Autophagy inhibits high glucose induced cardiac microvascular endothelial cells apoptosis by mTOR signal pathway

Abstract

Cardiac microvascular endothelial cells (CMECs) dysfunction is an important pathophysiological event in the cardiovascular complications induced by diabetes. However, the underlying mechanism is not fully clarified. Autophagy is involved in programmed cell death. Here we investigated the potential role of autophagy on the CMECs injury induced by high glucose. CMECs were cultured in normal or high glucose medium for 6, 12 and 24 h respectively. The autophagy of CMECs was measured by green fluorescence protein (GFP)-LC3 plasmid transfection. Moreover, the apoptosis of CMEC was determined by flow cytometry. Furthermore, 3-Methyladenine (3MA), ATG7 siRNA and rapamycin were administrated to regulate the autophagy state. Moreover, Western blotting assay was performed to measure the expressions of Akt, mTOR, LC3 and p62. High glucose stress decreased the autophagy, whereas increased the apoptosis in CMECs time dependently. Meanwhile, high glucose stress activated the Akt/mTOR signal pathway. Furthermore, autophagy inhibitor, 3-MA and ATG7 siRNA impaired the autophagy and increased the apoptosis in CMECs induced by high glucose stress. Conversely, rapamycin up-regulated the autophagy and decreased the apoptosis in CMECs under high glucose condition. Our data provide evidence that high glucose directly inhibits autophagy, as a beneficial adaptive response to protect CMECs against apoptosis. Furthermore, the autophagy was mediated, at least in part, by mTOR signaling.

Knockdown of insulin-like growth factor 1 exerts a protective effect on hypoxic injury of aged BM-MSCs: role of autophagy

“…These two signals downregulated autophagy, thereby promoting apoptosis in aged BM-MSCs. Our previous studies showed that hypoxia increased autophagy via the downregulation of the mTOR/Akt pathway in BM-MSCs [ 25 ]. Although hypoxia also increased autophagy in both young and aged BM-MSCs in this study, our results revealed that the level of autophagy in aged BM-MSCs was significantly lower compared with young BM-MSCs under both normoxic and hypoxic conditions.…”

“…In accordance with 3-MA, to regulate autophagy of aged BM-MSCs, Atg7-specific small interference RNA (siRNA) was administrated to further inhibit autophagy by suppressing autophagic vacuoles formation [ 24 ]. In brief, aged BM-MSCs were placed on six-well plates (1 × 10 5 cells per cm 2 ) for 24 h before transfecting with siRNAs targeting Atg7 [ 25 ]. The aged BM-MSCs were transiently transfected with Atg7 siRNAs.…”

“…The aged BM-MSCs were transiently transfected with Atg7 siRNAs. For control group, aged BM-MSCs were also transfected with control siRNAs (Cell signal) transiently [ 25 ]. Lipofectamine™ 2000 was used as the transfection device based on the manufacturer’s guidance [ 24 ].…”

Overexpression of miR‑17‑5p protects against high glucose‑induced endothelial cell injury by targeting E2F1‑mediated suppression of autophagy and promotion of apoptosis

“…2J-M), suggesting that the downregulation of E2F1 inhibited HG-induced endothelial cell injury relative to the activation of autophagy. A previous study reported that certain types of autophagy inhibited cell damage under stress conditions (14). The tube formation assay showed that the downregulation of E2F1 restored angiogenesis, even under HG conditions ( Fig.…”

“…E2F1 is also important in the regulation of mammalian target of rapamycin complex 1 (mTORc1) during autophagy (12,13). Increasing evidence has shown that certain autophagic activations inhibit HG-induced endothelial cell apoptosis via the mTOR signaling pathway (14); however, the regulatory mechanisms of E2F1 in autophagy and HG-induced endothelial cell apoptosis remain to be fully elucidated.…”