ELUCIDATING THE ROLE OF COATOMER COMPLEX COPI IN SKELETAL DYSPLASIA

项目总结

PROJECT SUMMARY This proposal describes a five-year mentored training experience designed to prepare the applicant for a career in basic and translational science research. The applicant holds M.D. and Ph.D. degrees, and is certified by the American Board of Medical Genetics and Genomics. The applicant’s long-term goal is to become a physician- scientist studying the molecular genetic basis of skeletal dysplasias. The career development plan includes mentorship, formal coursework, lab meetings, seminars, national conferences, and meetings with the advisory committee. The plan is designed to broaden the applicant’s research skills, including coursework and experimental learning in model organisms, glycoproteomics, microscopy imaging, and biostatistics. In addition, the proposed plan will provide training in leadership, mentorship, laboratory management, scientific writing and editing, grant writing, and the ethical implications of research. The Department of Molecular and Human Genetics at Baylor College of Medicine has a long track record of training highly successful physician scientists. The mentor, Dr. Brendan Lee, is a leading expert in the field of skeletal dysplasia and has been the primary research mentor for over 9 K and VA career development awardees, all of whom have gone onto independent laboratory- research based careers. The advisory committee was selected to complement the mentor’s expertise and to provide important research and career guidance for the applicant. The proposed study will investigate the functional, cellular, and biochemical consequences of COPB2 haploinsufficiency in bone. Loss-of-function variants in COPB2, a subunit of the COPI coatomer complex, were identified in children with developmental delay and bone fragility. The COPI functions in trafficking between the ER and Golgi, and within the Golgi cisternae. Vesicular trafficking defects, including COPI dysfunction, have been implicated in skeletal dysplasia. Preliminary data demonstrated that Copb2+/- mice exhibit a low bone mass phenotype, and copb2-null zebrafish embryos show abnormal secretion of procollagen. The applicant proposes that COPB2 deficiency leads to bone fragility by causing delayed collagen trafficking, Golgi-ER dysfunction, and altered autophagy, resulting in disruption of osteoblast differentiation. The proposed study involves analysis of the skeletal phenotype in COPB2-deficient mouse models, including selective deletion of Copb2 in bone during specific stages of osteoblast cell differentiation (“conditional knock-out”). By taking this approach, the applicant will determine at which time point during skeletal development the deficiency of COPB2 becomes critical. The proposed study also aims to check if COPB2 deficiency alters protein glycosylation, and causes an ER-Golgi dysfunction, and whether these changes may be amenable to therapy. The study will involve the analysis of COPB2-deficient mouse models and cells. This application, which provides a broad research experience and utilizes advanced technologies, and the proposed career development plan will prepare this applicant for a career as an independent research scientist.