The overall goal of this proposal is to build a new interdisciplinary research team of investigators from population genetics and from the molecular genetics laboratory to begin the task of establishing whether the novel findings from genome-wide association studies (GWAS) can be shown to be functionally important to skeletal biology. This will be accomplished through a new collaboration between the genetic epidemiology group of Dr. Douglas P. Kiel, Associate Professor of Medicine at Harvard Medical School, who has been the principal investigator of the Framingham Osteoporosis Study for the past 20 years, and the cellular biology and molecular genetics group of Dr. Laurie Glimcher, Irene Heinz Given Professor of Immunology at Harvard School of Public Health and Professor of Medicine at Harvard Medical School.
The aim of this project is to take advantage of results from the largest available GWAS meta-analysis of bone mineral density (BMD) traits that were generated by the parent grant (R01 AR/AG 41398) and combine this with large-scale functional RNAi screens performed in relevant bone cell culture systems to identify a defined list of genes with both genetic and functional evidence of association with osteoporosis. Specifically, we will use the results from our GWAS meta-analysis in close to 40,000 individuals from European descent to select 300 novel candidate genes for """"""""ribonucleic acid interference"""""""" (RNAi) screening. Selection of the most promising 300 candidates will be based on bioinformatic studies. Genes that are already well-known regulators of bone metabolic pathways will not be selected. Instead, novel genes will be selected based on the demonstration that single nucleotide polymorphisms (SNPs) from the GWAS results are associated with increased expression of the gene in various tissue sample and cell culture databases available to us. We hypothesize that many of the novel genes identified via the GWAS will have direct functional relevance (as demonstrated by the RNAi screens) in the cells that govern bone metabolism: the osteoblast and osteoclast. The most promising two novel candidates will then be further validated by measuring skeletal indices in knock out animals. This BIRT project addresses the current challenge of taking the results emerging from GWAS and developing methods of testing the functional significance of novel new candidate genes. The combined expertise of the two groups is expected to lead to significant advances beyond the progress expected from the individual researchers alone because Dr. Kiel's parent grant would not otherwise be able to take the results from the GWAS to screening of novel genes for their functional importance to skeletal biology. This elucidation of the genetics of bone physiology is a current focus of NIAMS long range strategic plan for which several recent program announcements and funding opportunity announcements have been issued. Dr. Kiel's group will initially derive the most promising findings from GWAS meta-analysis and this will be followed by Dr. Glimcher's laboratory performing the RNAi screens and phenotypic validation in knock out mice. These initial efforts are expected to lead to a future collaboration that will expand the work to include multiple skeletal phenotypes. Furthermore, once the novel functional genes are confirmed, additional studies will move to fine mapping and sequencing of human samples to find common and rare variants associated with the skeletal phenotypes.
The public health importance of this project is that it will create a new interdisciplinary research team of investigators from two different disciplines. The first group is involved with the discovery of novel genes related to osteoporosis, and the second group employs modern molecular genetic techniques to confirm whether these newly identified genes are actually important for skeletal health. Ultimately this could lead to the development of new treatments for osteoporosis.
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