AMPK as a metabolic sensor regulates inflammatory response during ischemic insults

AMP‐activated Protein Kinase (AMPK) is a stress‐activated kinase that protects against cardiomyocyte injury via modulating substrate metabolic shift between glucose and fatty acid during ischemia and reperfusion. c‐Jun N‐terminal kinase (JNK), a mitogen activated protein kinase, is activated by ischemia and reperfusion for modulating inflammatory response. NF‐κB is an important transcription factor involved in inflammation cascade during ischemia and reperfusion injury. Methods and Results The intrinsic activation of AMPK attenuates inflammation occurred during ischemia/reperfusion through modulating the JNK mediated NF‐κB signaling pathway. Rat cardiac myoblast H9c2 cells were subjected to hypoxia and/or reoxygenation to investigate the signal transduction that occurred during myocardial ischemia/reperfusion. Mitochondrial function was measured by the Seahorse XF24 V7 PS system. Hypoxia treatment triggered AMPK activation in H9c2 cells in a time dependent manner. Inhibition of hypoxic AMPK activation by pharmacological approach (Compound C) or siRNA knockdown of AMPK α catalytic subunits caused dramatic augments in JNK activation, inflammatory NF‐κB phosphorylation, and apoptosis during hypoxia and reoxygenation. Inhibition of AMPK activation significantly impaired mitochondrial function and increased the generation of reactive oxygen species (ROS) during hypoxia and reoxygenation. In contrast, pharmacological activation of AMPK by a diabetes drug metformin significantly inhibited mitochondrial permeability transition pore (mPTP) opening and ROS generation. Moreover, AMPK activation significantly attenuated JNK‐NF‐κB signaling cascade and inhibited mRNA levels of pro‐inflammatory cytokines such as TNF‐α and IL‐6 during hyopoxia/reoxygenation in H9c2 cells. Intriguingly, both pharmacologic inhibition of JNK by JNK‐IN‐8 and siRNA knockdown of JNK signaling pathway attenuated NF‐κB phosphorylation and apoptosis but did not affect AMPK activation in response to hypoxia and reoxygenation. The results indicate that AMPK as a metabolic sensor regulates substrate metabolism and maintains the integrity of mitochondria in order to limit the inflammatory response during ischemia and reperfusion stress conditions. Conclusions AMPK activation regulates substrate metabolism and modulates JNK‐NF‐kB signaling cascade during hypoxia and reoxygenation stress conditions. Cardiac AMPK activation plays a critical role in maintaining mitochondrial function and inhibiting the inflammatory response caused by ischemic insults. Support or Funding Information American Diabetes Association 1‐17‐IBS‐296, NIH R01AG049835, R01HL12587701, P01HL051971, and P20GM104357 This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .