ANTIAPOPTOTIC EFFECTS OF TESTOSTERONE AND 17beta-ESTRADIOL IN SKELETAL MUSCLE

PRONSATO L; LA COLLA A; RONDA A,; MILANESI L; VASCONSUELO A; BOLAND R

Potrero de los Funes

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2011

SAIB

We previously described that testosterone (T) and 17beta-estradiol (E2) protect C2C12 muscle cells from apoptosis induced by H2O2. Thus, H2O2 promoted typical changes of apoptosis such as nuclear fragmentation, cytoskeleton disorganization, mitochondrial reorganization/dysfunction and cytochrome c release that were abolished upon treatment of cells with the hormones. In the present work we studied further in depth the mechanism of action of these steroids in apoptosis. Competitive binding assays, immunocytochemistry and immunoblottings revealed that androgen receptors with a non-classical localization (mainly mitochondria) are involved in the protective role of T. Thus, T inhibits PARP cleavage and Bax expression induced by H2O2 but in presence of flutamide this antiapoptotic effect is not observed. By flow cytometry using the fluorescent dye JC-1, it was also demonstrated that T prevents mitochondrial membrane potential depolarization in response to H2O2, as described before for E2. This loss of membrane potential may be due to the opening of the mitochondrial permeability transition pore (MPTP), as flow cytometry and fluorescence microscopy with calcein-AM demonstrated that E2 can inhibit the continuous activation of MPTP by H2O2. Altogether, our studies suggest a role of T and E2 in the regulation of apoptosis with a clear action at the mitochondrial level in muscle cells.