Phillyrin protects against myocardial ischemia/reperfusion injury by promoting KNL1 K605 acetylation to inhibit the p53/p21 pathway

Reperfusion therapy is critical for acute myocardial infarction but is often accompanied by myocardial ischemia/reperfusion injury (MIRI). Phillyrin, a natural lignan from Forsythia suspensa, exerts anti-inflammatory and antioxidant effects; however, its role and mechanism in MIRI remain unclear. In this study, HL-1 cardiomyocytes are subjected to oxygen-glucose deprivation/reperfusion (OGD/R). Cell viability, apoptosis, oxidative stress, and inflammation are measured after phillyrin treatment. Multiomics (mRNA-seq, proteomics, and acetylproteomics) is used to identify key targets and pathways. Molecular docking, coimmunoprecipitation, site-directed mutagenesis, and Western blot analysis are used to validate posttranslational regulation. A mouse MIRI model is established to confirm the in vivo cardioprotective effects of phillyrin. Phillyrin preserves cell viability and reduces apoptosis, oxidative stress, and inflammation in OGD/R-injured HL-1 cells. Multiomics integration reveals that phillyrin acts primarily through posttranslational regulation and highlights kinetochore scaffold 1 (KNL1) as the only protein that is both upregulated and hyperacetylated at lysine 605 (K605). Mechanistically, phillyrin may bind to the KNL1 C-terminus and enhance the interaction between KNL1 and acetyltransferase p300/CBP. KNL1 K605R mutation and Knl1 knockdown reduce KNL1 protein expression and reverse the inhibitory effects of phillyrin on p53 pathway-mediated apoptosis, oxidative stress, and inflammation. In mouse MIRI models, phillyrin reduces infarct size, myocardial damage, and cardiomyocyte apoptosis; these effects are abolished by knockdown of Knl1 . Therefore, phillyrin promotes KNL1 acetylation at K605 to increase KNL1 protein expression, thereby inhibiting p53 signaling and alleviating apoptosis, oxidative stress, and inflammation in MIRI. This study identifies KNL1 acetylation at K605 as a novel posttranslational modification target for cardioprotection.