Oxymatrine Inhibits Homocysteine-Mediated Autophagy via MIF/mTOR Signaling in Human Umbilical Vein Endothelial Cells

Abstract

Background/Aims: Genetic or nutritional deficiencies in homocysteine (Hcy)metabolism lead to the accumulation of Hcy and its metabolites in the blood. This can lead to hyperhomocysteinemia (HHcy), which is an independent risk factor for cardiovascular disease. Studies have shown that HHcy leads to endothelial dysfunction, a hallmark of atherosclerosis, which may explain this link. The precise mechanism remains unclear, but a strong possibility is excessive HHCy-induced autophagy. Autophagy has been better studied in ischemia/reperfusion (I/R) injuries, and previous work showed that Oxymatrine (OMT), a quinolizidine alkaloid, protects cells against myocardial I/R injury by inhibiting autophagy. The aim of this study was to determine whether OMT inhibits autophagy in HHcy. Methods: Autophagy in HUVEC cells treated with Hcy in the presence and absence of OMT was visualized bytransmission electron microscopy and the degree was determined by western blotting and qRT-PCR. Small interfering RNA (siRNA)was used to determine the efficiency of Macrophage migration inhibitory factor (MIF) inhibition. Cell apoptosis wasdetected by western blotting and flow cytometric analysis. Results: OMT inhibited autophagy, MIF, and mTOR in HUVECs during Hcy exposure, depending on the dose. siRNA-mediated MIF knockdown decreased Hcy-induced autophagy, while administration of 3-methyladenosine and rapamycin showed that they also induce autophagy. Furthermore, OMT dose-dependently inhibited the Hcy-induced HUVEC apoptosis/death. Conclusions: These results suggest that Hcy can evokeautophagy-activated HUVEC apoptosis/death via a MIF/mTOR signaling pathway, which can be reversed by OMT. Our results provide a new insight into a functional role of OMT in the prevention of Hcy-induced HUVEC injury and death.

Epicatechin Gallate Protects HBMVECs from Ischemia/Reperfusion Injury through Ameliorating Apoptosis and Autophagy and Promoting Neovascularization

“…It is similar to apoptosis; autophagic bodies in ECG- and EGCG-treated cells were significantly less than those in the solvent control group, and EGCG-treated cells produced even more autophagic bodies than did ECG-treated cells. During ischemia/reperfusion injury, oxidative stress may induce epithelial cell apoptosis [50–53] and/or autophagy [51, 54, 55]. Autophagy is a widely existing metabolic and strictly regulated process, and excessive or deficient autophagy may contribute to pathogenesis [56].…”

Homocysteine enhances neural stem cell autophagy in in vivo and in vitro model of ischemic stroke

“…It has been observed in several different cell types that Hcy-induced cell injury by stimulating autophagy. For instance, human umbilical vein endothelial cells damaged by Hcy exhibit features of autophagic/lysosomal cell death accompanying with the higher expression levels of the autophagy-related genes Atg 5 and Beclin 1, greater degradation of LC3 I to LC3 II and the cytoplasmic autophagic vacuoles 16 . Zhao et al reported that Hcy treatment aggravated neuronal cell death, significantly increased the formation of autophagosomes and the expression of LC3B and Beclin 1 in the brain cortex after middle cerebral artery occlusion-reperfusion 17 .…”

Homocysteine induces human mesangial cell apoptosis via the involvement of autophagy and endoplasmic reticulum stress

“…Regarding the key role of MCs in glomerular function, the Hcy-induced apoptosis of MCs may be an important factor in the development and progression of CKD. Hcy has been reported to affect cell viability and induce apoptosis in various cell types, such as neuronal cells, 8,9 vascular endothelial cells, 12,13 SMCs, 14 and podocytes. 28 In the present study, we found that the viability of MCs was clearly decreased with the increase of Hcy concentration from 50 to 1000 mmol L À1 .…”

“…6 Enhanced apoptosis is a universal nding in both clinical and experimental kidney diseases that involve the mesangium, which irreversibly affects the pool of MCs and leads to their disappearance from mesangium. 7 On the other hand, previous studies showed that Hcy could induce the apoptosis of neuronal cells, 8,9 cardiomyocytes, 10,11 vascular endothelial cells, 12,13 and smooth muscle cells (SMCs). 14 Interestingly, there is a similarity in the mechanism that Hcy could induce the apoptosis of these cell types by activating endoplasmic reticulum stress (ERS) and autophagy.…”