717-P: Small Molecule Allosteric Activators of SERCA Improve β-Cell Viability and Calcium Homeostasis

Introduction and Objective: Type 2 diabetes mellitus (T2DM) is a chronic metabolic condition where insulin resistance and impaired insulin secretion lead to hyperglycemia. Pancreatic β-cells regulate insulin production and secretion; however, pathological stressors encountered during diabetes development, including endoplasmic reticulum (ER) stress, contribute to decreased β-cell mass and function and altered cell identity. The ER serves as the central Ca²⁺ storage organelle for the β-cell, and Ca²⁺ is actively transported from the cytosol into the ER by the sarco/endoplasmic reticulum Ca²⁺ ATPase (SERCA). We have shown that pancreatic islet expression of SERCA2 is decreased in mouse models of obesity and in organ donors with T2DM. Furthermore, loss of SERCA2 activity impairs insulin secretion and β-cell survival. Here, we determined whether ER stress-induced β-cell death is ameliorated through SERCA activation.Methods: INS-1 cells and human pancreatic islets were used to screen a series of small molecule allosteric SERCA activators to determine the effect on ER Ca²⁺ dynamics and β-cell viability. Cells and islets were co-treated with tunicamycin (300 nM) and SERCA activators for 24 hours. To determine ER Ca²⁺ concentrations, cells were transfected with pCMV G-CEPIA1er and imaged using an upright confocal laser scanning microscope. Cell viability was determined by Sytox green, a nucleic acid stain, and quantified with a Sartorius IncuCyte S3/SX1 live cell imaging and analysis system.Results: As expected, tunicamycin treatment of INS-1 cells and islets increased cell death and lowered ER Ca²⁺ levels; however, when cells were co-incubated with tunicamycin and small molecule SERCA allosteric activators, cell survival was increased and ER Ca²⁺ levels were maintained compared to cells and islets treated with tunicamycin alone.Conclusion: Our findings suggest that SERCA activation with small molecules holds promise as a therapeutic strategy to treat ER stress-mediated β-cell dysfunction during T2DM.

D.J. Sanchez Rodriguez: None. T. Kono: None. R. Dahl: None. C. Evans-Molina: Advisory Panel; DiogenX. Research Support; Bristol-Myers Squibb Company, Lilly Diabetes. Advisory Panel; Isla Technologies, Neurodon. Research Support; Neurodon. R.C. Branco: None.

Funded by Breakthrough T1D



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