title: Vitamin D upregulates expression of ECaC1 mRNA in semicircular canal.
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.
authors.affiliation: Cellular Biophysics Laboratory, Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, USA.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Yamauchi
authors.forename: Nithya N
authors.initials: NN
authors.lastname: Raveendran
authors.forename: Satyanarayana R
authors.initials: SR
authors.lastname: Pondugula
authors.forename: Suresh B
authors.initials: SB
authors.lastname: Kampalli
authors.forename: Joel D
authors.initials: JD
authors.lastname: Sanneman
authors.forename: Donald G
authors.initials: DG
authors.lastname: Harbidge
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Marcus
mesh_terms: D000818:Animals; D001483:Base Sequence; D002117:Calcitriol / Q000494:pharmacology*; D015220:Calcium Channels / Q000235:genetics*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D017931:DNA Primers; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012665:Semicircular Canals / Q000378:metabolism*; D019831:Sodium-Calcium Exchanger / Q000378:metabolism; D050916:TRPV Cation Channels; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D015220:Calcium Channels; D017931:DNA Primers; D012333:RNA, Messenger; D019831:Sodium-Calcium Exchanger; D050916:TRPV Cation Channels; C492241:TRPV5 protein, rat; D000252:Calcium-Transporting ATPases; D002117:Calcitriol