefontaine, Bong-Gun Ju, Kenneth A. Ohgi, Kasey Hutt, Xiaoyan Zhu and Yun Yung, Howard Hughes Medical Institute, Department of Molecular Medicine, UCSD School of Medicine; and Thorsten Cramer, Division of Endocrinology, UCSD Department of Medicine.

The research was funded in part by the Howard Hughes Medical Institute and the National Institutes of Health.

Contact: Debra Kain
ddkain@ucsd.edu
619-543-6163
University of California – San Diego

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July 13, 2007 Posted by | Alberta, Baltimore, Barcelona, Bethesda, Biological Sciences, Calgary, Chile, DNA, Genes, Genetic, Genetics, Genome, Genomic, Global, Global Health Vision, Global News, Howard Hughes Medical Institute, Human Genome, Irvine, Italy, Japan, National Institutes of Health, Newfoundland, News, News Australia, News Canada, News Israel, News Italy, News Jerusalem, News Switzerland, News UK, News US, News USA, NIH, Nova Scotia, Osaka, Ottawa, Pennsylvania, Prince Edward Island, Proteins, Quebec, Research, Research Australia, RSS, RSS Feed, Slovakia, Spain, Toronto, UCSD, University of California, Virginia, WASHINGTON, Washington DC, Washington DC City Feed, World News | Leave a comment

New genetic test developed at Emory advances detection and diagnosis of muscular dystrophy

Contact: Holly Korschun
hkorsch@emory.edu
404-727-3990
Emory University

A new genetic test targeting the most common types of muscular dystrophy–those caused by mutations in the dystrophin gene–is far quicker with greater accuracy and sensitivity than existing tests. It can be used to confirm clinical diagnoses, to test female family members who may be carriers, and to perform prenatal testing.

The test was developed by Michael Zwick, PhD, and Madhuri Hegde, PhD, assistant professors in the Department of Human Genetics and the Emory Genetics Laboratory in the Emory University School of Medicine.

Muscular dystrophy includes more than 30 genetic diseases characterized by progressive weakness and degeneration of the skeletal muscles that control movement. Some forms are seen in infancy or childhood, while others may not appear until middle age or later. Duchenne muscular dystrophy (DMD) is the most common form of muscular dystrophy and primarily affects boys. It is caused by absence of dystrophin, an important muscle protein involved in maintaining the strength of muscle fibers.

According to the National Institute of Neurodegenerative Diseases and Stroke (NINDS), DMD onset is between 3 and 5 years, with rapid progression. Most boys are unable to walk by age 12 and later need a respirator to breathe. Girls in these families have a 50 percent chance of inheriting and passing the defective gene to their children. Becker muscular dystrophy, which is similar to Duchenne but less severe, results from faulty or not enough dystrophin.

As currently implemented the new test, called EmArray Dystrophin, detects 99 percent of mutations in the dystrophin gene including deletions, duplications and point mutations.

The EmArray Dystrophin test uses a new kind of microarray technology that contains the entire sequence of the dystrophin gene, the largest known gene in humans, on a chip the size of a microscope slide. The test initially detects deletions and duplications, then microarray-based resequencing is used to rapidly identify subtle genetic variations that may cause muscular dystrophy.

The EmArray Dystrophin test confirms clinical diagnosis of Duchenne and Becker muscular dystrophy in a male and characterizes the type and size of the mutation. Women with a family history of Duchenne or Becker who are at risk to be carriers can be tested, then, if found to be carriers, can have prenatal testing.

“Previously, access to prenatal testing was limited for some women when the affected male relative was not available for testing. The EmArray Dystrophin test greatly improves access to prenatal and carrier testing for women without the need to test a male relative, in a rapid timeframe,” according to Vanessa Rangel Miller, MS. In addition to improved testing, the Emory Genetics Laboratory, Parent Project Muscular Dystrophy, leading researchers and clinicians are working together to develop a database for mutations and clinical data.

“Our new genetic test, along with new therapies currently in clinical trials, is a very positive development for muscular dystrophy patients and their families,” says Dr. Hegde.

