Protective effects of miR-25 against hypoxia/reoxygenation-induced fibrosis and apoptosis of H9c2 cells

Abstract

It has been previously demonstrated that microRNA (miR)-25 plays critical roles in collagen deposition. Ischemia/reperfusion injury to the myocardium results in fibrosis and collagen deposition. However, whether miR-25 is involved in the development of hypoxia/reoxygenation (H/R)‑induced fibrosis in cardiomyocytes or not remains largely unknown. For this purpose, in the present study, cardiomyocyte H9c2 cells were subjected to H/R. The techniques of flow cytometry, western blot analysis and RT-qPCR were used and we observed increases in the cell apoptosis rate and fibrosis as well as blocking of the cell cycle in the G1 phase. Moreover, the expression of miR-25 was downregulated after H/R and high‑mobility group box 1 (HMGB1) expression was increased. We also found that the overexpression of miR-25 under conditions of H/R inhibited fibrosis and cell apoptosis as well as reversing the cell cycle blocking. Additionally, the targeting of HMGB1 by miR-25 was confirmed by a dual‑luciferase reporter gene assay. Moreover, the effects of miR-25 were further enhanced by a transforming growth factor-β1 (TGF-β1)/Smad3 inhibitor, SB431542, as fibrosis was reduced and apoptosis was suppressed. In conclusion, the protective effects of miR-25 against H/R-induced fibrosis and apoptosis H9c2 cells were due to direct targeting of HMGB1 through the downregulation of the TGF-β1/Smad3 signaling pathway.

miR-25 inhibits sepsis-induced cardiomyocyte apoptosis by targetting PTEN

“…Pan et al [ 18 ] reported that miR-25 could protect cardiomyocytes from oxidative damage. Liu et al [ 7 ] found that miR-25 could inhibit cardiomyocyte apoptosis. These suggested that miR-25 might be an important regulator in myocardial function.…”

“…Zhou et al [ 6 ] reported that miR-155 alleviated myocardial injury in septic rats by inhibiting JNK-related inflammatory signaling. MiR-25 has been found as an inhibitor for cardiomyocyte apoptosis induced by hypoxia/re-oxygenation [ 7 ], which suggest that miR-25 may be related to myocardial function. Previous studies have also found that miR-25 expression is down-regulated in patients with sepsis [ 8 , 9 ].…”

Characteristic MicroRNA Expression Induced by δ-Opioid Receptor Activation in the Rat Liver Under Prolonged Hypoxia

“…Though none of these miRNAs are reported in current literature to be directly involved in hypoxia regulation in the liver, they do take part in functional regulation in other organs in hypoxia. For example, miR-7a-5p attenuates post-myocardial infarction remodeling and protects cardiac myocyte from hypoxia-induced apoptosis involving Sp1 and PARP-1 in mice [36-38] and miR-25 protects against hypoxia/reoxygenation-induced fibrosis and apoptosis in cardiomyocytes by targeting HMGB1 [39]. Also, miR-26 is induced in response to low oxygen and decreases proapoptotic signaling in a hypoxic environment [40], while miR-122-5p inhibition attenuates hypoxia/reoxygenation-induced myocardial cell apoptosis by targeting GATA4 [41].…”

Hypoxia Suppresses TGF-B1-Induced Cardiac Myocyte Myofibroblast Transformation by Inhibiting Smad2/3 and Rhoa Signaling Pathways

“…The promoters of two key genes involved in the EMT process, E-cadherin and α-SMA, contain a number of E-box motifs that enable the binding of E2A transcription factors [22, 25]. Because cardiac myocytes may be induced to undergo myofibroblast transformation, and hypoxia/reoxygenation can increase the expression of fibrosis-related proteins, including fibronectin, collagen I and III in cardiomyocyte H9c2 cells [26], in light of the possibility that the interplay between hypoxia and TGF-β is cell type-specific, we explore the interplay between hypoxia and TGF-β1 on myofibroblast transformation in cardiomyocyte H9c2 cells.…”