Abstract P46: Protective Role of Mitochondrial Antiviral Signaling (MAVS) under H2O2-induced Oxidative Stress in the Cardiac Myocyte
Mitochondrial antiviral signaling (MAVS) protein has been found to be a key molecule in innate antiviral defense and highlights a novel function of mitochondria in host defense mechanisms. Since mitochondria have been implicated in cardioprotection against various stresses, the discovery of MAVS protein led us to explore unidentified crosstalk between innate immune and cardioprotective mechanisms that involve the mitochondria within the cardiac myocyte. We hypothesized that MAVS plays an important role in cardioprotection mechanisms not only under conditions with virus infection but also under non-virus stress conditions. To test the hypothesis, here we examined the effect of MAVS knockdown on the mitochondrial transmembrane potential (MTP) under H2O2-induced oxidative stress in the cardiac myocyte. We generated adenovirus vector expressing short-hairpin RNA that can knockdown more than 80% of mouse MAVS (Ade-shmMAVS). The knockdown efficiency was evaluated using NIH3T3 and embryonic mouse cardiac myocytes (EMCM) at 48 hours post the virus infection at a multiplicity of infection (MOI) of 10. As a negative control, we also generated adenovirus vector expressing short-hairpin RNA that harbors random sequence (Ade-shNC). The MTP was evaluated by using a cationic dye, MitoCapture™ (BioVison) according to manufacture’s instruction. As a baseline phenotype, we found no abnormalities of MTP in EMCM when infected with Ade-shmMAVS or Ade-shNC at MOI of 10 for 24 hours followed by 72 hours of culture under10% fetal bovine serum conditions. However, when we cultured EMCM for 72 hours under serum-free conditions following the 24 hours of the infection, we found clear alteration of MTP in the Ade-shmMAVS infected EMCM compared to the control, Ade-shNC infected EMCM. Subsequently, we provoked oxidative stress in the Ade-shmMAVS infected EMCM at 24 hours post serum starvation, and found severe impairment of MTP compared to the control EMCM when we added 0.2 mM H2O2 for 2 hours. These results indicate a protective role of MAVS under H2O2-induced oxidative stress condition in the cardiac myocyte. MAVS might have additional roles when the myocyte is exposed to various devastating conditions such as acute pressure overload, ischemia, and drug toxicity.