SAT063 Dopaminergic Agonist Cabergoline Inhibits Autophagic Flux In Beta Pancreatic Cells

Abstract

Abstract Disclosure: L.F. Mendez: None. L. Etcheverry Boneo: None. D. Becu-Villalobos: None. E. Sorianello: None. Autophagy is a lysosomal degradation process necessary for the maintenance of cellular homeostasis, which is based on constantly removing ubiquitinated proteins and dysfunctional organelles that are eventually toxic to the cell. Since alteration of this process in pancreatic beta cells can lead to the development of diabetes, autophagy modulators arise as interesting therapeutic compounds for the treatment of this prevalent human pathology. Previous studies indicate that activation of the dopamine D2 receptor (D2R) alters autophagy in several cell types. In this context, we aimed at determining the effect of D2R activation by its agonist Cabergoline (CAB) on the autophagic process in pancreatic beta cells. To that end, we stimulated the murine pancreatic beta cell line MIN6B1 with 10-5 M CAB for 1, 6 and 24h to evaluate the kinetics of autophagic vesicle formation. Additionally, 10-5 M CAB in the presence or absence of Chloroquine (CQ), an inhibitor of late stages of the autophagy process, was used to study the autophagic flux. Using Western Blot and immunofluorescence and confocal microscopy, the autophagy markers LC3 (autophagic vesicle marker) and p62/SQSTM1 (autophagy cargo receptor and degradation substrate) were analyzed. CAB increased LC3 nucleation as a function of stimulation time, showing significant differences relative to the control after 6h (one-way repeated measures ANOVA p=0.0038; Tukey: Control vs CAB6h p<0.05, vs CAB24h p<0.01). Moreover, CAB significant increased p62/SQSTM1 levels after 24h of stimulation (one-way repeated measures ANOVA: p=0.0157; Tukey: Control vs CAB24h p<0.05). When studying the effect of CAB on the autophagic flux, we observed that CQ significantly increased LC3 and p62/SQSTM1 levels at 24h of incubation (two-way repeated measures ANOVA (CQ and CAB): for LC3: interaction p<0.05, Tukey: CQ vs Control p<0.0001; for p62/SQSTM1: CQ pretreatment effect p<0.05), as expected. Interestingly, CAB diminished the accumulation of LC3 (Test-T Delta (CQ-Control) vs Delta (CQCAB-CAB): p=0.04) and p62/SQSTM1 (Test-T Delta (CQ-Control) vs Delta (CQCAB-CAB): p=0.01) elicited by CQ at 24h. We conclude that CAB is able to increase autophagic vesicle formation and, in addition, to decrease autophagic flux after 24h of stimulation in MIN6B1 pancreatic beta cells. This work was funded by CONICET, ANPCyT, Fundación René Barón and Fundación Williams. Presentation: Saturday, June 17, 2023