SOCS-6 promotes mitochondrial fission and cardiomyocyte apoptosis and is negatively regulated by QKI mediated miR-19b

Background: Ischemia/reperfusion (IR) injury following myocardial infarction can result in debilitating complications and morbidity. Mitochondrial dysfunction and abnormal mitochondrial fission have been implicated in the complications associated with IR injury as cardiomyocytes are abundant in mitochondria. SOCS-6 is known to participate in mitochondrial fragmentation but its exact involvement and the pathways associated are uncertain. Results In the present study, we examine the biological role and regulation of SOCS-6 in mitochondrial dynamics using hypoxia and reoxygenation (H/R) in cardiomyocytes and with a murine model of IR injury. We found that SOCS-6 inhibition by RNA interference attenuated H/R-induced mitochondrial fission and apoptosis in cardiomyocytes. A luciferase assay indicated that SOCS-6 is a direct target of miR-19b. The overexpression of miR-19b decreased mitochondrial fission and apoptosis in vitro . Moreover, the presence of miR-19b reduced the level of SOCS-6 and the injury caused by IR in vivo . There were less apoptotic cells in the myocardium of mice injected with miR-19b. In addition, we found that the RNA-binding protein, QKI, participates in the regulation of miR-19b expression. Conclusions Our results indicate that the inhibition of mitochondrial fission through downregulating SOCS-6 via the QKI/miR-19b/SOCS-6 pathway attenuated the damage sustained by IR. The QKI/miR-19b/SOCS-6 axis plays a vital role in regulation of mitochondrial fission and cardiomyocyte apoptosis and could form the basis of future research in the development of therapies for the management of cardiac diseases.