title: Extrarenal vitamin D activation and interactions between vitamin D₂, vitamin D₃, and vitamin D analogs.
abstract: Our understanding of the mechanism of action of vitamin D has been broadened by the discovery of the extrarenal 1α-hydroxylase (CYP27B1) in various vitamin D target tissues around the body and the implications of this for the putative paracrine actions of 1α,25-dihydroxyvitamin D₃. This review updates our current knowledge of the cytochrome P450-mediated steps of vitamin D activation (CYP2R1, CYP27B1) and inactivation (CYP24A1, CYP3A4) and the newest physiological roles of vitamin D. The review goes on to examine how well exogenously supplied vitamin D compounds, whether dietary vitamin D₂ supplements or prescribed vitamin D analogs, substitute for their natural counterparts; how in some cases vitamin D can be used in conjunction with vitamin D analogs; and the overall impact of these supplements and drugs on the components of the vitamin D signal transduction machinery.
authors: Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada K7L 3N6. gj1@queensu.ca
authors: Glenville
authors: G
authors: Jones
mesh_terms: D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000378:metabolism*; D000818:Animals; D002762:Cholecalciferol / Q000031:analogs & derivatives / Q000378:metabolism / Q000627:therapeutic use; D004032:Diet / Q000009:adverse effects; D019587:Dietary Supplements; D004872:Ergocalciferols / Q000737:chemistry / Q000378:metabolism / Q000627:therapeutic use; D006801:Humans; D015398:Signal Transduction; D014807:Vitamin D / Q000031:analogs & derivatives / Q000378:metabolism* / Q000627:therapeutic use; D014808:Vitamin D Deficiency / Q000178:diet therapy / Q000209:etiology / Q000378:metabolism
chemical_list: D004872:Ergocalciferols; D014807:Vitamin D; D002762:Cholecalciferol; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase