Knockdown of ARID1A Protects H9c2 Cells Against Hypoxia/Reoxygenation (H/R)-Induced Injury by Targeting SOX9

BACKGROUND AND OBJECTIVES: Hypoxia/reoxygenation (H/R) injury is a major contributor to cardiac damage. The role of AT-rich interaction domain 1A (ARID1A) in cardiomyocyte H/R injury and its underlying mechanisms remain unclear. METHODS: An H/R injury model was established using H9c2 cardiomyoblasts. Key assessments included cell viability (cell counting kit-8), apoptosis (Terminal deoxynucleotidyl transferase dUTP Nick End Labeling), DNA fragmentation, inflammatory cytokine levels (interleukin [IL]-1β, IL-6, IL-18), cardiac injury markers (creatine kinase-MB [CK-MB], cardiac troponin-I [cTn-I]), oxidative stress markers (lactate dehydrogenase [LDH] release, reactive oxygen species [ROS], glutathione peroxidase [GSH-Px], superoxide dismutase [SOD] activity), pyroptosis marker expression (NLR family pyrin domain containing 3 [NLRP3], caspase-1, gasdermin D [GSDMD]; Western blot), and ARID1A-SOX9 interaction (co-immunoprecipitation). RESULTS: H/R significantly upregulated ARID1A and SOX9 expression in H9c2 cells. ARID1A knockdown effectively attenuated H/R-induced damage, including improved cell viability, reduced apoptosis and DNA fragmentation, suppressed pro-inflammatory cytokine release (IL-1β, IL-6, IL-18), lowered CK-MB and cTn-I levels, decreased LDH release and ROS generation, enhanced antioxidant enzyme activity (GSH-Px, SOD), and reduced expression of pyroptosis markers (NLRP3, caspase-1, GSDMD). Mechanistically, ARID1A physically bound to SOX9 and promoted its expression. Crucially, the protective effects of si-ARID1A against H/R injury (apoptosis, inflammation, oxidative stress, pyroptosis) were consistently reversed by SOX9 overexpression. CONCLUSIONS: ARID1A is upregulated during H/R injury and exacerbates cardiomyocyte damage by promoting apoptosis, inflammation, oxidative stress, and pyroptosis. ARID1A exerts its effects by binding to and positively regulating the expression of SOX9. Targeting the ARID1A/SOX9 axis represents a potential therapeutic strategy for mitigating H/R-induced cardiac injury.