INDUCTION OF GAP JUNCTIONAL INTERCELLULAR COMMUNICATION BY VITAMIN-D IN HUMAN SKIN FIBROBLASTS IS DEPENDENT ON THE NUCLEAR VITAMIN-D-RECEPTOR

The physiologically active metabolite of vitamin D, 1 alpha,25-dihydro xyvitamin D-3 (calcitriol), induces gap junctional intercellular commu nication in human skin fibroblasts 161BR at a concentration of 10(-7) M. In human skin fibroblasts, FIB5, devoid of a functional nuclear vit amin D receptor (VDR), there is no effect on gap junctional intercellu lar communication. Parallel to the increase in cell-cell communication , we observed a VDR-dependent increase in connexin43 protein and conne xin43 mRNA levels. These results suggest that 1 alpha,25-dihydroxyvita min D-3 affects gap junctional intercellular communication at the leve l of transcription or of mRNA stability via the nuclear VDR.