Novel Drp1-Parkin-VMP1-pathway of selective mitophagy in acute pancreatitis.

V. VANASCO, A. ROPOLO, D. GRASSO, S. ALVAREZ, M.I. VACCARO

Miami

Congreso; American Pancreatic Association/International Association of Pancreatology Joint Meeting 2018; 2018

American Pancreatic Association

Novel Drp1-Parkin-VMP1-pathway of selective mitophagy in acute pancreatitis.V. Vanasco, A. Ropolo, D. Grasso, S. Alvarez, M.I. VaccaroInstitute of Biochemistry and Molecular Medicine (IBIMOL-CONICET), School of Pharmacy andBiochemistry, University of Buenos Aires, Buenos Aires, Argentina.Background: We analyze mitophagy in Acute Pancreatitis (AP), its molecular mechanisms and itsrelationship with mitochondrial dynamics during selective autophagy induced by acute pancreatitisin animal and cellular models.Methods: Cerulein rat-model of AP and cell-model using AR42J cells cultured with 7.4μMcerulein. Mitophagy was analyzed through the pMITO-RFP-GFP tandem probe and Parkinexpression. Mitochondrial dynamics were determined by OPA1 and DRP1 expressions. TMRMprobe was used to measure membrane potential, as parameter of mitochondrial function.Results: In the cell model, mitochondrial membrane potential was decreased by 15% at 30min(p<0.01). Mitochondrial dynamics showed significant induction of the mitochondrial fissionprotein DRP1 at 15min, while the mitochondrial fusion protein OPA1 was maximal at 1h. Thiswas accompanied by an increase in the expression of Parkin and recruitment of LC3-RFP.Redistribution of EGFP-VMP1 showed the sequestration of damaged mitochondria inautophagosomes. Confocal analysis using the specific probe and electronic microscopy confirmedmitophagy and mitochondrial dynamics in the cell model. Interestingly, inhibition of mitophagyby downregulation of VMP1 leads to a dramatic decrease of 60% in mitochondrial function. Toevaluate the pathophysiological relevance of these findings, we study mitophagy, mitochondrialdynamics and function in the rat model. Mitochondrial respiration and ATP production weredecreased by 35% at 1h (p<0.01). DRP1 expression was maximal at 15min and was not detectableafter 30min, whereas increased of OPA1 expression was observed after 1h. LC3II, VMP1 andParkin expressions as well as isolation of autophagosomes demonstrated VMP1-relatedmitophagy. All the parameters returned to control values when pancreatic morphology wasrecovered.Conclusion: We have identified the Drp1-Parkin-VMP1-pathway of selective mitophagy in AP,which removed damaged mitochondria, allowing the recovery of energetic status by the OPA1mediated fusion and elongation. Our findings provide novel evidence of the potential relevance ofVMP1-mediated selective autophagy in acute pancreatitis.