【作者】 梁滔；

【导师】 瞿安连；

【作者基本信息】 华中科技大学 ， 生物物理学， 2005， 硕士

【摘要】 葡萄糖是人体最直接和重要的能量来源,血液中葡萄糖浓度的稳定对于人体正常功能的行使具有非常重要的作用。而胰岛素是调节血糖平衡的最重要的激素,它能在血糖升高时有效地促使细胞对葡萄糖的吸收,从而保持血糖的稳定,这一过程的紊乱将导致糖尿病的产生。目前II型糖尿病的发病率增长很快,对其发病机理和治疗方法的研究是目前国际上医学和生物学研究的一个重点。研究表明细胞对葡萄糖的吸收是通过葡萄糖转运体（Glucose Transpoters,GLUTs）家族之一葡萄糖转运子4（GLUT4）来介导的,胰岛素的作用通过GLUT4来实现,GLUT4的转运障碍可能与II型糖尿病的某些致病因素有关。因此对GLUT4在细胞中的转运机制的基础研究具有重要的理论价值及实际指导意义。研究过程中使用消散场显微成像技术和单微粒跟踪技术直观地观察了活体细胞内单个葡萄糖转运子4囊泡（GLUT4 Storage Vesicle, GSV）和神经内分泌细胞内的致密核心大囊泡（Large Dense Core Vesicle,LDCV）的三维运动轨迹,发现两种囊泡都具有三种运动模式。定量分析显示,作自由扩散运动和方向性扩散运动的GSV数量明显多于LDCV。对比GSV和LDCV的三维扩散系数, GSV的扩散系数中值为7.2 ×10^-4 μm²/s,而LDCV仅为1.94 ×10^-4 μm²/s。虽然GSV和LDCV上含有许多相同的蛋白,但是我们的结果说明GSV的活动性远大于LDCV,提示二者的胞内转运过程涉及不同的分子机制。这一结果为进一步研究GSV转运过程中涉及到到蛋白质和分子生物学机制打下了基础。同时,通过对GSV胞吐的研究,发现胰岛素显著地缩短了参与胞吐的GSV的锚定时间,在活体细胞中从单囊泡水平上揭示了胰岛素对GSV胞吐和GLUT4上膜过程的影响。更多还原

【Abstract】 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.更多还原