BAG3 Overexpression Attenuates Ischemic Stroke Injury by Activating Autophagy and Inhibiting Apoptosis

Abstract

Background: The ubiquitin-proteasome system (UPS) and autophagy are 2 major protein degradation pathways in eukaryotic cells. We previously identified a switch from UPS to autophagy with changes in BAG3 (B-cell lymphoma 2-associated-athanogene 3) expression after cerebral ischemia in mice. BAG3 is an antiapoptotic-cochaperone that is directly involved in cellular protein quality control as a mediator for selective macroautophagy. Here, we aimed to investigate the role of BAG3 in ischemic stroke. Methods: Middle cerebral artery occlusion/reperfusion (MCAO/R) and oxygen-glucose deprivation/reoxygenation were used to mimic cerebral ischemia in vivo and in vitro. The UPS inhibitor MG132 and autophagy inhibitor 3-MA (3-methyladenine) were administered to mice to identify how BAG3 was involved after MCAO/R. Adeno-associated virus and lentiviral vector were used to regulate BAG3 expression in vivo and in vitro, respectively. Behavioral tests, 2,3,5-triphenyltetrazolium chloride staining, and Hematoxylin & Eosin staining were performed to evaluate cerebral injury following MCAO/R, and a Cell Counting kit-8 assay was conducted to assess oxygen-glucose deprivation/reoxygenation–induced injury in cells. Brain tissues and cell lysates were collected and analyzed for UPS activation, autophagy, and apoptosis. Results: The UPS inhibitor alleviated MCAO injury in mice and increased autophagy and BAG3 expression, whereas the autophagy inhibitor exacerbated MCAO/R-induced injury. In addition, BAG3 overexpression significantly improved neurological outcomes, reduced infarct volume in vivo, and enhanced cell survival by activating autophagy and suppressing apoptosis in vitro. Conclusions: Our findings indicate that BAG3 overexpression activates autophagy and inhibits apoptosis to prevent cerebral ischemia/reperfusion and hypoxia/reoxygenation injury, suggesting a potential therapeutic benefit of BAG3 expression in cerebral ischemia.

Exploring the autophagy-related pathogenesis of active ulcerative colitis

“…The predicted core genes are critical to the pathogenesis+ADs- hSPA5, for example, offering neuroprotection in ischemic strokes[ 34 ]. BAG3 overexpression is shown to improve neurological outcomes associated with middle cerebral artery embolism in mice, reducing infarct volume and enhancing cell survival by activating autophagy and inhibiting apoptosis[ 35 ]. Ischemia-induced neuronal autophagy is shown to exacerbate microglial inflammation post-stroke, possibly due to the reduced CX3CL1 expression in autophagic neurons[ 36 ].…”

β-asarone induces viability and angiogenesis and suppresses apoptosis of human vascular endothelial cells after ischemic stroke by upregulating vascular endothelial growth factor A

“…NO, as a potent vasodilator, can improve blood flow, reduce vascular inflammation, and inhibit apoptosis ( Chen et al, 2023 ). Apoptosis is one of the key factors leading to neuronal death in patients with IS ( Liu et al, 2023 ). Thus, activating the VEGFA/eNOS pathway can weaken apoptosis and improve neurological recovery after cerebral ischemia ( Liu et al, 2020b ).…”

Role of autophagy in ischemic stroke: insights from animal models and preliminary evidence in the human disease

“…Recently, in mice undergoing MCAO, autophagy inhibition with 3-Methyladenine (3-MA) was shown to exacerbate brain injury. Mechanistically, overexpression of BAG3 (B-cell lymphoma 2-associated-athanogene 3), a protein involved in cellular protein quality control, activates autophagy and prevents both apoptosis and cerebral injury ( Liu et al, 2023 ). Another study demonstrated that CAPN1 (calpain1), an intracellular Ca 2+ -regulated cysteine protease, is activated in the cortex of rats undergoing permanent MCAO.…”