CALCITRIOL SIGNALING THROUGH MAP KINASES IN SKELETAL MUSCLE CELLS

BUITRAGO CLAUDIA; RONDA ANA; RUSSO DE BOLAND ANA; BOLAND RICARDO

IGUAZÚ, MISIONES, ARGENTINA

Congreso; SAIB XL REUNIÓN ANUAL; 2004

SOCIEDAD ARGENTINA DE INVESTIGACIÓN EN BIOQUÍMICA Y BIOLOGÍA MOLECULAR

In skeletal muscle, calcitriol (1a,25-dihydroxy-vitamin D3), the hormonally active form of vitamin D, regulates intracellular calcium levels and contraction, and promotes muscle cell proliferation and differentiation. The mitogen activated proteins kinases (MAPKs): ERKs, p38 kinase and JNK (c-jun NH2-terminal kinase), have been shown to be involved in cellular growth and differentiation. In this work, using as experimental model the skeletal muscle cell line C2C12, we demonstrate that calcitriol activates p38 kinase and JNK. Both kinases were rapidly phosphorylated and activated with different temporal profiles, maximal phosphorylation of the p38 and JNK was reached at physiological doses of calcitriol (1 nM). Of relevance, the hormone induced in the C2C12 line the stimulation of MAPKAP-kinase 2 and subsequent phosphorylation of HSP27 in a p38 kinase activation-dependent manner. As the MAPKAP-kinase 2/HSP27 pathway modulates F-actin polimerization promoting thereby cellular proliferation, additional studies are required to elucidate the signalling events involved in the final stage of regulation of muscle cell proliferation by calcitriol.