In the last five years DMD research has accelerated, resulting in more knowledge about the role of the dystrophin gene and an increased understanding about what happens to a muscle cell lacking the dystrophin protein. Researchers around the world are investigating a number of different treatment strategies, all with the goal of slowing or stopping muscle degeneration. Several clinical trials are underway and many others are in development, including testing of an oral medication intended to circumvent mutations in the dystrophin gene and increase normal gene expression.

According to Dr. Hegde, about 13 percent of mutations in the dystrophin gene are nonsense mutations–point mutations in a sequence of DNA that can result in mistakes in gene expression and nonfunctional proteins. New data published online in the current edition of the journal Nature show that PTC124, an investigational new drug designed to bypass dystrophin nonsense mutations and restore a functional protein, was effective in a preclinical (animal) model of Duchenne muscular dystrophy (DMD). (www.clinicaltrials.gov).

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Other treatment for symptoms associated with muscular dystrophy may include physical therapy, respiratory therapy, speech therapy, orthopedic appliances and corrective orthopedic surgery. Drug therapy may include corticosteroids, anticonvulsants, immunosuppressants and antibiotics.

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June 27, 2007 Posted by | Clinical Trials, Emory Genetics Laboratory, Emory University, Genes, Genetic, Genetics, Genome, Genomic, Global, Global Health Vision, Global News, Human Genome, Muscular Dystrophy, News, News Australia, News Canada, News Israel, News Jerusalem, News UK, News US, Research, Virginia, WASHINGTON, Washington DC, World News | 2 Comments

Researchers Create Model of Cancer-Preventing Enzyme, Study How It Works

May 11 2007

Contact: Katherine Kostiuk
Sr. Information Specialist
573-882-3346
KostiukK@missouri.edu

Proline dehydrogenase is important because it plays a role in apoptosis, the process of cell death, by enabling the creation of superoxide, a highly reactive electron-rich oxygen species. Superoxide is involved in the destruction of damaged cells and therefore is important in preventing the development and spread of cancer. The protein proline dehydrogenase “opens up to allow oxygen to ‘steal’ electrons” and create a superoxide, said Tommi A. White, an MU doctoral student in biochemistry.

White worked with John J. Tanner, professor of chemistry and biochemistry in MU’s College of Arts and Science, and Navasona Krishnan, a doctoral student at the Unviersity of Nebraska-Lincoln, and Donald F. Becker, an associate professor at the University of Nebraska-Lincoln, to create the first model of proline dehydrogenase. Because the human form of this enzyme is difficult to work with, the team studied proline dehydrogenase from the bacteria Thermus thermophilus. They used bioinformatics and biochemical studies to show that this enzyme is functionally similar to the human version, so their results can be generalized to the human version, as well as the bacterial version.

Using X-ray crystallography and biochemical analysis, the team created a model of proline dehydrogenase that can tell scientists more about the molecule’s structure and functions.

“The three-dimensional model tells us a lot about the structure of the molecules and helps us understand how they work,” Tanner said. “This protein is important in cancer prevention because it enables the creation of superoxide, which aid in cell death. Cells aren’t meant to live forever, and at some point, they need to die and be destroyed. Cells that are damaged or diseased are usually destroyed in this process. Our structure tells us how oxygen gets access to electrons stored in the enzyme. We think we’ve identified a gate that opens to let oxygen into the enzyme where the electrons are stored.”

In this way, proline dehydrogenase is important in preventing cancer. White said it’s unusual for proline dehydrogenase to be involved in such a process because the usual job of this type of enzyme is to transfer electrons to the mitochondrial membrane, not allow them to be attached to oxygen to create highly reactive superoxides.

Tanner and White said they hope to continue to study proline dehydrogenase and the molecules that can inactivate it. They also plan to examine another protein they suspect works in collaboration with proline dehydrogenase to understand how that protein affects the cancer-preventing abilities of proline dehydrogenase.
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On the Net:
University of Missouri
http://www.chem.missouri.edu/

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May 11, 2007 Posted by | Cancer, Clinical Trials, DNA, Enzymes, Genetics, Global, Global Health Vision, Global News, Human Genome, News, Uncategorized, University of Missouri, Washington DC | Leave a comment

Landmark study identifies large number of new proteins implicated in Huntington’s disease

Contact: Kris Rebillot
krebillot@buckinstitute.org
415-209-2260
Buck Institute for Age Research

