Mechanism Study of Glucose Regulation of Syntaxin 1A on INS-1 Cell Membranes by Direct Stochastic Optical Reconstruction Microscopy

The level and rate of insulin secretion are regulated by glucose concentration. Syntaxin 1A (STX-1A) is a core component of soluble N-ethylmaleimide-sensitive factor attachment proteins receptor (SNARE) complex and is essential for mediating the docking and fusion of insulin granules with cell membranes during insulin secretion. However, the mechanism of whether and how glucose regulates STX-1A to affect insulin release is still not well elucidated. To address this issue, the regulatory effect of glucose on STX-1A on INS-1 cell membranes was investigated by direct stochastic optical reconstruction microscopy (dSTORM). It was found that the elevated glucose concentration increased the expression of STX-1A on the cell membrane, and the density and aggregation of STX-1A protein clusters on the cell membrane were also increased. However, the glucotoxicity caused by chronic stimulation with high glucose concentration severely reduced the expression of STX-1A protein on the cell membrane, while the density and aggregation of STX-1A protein clusters on the cell membrane were also significantly reduced. By linking the expression and spatial distribution characteristics of STX-1A on cell membranes to insulin-secreting cell functions, the role of glucose in regulating the functional organization of STX-1A at the molecular level was revealed, which provided new insights into the mechanisms by which SNAREs regulate insulin release.