VLDL induces EZH2/PRC2 complex-mediated cellular senescence in metabolic syndrome to enhance cardiotoxicity

Abstract

Abstract Introduction In metabolic syndrome, very-low-density lipoprotein (VLDL) carries cardiotoxic lipids that cannot be completely modified by lipid-lowering medications. VLDL isolated from patients with metabolic syndrome (ms-VLDL) induces cardiac remodeling compared with that isolated from non-metabolic syndrome subjects (n-VLDL). Purpose This study focused on identifying dysregulated molecular pathways of ms-VLDL-associated with senescence. Methods RNA-sequencing, accompanied with IPA and KEGG pathway analysis were used to identify differentially expressed genes (DEGs) in cardiomyocytes after two different VLDL incubations, and the identified DEGs were subjected to functional annotation, including enriched molecular pathway and gene ontology analyses. A Seahorse XFe96 Analyzer was used to determine the mitochondrial biosynthesis oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). Molecules involved in the mitochondrial pathway were validated using Western blotting, qPCR, and immunofluorescence. Results Compared to the n-VLDL group, the ms-VLDL group had a larger number of significant DEGs involved in several critical biological processes and molecular pathways, such as cardiomyocyte injury (ms-VLDL vs. n-VLDL for significant DEGs numbers, 2,642 vs. 1,725), senescence (259 vs. 184), and mitochondrial dysfunction (137 vs. 68). In terms of mitochondrial biosynthetic function, ms-VLDL induced 8.5 folds OCR reduction compared to n-VLDL, along with intra-mitochondrial calcium overload and excessive ROS. The essential genes involved in these pathways were shown to be differentially regulated, and our analysis identified the Ezh2/PRC2 complex, which is strongly linked to ms-VLDL-induced cardiomyocyte senescence and lipotoxicity. Conclusion This study identified the crucial roles of epigenetic modification enzyme Ezh2/PRC2 complex in induction the senescence pathway, which represents a potential mechanism for ms-VLDL-induced adverse cardiac remodeling in metabolic syndrome. Further functional studies are required to validate their roles in the pathogenesis of lipotoxicity and the connection of cardiomyopahty.RNA-seq of VLDL treated cardiomyocyteSenescence induction of VLDL