Early-phase impact of obesity-associated stress on murine vascular smooth muscle cells depends on EGFR and sex.

Abstract

Obesity leads to vascular dysfunction mediated partially by the vascular smooth muscle cell (VSMC) EGF-receptor (EGFR). We investigate the impact of obesity-associated metabolic and humoral stress on primary murine VSMC with conditional EGFR knockout (KO) and wildtype (WT) VSMC, focusing on early-phase impact to test the hypothesis of an EGFR-dependent stressor synergism. Cells are exposed to three stress conditions (high glucose + free fatty acids; angiotensinII + noradrenaline; combined = all stressors) and bulk RNA-sequencing with bioinformatics analysis, followed by phenotypical assessment is performed. RNASeq-results show stressor synergy in male WT-VSMC but not in KO VSMC or endothelial cells (EC). Bioinformatic analysis predicts dysregulation of functions related to DNA-synthesis/cell cycle, lipid handling, contraction and motility for male WT-VSMC. Functional validation confirms synergy concerning DNA-synthesis and lipid accumulation in male WT-VSMC but not in female WT-VSMC. Altered contraction or motility are not confirmed. Male WT-VSMC show higher EGFR-expression than female WT-VSMC and respond with enhanced SRF^S103-phosphorylation, a classical downstream target of EGFR, to the stressors. Obesity-associated metabolic and humoral stressors induce synergistic transcriptomic effects in male WT-VSMC, initiating proliferative and lipogenic dedifferentiation. This early-phase effect requires EGFR and was not observed in female VSMC.