Abstract 279: Effects of Acute Oxidative Stress on Cardiac Proteome Dynamics

Abstract

Introduction: Acute reactive oxygen species exposure is thought to trigger endoplasmic reticulum (ER) stress and unfolded protein response (UPR) commonly observed in pathological hearts. The pathways and molecular features impacted by acute oxidative stress are incompletely understood. To understand how proteostatic stressors impact cardiac protein dynamics, we investigate the effect of low to high doses of acute oxidant on the cardiac proteome using a paraquat-induced oxidative stress model. Methods: C57BL/6J mice were exposed to low, mid, or high doses of paraquat for up to 48 hours. Cardiac proteins were extracted and digested on-filters into tryptic peptides. The peptides were then tagged with isobaric stable isotope tandem mass tags (TMT) followed by high-pH reversed-phase (RP) fractionation. Each fraction was further separated by low-pH RP liquid chromatography and analyzed on a Q-Exactive HF Plus high-resolution mass spectrometer to obtain proteome-wide abundance levels across treatment groups. We then focused on the differential expression in the mitochondrial and ER subproteomes as well as their respective protein quality control pathways. Results: We found prominent differential expression in specific quality control proteins in response across low and high doses of oxidative stresses. The data suggest that oxidative stress activates UPR pathways including notably mitochondrial UPR (UPRmt) components in a dose-specific manner. In particular, we observed the repression of mitochondrial protein import machinery components as a specific feature of low but not high oxidative stress response. In addition, the differential expression of pyruvate metabolism proteins may constitute a link between cardiac metabolism and UPRmt, and serve as a determinant between adaptive and maladaptive responses to reactive oxygen species. Conclusion: Our results indicate that the activation of the UPRmt pathways may be an overlooked feature of acute oxidative insults that underlies stress response in cardiac cells. Future work will interrogate the molecular crosstalks between mitochondria and ER stress response pathways.