Peroxynitrite nitrates adenine nucleotide translocase and Voltage-Dependent Anion Channel 1 and alters their interactions and association with hexokinase II in mitochondria

In this study, we explored whether IR injury in isolated hearts induces tyrosine nitration of adenine nucleotide translocase (ANT) and alters its interaction with the voltage-dependent anion channel 1 (VDAC1). We found that IR injury induced tyrosine nitration of ANT and that exposure of isolated cardiac mitochondria to ONOO− induced ANT tyrosine, Y81, nitration. The exposure of isolated cardiac mitochondria to ONOO− also led ANT to form high molecular weight proteins and dissociation of ANT from VDAC1. We also found that IR injury in isolated hearts, hypoxic injury in H9c2 cells, and ONOO− treatment of H9c2 cells and isolated mitochondria, each decreased mitochondrial bound-hexokinase II (HK II), which suggests that ONOO− caused HK II to dissociate from mitochondria. Moreover, we found that mitochondria exposed to ONOO− induced VDAC1 oligomerization which may decrease its binding with HK II. We have reported that ONOO− produced during cardiac IR injury induced tyrosine nitration of VDAC1, which resulted in conformational changes of the protein and increased channel conductance associated with compromised cardiac function on reperfusion. Thus, our results imply that ONOO− produced during IR injury and hypoxic stress impeded HK II association with VDAC1. ONOO− exposure nitrated mitochondrial proteins also led to cytochrome c (cyt c) release from mitochondria. In addition, in isolated mitochondria exposed to ONOO− or obtained after IR, there was significant co...
Source: Mitochondrion - Category: Biochemistry Source Type: research