TRIM24在葡萄糖代谢稳态中的作用与分子机制研究

胰岛素／PKB通路与AMPK通路在葡萄糖代谢稳态调控中起重要作用，其异常会导致2型糖尿病，但这两个通路的下游组分以及它们调控糖稳态的分子机制尚不完全清楚。申请人团队前期利用磷酸化蛋白质组学方法，发现TRIM24是PKB和AMPK的共同新型磷酸化底物。进一步分析表明PKB和AMPK都可以磷酸化TRIM24的丝氨酸1043位点。另外，我们制备了TRIM24全身性敲除小鼠，发现该小鼠比野生型对照表现出更好的葡萄糖耐受能力以及更高的胰岛素敏感性。基于这些前期工作，我们提出“TRIM24是胰岛素／PKB和AMPK通路调控全身葡萄糖代谢稳态的关键因子”的工作假设，本申请拟通过基因工程小鼠模型结合生理、生化、细胞生物学、组学等手段，对这一假设进行深入研究。本项研究有助于阐明胰岛素／PKB通路和AMPK通路调控全身葡萄糖稳态的分子机制，为2型糖尿病的预防和治疗提供新靶点和新思路。

The insulin−PKB and AMPK pathways play critical roles in regulating whole-body glucose homeostasis, whose deregulation is linked to the pathogenesis of type 2 diabetes. However, the distal components of these two pathways and their function in regulating glucose homeostasis are still not fully understood. In an attempt to address this issue, we performed a phospho-proteomics study in mouse skeletal muscle that was subjected to in situ contraction, and identified TRIM24 as a phosphoprotein that was regulated by muscle contraction. We further demonstrated that AMPK that is activated by muscle contraction could phosphorylate TRIM24 on its Ser1043 site. Furthermore, we found that the insulin−PKB pathway could also regulate TRIM24, and PKB could phosphorylate TRIM24 also on its Ser1043 site. We generated a TRIM24 whole-body knockout mouse model, and found that TRIM24-KO mice were more sensitive to insulin as compared to their wild-type littermates. Moreover, they were more tolerant to oral glucose administration than their wild-type littermates. Based on these preliminary observations, we propose that TRIM24 is a key distal component in both insulin−PKB and AMPK pathways, and mediates the effects of these two pathways in regulation of whole-body glucose homeostasis. In this proposal, we aim to address this hypothesis through multiple approaches involving various mouse models. This proposed work shall help to elucidate the molecular mechanisms underlying regulation of whole-body glucose homeostasis by the insulin−PKB and AMPK pathways and to identify novel protein targets to combat type 2 diabetes.