cFLIPL Alleviates Myocardial Ischemia-Reperfusion Injury by Inhibiting Endoplasmic Reticulum Stress

Cardiovasc Drugs Ther. 2023 Apr;37(2):225-238. doi: 10.1007/s10557-021-07280-1. Epub 2021 Nov 12.

Abstract

Purpose: Endoplasmic reticulum stress (ERS) plays a crucial role in myocardial ischemia-reperfusion injury (MIRI). Cellular FLICE-inhibitory protein (cFLIP) is an essential regulator of apoptosis and plays a major role in regulating ERS. The present study aimed to investigate the effects of long isoform cFLIP (cFLIPL) on endogenous apoptosis and the mechanism of ERS in MIRI.

Methods: The cFLIPL recombinant adenovirus vector was used to infect H9c2 cells and Sprague-Dawley (SD) rats. After infection for 72 h, ischemia was induced for 30 min, and reperfusion was then performed for 2 h to establish the MIRI model in SD rats. H9c2 cells were hypoxic for 4 h and then reoxygenated for 12 h to simulate ischemia/reperfusion (I/R) injury. Model parameters were evaluated by assessing cardiomyocyte viability, cell death (apoptosis), and ERS-related protein expression. In addition, tunicamycin (TM), an ERS agonist, was also added to the medium for pretreatment. Coimmunoprecipitation (Co-IP) of cFLIPL and p38 MAPK protein was performed.

Results: cFLIPL expression was decreased in I/R injury and hypoxia/reoxygenation (H/R) injury, and cFLIPL overexpression reduced myocardial infarction in vivo and increased the viability of H9c2 cells in vitro. I/R and H/R upregulated the protein expression of GRP78, IRE-1, and PERK to induce ERS and apoptosis. Interestingly, overexpression of cFLIPL significantly inhibited ERS and subsequent apoptosis, which was reversed by an agonist of ERS. Moreover, Co-IP showed that cFLIPL attenuated ERS and was associated with inhibiting the activation of p38 protein.

Conclusion: The expression of cFLIPL is significantly downregulated in MIRI, and it is accompanied by excessive ERS and apoptosis. Upregulated cFLIPL suppresses ERS to reduce myocardial apoptosis, which is associated with inhibiting the activity of p38 MAPK. Therefore, cFLIPL may be a potential intervention target for MIRI.

Keywords: Cellular FLICE-inhibitory Protein; Endoplasmic Reticulum Stress; Hypoxia/reoxygenation Injury; Myocardial Ischemia-Reperfusion Injury.

MeSH terms

  • Animals
  • CASP8 and FADD-Like Apoptosis Regulating Protein / genetics
  • CASP8 and FADD-Like Apoptosis Regulating Protein / metabolism
  • CASP8 and FADD-Like Apoptosis Regulating Protein / pharmacology
  • Endoplasmic Reticulum Stress
  • Myocardial Reperfusion Injury* / metabolism
  • Myocardial Reperfusion Injury* / prevention & control
  • Rats
  • Rats, Sprague-Dawley
  • p38 Mitogen-Activated Protein Kinases / metabolism
  • p38 Mitogen-Activated Protein Kinases / pharmacology

Substances

  • CASP8 and FADD-Like Apoptosis Regulating Protein
  • p38 Mitogen-Activated Protein Kinases