Characterization of Plasma Membrane Vitamin D Receptor

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DESCRIPTION (provided by applicant): Historically Black Colleges and Universities like Lincoln University are a major source of under represented students graduating with science degrees . Successful candidates to graduate and professional schools often have research experience obtained during their undergraduate years. To increase the competitiveness of our undergraduate students it is desirable to develop a competitive research program at Lincoln University. Therefore, the PI is seeking the research experience described below. This research will provide Lincoln students and PI with projects involving physiology, endocrinology, and molecular biology. The research plan focuses on characterization of a candidate mammalian plasma membrane vitamin D receptor (pmVDR). The best described active vitamin D metabolite, 1,25(OH)2D3, operates through nuclear receptor-mediated and plasma membrane- initiated mechanisms that are pharmacologically separable. The identity of a nuclear receptor is well documented, but the identity of an unequivocal membrane receptor for 1,25(OH)2D3 remains unknown. A 66kD protein from chicken intestine basal lateral membrane has been isolated by Nemere and colleagues and identified as a candidate receptor. The PI and collaborator have identified a candidate binding protein for the pmVDR whose N terminus is identical to that of the 66kD protein. They hypothesize that this recently identified l pmVDR participates in the generation of rapid responses in target cells to 1,25(OH)2D3. This application describes studies that will permit the evaluation of various expression constructs and transfected cell lines for the development of an optimal system for studying the physiology of the candidate pmVDR. Specifically, they will measure differences in the levels of rapid responses to 1,25(OH)2D3 in transfected cells compared to nontransfected controls. They will study tissue expression of the candidate pmVDR using various antibodies raised against different lengths of the sequence and use bioinformatics to help determine some of the proteins potential functions. These results might help lead to the development of new bioactive sterols with improved therapeutic potential and fewer side effects such as hypercalcemia.