THE ANTIAPOPTOTIC EFFECT OF 17beta-ESTRADIOL IN SKELETAL MUSCLE CELLS INVOLVES PKCgama, JNK AND p66Shc

LA COLLA, ANABELA; PRONSATO, LUCIA; MILANESI, LORENA; BOLAND, RICARDO; VASCONSUELO, ANDREA

Bs As

Congreso; Reunion anual de AAOMM; 2014

AAOMM

The hormone 17¥â-Estradiol (E2) acts on several non-reproductive tissues, including skeletal muscle. We have shown that E2 at physiological concentrations prevented apoptosis induced by hydrogen peroxide (H2O2) in skeletal myoblasts. The present work further characterizes the signaling mechanisms modulated by E2, responsible of apoptosis inhibition inskeletal muscle cells. We found that H2O2 induces activation of PKC¥ä and JNK in C2C12 cells. By TUNEL assays using specific inhibitors, we demonstrated that the H2O2-induced activation of PKC¥ä and JNK are necessary to trigger apoptosis in skeletal muscle cells. Moreover, immunological assays support the data that PKC¥ä acts upstream JNK. We observed that E2 inhibits the activation of these kinases, resulting  in  the  inhibition  of  phosphorylation  and  translocation  to  mitochondria  of  the  adaptor protein p66Shc associated to oxidative stress. Additionally, we found that E2 diminishes the H2O2-induced p66Shc messenger RNA (mRNA) level. Tetramethylrhodamine methyl ester (TMRM) staining showed that pretreatment with E2 conduces to protection of the mitochondrial membrane potential (∆¥÷m) in line with the inhibition of p66Shc translocation to mitochondria. In agreement, by qRT-PCR we demonstrated that E2 diminishes the H2O2-induced mRNA levels of the apoptotic proteins PERP and Puma associated to ∆¥÷m loss, and increases those of the antiapoptotic protein Bcl-2. Our results provide basis for a putative mechanism by which E2 exerts beneficial effects on mitochondria, against oxidative stress, in skeletal muscle cells, helping to find new targets for the development of therapies for myophaties associated to deregulated apoptosis by hormonal deficits.