Vitamin D increases tight-junction conductance and paracellular Ca21 transport in Caco-2 cell cultures
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چکیده
Chirayath, Mary V., Leszek Gajdzik, Wolfgang Hulla, Jürg Graf, Heide S. Cross, and Meinrad Peterlik. Vitamin D increases tight-junction conductance and paracellular Ca21 transport in Caco-2 cell cultures. Am. J. Physiol. 274 (Gastrointest. Liver Physiol. 37): G389–G396, 1998.—We investigated the effects of 1a,25-dihydroxyvitamin D3 [1,25(OH)2D3] on paracellular intestinal Ca21 absorption by determination of transepithelial electric resistance (TEER), as a measure of tight-junction ion permeability and bidirectional transepithelial 45Ca21 fluxes in confluent Caco-2 cell cultures. The rise of TEER to steady-state levels of ,2,000 V · cm2 was significantly attenuated by 1,25(OH)2D3 (by up to 50%) in a dose-dependent fashion between 10211 and 1028 M. Synthetic analogs of 1,25(OH)2D3, namely, 1a,25-dihydroxy16-ene,23-yne-vitamin D3 and 1a,25-dihydroxy-26,27-hexafluoro-16-ene,23-yne-vitamin D3, exhibited similar biopotency, whereas their genomically inactive 1-deoxy congeners were only marginally effective. Enhancement of transepithelial conductance of Caco-2 cell monolayers by vitamin D was accompanied by a significant increase in bidirectional transepithelial 45Ca21 fluxes. Although 1,25(OH)2D3 also induced cellular 45Ca21 uptake from the apical aspect of Caco-2 cell layers and upregulated the expression of calbindin-9kDa mRNA, no significant contribution of the Ca21-adenosinetriphosphatase-mediated transcellular pathway to transepithelial Ca21 transport could be detected. Therefore stimulation of Ca21 fluxes across confluent Caco-2 cells very likely results from a genomic effect of vitamin D sterols on assembly and permeability of tight-junctional complexes.
منابع مشابه
Vitamin D increases tight-junction conductance and paracellular Ca2+ transport in Caco-2 cell cultures.
We investigated the effects of 1α,25-dihydroxyvitamin D3[1,25(OH)2D3] on paracellular intestinal Ca2+absorption by determination of transepithelial electric resistance (TEER), as a measure of tight-junction ion permeability and bidirectional transepithelial45Ca2+fluxes in confluent Caco-2 cell cultures. The rise of TEER to steady-state levels of ∼2,000 Ω ⋅ cm2 was significantly attenuated by 1,...
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