Muscle-derived extracellular vesicles and their interactions with adipocytes in human metabolic dysfunction

ABSTRACT- PROJECT 5 There is growing recognition of the significant changes in extracellular vesicle (EV) biology in the pathogenesis of obesity and diabetes. Although evidence points to deviations in EV biogenesis and abundance in circulation, the mechanisms by which EVs are regulated are poorly understood. Research has mostly focused on the tissues of origin for circulating EVs but almost nothing is known about tissue-specific plasma membrane adaptations that either increase or decrease vesicle uptake. The proposed studies will investigate the role of membrane receptivity to circulating EVs in the pathophysiology of obesity and metabolic disorders. The project leader and mentors have already performed studies in this area and found an exciting EV communication axis from skeletal muscle to adipose tissue that is conserved in mice and humans. This led us to postulate that adipose tissue may become resistant to EV endocytosis in people with prediabetes and this endocytosis- resistance contributes to progression to diabetes. Changes in EV-uptake in adipose tissue may not be a primary dysfunction in adipose but rather may be a maladaptive tissue crosstalk response in prediabetic skeletal muscle. To test these hypotheses, we propose to recruit participants with and without prediabetes and subject them to a single bout of whole-body resistance exercise to simulate EV secretion. Biopsies will be obtained from subcutaneous adipose and vastus lateralis for transcriptomics analyses and primary cell cultures. Aim 1: Determine whether there is a baseline variance in EV receptivity in human adipose tissue and adipocyte cultures. EV uptake will be assessed 1) in vivo using adipose tissue mature miR-1 levels as a proxy, and 2) in vitro using non-stimulated myotube derived EVs that have been labeled with tetraspanin fluorescent reporter. Transcriptomics analysis will be used to analyze gene expression in both adipose tissue and adipocyte cultures. Aim 2: Assess the impact of exercise-induced muscle-derived EVs on adipose tissue and EV uptake in adipocyte cultures. Aim 3: Determine whether pre-diabetes impacts adipose tissue EV receptivity at baseline and following exercise. This proposal will provide the first evidence for this muscle-adipose EV communication and membrane resistance as a contributing factor in metabolic dysfunction and prediabetes.