Rosmarinic Acid Suppresses Keap1/Nrf2 Signaling Pathway via Targeting USP15 to Attenuate Myocardial Ischemia/Reperfusion Injury.

Myocardial ischemia-reperfusion injury (MI/RI) is a complication following the treatment of acute myocardial infarction. Although rosmarinic acid (RA) possesses potent antioxidant properties, its specific targets and mechanisms underlying its therapeutic effect against MI/RI remain unclear. Our study found that RA has therapeutic effects on both the rat MI/RI model and the H9c2 cell oxygen-glucose deprivation/reperfusion (OGD/R) model. Activity-based protein profiling (ABPP) identified ubiquitin-specific peptidase 15 (USP15) as a potential target of RA. Combining ABPP technology and RNA sequencing analysis, it was found that the therapeutic effect of RA on MI/RI may be related to oxidative stress (OS). Mechanistic studies revealed that RA directly binds to and upregulates USP15. Subsequently, USP15 interacts with Kelch-like ECH-associated protein-1 (Keap1). This interaction leads to a decrease in Keap1 levels, thereby increasing the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream targets NAD(P)H quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1). Collectively, these findings demonstrate that RA activates the Keap1/Nrf2 signaling pathway by targeting USP15 to relieve MI/RI.