Study Of Intracellular Transport And Exocytosis Of GSV

Glucose is the most immediate and important energy source of the body and the stabilization of the glucose level in the blood takes very important part in normal operation of the body. Insulin is the most important hormone for regulating the balance of blood glucose, because it helps to promote the glucose absorbability of the cell effectively when the level of the blood glucose rises, so the balance of the blood glucose can be retained, and the interruption of the process results to diabetes. The incidence of the type2 diabetes is increasing rapidly, so the study on the pathogenesis and the treatment has become the emphasis of the international biological research now. It is revealed that the glucose absorbability of the cell is transported by GLUT4, which is a member of the Glucose Transporters, which the effect of insulin is dependent on and that whose transportation abnormity the type2 diabetes is related with. Therefore the study on the transportation mechanism of GLUT4 in living cells is significant theoretically and practically. In this study, the mobility of GSV which comes from 3T3-L1 fibroblasts and LDCV which comes from neuroendocrine PC12 cells is compared. Evanescent-field microscopy and Gaussian-fit-based single particle tracking were used to follow the three-dimensional trajectories of single GSV and LDCV. By fitting appropriate equations to particular mean squared displacement of single vesicles, three different motion modes were revealed for both GSV and LDCV. Quantitative analysis showed that the number of GSV undergoing random diffusion and directed diffusion was much more thant LDCV. Furthermore, it was compared that three-dimensional diffusion coefficients for GSV and LDCV. The median diffusion coefficient of GSV is 7.2 ×10^-4 μm²/s and LDCV 1.94 ×10^-4 μm²/s. Although similar proteins have been found for both GSV and secretary vesicles, our results reveal a significant difference between GSV and LDCV in their mobility, suggesting there are different molecular mechanisms underlying the intracellular transport of GSV. At the same time, it was revealed that insulin can shorten the docking time of GSV by analyzing the fusion events.