Buck Institute faculty leads large scale screening of protein interactions to identify drug targets for possible treatment of incurable disease

Researchers from four organizations have identified more than 200 new proteins that bind to normal and mutant forms of the protein that causes Huntington’s disease (HD). HD is a fatal inherited disease that affects 30,000 Americans annually by laying waste to their nervous system. The research was led by Buck Institute faculty member Robert E. Hughes, PhD. Results of the study, which may facilitate the discovery of an effective treatment for HD, will be published in the May 11 edition of PLoS Genetics, an online, open-source journal, enabling scientists from around the world to take advantage of the findings immediately.

The work, which involved high-tech screening of the human genome and proteome, was unprecedented both in terms of its scale and in the way the protein interactions were validated in a genetic model of the disease. By conducting additional experiments in fruit flies genetically altered to express features of human HD, scientists showed that changing the expression of these interacting proteins affected the degree of damage seen in the fly neurons. This indicates that a significant number of the proteins might be potential drug targets for HD.

Now that researchers have discovered the interacting proteins using human libraries and human protein extracts and tested them in the fly, Hughes says the next step is to bring the research back into the mammalian world. The new genes and proteins discovered in this study are being screened and analyzed in cultured mammalian cells; the ones that show activity in ongoing experiments will be tested in mouse models of HD.

“Here at the Buck Institute, we’re going to be focusing on a few dozen proteins,” said Hughes. “Effective follow-up on any target protein depends, in large part, on how much expertise a scientist has with that target. We are hoping that researchers will look at this study and that those with specific expertise in a particular protein will move forward with their own inquiries.”

The work was supported by HD advocacy organizations. “We are very excited about this significant discovery,” said Allan Tobin, PhD, Senior Scientific Advisor to the High Q Foundation and CHDI, Inc. “This work helps define and refine possible therapeutic targets for a disease that lacks thorough understanding.” Tobin added, “We are pleased this study is being published in an open-access journal, which makes it easier for scientists at other organizations to get to work on following up on this landmark discovery.” Traditional peer-reviewed journals usually require scientists to pay a fee to access study results.

Tobin added that the need for further scientific inquiry is urgent. There is currently no effective treatment or cure for HD, which is typically characterized by involuntary movements and dementia. The disease slowly diminishes a person’s ability to move, think and communicate. Those affected eventually become totally dependent on others for their care and usually die from complications such as choking, heart failure or infection. The disease is hereditary; each child of a person with HD has a 50/50 chance of inheriting the fatal gene. Approximately 200,000 Americans are believed to be at risk of developing HD, a disease that affects as many people as hemophilia, cystic fibrosis or muscular dystrophy. The symptoms of HD typically begin to appear in mid-life, although the progression of the disease varies among individuals and within the same family.

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Joining Hughes as co-authors of the paper are Buck Institute scientists Cameron Torcassi, and Lisa Ellerby; along with Eliana Romano and Juan Botas from the Baylor College of Medicine in Houston; Andrew Strand, and James Olson from the Fred Hutchinson Cancer Research Center in Seattle; and Linda Kaltenbach, Sudhir Sahasrabudhe, Cornelia Kurschner, and John M. Peltier of Prolexys Pharmaceuticals in Salt Lake City. The work was supported by grants from the HighQ Foundation, CCHI Inc, the Hereditary Disease Foundation and National Institutes of Health.

The Buck Institute is an independent non-profit organization dedicated to extending the healthspan, the healthy years of each individual’s life. The National Institute of Aging designated the Buck a Nathan Shock Center of Excellence in the Biology of Aging, one of just five centers in the country. Buck Institute scientists work in an innovative, interdisciplinary setting to understand the mechanisms of aging and to discover new ways of detecting, preventing and treating age-related diseases such as Alzheimer’s and Parkinson’s disease, cancer, stroke, and arthritis. Collaborative research at the Institute is supported by genomics, proteomics and bioinformatics technology. For more information: http://www.buckinstitute.org.

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May 11, 2007 Posted by | Buck Institute, College of Medicine in Houston, Genetics, Global Health Vision, Global News, Human Genome, Huntington's disease, Proteome | Leave a comment