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Center for Genetic Medicine Research
Our Vision
To define a new era in pediatric health care through genome-enabled research, pre-clinical studies of experimental therapeutics, and clinical trials, with a primary focus on rare genetic disorders affecting children.
Major Strategic Goals
- Accomplish a seamless transition for promising therapeutic approaches in muscle disease, lung disease, urea cycle disorders, kidney, eye, and brain disorders through combined genome-enabled basic research, pre-clinical studies, and clinical trials.
- Initiate exon-skipping clinical trials for Duchenne muscular dystrophy through public/private partnerships and the CINRG clinical trial network.
- Expand research on asthma and respiratory tract diseases, through implementation of the NIH K12 career development Genetics and Genomics of Lung Disease training grant, basic research studies, AsthMaP, and collaborative projects with Children’s Goldberg Center for Community Pediatric Health.
- Implement population-based interventions for inactivity, obesity, and type 2 diabetes in children and young adults, including AIMM Young and FamFIT-DC.
- Coordinate systems in biology research, including bioinformatics, genome-wide integrated data sets (genomics, proteomics), and public access resources. This effort includes the creation of a new Department of Integrated Systems Medicine at the George Washington School of Medicine and Health Sciences and targeted recruitment. Research topics include systems biology of glucocorticoid action, insulin resistance in muscle, and stress response in vanishing white matter disease.
Strategic Plan Accomplishments
- Bringing therapeutic strategies to the muscular dystrophies. Research of Terence Partridge, PhD, and Toshifumi Yokota, PhD, showed clinical benefit of exon skipping (systemic morpholinos) in a dog model of Duchenne dystrophy. The Cooperative Neuromuscular International Research Group (CINRG) reorganized and completed a series of clinical trials, including demonstrating that weekend prednisone shows strong efficacy compared to daily steroids, and is working towards a public/private partnership to promote exon-skipping therapeutics in the United States.
- Integrating molecular insights with personalized medicine and community health in asthma and type 2 diabetes. The center was awarded a five-year K12 Genomics of Lung grant from the National Heart, Lung, and Blood Institute (NHLBI) at NIH, and expanded studies of the genetic variations leading to asthma in a larger pediatric population of Washington, DC. Additionally, the center, in collaboration with the newly-formed Obesity Institute, worked to develop community-based interventions that integrate genetics and molecular mechanistic understanding into experimental design and research of metabolic syndrome, type 2 diabetes, and childhood obesity.
Programmatic Areas
Programmatic Areas
Publications and Sponsored Research
During the last year, center faculty published more than 45 peer-reviewed research papers and received research awards totaling $8.3 million. Nearly half of these publications were collaborative efforts between two or more center faculty, and typically were interdisciplinary and translational in nature. In addition, Adeline Vanderver, MD, received a prestigious American Academy of Neurology Foundation Fellowship.
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NIH Center Grants with Public Access Web Portals
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Muscular Dystrophies
Pre-clinical drug testing facility for muscular dystrophies
Transition of potential therapeutic approaches for muscular dystrophy from the laboratory bench to human clinical trials involves obtaining “pre-clinical” data in mouse models. Currently, there is no consensus on the methods and protocols to assess therapeutic efficacy in the mouse models of muscular dystrophy. Therefore, Kanneboyina Nagaraju, DVM, PhD, organized an international workshop (October 2007) at Children’s National to identify methods and draft guidelines for preclinical tests. The Children’s National workshop was sponsored by the DC-Wellstone network, NIH, and the nonprofit Foundation to Eradicate Duchenne, Inc. The workshop established a basis for the follow-up preclinical standard operating procedures workshop in Zurich in June 2008, which was organized by the European TREAT-NMD (neuromuscular disease) network. This is the first example of a successful collaboration between the Wellstone network and the European network. The pre-clinical drug testing facility made significant progress in the last year and so far has performed more than 20 preclinical efficacy trials sponsored by industry, foundations, and academic investigators in mouse models of DMD, limb girdle muscular dystrophy 2B (LGMD2B), and autoimmune myositis.
