Vitamin D-inducible calcium transport and gene expression in three Caco-2 cell lines.
The parental cell line (P) of Caco-2 cells and two clones, BBe and TC7, were studied at 11 days postconfluence to test the facilitated diffusion model of vitamin D-mediated intestinal calcium absorption (CaTx). Nuclear vitamin D receptor (nVDR) and calbindin D(9k) (CaBP) were measured by Western blot; 1,25-hydroxyvitamin D(3) 24-hydroxylase (CYP24), CaBP, plasma membrane Ca-ATPase (PMCA), and Ca transport channel (CaT1) mRNA levels were examined by RT-PCR; and net apical-to-basolateral CaTx was examined after treating cells with vehicle or 10 nM calcitriol for 8 (mRNA levels) or 48 h (protein, CaBP mRNA, CaTx). nVDR level was lowest in BBe (38% P value) and directly related to CYP24 induction (TC7 = P, which were 1.56 times greater than BBe). nVDR was inversely related to the vitamin D-induced levels of CaT1 mRNA, CaBP mRNA, PMCA mRNA, and net CaTx, with the highest induction seen in BBe. Basal CaBP mRNA (86 times greater than P) and protein levels were highest in TC7 cells and were not associated with higher net CaTx, suggesting CaBP may not be rate limiting for CaTx in these cells.
Fleet
James C
JC
Department of Foods and Nutrition, Purdue University, West Lafayette, Indiana 47906, USA. fleetj@cfs.purdue.edu
Eksir
Faria
F
Hance
Kenneth W
KW
Wood
Richard J
RJ
D000042:Absorption; D001692:Biological Transport / Q000187:drug effects; D018938:Caco-2 Cells; D064026:Calbindins; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000235:genetics; D000252:Calcium-Transporting ATPases / Q000235:genetics; D002462:Cell Membrane / Q000201:enzymology; D002467:Cell Nucleus / Q000378:metabolism; D002999:Clone Cells; D015870:Gene Expression / Q000187:drug effects*; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D018167:Receptors, Calcitriol / Q000378:metabolism; D064030:S100 Calcium Binding Protein G / Q000235:genetics / Q000378:metabolism; D050916:TRPV Cation Channels; D014807:Vitamin D / Q000494:pharmacology*
D064026:Calbindins; D015220:Calcium Channels; D012333:RNA, Messenger; D018167:Receptors, Calcitriol; D064030:S100 Calcium Binding Protein G; D050916:TRPV Cation Channels; C120776:TRPV6 channel; D014807:Vitamin D; D000252:Calcium-Transporting ATPases; D002118:Calcium