Activation of Atypical PKC by Insulin and Other Agonists

胰岛素和其他激动剂对非典型 PKC 的激活

• 批准号: 8258288
• 负责人: ROBERT V FARESE
• 金额: $ 6.8万
• 依托单位: ROSKAMP INSTITUTE, INC.
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2012-07-08
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8258288
• 关键词: 1-Phosphatidylinositol 3-Kinase; Accounting; Acute; Adipocytes; Adult; Agonist; Alleles; Binding Proteins; Biochemical; Blood Circulation; Blood Glucose; Carbohydrates; Cardiovascular Diseases; Central obesity; Defect; Development; Diet; Disease; Elements; Enzymes; Fatty acid glycerol esters; Gluconeogenesis; Glucose; Glucose Intolerance; Health; Heart; Hepatic; Hepatocyte; High Density Lipoprotein Cholesterol; Human; Hyperglycemia; Hyperinsulinism; Hyperlipidemia; Hypertension; Hypertriglyceridemia; Insulin; Insulin Resistance; Knock-out; Knockout Mice; LDL Cholesterol Lipoproteins; Lipids; Liver; Mediating; Metabolic; Metabolic syndrome; Methods; Modeling; Molecular; Multiple Abnormalities; Mus; Muscle; Mutagenesis; Non-Insulin-Dependent Diabetes Mellitus; Obesity; Phosphoenolpyruvate Carboxylase; Population; Production; Protein Kinase C Inhibitor; Reporting; Rodent; Rodent Model; Serum; Signal Transduction; Site; Skeletal Muscle; Sterols; Therapeutic Agents; Tissues; Triglycerides; Up-Regulation; adenoviral-mediated; atypical protein kinase C; cytokine; effective therapy; glucose disposal; glucose tolerance; glucose transport; glucose-6-phosphatase; hypercholesterolemia; improved; inhibitor/antagonist; insulin signaling; mouse model; novel; novel strategies; novel therapeutics; public health relevance; receptor; restoration

DESCRIPTION (provided by applicant): We have (a) defined upstream activators of atypical protein kinase C (aPKC) and Akt during insulin action in muscle, adipocytes and liver and (b) showed that aPKC is required for insulin-stimulated increases in glucose transport in muscle and adipocytes and activation of lopogenic enzymes in liver. Also, in multiple rodent models of obesity (O) and type 2 diabetes mellitus (T2DM), we defined the following tissue-specific defects in insulin signaling factors: (a) aPKC activation is impaired in muscle and adipocytes in all O and T2DM models via diminished IRS-1-dependent phosphatidylinositol 3-kinase (PI3K) activation, but, in contrast, fully conserved in liver via IRS-2-dependent PI3K; and (b) Akt activation is impaired via diminished IRS-1/PI3K activation in muscle in most O and T2DM models, and in liver in all T2DM models. Selective conservation of hepatic IRS-2/aPKC activation in O and T2DM is problematic, as hyperinsulinemia therein causes excessive activation of sterol receptor element binding protein-1c (SREBP-1c), which increases expression of multiple enzymes that control hepatic lipid synthesis, and this upregulation provokes many "metabolic syndrome" (MS) abnormalities. Indeed, using adenoviral-mediated expression methods, selective inhibition of hepatic aPKC in multiple O/MS and T2DM models elicits rapid and dramatic improvements in hepatosteatosis, hyperlipidemia, glucose intolerance, hyperinsulinemia, and insulin signaling in muscle and liver; also, as an added benefit, inhibition of hepatic aPKC surprisingly diminishes expression of glucogenic enzymes, phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase). In other words, hepatic aPKC inhibition has insulin-like effects on these hepatic enzymes that regulate blood glucose levels. Similarly, in preliminary studies, two newly discovered highly specific aPKC inhibitors preferentially inhibited hepatic aPKC and thereby diminished expression of hepatic enzymes that promote both lipid and glucose synthesis/release in both human hepatocytes and intact rodent liver; furthermore, in an mouse model of O/MS/T2DM, these biochemical agents selectively inhibited hepatic aPKC and this was attended by (a) a rapid and complete or nearly complete reversal of O/MS features, viz., abdominal obesity, hepatosteatosis, and hypertriglyceridemia and (b) restoration of insulin signaling in muscle, fat and liver, and normalization of serum glucose-lowering effects of insulin. Clearly, we need to further develop agents that selectively diminish aPKC activation in liver and thereby effectively control O/MS and T2DM. Accordingly, there is an urgent need to: Specific Aim 1, define insulin signaling mechanisms and consequences of aPKC inhibition in human hepatocytes; Specific Aim 2, elucidate molecular mechanisms for aPKC activation; and Specific Aim 3, further develop our novel biochemical inhibitors of hepatic aPKC and define their metabolic effects in mouse O/MS/T2DM models. We are confident that the proposed studies will provide a new approach for effective treatment of O/MS and T2DM. PUBLIC HEALTH RELEVANCE: These findings will provide new avenues for finding treatments for the metabolic syndrome and type 2 diabetes, which together are estimated to cause at least 50% of the cardiovascular disorders seen in the US population, and which are exceedingly costly health issues.

