The Role And Mechanism Of GSDMD In Myocardial Ischemia Reperfusion Injury

Myocardial ischemia-reperfusion injury is a pathological process in which vascular recanalization is performed in a short time in order to save the heart function after acute coronary artery obstruction,but the blood flow recovery leads to progressive and aggravated tissue injury.In the myocardial ischemia reperfusion injury,precise control of cardiomyocyte viability and reduction of myocardial cell death are the key points of treatment.Pyroptosis is a newly discovered mode of cell death.Recent studies have shown that GSDMD is involved in myocardial ischemia reperfusion injury as an executive protein of pyroptosis,but its effect on apoptosis and other forms of cell death remains unclear.In this study,we found that both GSDMD and GSDMD-N proteins were significantly upregulated in myocardial ischemia reperfusion model of mice,suggesting that GSDMD is indeed involved in the pathological process of myocardial ischemia reperfusion injury.We further analyzed the pathological phenotypes of GSDMD KO and WT mice in the acute and chronic phase of myocardial ischemia-reperfusion by measuring echocardiography,serum LDH,myocardial infarction area,and myocardial fibrosis area.Compared with WT,Genetic inactivation of GSDMD showed a significant protective effect in the acute phase of ischemia reperfusion,but aggravated myocardial injury in the chronic phase of ischemia reperfusion.Mechanistically,we detected myocardial apoptosis proteins and found that caspase-3,-7 and-8 were significantly activated after GSDMD inhibition.Meanwhile,flow cytometry confirmed that apoptosis of cardiomyocytes significantly increased after GSDMD inhibition.This result indicated that inhibition of GSDMD in cardiomyocytes blocked pyroptosis,but more activated apoptosis.Through CoIP-MS analysis,it was found that there was mutual binding between GSDMD and PARP-1,and inhibition of GSDMD could significantly induce the activation of PARylation,thus promoting the consumption of NAD+and ATP,leading to cardiomyocyte death.In addition,PARP-1 inhibitor alleviated myocardial injury caused by GSDMD deficiency and better protect cardiac function.Our results reveal a novel action modality of GSDMD in the regulation of cardiomyocyte death,inhibition of GSDMD activates PARylation and promote apoptosis,suggesting the multidirectional role of GSDMD in I/R,and providing a new theory for reducing myocardial injury and saving cardiac function in clinical treatment.