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Muscle Inflammation
Muscle inflammation is a characteristic feature of several genetic and autoimmune muscle diseases. Dr. Nagaraju and Eric Hoffman, PhD, recently uncovered novel mechanisms of muscle fiber damage in dysferlin deficiency, the underlying defect in LGMD2B. These findings form the basis for ongoing preclinical trials in LGMD2B. Dr. Nagaraju is funded by NIH to investigate immune and non-immune mechanisms of muscle fiber damage and dysfunction in autoimmune and genetic muscle disease. He also has several ongoing projects with Dr. Hoffman and Yi-Wen Chen, DVM, PhD, to investigate inflammatory processes in DMD and LGMD2B.
Susan Sparks, MD, PhD, received a Wellstone Translational Fellowship Award from the NIH, and studies the neurologic and muscle phenotypes of patients with undiagnosed congenital muscular dystrophies (CMD) caused by defects in enzymes that glycosylate alpha-dystroglycan and other components of the muscle fiber. It is anticipated that there are 10 to 15 steps involved in the O-mannosylation of alphadystroglycan and of these, six genes have been identified, with three having known function.
This year, Dr. Sparks continued to screen muscle from undiagnosed CMD patients for defects in glycosylation. She is a member of the newly organized consortium for congenital muscular dystrophies. In addition, she expanded her research to include the limb girdle muscular dystrophies (LGMD) caused by glycosylation defects, in particular LGMD-2I.
Supported by an NIH pilot grant from the Wellstone Muscular Dystrophy Center Yetrib Hathout, PhD, began studies of fibrosis in muscular dystrophy. Most muscular dystrophies show loss of muscle fiber integrity accompanied by progressive accumulation of connective tissue and other extracellular matrix proteins. The extracellular matrix (ECM) of muscle fibers is maintained by highly organized interaction between secreted proteins and cell surface proteins. Dr. Hathout’s laboratory initiated a pilot project study of the secretome and peripheral proteins in dystrophic versus normal muscle cells. This pilot study is supported by Wellstone Muscular Dystrophy Center Pilot Project fund and might lead to molecular mechanisms involved in fibrosis in muscular dystrophy.
Dr. Chen dissects the molecular pathophysiology of facioscapulohumeral muscular dystrophy (FSHD). By comparing genome-wide gene expression of FSHD to profiles generated from other neuromuscular disorders, the center found that paired-like homeodomain transcription factor 1 (PITX1) was specifically up-regulated in patients with FSHD. In collaboration with Dr. Alexandra Belayew at the University of Mons-Hainaut, Belgium, Dr. Chen’s group recently reported that DUX4 was expressed in myoblasts of patients with FSHD but not in those of healthy individuals. In addition, the DUX4 protein is a transcription activator of paired-like homeodomain transcription factor 1 (PITX1). A conditional muscle-specific Pitx1 transgenic mouse model was generated to study the function of the gene in skeletal muscles. Over-expression of Pitx1 leads to muscle atrophy and weakness in the transgenic mice with pathology similar to human FSHD. The model is a valuable tool to study the pathological mechanisms of muscle atrophy in FSHD and for developing treatments of the disease.
To study the effect of TGF_1 over-expression in skeletal muscles, a conditional muscle-specific TGF_1 transgenic mouse model was generated. The goal is to cross the TGF_1 transgenic mouse with the mdx mouse, an animal model of DMD, to study the involvement of TGF_1 in the progression of DMD.
The Cooperative Neuromuscular International Research Group (CINRG) underwent extensive restructuring in 2007–2008, including the recruitment of Avital Cnaan, PhD, from the Children’s Hospital of Philadelphia to direct the Statistics and Data Management Core for CINRG, and the promotion of Robert Leshner, MD, to medical director of the network. Formal by-laws were formulated by the 21 site international clinical trial group, a steering committee formed, and policies developed. The network completed a series of clinical trials, including demonstrating that weekend prednisone shows strong efficacy compared to daily steroids, and is working towards a public/private partnership to promote exon-skipping therapeutics in the United States.
Eric Hoffman, PhD, continued his productive research on the molecular pathophysiology of Duchenne dystrophy, Becker dystrophy, dysferlin-deficiency, and other muscle diseases. Research done collaboratively with the laboratory of Terence Partridge, PhD, showed clinical benefit of exon skipping (systemic morpholinos) in a dog model of Duchenne dystrophy.
