Specific 1,25(OH)2D3-mediated regulation of transcellular calcium transport in Caco-2 cells.
Calcium transport in the apical-to-basolateral (A-to-B) or B-to-A direction was examined in cells treated with 10 nM 1, 25-dihydroxyvitamin D3 [1,25(OH)2D3, calcitriol] for up to 72 h. Net A-to-B calcium transport was positive at all time points and increased from 0.14 +/- 0.06 to 0.50 +/- 0.01 nmol. well-1. min-1 after 72 h of calcitriol treatment. Neither phenol red transport nor transepithelial electrical resistance was altered by calcitriol treatment, suggesting that the increase in net A-to-B calcium transport was not due to paracellular movement. Neither 25-hydroxyvitamin D3 nor 24,25-dihydroxyvitamin D3 (100 nM, 48 h) alters basal or calcitriol-stimulated A-to-B calcium transport. Treatment with the calmodulin antagonist trifluoperazine (50 microM) reduced calcitriol-stimulated A-to-B Ca transport by 56%. The transcription inhibitor actinomycin D inhibited calcitriol-regulated A-to-B calcium transport as well as calbindin D9k and 24-hydroxylase mRNA accumulation. These data demonstrate that calcitriol-mediated A-to-B calcium transport in Caco-2 cells is a specific, transcellular process that requires transcriptional events normally mediated through the vitamin D receptor.
Fleet
J C
JC
Department of Nutrition and Foodservice Systems, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, USA. jim_fleet@uncg.edu
Wood
R J
RJ
D015650:24,25-Dihydroxyvitamin D 3 / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D018938:Caco-2 Cells; D002112:Calcifediol / Q000494:pharmacology; D002117:Calcitriol / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000037:antagonists & inhibitors; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D006706:Homeostasis; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000187:drug effects; D014268:Trifluoperazine / Q000494:pharmacology
D002147:Calmodulin; D003609:Dactinomycin; D014268:Trifluoperazine; D015650:24,25-Dihydroxyvitamin D 3; D003513:Cycloheximide; D002117:Calcitriol; D002112:Calcifediol; D002118:Calcium