Role of PI 3-Kinase isoforms in insulin action

PI 3-激酶亚型在胰岛素作用中的作用

• 批准号: 8463502
• 负责人: C RONALD KAHN
• 金额: $ 35.95万
• 依托单位: JOSLIN DIABETES CENTER
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-06-01 至 2016-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8463502
• 关键词: 1-Phosphatidylinositol 3-Kinase; Beta Cell; Catalytic Domain; Cell Line; Cells; Complex; Development; Diabetes Mellitus; Disease; Enzymes; Failure; Family; Functional disorder; Gene Expression Regulation; Generations; Genes; Goals; Grant; Human; Hyperinsulinism; In Vitro; Insulin; Insulin Resistance; Insulin Signaling Pathway; JNK-activating protein kinase; Knock-out; Knockout Mice; Link; Liver; MAPK14 gene; Metabolism; Molecular; Mouse Cell Line; Mus; Muscle; Mutation; Obesity; PTEN gene; Pancreas; Pathway interactions; Phosphoric Monoester Hydrolases; Physiological; Play; Point Mutation; Pregnancy; Property; Protein Isoforms; Proteins; Proteomics; Regulation; Role; Signal Pathway; Signal Transduction; Site; Somatotrophin increased; Stress; Structure of beta Cell of islet; System; Tissues; United States National Institutes of Health; Work; biological adaptation to stress; diabetic; endoplasmic reticulum stress; glucose transport; in vivo; insulin secretion; insulin signaling; mutant; novel; protein complex; reconstitution; response; stoichiometry; transcription factor

DESCRIPTION (provided by applicant): This is a competitive renewal of NIH grant DK55545 which is focused on the role of PI 3-kinase in insulin action. PI 3-kinase is a critical node in insulin action in control of metabolism and a key point of divergence of insulin signaling. In previous work under this grant using both in vitro and in vivo approaches, including creation and characterization of mice and cell lines in which specific isoforms of PI 3-kinase regulatory and catalytic subunits have been deleted, we have demonstrated that this enzyme controls insulin signaling in both positive and negative ways, and is involved in much more than simply generation of PIP3. This includes differences in the activity and properties of the different regulatory (p85) and catalytic (p110) subunits of PI 3-kinase; important effects of stoichiometry between regulatory and catalytic subunits on insulin action; the ability of PI 3-kinase to allow divergence of the downstream signal between Akt and atypical PKCs; and alterations in PI 3-kinase activity in disease states. In addition, we have identified several previously unrecognized links between the PI 3-kinase pathway and other signaling pathways, including differences between the p110a and p110b catalytic subunits in support of downstream insulin actions and important links between the p85 regulatory subunits and several pathways involved in insulin resistance, including the stress kinases JNK and p38; the major PIP3 phosphatase in cells and tissues PTEN; and a novel link between PI 3-kinase, endoplasmic reticulum (ER) stress and the unfolded protein response. The latter occurs through interaction of p85a with the transcription factor XBP-1 and can modify the ER stress response involved in insulin resistance. This has led us to new hypotheses about the important role of the different PI 3-kinase catalytic and regulator subunits as both sites of divergence in the insulin signaling pathway and sites of both positive and negative regulation in physiological and pathological states, as well as sites for cross-talk with other signaling systems. In the next five years, we will expand upon these observations at both the molecular and physiological levels by defining how different signals are generated by different regulatory and catalytic subunits of PI 3- kinase, the specific signaling complexes involved, and the role of this system in vivo in insulin resistant and diabetic states. Specificall we will further elucidate the link between PI 3-kinase regulatory subunits and induction of ER stress by defining the specific pathways and molecules interacting with the p85 regulatory subunits in vivo and muscle and determining if p85 plays a role in the ER stress response in pancreatic b-cells in diabetes and other states with altered insulin secretion. This will be done i vitro and in vivo through creation of b-cell specific p85a KO mice crossed with a mouse that secretes a mutant insulin molecule or mice with states of obesity and hyperinsulinemia. We will also characterize the first human mutation in p85 associated with severe insulin resistance and determine the differential roles of the PI 3-kinase catalytic subunits p110a and p110b in divergent insulin signaling in the PI 3-kinase pathway.

描述（由申请人提供）：这是NIH拨款DK55545的竞争性更新，其重点是PI 3-激酶在胰岛素作用中的作用。PI - 3激酶是胰岛素作用控制代谢的关键节点，也是胰岛素信号分化的关键节点。在之前的研究中，我们使用了体外和体内的方法，包括对PIP3激酶调节和催化亚基的特定同工型被删除的小鼠和细胞系的创建和表征，我们已经证明了这种酶以积极和消极的方式控制胰岛素信号传导，并且参与的不仅仅是PIP3的生成。这包括PI 3-激酶的不同调控亚基（p85）和催化亚基（p110）的活性和性质的差异；调节亚基和催化亚基之间的化学计量学对胰岛素作用的重要影响pi3激酶允许Akt和非典型PKCs之间的下游信号分化的能力；以及疾病状态下PI 3激酶活性的改变。此外，我们还发现了PI 3-激酶途径与其他信号通路之间的一些先前未被认识到的联系，包括支持下游胰岛素作用的p110a和p110b催化亚基之间的差异，以及p85调节亚基与胰岛素抵抗相关的几种途径（包括应激激酶JNK和p38）之间的重要联系；细胞和组织中主要的PIP3磷酸酶PTEN；以及PI 3-激酶、内质网（ER）应激和未折叠蛋白反应之间的新联系。后者是通过p85a与转录因子XBP-1的相互作用发生的，可以改变参与胰岛素抵抗的内质网应激反应。这使我们对不同的PI 3-激酶催化和调节亚基作为胰岛素信号通路的发散位点、生理和病理状态的正调控和负调控位点以及与其他信号系统的串扰位点的重要作用提出了新的假设。在接下来的五年里，我们将通过定义PI 3-激酶的不同调控和催化亚基如何产生不同的信号，所涉及的特定信号复合物，以及该系统在体内胰岛素抵抗和糖尿病状态中的作用，在分子和生理水平上扩展这些观察结果。具体来说，我们将进一步阐明PI 3-激酶调节亚基与内质网应激诱导之间的联系，通过定义体内和肌肉中与p85调节亚基相互作用的特定途径和分子，并确定p85是否在糖尿病和其他胰岛素分泌改变的状态下胰腺b细胞的内质网应激反应中发挥作用。这将在体外和体内通过创建b细胞特异性p85a KO小鼠与分泌突变胰岛素分子的小鼠或肥胖和高胰岛素血症状态的小鼠杂交来完成。我们还将描述与严重胰岛素抵抗相关的第一个人类p85突变，并确定PI 3激酶催化亚基p110a和p110b在PI 3激酶途径中不同的胰岛素信号传导中的差异作用。