Susan Knoblach, PhD, received pilot funding from the Wellstone Muscular Dystrophy Center for a project focused on evaluating the role of Rho-A and Rho kinases (ROCK1/2) in a mouse model of LGMD2B. The hypothesis for this work is that enhanced monocyte invasion, activation, and phagocytosis seen in LGMD2B patients contribute to myofiber inflammation and damage. Because the persistent expression of Rho-A and ROCK in monocytes is essential to their activation and engulfment activity, inhibition of Rho-A and ROCK may effectively block these processes. Dr. Knoblach is using the behavioral paradigms developed by Kanneboyina Nagaraju, DVM, PhD, to study whether oral Fasudil, a ROCK inhibitor, effectively delays behavioral deterioration, phagocytosis, inflammation and muscular degeneration in the SJL mouse model of LGMD2B. Fasudil was selected for evaluation because it is already used clinically for the treatment of other diseases; thus if it proves effective in this translational study it could quickly be tested as a potential treatment for human LGMD2B.
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Asthma and Respiratory Tract Diseases
The center continued to build interdisciplinary research programs with Children’s National clinical divisions of Emergency Medicine, Community Pediatric Health, Pulmonology, and Otolaryngology that focus on asthma, lung-complications of sepsis, otitis media (OM), and chronic rhinosinusitis (CRS). Additionally, in September 2007, the center was awarded a five year K12 Genomics of Lung grant from the National Heart, Lung, and Blood Institute (NHLBI) at NIH, which will markedly increase our ability to train young investigators in genetic and proteomic approaches to lung disease.
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Asthma
Asthma research continued its rapid growth within the center this past year through translational and multidisciplinary approaches. These may ultimately impact our understanding of host gene and environmental interactions and patient care, especially with regard to personalized medicine. In response to the inordinate rate of asthma in the pediatric population in Washington, DC, Robert Freishtat, MD, MPH, in collaboration with Stephen Teach, MD, MPH, of the Center for Clinical and Community Research, initiated, and now continues to expand, the AsthMaP (Asthma Severity Modifying Polymorphisms) Project with new patients and additional funding. They are studying 500 Washington, DC, asthmatic children to understand the genetic variations that lead to racial disparities in chronic asthma severity, medication responsiveness, and the effect of second-hand smoke. Additionally, a protein abnormally secreted by epithelial cells of asthmatic children in response to second-hand tobacco smoke has been identified (Dr. Freishtat), as has a secretory mucin that may be an innate immune responder to asthmatic triggers (Mary Rose, PhD).
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Mucin Hypersecretion in Respiratory Tract Diseases
The overproduction of mucins, e.g. mucin hypersecretion, by goblet and mucosal glandular cells contributes to the morbidity and/or mortality of diseases both in the upper and lower respiratory tracts. Mucin overproduction impacts the lower respiratory tract in asthma and cystic fibrosis (CF). Studies on the regulation of mucin gene expression by inflammatory mediators and of mucin gene repression by glucocorticoids (which are used during asthmatic exacerbations) are a focus of Dr. Rose. Goblet cell hyperplasia also contributes to mucin overproduction in lung diseases. Dr. Rose’s lab investigates pathways that lead to goblet cell metaplasia in IL-13 induced murine models of allergic asthma.
The mucin hypersecretion in children with chronic rhinosinusitis (CRS) reflects submucosal gland hyperplasia in the sinuses of the upper respiratory tract, as reported recently by Maria Pena, MD. Dr. Pena performed microarray expression profiling on sinus mucosa tissues from control patients, patients with CRS, and patients with CRS/CF and shown that previously unreported chemokines are markedly upregulated in the sinus mucosa of CRS patients. Together with Dr. Rose, she is developing an in vitro glandular model system to investigate pathways that lead to glandular development in respiratory tracts, studies of which may ultimately impact the ability to revert glandular hyperplasia.
Mucin hypersecretion also contributes to the pathology of otitis media (OM). Mechanisms that lead to OM are being investigated by Diego Preciado, MD, now a K12 Genomics of Lung Scholar who is investigating the effect of cytokines and of tobacco smoke on mucin gene regulation in middle ear epithelial cells in vitro and in vivo. Dr. Preciado found that dissolved cigarette smoke particulate matter increases secretory mucin gene expression in cultured cells, providing a mechanistic link to explain the increased relative risk of OM in children with environmental smoke exposure.
