Systematic Expression and Localization Profiling of Piezo2 in Rodent Pancreatic Islets.

Background: Impaired insulin secretion by pancreatic beta cells drives chronic hyperglycemia, which characterizes type 2 diabetes mellitus. The mechanosensitive ion channel Piezo2 has been implicated in various physiological processes. However, its expression and functional role in pancreatic endocrine cells remain poorly understood. Methods: We investigated the expression, cellular localization, and potential functional significance of Piezo2 in the pancreatic islets of mice fed normal- and high-fat diets (HFD) using molecular, immunohistochemical, and immunofluorescence approaches. Results: Piezo2 mRNA and protein expression were detected in rat pancreatic tissue and the pancreatic beta cell line INS-1 via polymerase chain reaction and Western blotting analyses. Hematoxylin and eosin staining and histopathological analysis were performed to determine the localization of Piezo2, insulin, and glucagon in the islets of Langerhans from mouse pancreas. Immunofluorescence revealed that Piezo2 colocalized with insulin, glucagon, pancreatic polypeptide (PP, a pancreatic cell marker), and insulin/PP (suggesting Ppy-lineage beta cells). Piezo2 expression is significantly reduced in islets from HFD-fed mice and downregulated under high glucose conditions in INS-1 cells. Stretch stimulation, with or without D-GsMTx4 (a Piezo2-specific inhibitor), enhanced glucose-stimulated insulin secretion, whereas ruthenium red (a non-specific Piezo channel inhibitor) did not alter the response to high glucose. Conclusions: These findings demonstrate Piezo2 expression in pancreatic islets and suggest that it is enriched in beta cells and Ppy-lineage beta cells, minority in alpha cells and is responsive to metabolic stress. Although Piezo2 may contribute to beta-cell adaptation, its role in insulin secretion remains unclear.