Cardiac Muscle Ring Finger‐1 (MuRF1) alters myocardial ROS production in vivo

Muscle ring finger protein‐1 (MuRF1) is a muscle‐specific ubiquitin ligase that regulates cardiac metabolism at multiple points in vivo . We have identified these mechanisms using transgenic (MuRF1 Tg+) and knockout mice (MuRF1 −/−). Microarray analysis of the MuRF1 Tg+ hearts revealed significant alterations in genes involved in mitochondrial oxidative phosphorylation. We therefore investigated the effects of cardiac MuRF1 expression on mitochondrial function. Isolated permeabilized muscle fibers from MuRF1 Tg+ and MuRF1 −/− hearts were assayed for their oxygen utilization in the presence of a number of Kreb's cycle intermediates. Mitochondria O 2 consumption from MuRF1 Tg+ and MuRF1 −/− mice did not significantly differ from wild type mice in the presence of pyruvate, malate, glutamate, and succinate (+/−ADP), although MuRF1 Tg+ trended to consume less oxygen. Mitochondria uncoupling was not detected in the presence of oligomycin in either mouse model. Quite unexpectedly, however, mitochondrial hydrogen peroxide production determined by Amplex Red was significantly reduced by >60% in MuRF1 Tg+ hearts, indicating increased MuRF1 inhibited the formation of reactive oxygen species. These findings are consistent with MuRF1's cardioprotective role in ischemia reperfusion injury, whereby the formation of ROS play a critical role in the pathogenesis of disease. Supported by NIH R01HL104129.