Insulin Signaling and Metabolic Effects through CLK2 Kinase

CLK2 激酶的胰岛素信号传导和代谢效应

• 批准号: 8242706
• 负责人: Pere Puigserver
• 金额: $ 38.6万
• 依托单位: DANA-FARBER CANCER INST
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2016-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8242706
• 关键词: Affect; Applications Grants; Binding; Biochemical; Blood Glucose; Buffers; Clinical; Complex; Defect; Diabetes Mellitus; Diabetic mouse; Diet; Disease; Fasting; Gene Expression; Genes; Genetic; Gluconeogenesis; Glucose; Glycogen; Glycolysis; Goals; Hepatic; Hepatocyte; Homeostasis; Hormones; Hyperglycemia; In Vitro; Insulin; Insulin Resistance; Investigation; Laboratories; Lipids; Liver; Mediating; Mediator of activation protein; Metabolic; Metabolic Control; Metabolic Diseases; Metabolic syndrome; Metabolism; Mitochondria; Molecular; Mus; Non-Insulin-Dependent Diabetes Mellitus; Nutrient; Obesity; Outcome Study; PGC-1 protein; Pathway interactions; Phosphorylation; Phosphorylation Site; Phosphotransferases; Process; Proteins; Proteomics; Regulation; Repression; Signal Transduction; Testing; Tissues; Transcription Coactivator; Translating; adenoviral-mediated; base; blood glucose regulation; db/db mouse; diabetic; fatty acid oxidation; feeding; forkhead protein; genetic analysis; glucose metabolism; glucose output; glucose production; glucose tolerance; glucose transport; hepatic gluconeogenesis; in vivo; insulin signaling; insulin tolerance; lipid metabolism; loss of function; metabolic abnormality assessment; mouse model; mutant; novel; programs; protein complex; protein degradation; public health relevance; research study; response; restoration; small hairpin RNA; transcription factor; ubiquitin ligase

DESCRIPTION (provided by applicant): Nutrient homeostasis is maintained through a complex regulatory network formed by signaling and transcriptional components that control metabolic genes. The liver is one of the key tissues that depending of the physio/pathological conditions buffers whole body nutrient homeostasis. Insulin is one of the most powerful hormones that affect nutrient regulation and clinically, insulin resistance is a hallmark of the metabolic syndrome including type 2 diabetes. As a consequence of insulin resistance one of the metabolic processes that contribute to maintain the diabetic state is hepatic glucose production that is controlled, at least in part, at the transcriptional level. The PI3K/Akt pathway is one of the main effectors of insulin metabolic action. Akt controls expression of metabolic genes through direct phosphorylation and negative regulation of the forkhead transcription factor FoxO1 and coactivators such as PGC-11 and CRCT2, key components of the transcriptional gluconeogenic program. Although Akt can directly mediate this action, there are conditions such as late refeeding or diabetic states where active Akt does not entirely correlate with suppression hepatic glucose production. This indicates that additional key regulatory components, likely kinases, could mediate this repression. Along these lines, we have recently identified Cdc2-like kinase 2 (Clk2) as a novel component downstream of insulin/Akt and functions as part of the hepatic feeding response. Notably, Clk2 controls expression of gluconeogenic genes, hepatic glucose output and blood glucose levels. Moreover, obese/diabetic db/db mice have lower amounts of Clk2 protein and restoration of the levels corrects hyperglycemia. This result suggests that Clk2 might be dysregulated in conditions of obesity/diabetes and contributes to the clinical manifestations. Based on these findings, the major goal of this proposal is to identify the molecular mechanisms by which insulin controls Clk2 kinase activity and to test Clk2 metabolic functionality in-vitro and in in-vivo mouse models. We have three Specific Aims: Aim 1 is to perform molecular and functional analysis of how insulin controls Clk2 kinase activity focusing on regulation of Clk2 protein degradation through ubiquitin ligases. Aim 2 is devoted to carry out molecular and functional analysis of Clk2- mediated suppression of hepatic gluconeogenesis. We focus on the Clk2-induced phosphorylation and repression of PGC-11. Aim 3 will determine the effects of Clk2 on hepatic glucose and lipid metabolism in mice through loss-of-function of hepatic Clk2 in fasting/feeding cycles and genetic and diet-induced obesity. The outcomes of these studies will provide the identification of the molecular mechanisms by which insulin controls glucose and lipid metabolic effects through Clk2 kinase. Since insulin resistance and as a consequence increased and uncontrolled hepatic glucose output is a major defect that occurs in type 2 diabetes, our investigation on the regulation of Clk2 and PGC-11 might translate into potential therapies to treat this disease. PUBLIC HEALTH RELEVANCE: Insulin resistance and increased hepatic glucose production are hallmarks of metabolic diseases such as obesity and type 2 diabetes, thus studies in this grant proposal focusing on key regulators of these processes including a novel kinase Clk2 and PGC-11 might translate into potential therapies.

