The effect of differentiation on 1,25 dihydroxyvitamin D‐mediated gene expression in the enterocyte‐like cell line, Caco‐2

Abstract

We examined 1,25 dihydroxyvitamin D (1,25(OH) 2 D 3 )-induced expression of 25-hydroxyvitamin D 3 24-hydroxylase (CYP24) and apical calcium channel (TRPV6) mRNA levels in 2, 9 and 15 day cultures Caco-2 cells that model proliferating, post-proliferative, and differentiated enterocytes. 1,25(OH) 2 D 3 -induced (10 nM, 8 h) CYP24 and TRPV6 mRNA levels were significantly greater in differentiated and post-proliferative than proliferating Caco-2 cells (> 16X and > 3X, respectively). Neither CYP24 mRNA half-life nor induction of a -298 bp rat CYP24 promoter-luciferase reporter construct (10 nM 1,25(OH) 2 D 3 , 24 h) were different between proliferating and post-proliferating Caco-2 cells. We next tested whether the blunted response of natural genes to 1,25(OH) 2 D 3 in proliferating Caco-2 cells is due to altered chromatin remodeling. VDR and coactivator protein levels do not increase with differentiation but the level of the corepressor Alien falls by 50% with differentiation. Over-expression of Alien reduced 1,25(OH) 2 D 3 -induced activity of a minimal VDRE containing promoter-luciferase construct by more than 60% in differentiated Caco-2 cells while siRNA knockdown of Alien in proliferating Caco-2 cells increased 1,25(OH) 2 D 3 -induced CYP24 mRNA level by 40%. These observations suggest that Alien is a regulator of VDR-mediated gene transcription in Caco-2 cells. In addition, we found that 1,25(OH) 2 D 3 -induced association of VDR with chromatin and with the CYP24 promoter was lower in proliferating cells. This suggests that decreased recruitment of VDR to vitamin D response elements also contributes to the blunted transcriptional responsiveness to 1,25(OH) 2 D 3 in proliferating Caco-2 cells.

Vitamin D3 and Its Nuclear Receptor Increase the Expression and Activity of the Human Proton-Coupled Folate Transporter

“…1B). It has been reported that vitamin D 3 -induced gene expression increases as Caco-2 cells differentiate (Cui et al, 2009). Thus, our current findings on VDRmediated regulation of PCFT expression provide a possible molecular mechanism for a prior observation that folate uptake into Caco-2 cells is enhanced upon confluence-associated differentiation (Subramanian et al, 2008b).…”

Quercetin Enhances VDR Activity, Leading to Stimulation of Its Target Gene Expression in Caco-2 Cells

“…It has been considered that TRPV6, which is a calcium channel found on the luminal side of the epithelial cells ( 21 ), functions as a gatekeeper of calcium entry across epithelia. A previous study demonstrated that 1,25-(OH) 2 D 3 -induced TRPV6 mRNA level is significantly greater in differentiated Caco-2 cells than in undifferentiated Caco-2 cells ( 22 ). It should be noted that quercetin efficiently increased the level of TRPV6 mRNA in undifferentiated Caco-2 cells rather than in differentiated Caco-2 cells in the present study.…”

New tools to assess toxicity, bioaccessibility and uptake of chemical contaminants in meat and seafood

“…Caco-2, Fig. 1e; T84; HT29) do not derive from the small intestine, have tumorigenic phenotype distinct from the normal intestinal epithelia, different growth properties, signalization, and express modified surface glycoconjugates (Cui, Klopot, Jiang, & Fleet, 2009;Takahashi et al, 1996). These tumorigenic cell lines are mostly cultivated as monolayers on plastic surfaces in experimental models, where the establishment of functional epithelial character is not defined (Tremblay et al, 2006).…”