Elucidating the pathophysiology and molecular mechanisms of renal insulin resistance

项目摘要 2型糖尿病(T2D)是21世纪决定性的医学挑战之一，每三个美国人中就有一个 2000年出生的人估计在他们的一生中会患上糖尿病。T2D的特点是多器官胰岛素抵抗 并扰乱全身葡萄糖的动态平衡。在过去的三十年里，有迹象表明， 肾脏在糖尿病全身糖稳态失调中起着重要的病理生理作用。 一项开创性的研究表明，肾脏的葡萄糖产量将增加300%，达到肝脏的85%。 尽管如此，肾脏中的胰岛素抵抗仍然存在争议，任何潜在的机制都是 未知。明确这些机制和精确的病理生理学将会对公众健康有很大的好处。 在肾脏中的胰岛素抵抗，因为这可能有无数的翻译含义。在这项提案中，我们将 建立在我们强有力的初步证据的基础上，肾脏皮质确实会因高血糖而产生胰岛素抵抗。 脂肪饮食(HFD)喂养。在进一步的初步数据中，我们观察到二酰基甘油(DAG)的积累 和蛋白激酶Cε(PKCε)在小鼠肾皮质中的易位，增加了饮食诱导 肾脏胰岛素抵抗可能由与肝脏相似的机制介导，在肝脏中，高脂肪喂养会导致 DAG积聚，激活蛋白激酶Cε。PKCε随后在Thr1160处使胰岛素受体(IR)磷酸化， 导致胰岛素信号被废除。在这项建议中，我们将仔细评估胰岛素信号缺陷。 与肾脏胰岛素抵抗相关，并进一步表征是否存在异常的DAG-PKCE-IR轴 激活。我们还将使用两种新的13C同位素示踪策略来了解氧化和糖异生 胰岛素抵抗肾皮质的缺陷。此外，我们将直接测试DAG-PKCE-IR的假设 Axis利用已经产生的小鼠模型导致肾脏胰岛素抵抗，其中关键的Thr1160 IR的残基被突变为丙氨酸，不能被PKCε磷酸化。我们预测这些老鼠将会是 当喂食高脂饮食时，可防止肾脏胰岛素抵抗的信号和代谢流表现。这 提案代表了一种综合的科学方法和新的学习经验，可以利用 生理学、细胞生物学和分析化学，以产生对机制和 病理生理学或肾脏胰岛素抵抗。

Project Summary Type 2 diabetes (T2D) is one of the defining medical challenges of the 21st century, with one in three Americans born in 2000 estimated to develop diabetes in their lifetime. T2D is characterized by multi-organ insulin resistance and perturbed whole-body glucose homeostasis. Over the past three decades, there have been hints that the kidney plays a central pathophysiologic role in dysregulated whole-body glucose homeostasis in diabetes, with a seminal study suggesting renal glucose production to be increased 300%, climbing to 85% that of the liver. Notwithstanding, insulin resistance in the kidney has remained controversial and any potential mechanisms are unknown. It would be of great public health interest to crystallize the mechanisms and precise pathophysiology of insulin resistance in the kidney, as this may have myriad translational implications. In this proposal, we will build upon our strong preliminary evidence that the renal cortex does, indeed, become insulin resistant with high fat diet (HFD) feeding. In further preliminary data, we have observed both diacylglycerol (DAG) accumulation and Protein Kinase Cε (PKCε) translocation in the mouse renal cortex, raising the possibility that diet-induced renal insulin resistance may be mediated by a similar mechanism as in the liver, where high fat feeding leads to DAG accumulation, which activates PKCε. PKCε subsequently phosphorylates insulin receptor (IR) at Thr1160, causing abrogated insulin signaling. In this proposal, we will carefully assess the insulin signaling defects associated with renal insulin resistance and also further characterize if there is aberrant DAG-PKCe-IR axis activation. We will also use two novel 13C isotopic tracer strategies to understanding oxidative and gluconeogenic defects in the insulin resistant renal cortex. Further, we will directly test the hypothesis that the DAG-PKCe-IR axis causes renal insulin resistance by utilizing an already-generated mouse model where the critical Thr1160 residue of IR is mutated to an alanine, which cannot be phosphorylated by PKCε. We predict these mice will be protected from signaling and metabolic flux manifestations of renal insulin resistance when fed a HFD. This proposal represents an integrated scientific approach and new learning experiences that harness techniques of physiology, cell biology, and analytical chemistry to yield novel insights into the mechanisms and pathophysiology or renal insulin resistance.