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Lung-Related Diseases
Lung-related research by center investigators involved the Center for Genetic Medicine Research, clinical divisions and other faculty Children’s National, and other medical centers. This year Dr. Freishtat led Children’s efforts on behalf of NIHfunded multicenter studies of genetic changes in overwhelming infections (sepsis) in children and inherited disorders of blood platelets. Additionally, his studies identified a new blood platelet protein target for sepsis treatment.
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Urea Cycle Disorders
The Center for Genetic Medicine has become a leading international center for the study of rare disorders, including research on congenital urea cycle disorders. Hiroki Morizono, PhD, Ljubica Caldovic, PhD, Daniel Shi, PhD, and Mendel Tuchman, MD, discovered new protein:protein interactions among the mitochondrial urea cycle enzymes, and explored new extrahepatic roles of the urea cycle genes.
Building on his recent discovery of two novel pathways of microbial arginine biosynthesis, Dr. Morizono has synthesized a specific inhibitor of acetylornithine transcarbamylase. He identified a multiply antibiotic resistant pathogen, Stenotrophomonas maltophilia that requires this enzyme for arginine biosynthesis. An R21 grant was submitted to further study S. maltophilia and the bacteriocidal or bacteriostatic effects of this inhibitor as a potential treatment of S. maltophilia infections. Dr. Morizono also began work on a preclinical study of adenoassociated gene therapy of ornithine transcarbamylase deficiency with funding from a new NIH program project grant awarded to Mark Batshaw, MD, and his long term collaborator, James Wilson, MD, PhD, at the University of Pennsylvania.
Dr. Caldovic’s laboratory showed that the protein:protein interactions of enzymes in the urea cycle are mediated by post-translational modification of N-acetylglutamate synthase (NAGS). These data were the basis for a model of how post-translational modification of NAGS regulates the activity of the urea cycle. Insights from this model better explain how patients with the same mutation can have very different presentations of hyperammonemia. Dr. Caldovic received an NIH K01 award to study the molecular mechanisms regulating the amounts of urea cycle enzymes in response to changing dietary nitrogen loads.
Dr. Shi succeeded in determining the very first crystal structures of any NAGS and is using the insights derived from this structure to improve the quality of NAGS crystals from other organisms.
Dr. Tuchman was awarded an R01 to study carbamylglutamate in treating patients with hyperammonemia. These pre-clinical studies link directly to the NIH Rare Diseases Clinical Research Center in Urea Cycle Disorders, directed by Dr. Batshaw and Dr. Tuchman, which is housed under the Center for Clinical and Community Research.
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Type 2 Diabetes, Inactivity, and Obesity
Eric Hoffman, PhD, continued a series of NIH-funded studies of genetic predispositions to metabolic syndrome and endophenotypes of type 2 diabetes in children and young adults. Dr. Hoffman’s group is working closely with the newly-formed Obesity Institute at Children’s National (Denice Cora-Bramble, MD, MBA) to develop community-based interventions that integrate genetics and molecular mechanistic understanding into experimental design and research. Chiatogu Onyewu, MD, PhD, received a prestigious UNFMerck fellowship to pursue research with Dr. Hoffman, as well as an NIH-supplement for studies of Howard University students with regards to metabolic syndrome.
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White Matter and Spinal Cord Disorders
Adeline Vanderver, MD, spearheaded research on white matter disorders (leukodystrophies), funded by a prestigious young investigator fellowship from the American Academy of Neurology Foundation. Her research on vanishing white matter disease, a progressive neurologic disorder of children where a mild viral illness may trigger a sudden and potentially fatal loss of white matter, has made significant progress. Working together with Yetrib Hathout, PhD, Dr. Vanderver’s group published a new biomarker in cerebrospinal fluid for vanishing white matter disease, and also is using proteomic approaches to study the mechanisms of neurodegeneration in this disease. Her laboratory has become a national referral center for these patients and other leukodystrophies. In addition, she hosted a national research/parent conference on Aicardi Goutieres Syndrome (another white matter disorder) in September 2008.
