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的胰岛素分泌(GSIS)的机制，特别是在面临胰岛素抵抗的情况下，对于理解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，即使是胰岛β细胞中葡萄糖激酶(GK)活性的微小变化也会影响GSIS，胰岛素在β细胞中的作用调节GSIS，以及胰岛素在转录和翻译后水平上影响GK基因的表达。这项提案将探讨GK监管和职能的几个方面。我们将继续把重点放在胰腺β细胞，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，以及新的小鼠模型的产生。然而，一些研究将涉及GK表达的其他部位，如大脑，以了解更多关于GK在某些神经元中的表达如何有助于控制血糖浓度的调节反馈环。在目标1中，我们将通过建立和鉴定大脑特异的GK基因敲除小鼠来确定GK是否是神经葡萄糖感应所必需的。在目标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。在目标3中，我们将确定处理胰岛素受体的交替RNA在调节GK基因转录和胰岛β细胞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.