miR‐200a mediates protection of thymosin β‐4 in cardiac microvascular endothelial cells as a novel mechanism under hypoxia‐reoxygenation injury

Abstract

Thymosin β‐4 (Tβ4) is a ubiquitous protein, which has been suggested to regulate multiple cell signal pathways and a variety of cellular functions. However, the role Tβ4 plays in the cardiac microvascular endothelial cells (CMECs) under myocardial ischemia/reperfusion injury is currently unknown. Here we investigated the effects of Tβ4 on hypoxia/reoxygenation (H/R) induced CMECs injury and its potential molecular mechanism. Cultured CMECs were positively identified by flow cytometry using antibody against CD31 and VWF/Factor VIII, which are constitutively expressed on the surface of CMECs. Then the reduced level of Tβ4 was detected in H/R‐CMECs by a real‐time quantitative polymerase chain reaction. To determine the effects of Tβ4 on H/R‐CMECs, we transfected the overexpression or silence vector of Tβ4 into CMECs under H/R condition. Our results indicated that H/R treatment could reduce proliferation, increased apoptosis, adhesion, and reactive oxygen species (ROS) production in CMECs, which were attenuated by Tβ4 overexpression or aggravated by Tβ4 silencing, implying Tβ4 is able to promote CMECs against H/R‐induced cell injury. Furthermore, the microRNA‐200a (miR‐200a) level was also increased by Tβ4 in H/R‐CMECs or reduced by Tβ4 small interfering RNA. To investigated the mechanism of protective effects of Tβ4 on CMECs injury, the miR‐200a inhibitor was transfected into H/R‐CMECs. The results indicated that inhibition of miR‐200a inversed the protection of Tβ4 on H/R‐CMECs, specifically including cell proliferation, cell adhesion, cell apoptosis, and ROS production, as well as nuclear factor erythroid 2‐related factor 2 (Nrf2) nuclear translocation. In conclusion, our results determined that Tβ4 attenuated H/R‐induced CMECs injury by miR‐200a‐Nrf2 signaling.

MicroRNA-mediated regulation of Nrf2 signaling pathway: Implications in disease therapy and protection against oxidative stress

“…The miR-200a mediates the ameliorative impact of thymosin -4 (T-4) in cardiac microvascular endothelial cells after hypoxia-reoxygenation injury (Li et al , 2017). T-4 exerts a stimulatory effect on the expression of miR-200a.…”

MicroRNA gga-miR-200a-3p modulates immune response via MAPK signaling pathway in chicken afflicted with necrotic enteritis

“…Moreover, miR-200a mediated the proliferation of hepatic stellate cells and development of fibrosis by targeting the 3′-UTR of SIRT1 via the SIRT1/Notch signal pathway [12]. It was also involved in protecting thymosin β-4 in cardiac microvascular endothelial cells following hypoxia/reoxygenation injury via the NRF2 antioxidant pathway [13]. Moreover, expression of miR-200a was downregulated in fibrostenosing Crohn's disease [14], HBV-induced hepatocellular carcinoma [15] and human glioma [16], thereby highlighting its function as a suppressor of many diseases.…”

Long Noncoding RNA MALAT1 Regulates Hepatocellular Carcinoma Growth Under Hypoxia via Sponging MicroRNA-200a

“…Many researchers have reported that miR-200a inhibited HCC cell proliferation,27282930 and that it plays an important role in protecting cardiomyocyte survival under hypoxic conditions. Li, et al31 pointed that miR-200a level was decreased in H/R-cardiac microvascular endothelial cells (CMECs), and thymosin beta 4 attenuated hypoxia-reoxygenation induced CMECs injury by miR-200a-Nrf2 signaling. Sun, et al32 manifested that miR-200a was significantly downregulated in ischemic myocardial tissues and hypoxic cardiomyocytes, and suppression of Keap1 by miR-200a exerted cardioprotective effect against hypoxia-induced oxidative stress and cell apoptosis.…”