Astragaloside IV promotes cardiac remodeling after myocardial infarction by inhibiting DNMT3B-mediated Runx3 methylation via downregulating LncRNA MIRT1 expression

Abstract Astragaloside IV (AS-IV) has been shown to possess cardioprotective effect. However, the specific mechanism of AS-IV in myocardial infarction (MI) remains unclear. Our results showed that AS-IV intervention observably enhanced cell viability and reduced cell apoptosis, oxidative stress levels and inflammatory factor secretion. Expression of MIRT1 was significantly up-regulated in hypoxia-treated cells. In addition, ALCAM overexpression reversed the effects of AS-IV intervention on hypoxia-treated cell functions. MIRT1 facilitated Runx3 promoter methylation and its downregulated expression by recruiting DNA methyltransferase 3B (DNMT3B) to the Runx3 promoter region through binding with suppressor of Zeste 12 protein homolog (Suz12). Runx3 silencing reversed the effects of MIRT1 inhibition on hypoxia-treated cell functions. Betulinic acid suppressed the effects of AS-IV intervention on the behaviors of hypoxia-treated cells. AS-IV treatment improved the cardiac functions of mice with MI. Taken together, these findings demonstrated that AS-IV treatment inhibits DNMT3B-mediated Runx3 promoter methylation by restraining Suz12 expression and further blocks the NF-κB signaling pathway, and in turn improves the cardiac functions of mice with MI.