ROLE OF VDR EXPRESSION IN 1,25(OH)2-VITAMIN D3-INDUCED RAPID ACTIONS IN PROLIFERATING SKELETAL MUSCLE CELLS

BUITRAGO C; GONZALEZ PARDO V; BOLAND R

Workshop; Workshop of Vitamin D; 2012

1alpha,25(OH)2-vitamin D3 [1,25D] is a steroid hormone that rapidly elicits intracellular signals in various tissues. Upstream stimulation of MAPKs through c-Src by 1,25D in skeletal myoblasts has been previously demonstrated in our laboratory. Moreover, we reported that caveolae components mediate the fast effects of the hormone in the skeletal muscle cell line C2C12. In this work we obtained preliminary data indicating that the VDR is required in the non-genomic action of 1,25D. We knocked down (80%) vitamin D receptor expression by transfection of C2C12 cells with 2 shRNAs against VDR. In these cells (VDR-) Western blot analyses show that 1,25D-induced Src activation (tyr416 phosphorylation) and ERK1/2 and p38 MAPK phosphorylation are suppressed. In addition, caveolin 1 expression and Akt activation appeared to be dependent on VDR expression in C2C12 skeletal muscle cells. These data indicate that the VDR is involved in rapid events triggered by 1alpha,25(OH)2D3 in skeletal muscle cells, providing relevant information on the mechanism of initiation of the non-genomic hormone signal.