Vitamin D upregulates expression of ECaC1 mRNA in semicircular canal

Biochem Biophys Res Commun. 2005 Jun 17;331(4):1353-7. doi: 10.1016/j.bbrc.2005.04.053.

Abstract

The low luminal Ca2+ concentration of mammalian endolymph in the vestibular labyrinth is required for normal balance. We found transcripts in primary cultures of semicircular canal duct (SCCD) epithelial cells from neonatal rats representing a complete transport system for transepithelial absorption of Ca2+ that is comprised of the epithelial Ca2+ channels ECaC1 (CaT2, TRPV5) and ECaC2 (CaT1, TRPV6), calbindin (calbindin-D9k, calbindin-D28k), Na+/Ca2+ exchanger (NCX1, NCX2, and NCX3), and plasma membrane Ca2+-ATPase (PMCA1, PMCA3, and PMCA4) by RT-PCR. Further, vitamin D receptor was also expressed in SCCD and it was found by quantitative RT-PCR that incubation for 24 h with 1,25-dihydroxyvitamin D3 upregulated the expression of ECaC1, calbindin-D9k, and calbindin-D28k. These observations provide evidence for the first time of an ECaC-based Ca2+ transport system in SCCD that could maintain the low Ca2+ concentration in vestibular endolymph.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Base Sequence
  • Calcitriol / pharmacology*
  • Calcium Channels / genetics*
  • Calcium-Transporting ATPases / metabolism
  • Cell Membrane / enzymology
  • Cells, Cultured
  • DNA Primers
  • RNA, Messenger / genetics*
  • Rats
  • Rats, Wistar
  • Reverse Transcriptase Polymerase Chain Reaction
  • Semicircular Canals / metabolism*
  • Sodium-Calcium Exchanger / metabolism
  • TRPV Cation Channels
  • Up-Regulation / drug effects*

Substances

  • Calcium Channels
  • DNA Primers
  • RNA, Messenger
  • Sodium-Calcium Exchanger
  • TRPV Cation Channels
  • TRPV5 protein, rat
  • Calcium-Transporting ATPases
  • Calcitriol