TMC6 Protects Against Ischemic Neuronal Injury by Activating Rap1/Rac1 Signaling to Restore Mitochondrial Dynamics and Mitophagy.

Ischemic stroke (IS) is a leading cause of neurological disability, yet the molecular basis of neuronal injury and repair remains unclear. Three Gene Expression Omnibus datasets (GSE22255, GSE58294, and GSE37587) were integrated for differential expression analysis. Candidate genes were identified by combining protein-protein interaction network analysis with weighted gene co-expression network analysis and validated in GSE16561. The effects of transmembrane channel-like 6 (TMC6) were investigated in oxygen-glucose deprivation/reoxygenation (OGD/R)-treated HT22 cells and a rat middle cerebral artery occlusion (MCAO) model. Rap1/Rac1-related signaling was examined using geranylgeranyltransferase I inhibitor-298 (GGTI-298) and Rac1 knockdown. TMC6 was downregulated in IS. TMC6 overexpression reduced cortical and striatal infarction and mitigated neurological deficits in the MCAO rat. TMC6 overexpression alleviated neuronal apoptosis and improved cell viability in OGD/R-treated HT22 cells. Inflammatory response was suppressed, and mitochondrial membrane potential was preserved after TMC6 overexpression. TMC6 reprogrammed mitochondrial dynamics and quality control by increasing mitofusin 1 (MFN1) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), suppressing dynamin-related protein 1 (DRP1), and restoring the expression of the mitophagy-associated proteins PTEN-induced putative kinase 1 (PINK1) and Parkin RBR E3 ubiquitin-protein ligase (Parkin). TMC6 knockdown exacerbated OGD/R-induced injury.. Pharmacological inhibition of Rap1 using GGTI-298 or genetic silencing of Rac1 markedly abrogated TMC6-mediated neuroprotection. TMC6 alleviates experimental ischemic neuronal injury and preserves mitochondrial homeostasis. Rap1/Rac1-related signaling may be involved in these protective effects. These findings identify TMC6 as a potential therapeutic target for IS.