3114-LB: Extracellular Matrix Stiffness Regulates Beta-Cell Insulin Secretion via Piezo1-Mediated Changes in Mitochondrial Function

Introduction and Objective: Pancreatic islets are surrounded by extracellular matrix (ECM) which provides mechanical and biochemical cues that regulate insulin secretion. Increased ECM stiffness leads to dysfunction in insulin secretion that is directly coupled to glucose metabolism and mitochondrial function. Activation of the mechanosensing ion channel Piezo1 is thought to mediate stiffness induced changes in insulin secretion; however, the mechanisms driving this have not been studied in the islet. We hypothesize that increasing matrix stiffness impairs β-cell insulin secretion by Piezo1 mediated decreases in mitochondrial membrane potential (ΦM) and function. Methods: To determine the effect of changes in ECM stiffness on β-cell mitochondrial function and morphology we encapsulated MIN6 cells or primary mouse and human islets in a 3D poly(ethylene glycol) scaffold with increasing stiffness from 0.1-15kPa either alone or with the Piezo1 inhibitor GsMtx4 or activator Yoda1 for 24h. Glucose-stimulated insulin secretion and calcium signaling were analyzed by ELISA and confocal microscopy. Mitochondrial morphology and ΦM were determined by quantitative confocal microscopy with TMRE dye. Mitochondrial function was analyzed by 13C metabolic flux analysis. Results: We found that increasing scaffold stiffness decreased insulin secretion and caused dysfunction to calcium signaling that was rescued upon inhibition of Piezo1. Increased stiffness or activation of Piezo1 with Yoda 1 decreased ΦM and mitochondrial branching as measured by increased sphericity. Finally, increased ECM stiffness or Piezo1 activation altered glucose flux and glycolysis rates. Conclusion: Overall, our results support a role for ECM stiffness in regulating insulin secretion through Piezo1 mediated changes in mitochondrial function. This work provides insight into how changes in ECM stiffness as in T2D contribute to islet dysfunction and supports further investigation into modulation of Piezo1 to restore β-cell function. Disclosure C. Johansen: None. N.L. Farnsworth: None. Funding American Diabetes Association (7-21-JDF-020), NIDDK (R01 DK137221), Breakthrough T1D (3-SRA-2023-1367-S-B), NIDDK (1F31DK132926)