Vitamin D is a prohormone for the daughter metabolite 1 alpha,,25(OH)2D3, which is a steroid hormone. As a consequence of being highly conformationally flexible, la,25(OH)2D3 presents a wide variety of shapes to its cellular environment. This in turn allows the generation of a variety of biological responses by activation of signal transduction pathways via one or more receptors involved in the production of either classic genotropic transcription of genes and/or rapid non-geriotropic biological responses. The 1 alpha,25(OH)2D3-mediated transcription of genes has been well studied and it is known to regulate a variety of cells and tissues. Conversely, the non-genotropic responses being activated by 1alpha,25(OH)2D3 appear to be mediated by a different signal pathway since the time frame of these responses which occur from seconds to minutes contrary to the genotropic frame of hours. Additionally, these types of responses can be separated from each other using a variety of path or action-specific derived analogs for 1 alpha,25(OH)2D3. The relevance to this proposal occurs in the study of the latter mechanism, in which a putative membrane receptor is believed to be responsible for mediating these responses. Thus, I propose to isolate and biochemical characterize the protein(s) responsible of 1 a,25(OH)2D3-mediated nongenotropic responses in plasma membrane invaginations or vesicles called caveolae. In other systems, caveolae have been linked to other steroid mediated rapid responses in which receptors to the respective ligands were shown to reside.
We aim to isolate and purify the proposed membrane receptor which selectively binds 1 a,25(OH)2D3 with high affinity. This followed by characterization of the protein, leading to cloning and expression to learn its biological properties.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Predoctoral Individual National Research Service Award (F31)
Project #
1F31DK062673-01
Application #
6552044
Study Section
Special Emphasis Panel (ZRG1-F10 (29))
Program Officer
Hyde, James F
Project Start
2002-08-01
Project End
2006-07-31
Budget Start
2002-08-01
Budget End
2003-07-31
Support Year
1
Fiscal Year
2002
Total Cost
$25,211
Indirect Cost
Name
University of California Riverside
Department
Biochemistry
Type
Schools of Earth Sciences/Natur
DUNS #
City
Riverside
State
CA
Country
United States
Zip Code
92521
Olivera, Christopher J; Bula, Craig M; Bishop, June E et al. (2004) Characterization of five 19-nor-analogs of 1alpha,25(OH)2-Vitamin D3 with 20-cyclopropyl-modified side-chains: implications for ligand binding and calcemic properties. J Steroid Biochem Mol Biol 89-90:99-106
Huhtakangas, Johanna A; Olivera, Christopher J; Bishop, June E et al. (2004) The vitamin D receptor is present in caveolae-enriched plasma membranes and binds 1 alpha,25(OH)2-vitamin D3 in vivo and in vitro. Mol Endocrinol 18:2660-71
Norman, Anthony W; Olivera, Christopher J; Barreto Silva, Fatima R M et al. (2002) A specific binding protein/receptor for 1alpha,25-dihydroxyvitamin D(3) is present in an intestinal caveolae membrane fraction. Biochem Biophys Res Commun 298:414-9