Estrogen and testosterone protect against apoptosis via p53, p66Shc, PKCδ and JNK in C2C12 cells

LUCÍA PRONSATO; ANABELA LA COLLA; ANDREA VASCONSUELO; LORENA MILANESI

Rosario

Congreso; L Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2014

In aged skeletal muscle, a prominent apoptosis associated to a deficit of sex hormones is observed, contributing to the pathogenesis of sarcopenia. We have previously demonstrated that 17β-estradiol (E2) and testosterone (T) inhibit H2O2-induced apoptosis in C2C12 muscle cells. This work further characterizes the molecular mechanisms involved in the antiapoptotic action of both steroids. We observed that H2O2activates p53 in a time-dependent fashion; and this activation is reduced by T treatment. P53 induces apoptosis via p66Shc activation, an adaptor protein that amplifies the generation of mitochondrial H2O2. We found that both T and E2 reduce the H2O2-induced p66Shc mRNA level. Additionally, the steroids inhibit PKCδ and JNK activation, resulting in the inhibition of the phosphorylation and translocation to mitochondria of p66Shc, events associated to oxidative stress. Tetramethylrhodamine methyl ester (TMRM) staining showed that E2 protects the mitochondrial membrane potential in line with the inhibition of p66Shc translocation to mitochondria. Finally, we demonstrated by qRT-PCR that both steroids diminish the H2O2-induced mRNA levels of the apoptotic proteins PERP and Puma and increase those of the antiapoptotic protein Bcl-2. These data provide insights into the molecular basis of sarcopenia associated to sex hormones deficit states.