Inhibition of microRNA-101 attenuates hypoxia/reoxygenation-induced apoptosis through induction of autophagy in H9c2 cardiomyocytes

Abstract

Abstract. Autophagy is a cellular self-catabolic process responsible for the degradation of proteins and organelles. Autophagy is able to promote cell survival in response to stress, and increased autophagy amongst cardiomyocytes has been identified in conditions of heart failure, starvation and ischemia/reperfusion. However, the detailed regulatory mechanisms underlying autophagy in heart disease have remained elusive. MicroRNAs (miRNAs) have been implicated in the regulation of autophagy in cells under stress. In the present study, the protective effect of miRNA (miR)-101 on hypoxia/reoxygenation (H/R)-induced cardiomyocyte apoptosis was investigated. It was revealed that H/R induced apoptosis in H9c2 cardiomyocytes, accompanied by a downregulation of miR-101 expression. Further investigation identified Ras-related protein Rab-5A (RAB5A) as a direct target of miR-101. RAB5A was previously reported to be involved in autophagy; therefore, the present study further focused on the role of miR-101 in the regulation of autophagy under H/R and found that the inhibition of miR-101 attenuated H/R-induced apoptosis, at least partially, via the induction of autophagy. In conclusion, the results of the present study revealed a beneficial effect of miR-101 inhibition on H/R-induced apoptosis in cardiomyocytes, indicating that miR-101 inhibition may present a potential therapeutic agent in the treatment or prevention of heart diseases. IntroductionAutophagy is a cellular self-catabolic process responsible for the degradation of long-lived proteins and organelles. During autophagy, cytoplasmic constituents are sequestered into autophagosomes and degraded via the lysosomal pathway (1).Autophagy is able to promote cell survival in response to stress. However, progressive autophagy also induces cell death (2). Therefore, autophagy not only has a crucial role in the regulation of normal development, but dysregulated or defective autophagy is associated with disease.MicroRNAs (miRNAs) are a group of endogenous, non-coding, single-strand, small RNAs of 22-25 nucleotides, which regulate gene expression at the post-transcriptional level, predominantly through base pairing with the 3'-untranslated region (3'-UTR) of target mRNAs, which results in mRNA degradation or translational repression (3). It has been revealed that miRNAs regulate >30% of genes, which are associated with almost all major cellular processes, including cell proliferation, differentiation, apoptosis and migration, as well as immune responses (4). Myocardial tissue injury induced by ischemia and hypoxia is a major factor underlying the development of fatal diseases. The main cause of myocardial ischemic injury is myocardial cell apoptosis induced by myocardial hypoxia (5). Furthermore, subsequent reoxygenation may further aggravate the damage (6). Multiple miRNAs have been shown to function as protectors against hypoxia/reoxygenation (H/R)-induced myocardial injury (7-9). However, the specific molecular mechanisms underlying this effect have remained elusive.Accumu...

MicroRNA regulation of autophagy in cardiovascular disease

“…Rat cardiac fibroblasts express miR-101, a regulator of ATG4, and expression is decreased under hypertrophic conditions as well as in the peri-infarct area 4 weeks after MI, however, TGF-β1 was identified as the target in this study (30, 75, 106). While they did not identify an autophagic target, this does not rule out autophagy’s involvement, and aligns with Wu et al findings in hypoxia/reoxygenation (H/R) studies with H9c2 cells (106,107). …”

“…Compensatory administration of miR-188-3p prevents death and minimizes infarct size in murine models of MI (78). It was reported by Wu et al that miR-101 is down regulated when H9c2 cells are treated under hypoxia/reoxygenation conditions and undergo apoptosis (107). They looked at the role of RAB5a in regulating autophagy and found that inhibition of miR-101 prevented apoptosis and elevated levels of autophagy (107).…”

“…It was reported by Wu et al that miR-101 is down regulated when H9c2 cells are treated under hypoxia/reoxygenation conditions and undergo apoptosis (107). They looked at the role of RAB5a in regulating autophagy and found that inhibition of miR-101 prevented apoptosis and elevated levels of autophagy (107). It is of note, however, that miR-101 has also been shown to target other elements of the autophagy machinery such as ATG4 and ULK1/2 (67,75).…”

Circulating miRNA Expression Profiling and Target Prediction in Patients Receiving Dexmedetomidine

“…Inhibition of miR-101 was shown to attenuate hypoxia/ reoxygenation-induced apoptosis through induction of autophagy in H9C2 cardiomyocytes [41]. In another study, the level of miR-101-3p was significantly higher in heart transplant recipients with histologically verified acute cellular rejection compared with a control group and could discriminate between patients with and without allograft rejection [42].…”

“…Regulation of the miR-101/MAPK pathway plays an important role in proliferation and metastasis of gallbladder carcinoma [47], in LPS-activated Cellular Physiology and Biochemistry Cellular Physiology and Biochemistry macrophages [48], in systemic lupus erythematosus [49] and in proliferation and migration of cardiac fibroblast [50]. Wang et al found that inhibition of miR-101could attenuate H9C2 apoptosis induced by hydrogen peroxide [41]. Thus, future studies are warranted to elucidate effects of dexmedetomidine on the miR-101/MAPK pathway.…”