9317 Diabetogenic Stress-Mediated Beta Cell Extracellular Vesicle:Autophagy Pathway Crosstalk

Abstract Disclosure: A. Roy: None. G. Ariyaratne: None. A. Matveyenko: None. N. Javeed: None. Diabetogenic stressors including elevated free fatty acids (lipotoxicity), low-grade systemic inflammation, and proteotoxicity are central to the development of Type 2 Diabetes (T2D). Due to their high protein synthetic burden, β-cells employ autophagy and endo/lysosomal pathways to reduce protein aggregates, and protect β-cell mass and function. Recently, extracellular vesicles (EVs; 30-150 nm sized nanoparticles) have been shown to work in tandem with autophagy to facilitate cellular adaptation and intercellular communication. As diabetogenic stressors have been shown to perturb autophagy via lysosomal defects, our group has noted enhanced EV secretion. Thus, we hypothesize that diabetogenic factors enhance EV secretion through activation of an EV-based secretory autophagy pathway and that re-balancing of both pathways could improve β-cell function in T2D. To test this, MIN6 cells were exposed to free fatty acid palmitate (PAL; 24h), or pro-inflammatory cytokines IL-1β, TNFα, and IFNγ (CYTO; 48h). Expression of autophagic markers, LC3 and p62 were increased in CYTO and PAL conditions suggesting defects in auto/lysosomal function. Upon PAL/CYTO treatment in MIN6 cells, conditioned media EVs were isolated using differential ultracentrifugation. We noted enhanced protein expression of LC3-II and p62 in PAL- and cytoEVs, suggesting a diversion of immature autophagosome components into EVs due to lysosomal inhibition. To restore balance between autophagy:EV flux, we used EV biogenesis inhibitor, GW4869 (GW; 24h) or autophagy inducer, rapamycin (Rapa; 24h) on MIN6 cells exposed to PAL or CYTO. Isolated EVs were subjected to Nanoparticle Tracking Analysis (NTA) which showed a significant reduction in EV concentration with GW or Rapa addition (p.05). Isolated mouse islet exposed to CYTO+GW/Rapa or PAL+GW/Rapa showed significant improvements in glucose stimulated insulin secretion (vs. CYTO or PAL; p.05). Taken together, these data implicate activation of EV-based secretory autophagy in response to diabetogenic stressors and thus, potential targets to improve functional β-cell mass. Presentation: 6/2/2024