Protein kinase C is involved in 24-hydroxylase gene expression induced by 1,25(OH)2D3 in rat intestinal epithelial cells.
Effects of protein kinase C (PKC) inhibitor and activator on 1,25(OH)2D3-induced gene expression were examined in rat intestinal epithelial cells, IEC-6 cells. A potent PKC inhibitor, H-7 (20 microM), completely abated 1,25(OH)2D3-induced 24-hydroxylase gene expression at 3 and 6 h. The effect of H-7 was dose dependent with IC50 around 5 microM. Other protein kinase inhibitors, HA-1004 and H-89 (20 microM), had no effects. Furthermore, the activation of PKC by 12-O-tetradecanoylphorbol-13-acetate (TPA) potentiated the effect of 1,25(OH)2D3 by 1 h. TPA appeared to exert its effect at a transcriptional step, since mRNA stability was not affected by TPA treatment. At 3 h after the treatment of the cells with H-7 and TPA, vitamin D receptor (VDR) contents estimated by 3H-1,25(OH)2D3 binding capacity were 72.4 and 63.2% of vehicle-treated cells without significant changes of binding affinities, suggesting that the effect of H-7 and TPA was not the result of changes in VDR content or its binding affinity. In conclusion, PKC is involved in 1,25(OH)2D3-induced 24-hydroxylase gene expression in IEC-6 cells between 1,25(OH)2D3-VDR binding and VDR-induced gene transactivation.
Koyama
H
H
Second Department of Internal Medicine, Osaka City University Medical School, Japan.
Inaba
M
M
Nishizawa
Y
Y
Ohno
S
S
Morii
H
H
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000818:Animals; D001483:Base Sequence; D002117:Calcitriol / Q000494:pharmacology*; D002460:Cell Line; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D004789:Enzyme Activation / Q000187:drug effects; D004848:Epithelium / Q000201:enzymology; D015870:Gene Expression / Q000187:drug effects*; D007422:Intestines / Q000201:enzymology*; D007527:Isoenzymes / Q000235:genetics; D007546:Isoquinolines / Q000494:pharmacology; D008969:Molecular Sequence Data; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D013250:Steroid Hydroxylases / Q000235:genetics*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D065668:Vitamin D3 24-Hydroxylase
D007527:Isoenzymes; D007546:Isoquinolines; D010879:Piperazines; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; D065668:Vitamin D3 24-Hydroxylase; D011493:Protein Kinase C; D002117:Calcitriol; D013755:Tetradecanoylphorbol Acetate