描述（由申请人提供）：我们 (a) 定义了肌肉、脂肪细胞和肝脏中胰岛素作用期间非典型蛋白激酶 C (aPKC) 和 Akt 的上游激活剂，以及 (b) 表明 aPKC 是胰岛素刺激葡萄糖增加所必需的肌肉和脂肪细胞中的运输以及肝脏中的本地生成酶的激活。此外，在肥胖 (O) 和 2 型糖尿病 (T2DM) 的多种啮齿动物模型中，我们定义了胰岛素信号因子中的以下组织特异性缺陷：(a) 在所有 O 和 T2DM 模型中，肌肉和脂肪细胞中的 aPKC 激活均受损通过减少 IRS-1 依赖性磷脂酰肌醇 3-激酶 (PI3K) 激活，但相反，通过 IRS-2 依赖性 PI3K 在肝脏中完全保守； (b) 在大多数 O 型和 T2DM 模型中肌肉中以及在所有 T2DM 模型中肝脏中 IRS-1/PI3K 激活减弱，Akt 激活受到损害。 O 型和 T2DM 中肝脏 IRS-2/aPKC 激活的选择性保留是有问题的，因为其中的高胰岛素血症会导致甾醇受体元件结合蛋白 1c (SREBP-1c) 的过度激活，从而增加控制肝脏脂质合成的多种酶的表达，并且这种上调会引发许多“代谢综合征”（MS）异常。事实上，使用腺病毒介导的表达方法，在多种 O/MS 和 T2DM 模型中选择性抑制肝脏 aPKC 可引起肝脂肪变性、高脂血症、葡萄糖耐受不良、高胰岛素血症以及肌肉和肝脏中胰岛素信号传导的快速且显着的改善；此外，抑制肝脏 aPKC 的另一个好处是令人惊讶地减少生糖酶、磷酸烯醇丙酮酸羧激酶 (PEPCK) 和葡萄糖 6 磷酸酶 (G6Pase) 的表达。换句话说，肝脏 aPKC 抑制对这些调节血糖水平的肝酶具有类似胰岛素的作用。同样，在初步研究中，两种新发现的高度特异性的 aPKC 抑制剂优先抑制肝脏 aPKC，从而减少促进人类肝细胞和完整啮齿动物肝脏中脂质和葡萄糖合成/释放的肝酶的表达；此外，在 O/MS/T2DM 小鼠模型中，这些生化药物选择性抑制肝脏 aPKC，并且伴随着 (a) O/MS 特征快速、完全或几乎完全逆转，即腹部肥胖、肝脂肪变性、和高甘油三酯血症，以及（b）肌肉、脂肪和肝脏中胰岛素信号的恢复，以及胰岛素降低血糖作用的正常化。显然，我们需要进一步开发选择性减少肝脏 aPKC 激活的药物，从而有效控制 O/MS 和 T2DM。因此，迫切需要： 具体目标 1，定义胰岛素信号传导机制以及人肝细胞中 aPKC 抑制的后果；具体目标2，阐明aPKC激活的分子机制；和具体目标 3，进一步开发我们的新型肝 aPKC 生化抑制剂，并定义其在小鼠 O/MS/T2DM 模型中的代谢作用。我们相信，所提出的研究将为有效治疗 O/MS 和 T2DM 提供新方法。 公共健康相关性：这些发现将为寻找代谢综合征和 2 型糖尿病的治疗方法提供新途径，据估计，美国人口中至少 50% 的心血管疾病是由这两种疾病引起的，而且是代价极其高昂的健康问题。