Enriched environment inhibits GLT-1 ubiquitination by downregulating SMURF1 to attenuate ischemic brain injury induced excitotoxicity

Abstract

Abstract Background Excitotoxicity induced by glutamate contributes significantly to ischemic brain injury. The role of enriched environment (EE) in promoting neurological recovery post-stroke is well-established, yet its impact on excitotoxicity remains unclear. This study aimed to elucidate the mechanisms through which EE modulates excitotoxicity in ischemic brain injury using in vivo and in vitro experiments. Results EE exposure effectively reduced ischemic brain injury and glutamate-induced excitotoxicity in middle cerebral artery occlusion (MCAO) rat models. Notably, EE led to upregulated expression of GLT-1, which enhanced glutamate uptake by astrocytes and mitigated cytotoxicity and neuronal death induced by oxygen-glucose deprivation/reperfusion (OGD/R). Furthermore, EE suppressed the upregulation of SMURF1, which interacted with GLT-1 to facilitate its ubiquitin-mediated degradation and downregulate GLT-1 expression. Additionally, EE enhanced m6A modification of SMURF1, promoting YTHDF2-mediated mRNA decay and reducing SMURF1 expression. Knockdown of SMURF1 boosted GLT-1 expression, improving glutamate uptake and alleviating neuronal injury and death caused by OGD/R. Conversely, overexpression of SMURF1 or knockdown of GLT-1 attenuated the neuroprotective effects of EE against excitotoxicity in MCAO rats. Conclusion EE mitigates excitotoxicity in ischemic brain injury by inhibiting SMURF1 expression through m6A modification-YTHDF2-dependent pathways, thereby suppressing GLT-1 ubiquitin-mediated degradation and enhancing glutamate uptake.

Keywords

• Enriched environment
• Ischemic brain injury
• Excitotoxicity
• SMURF1
• GLT-1