Glucokinase Gene Expression in Pancreatic Beta Cell

描述（由申请人提供）：了解胰腺β细胞调节葡萄糖刺激胰岛素分泌（GSIS）的机制，特别是在胰岛素抵抗的情况下，对了解2型糖尿病的发病机制至关重要。在之前的项目期间，已经清楚的是，即使胰腺β细胞中葡萄糖激酶（GK）活性的微小变化也会影响GSIS， β细胞中的胰岛素作用调节GSIS，胰岛素在转录和翻译后水平上影响GK基因表达。本提案将探讨GK调控和功能的几个方面。我们将继续把重点放在胰腺β细胞上，因为它在大多数血糖紊乱中起主要作用，并作为其他葡萄糖敏感细胞的模型，并在新的小鼠模型的产生上。然而，一些研究将涉及GK表达的其他部位，如大脑，以便更多地了解某些神经元中GK的表达如何参与控制血糖浓度的调节反馈回路。在Aim 1中，我们将通过生成和表征脑特异性GK基因敲除小鼠来确定GK是否为神经葡萄糖传感所必需。在Aim 2中，我们将建立PHHI和MODY-2的真实小鼠模型，以便将酶动力学的变化与胰岛素分泌和葡萄糖稳态联系起来。在Aim 3中，我们将确定胰岛素受体的替代RNA加工在调节胰腺β细胞中GK基因转录和亚细胞定位中的作用。

DESCRIPTION (provided by applicant): Knowledge of the mechanisms that modulate glucose-stimulated insulin secretion (GSIS) by pancreatic beta cells, particularly in the face of insulin resistance, is of paramount importance for understanding the pathogenesis of type 2 diabetes mellitus. Over the previous project period, it has become clear that even small changes in glucokinase (GK) activity in the pancreatic beta cell affect GSIS, that insulin action in the beta cell modulates GSIS, and that insulin affects GK gene expression, both at the transcriptional and post-translational levels. This proposal will explore several aspects of GK regulation and function. We will continue to place an emphasis both on the pancreatic beta cell, since it plays a principal role in most glycemic disorders and serves as a model for other glucose-sensitive cells, and on the generation of novel new mouse models. However, some studies will involve other sites of GK expression, such as the brain, in order to learn more about how the expression of GK in certain neurons contributes to the regulatory feedback loops that control the blood glucose concentration. In Aim 1 we will determine whether GK is necessary for neural glucose sensing by generating and characterizing brain-specific GK gene knockout mice. In Aim 2 we will establish true mouse models for PHHI and MODY-2 in order to correlate changes in enzyme kinetics with insuIin secretion and glucose homeostasis. In Aim 3 we will determine the role of alternate RNA processing the insulin receptor in modulating both GK gene transcription and subcellular localization in the pancreatic beta cell.