Regulation of the epithelial Ca2+ channels TRPV5 and TRPV6 by 1α,25-dihydroxy vitamin D3 and dietary Ca2+

Active, transepithelial Ca2+ transport is a pivotal process in the regulation of Ca2+ homeostasis and consists of three sequential steps: apical Ca2+ influx, diffusion towards the basolateral membrane and subsequent extrusion into the blood compartment. TRPV5 and TRPV6 (renamed after ECaC1 and ECaC2/CaT1, respectively) constitute the rate-limiting influx step of transepithelial Ca2+ transport and these highly selective Ca2+ channels are controlled by several factors. This review focuses on the regulation of TRPV5 and TRPV6 abundance and/or activity by 1alpha,25-dihydroxyVitamin D-3 (1alpha,25(OH)(2)D-3), dietary Ca2+ and the auxiliary protein pair S100A10/annexin 2. Finally, the implications for our understanding of transcellular Ca2+ transport will be discussed. (C) 2004 Elsevier Ltd. All rights reserved.