描述（由申请人提供）：营养稳态是通过控制代谢基因的信号传导和转录成分形成的复杂调节网络来维持的。肝脏是根据生理/病理状况缓解全身营养稳态的关键组织之一。胰岛素是影响养分调节和临床的最强大激素之一，胰岛素抵抗是包括2型糖尿病（包括2型糖尿病）的代谢综合征的标志。由于胰岛素抵抗有助于维持糖尿病状态的代谢过程之一是肝葡萄糖产生，至少部分在转录水平上受到控制。 PI3K/AKT途径是胰岛素代谢作用的主要效应子之一。 AKT通过直接磷酸化和叉头转录因子FOXO1和共激活因子（例如PGC-11和CRCT2）来控制代谢基因的表达，这是转录糖原性程序的关键成分。尽管AKT可以直接介导此作用，但在某些情况下，例如晚期再喂养或糖尿病状态，活动AKT与抑制肝葡萄糖的产生并不完全相关。这表明其他关键的调节成分（可能激酶）可能会介导这种抑制作用。沿着这些线路，我们最近将cdc2样激酶2（CLK2）鉴定为胰岛素/AKT下游的一种新成分，并且功能是肝喂养反应的一部分。值得注意的是，CLK2控制糖原性基因，肝葡萄糖输出和血糖水平的表达。此外，肥胖/糖尿病DB/DB小鼠的CLK2蛋白质较低，水平的恢复可以纠正高血糖。该结果表明，在肥胖/糖尿病的情况下，CLK2可能失调，并导致临床表现。基于这些发现，该提案的主要目标是确定胰岛素控制CLK2激酶活性并测试VITRO和体内小鼠模型中CLK2代谢功能的分子机制。我们有三个特定的目的：目标1是对胰岛素如何控制CLK2激酶活性如何通过泛素连接酶调节CLK2蛋白降解的CLK2激酶活性进行分子和功能分析。 AIM 2致力于对CLK2介导的肝糖异生抑制的分子和功能分析。我们专注于CLK2诱导的PGC-11的磷酸化和抑制。 AIM 3将通过在禁食/喂养周期以及遗传和饮食诱导的肥胖症中肝CLK2的功能丧失，确定CLK2对小鼠肝葡萄糖和脂质代谢的影响。这些研究的结果将提供分子机制的鉴定，胰岛素通过CLK2激酶控制葡萄糖和脂质代谢作用。由于胰岛素抵抗和随之增加，肝葡萄糖输出不受控制，是在2型糖尿病中发生的主要缺陷，因此我们对CLK2和PGC-11的调节的研究可能会转化为治疗这种疾病的潜在疗法。 公共卫生相关性：胰岛素抵抗和肝葡萄糖产生的增加是肥胖和2型糖尿病等代谢疾病的标志，因此，该赠款提案的研究重点是这些过程的关键调节剂，包括新型的激酶CLK2和PGC-11，可能会转化为潜在的疗法。