A time series proteome profiling study of the reticulum endoplasmic stress response was published by the Hathout and Vanderver groups in the Journal of Proteomes Research (Mintz et al. 2008). In this study they report the discovery of new proteins as key players in Ca2+ homeostasis during endoplasmic reticulum (ER) stress response. This strategy could be widely implemented to study protein trafficking in a number of human pathologies involving ER stress response. Work continues on the spinal cord injury expression profiling data set described in previous years’ reports. This year, Susan Knoblach, PhD, and Jinwook Seo, PhD, produced and tested a web-based interface that makes this database more user-friendly to biologists who may not have experience with microarray analysis. Dr. Seo designed and implemented a web site, SpinalCordLink, which allows users to search for major pathways and genes of interest within the database or within their own data. The web site is freely accessible and uses GenMapp/Wikipathways open-access tools, which are maintained by the scientific community. Thus, the web site enables users to analyze the enormous amount of information that is available within the database without resorting to costly, proprietary, pathway-driven software.
Susan Knoblach, PhD, and Bruce Lerman, a George Washington University PhD student, also continue work on the role of galectins in amyotrophic lateral sclerosis (ALS). Recently, Mr. Lerman cross-bred galectin 3 knock-out mice with the ALS mouse (human SOD1 gain of function mouse) and is evaluating behavioral and glutamatergic function in the galectin-3 KO/SOD1 mice over time. These studies will help determine how galectin-3 modulates glutamateinduced excitotoxicity, as well as what effect this has on the progression of ALS and neurodegeneration.
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Age-Related Macular Degeneration (AMD)
The proteomics laboratory directed by Yetrib Hathout, PhD, greatly expanded this last year to include studies on agerelated macular degeneration (AMD), vanishing white matter disease, pediatric brain tumors, and neurofibromatosis type 1. This year Hathout et al. published several proteomics application manuscripts in prestigious journals. Stable isotope labeling by amino acid in cell cultures (SILAC) is used in the laboratory to quantify protein secretion and trafficking in different systems.
AMD is the leading cause of blindness in the elderly population and is characterized by macular deposits called drusen that occur beneath the retinal epithelium (RPE) and Bruch’s membrane. Dr. Hathout’s laboratory focuses on the study of RPE secreted proteins and their role in AMD pathology. They discovered that TNF-alpha modulates secretion of specific proteins that are involved in pathways relevant to AMD pathology (e.g. complement pathway).
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Neuro-Oncology
Yetrib Hathout, PhD, initiated a collaborative program with the Center for Cancer and Immunology Research (Tobey Macdonald, MD, and Brian Rood, MD) to tackle pediatric brain tumors for biomarker and therapeutic targets discovery. The program is supported by philanthropic donations and the NIH Pediatric Brain Tumor Consortium. The group published the first manuscript describing the proteome profiling of brain stem glioma using formalin fixed tissue (Nazarian et al. Proteomics. 2008).
Dr. Hathout’s laboratory also initiated a new collaboration with Children’s clinical Division of Neurology (Roger Packer, MD, executive director of the Center for Neuroscience and Behavioral Medicine) to study molecular mechanisms of neurofibromatsosis type 1 (NF-1). This study is supported by large philanthropic gift to improve understanding of molecular mechanism of NF-1 in children and define new therapeutic targets for treatments.
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Kidney Disease
Urinary Tract Infections (UTI), Vesicoureteral Reflux and Renal Scarring
This year the clinical Division of Urology succeeded in being awarded two grants from the National Institute of Diabetes, Digestive and Kidney Diseases (NIDDK), as part of a multiinstitutional research consortium for the purpose of studying children presenting with symptomatic urinary tract infections (UTI) with and without vesicoureteral reflux (VUR). These landmark studies are: (1) Randomized Intervention in Children with Vesicoureteral Reflux (RIVUR) and (2) Careful Urinary Tract Infection Evaluation (CUTIE). The specific aims of these clinical protocols include identifying clinical risk factors that predispose some children to recurrent UTIs and to progressive renal scarring. These awards also position the Division of Urology to submit an application to the NIH/ NIDDK for an ancillary study to access the tissue samples obtained from both of these protocols and stored at the NIH to investigate whether certain SNPs are responsible for modifying the risk for recurrent UTIs and renal scarring. These projects are under the supervision of Hans Pohl, MD, whose team presented work using an experimental model of UTI in the piglet at the National Kidney Foundation Scholar’s Day to demonstrate that renal scarring begins significantly earlier than had been previously thought.
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