miR-181c-5p Exacerbates Hypoxia/Reoxygenation-Induced Cardiomyocyte Apoptosis via Targeting PTPN4

Oxid Med Cell Longev. 2019 Apr 17;2019:1957920. doi: 10.1155/2019/1957920. eCollection 2019.

Abstract

Background: Activation of cell apoptosis is a major form of cell death during myocardial ischemia/reperfusion injury (I/RI). Therefore, examining ways to control cell apoptosis has important clinical significance for improving postischemic recovery. Clinical evidence demonstrated that miR-181c-5p was significantly upregulated in the early phase of myocardial infarction. However, whether or not miR-181c-5p mediates cardiac I/RI through cell apoptosis pathway is unknown. Thus, the present study is aimed at investigating the role and the possible mechanism of miR-181c-5p in apoptosis during I/R injury by using H9C2 cardiomyocytes.

Methods and results: The rat origin H9C2 cardiomyocytes were subjected to hypoxia/reoxygenation (H/R, 6 hours hypoxia followed by 6 hours reoxygenation) to induce cell injury. The results showed that H/R significantly increased the expression of miR-181c-5p but not miR-181c-3p in H9C2 cells. In line with this, in an in vivo rat cardiac I/RI model, miR-181c-5p expression was also significantly increased. The overexpression of miR-181c-5p by its agomir transfection significantly aggravated H/R-induced cell injury (increased lactate dehydrogenase level and reduced cell viability) and exacerbated H/R-induced cell apoptosis (greater cleaved caspases 3 expression, Bax/Bcl-2 and more TUNEL-positive cells). In contrast, inhibition of miR-181c-5p in vitro had the opposite effect. By using computational prediction algorithms, protein tyrosine phosphatase nonreceptor type 4 (PTPN4) was predicted as a potential target gene of miR-181c-5p and was verified by the luciferase reporter assay. The overexpression of miR-181c-5p significantly attenuated the mRNA and protein expression of PTPN4 in H9C2 cardiomyocytes. Moreover, knockdown of PTPN4 significantly aggravated H/R-induced enhancement of LDH level, cleaved caspase 3 expression, and apoptotic cell death, which mimicked the proapoptotic effects of miR-181c-5p in H9C2 cardiomyocytes.

Conclusions: These findings suggested that miR-181c-5p exacerbates H/R-induced cardiomyocyte injury and apoptosis via targeting PTPN4 and that miR-181c-5p/PTPN4 signaling may yield novel strategies to combat myocardial I/R injury.

MeSH terms

  • Animals
  • Apoptosis / physiology
  • Cell Hypoxia / physiology*
  • Male
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Myocardial Reperfusion Injury / metabolism*
  • Myocardial Reperfusion Injury / pathology
  • Myocytes, Cardiac / metabolism*
  • Myocytes, Cardiac / pathology
  • Protein Tyrosine Phosphatase, Non-Receptor Type 4 / genetics
  • Protein Tyrosine Phosphatase, Non-Receptor Type 4 / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Transfection

Substances

  • MIRN181 microRNA, rat
  • MicroRNAs
  • Protein Tyrosine Phosphatase, Non-Receptor Type 4
  • Ptpn4 protein, rat