Role of VDR in 1alfa,25-dihydroxyvitamin D3-dependent non-genomic activation of MAPKs, Src and Akt in skeletal muscle cells

CLAUDIA BUITRAGO; VERONICA GONZALEZ PARDO; BOLAND, RICARDO

JOURNAL OF STEROID BIOCHEMISTRY AND MOLECULAR BIOLOGY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2013

0960-0760

1 ,25-dihydroxyvitamin D3 [1,25D] is recognized as a steroid hormone that rapidly elicits intracellular signals in various tissues. In skeletal myoblasts, we have previously demonstrated that one of the 1,25D-induced non-genomic effects is the upstream stimulation of MAPKs through Src activation. In this work, the data obtained suggest that the classical receptor of vitamin D (VDR) participates in non-transcriptional actions of 1,25D. We significantly reduced VDR expression by infection of C2C12 murine myoblasts with lentiviral particles containing the pLKO.1 plasmid with information to express a shRNA against mouse VDR. In these cells (C2C12-shVDR), Western blot analyses show that 1,25D-induced p38 MAPK activa-tion and Src tyr416 phosphorylation were abolished. In addition, 1,25D-dependent activity of ERK1/2 was diminished in cells lacking VDR but to a lesser extent (¡­−60%). Phosphorylation of Akt by 1,25D, recently demonstrated in C2C12 cells, in the present work also appeared to be partially dependent on VDR expres-sion (¡­50% in C2C12-shVDR cells). Our results indicate that VDR is involved in 1,25D-induced rapid events related to survival/proliferation responses in skeletal muscle cells, providing relevant information on the mechanism of initiation of the non-genomic hormone signal. The participation of a VDR-independent non-genomic mechanism of action should also be taken into consideration. This article is part of a Special Issue entitled ¡®Vitamin D Workshop¡¯. ,25-dihydroxyvitamin D3 [1,25D] is recognized as a steroid hormone that rapidly elicits intracellular signals in various tissues. In skeletal myoblasts, we have previously demonstrated that one of the 1,25D-induced non-genomic effects is the upstream stimulation of MAPKs through Src activation. In this work, the data obtained suggest that the classical receptor of vitamin D (VDR) participates in non-transcriptional actions of 1,25D. We significantly reduced VDR expression by infection of C2C12 murine myoblasts with lentiviral particles containing the pLKO.1 plasmid with information to express a shRNA against mouse VDR. In these cells (C2C12-shVDR), Western blot analyses show that 1,25D-induced p38 MAPK activa-tion and Src tyr416 phosphorylation were abolished. In addition, 1,25D-dependent activity of ERK1/2 was diminished in cells lacking VDR but to a lesser extent (¡­−60%). Phosphorylation of Akt by 1,25D, recently demonstrated in C2C12 cells, in the present work also appeared to be partially dependent on VDR expres-sion (¡­50% in C2C12-shVDR cells). Our results indicate that VDR is involved in 1,25D-induced rapid events related to survival/proliferation responses in skeletal muscle cells, providing relevant information on the mechanism of initiation of the non-genomic hormone signal. The participation of a VDR-independent non-genomic mechanism of action should also be taken into consideration. This article is part of a Special Issue entitled ¡®Vitamin D Workshop¡¯.