Project Summary/Abstract The escalating prevalence of cardiometabolic risk factors including obesity and type 2 diabetes mellitus (T2DM) presents a critical cardiovascular challenge. Individuals with cardiometabolic disease harbor greater risk of cardiovascular disease (CVD) including accelerated vascular aging and premature atherosclerotic disease. Importantly, alterations in endothelial function predate the development of clinical CVD, making the vascular endothelium an important potential target for cardioprotection. Experimental studies and our prior work link altered metabolism to organelle stress including mitochondrial dysfunction and ER stress. In this proposal, we hypothesize that organelle stress induced by cardiometabolic traits drives vascular dysfunction and promotes CVD. We will leverage the unique resources of the planned Framingham Heart Study fourth examination cycle to prospectively collect fresh human endothelial cells (EC) from 2000 individuals. In Aim 1, we will investigate the association of T2DM and cardiometabolic traits with EC phenotype including organelle stress and nitric oxide signaling in a nested case-control sample of 450 individuals. In Aim 2, we will measure EC gene expression levels using RNA sequencing in 900 participants to identify and prioritize EC transcriptional programs linked to EC health phenotypes, cardiometabolic traits, and systemic metabolism. This proposal leverages a unique and highly experienced multidisciplinary team of investigators with expertise in obesity-related cardiovascular disease, endothelial biology, population science, translational patient-oriented research, multi-omics and bioinformatics. The proposed work will dwarf past efforts at defining endothelial health across disease states and will combine new deep phenotyping of EC conducted at scale in a community-based cohort with existing rigorous measures of cardiovascular health including metabolite profiles and genomic markers. These studies have the potential to provide important insights into mechanisms driving endothelial dysfunction and develop an unprecedented resource that will benefit vascular biology research.