L-cysteine, PIP3 and Insulin Signaling in Diabetes

描述（由申请人提供）：L-半胱氨酸、PIP 3和糖尿病中的胰岛素信号传导摘要： 糖尿病已经成为一种流行病，并且仍然是世界范围内的主要公共卫生问题。本申请的主要目的是发现L-半胱氨酸（LC）补充改善糖尿病患者的葡萄糖稳态的机制。糖尿病患者血液中L-半胱氨酸（LC）、硫化氢（H2S）和谷胱甘肽（GSH）水平较低。在糖尿病动物研究中，补充富含半胱氨酸的蛋白质（乳清蛋白和α-乳清蛋白）、LC或N-乙酰半胱氨酸（NAC）已被证明可降低血糖。然而，LC增加葡萄糖利用和降低葡萄糖的分子机制尚不清楚。我们的研究表明，在2型糖尿病模型LC补充ZDF大鼠中，肝脏中的PI 3 K活化和NF-κB抑制以及血糖降低。使用脂肪细胞模型的进一步研究表明，LC引起PI 3 K激活，PTEN抑制，以及在高葡萄糖（HG）处理的细胞中PIP 3（磷脂酰肌醇-3，4，5三磷酸）和葡萄糖利用的增加。LC对PIP 3和葡萄糖利用的影响被PAG（炔丙基甘氨酸）阻止，PAG是一种胱硫醚-γ-裂解酶（CSE）的抑制剂，其催化LC形成H2S。在HG处理的细胞中，LC、H2S或PIP 3处理增加了IRS 1、AKT和PKC β/λ的磷酸化，以及GLUT 4活化和葡萄糖利用。这些研究提供了一种新的分子机制的证据，LC可以增加PIP 3和上调胰岛素的代谢作用，从而改善葡萄糖代谢。该提议将检验LC上调由PIP 3上调介导的葡萄糖代谢的胰岛素依赖性（PI 3 K/AKT/PKC β/λ）和胰岛素非依赖性（SIRT 1，AMPK）信号级联的假设。将对数据进行统计分析。对LC补充改善葡萄糖稳态和降低血糖的机制的理解和验证应该支持使用新分子（含有硫化物和半胱氨酸部分）来改善葡萄糖代谢和预防糖尿病中的胰岛素抵抗（IR）的临床干预的设计。长期目标是发现一种相对低成本的膳食补充剂，可用作T2 D IR预防的辅助治疗。

DESCRIPTION (provided by applicant): L-cysteine, PIP3 and Insulin Signaling in Diabetes Abstract: Diabetes has become an epidemic and remains a major public health issue worldwide. The primary purpose of this application is to discover the mechanisms by which L-cysteine (LC) supplementation improves glucose homeostasis in diabetic patients. Diabetic patients have lower blood levels of L-cysteine (LC), hydrogen sulfide (H2S), and glutathione (GSH). Supplementation with cysteine-rich proteins (whey protein and α-lactoalbumin), LC, or N-acetyl cysteine (NAC) has been shown to lower glycemia in diabetic animal studies. However, the molecular mechanism by which LC increases glucose utilization and lowers glycemia is not known. Our study demonstrated activation of PI3K and inhibition of NF-κB in the liver and reduction in blood glucose in LC supplemented ZDF rats, a model of type 2 diabetes. Further studies using an adipocyte cell model showed that LC caused PI3K activation, PTEN inhibition, and an increase in PIP3 (phosphatidylinositol-3,4,5 trisphosphate) and glucose utilization in high glucose (HG)-treated cells. The effect of LC on PIP3 and glucose utilization was prevented by PAG (propargylglycine), an inhibitor of cystathionine-γ-lyase (CSE), which catalyzes H2S formation from LC. Treatment with LC, H2S, or PIP3 increased the phosphorylation of IRS1, AKT, and PKCζ/λ, as well as GLUT4 activation and glucose utilization in HG-treated cells. These studies provide evidence for a novel molecular mechanism by which LC can increase PIP3 and upregulate the metabolic actions of insulin, thus improving glucose metabolism. This proposal will test the hypothesis that LC upregulates both the insulin dependent (PI3K/AKT/PKCζ/λ) and insulin independent (SIRT1, AMPK) signaling cascades of glucose metabolism mediated by PIP3 upregulation. Data will be analyzed statistically. The understanding and validation of the mechanisms by which LC supplementation improves glucose homeostasis and lowers glycemia should support the design of clinical interventions using novel molecules (containing sulfide and cysteine moieties) to improve glucose metabolism and prevent insulin resistance (IR) in diabetes. The long-term goal is to discover a relatively low-cost dietary supplement that could be used as an adjuvant therapy for IR prevention in T2D.