Gq-coupled Receptors Inhibit PI 3-kinase/Akt Signaling Pathway

Gq 偶联受体抑制 PI 3 激酶/Akt 信号通路

• 批准号: 8003647
• 负责人: RICHARD Z LIN
• 金额: $ 10万
• 依托单位: STATE UNIVERSITY NEW YORK STONY BROOK
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-12-28 至 2010-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8003647
• 关键词: 1-Phosphatidylinositol 3-Kinase; Ablation; Address; Adrenergic Agonists; Adverse effects; Affect; Affinity; Animal Model; Animals; Area; Atrophic; Attenuated; Binding; Biological; Breeding; Cancer Patient; Clenbuterol; Clinical Treatment; Clinical Trials; Complex; Defect; Development; Disease; Embryo; Enzymes; Family; Fluorescence Spectroscopy; Funding; Gene Deletion; Genes; Goals; Growth; Health; Hindlimb Suspension; Histology; Hospitalization; Human; Hypertrophy; IGF1 gene; Insulin-Like Growth Factor I; Knock-out; Knockout Mice; Knowledge; Lead; Lesion; Maintenance; Malignant - descriptor; Malignant Neoplasms; Malignant neoplasm of pancreas; Measures; Medical; Molecular; Monitor; Mouse Strains; Mus; Muscle; Muscle Fibers; Muscular Atrophy; Organ; Pancreas; Pathway interactions; Patients; Pharmaceutical Preparations; Phenotype; Physical activity; Physiological; Play; Process; Protein Biosynthesis; Recovery; Research; Risk; Rodent; Role; Running; Scanning; Signal Pathway; Signal Transduction; Skeletal Muscle; Staging; System; Techniques; Testing; Tissues; Up-Regulation; Weight; cell growth; in utero; in vivo; insight; intraepithelial; mTOR protein; muscle form; muscle hypertrophy; pancreatic neoplasm; public health relevance; receptor coupling; research study; response; tumor; tumorigenesis; wasting

DESCRIPTION (provided by applicant): The goal of this proposal is to understand the role of class IA phosphatidylinositol 3-kinase (PI3K) p110a and p110¿ in regulating pathological and physiological cell growth in the pancreas and skeletal muscle. These two class IA PI3Ks are postulated to control protein synthesis and cell growth and survival. However, it has not been possible to investigate the biological roles of these enzymes using whole-body gene deletion due to embryonic lethality. To overcome this experimental problem, mouse strains in which the two PI3K genes can be selectively deleted in specific tissues were generated. Using these animals, this proposal addresses four research questions. Aim 1 determines if pancreas-specific ablation of p110a or p110¿ blocks the formation of pancreatic tumors induced by constitutively active KrasG12D. Mice with pancreas-specific expression of KrasG12D develop the full spectrum of malignant intraepithelial lesions commonly found in human pancreatic cancer. In addition, a fluorescence spectroscopy technique is used to measure the binding affinity between activated Kras and PI3K complexes containing p110a or p110¿, which might provide mechanistic insight into the phenotypes seen in the two knockout strains. Aim 2 investigates how insulin-like growth factor-1 (IGF-1) activates mammalian target of rapamycin (mTOR) signaling in myotubes prepared from muscle-specific p110a knockout mice. IGF-1 activation of PI3K and then mTOR is thought to be a central regulatory signal for stimulating muscle growth. These studies pursue the molecular mechanisms that explain the unexpected finding of enhanced mTOR signaling in response to IGF-1 in p110a-null muscle, even though Akt activation is greatly reduced. Aim 3 investigates if ablation of p110a or p110¿ affects skeletal muscle atrophy caused by hindlimb unloading or muscle regrowth following reambulation. This animal model mimics the process of muscle unloading and reloading that can occur during hospitalization. The degree of muscle atrophy and subsequent regrowth is monitored by microCT scans of muscle mass in the same animal. Aim 4 also uses microCT scans to determine if clenbuterol, a ¿2 adrenergic receptor agonist known to promote muscle growth in humans and rodents, can still stimulate muscle hypertrophy in muscle-specific p110a or p110¿ knockout mice. Clenbuterol signaling to mTOR is also investigated in myotubes prepared from knockout mice. Knowledge gained from these experiments is important because drugs that inhibit PI3K are already being tested in clinical trials for the treatment of cancer. The identification of cancer patients who will respond to this targeted signal transduction therapy remains a major challenge. Moreover, systemic inhibition of PI3K runs the risk of adverse side effects if these enzymes play important roles in regulating organ function, including maintenance of muscle mass. PUBLIC HEALTH RELEVANCE: Pancreatic cancer is a deadly disease with little efficacious treatment. One goal of this project is to understand if phosphatidylinositol-3 kinase (PI3K) plays a role in the development of this cancer. Muscle atrophy is a major health problem, with effects ranging from reduced physical activity to severely impaired mobility that can have severe medical and financial consequences on patients and their families. Another goal of this project is to understand if PI3K plays a role in controlling muscle wasting and growth. These studies will increase our knowledge about how alterations in PI3K signaling contribute to the development of these health problems and lead to better treatment of these conditions.

描述（由申请人提供）：本提案的目的是了解IA类磷脂酰肌醇3-激酶（PI 3 K）p110 a和p110 <$在调节胰腺和骨骼肌病理和生理细胞生长中的作用。假设这两种IA类PI 3 K控制蛋白质合成和细胞生长和存活。然而，由于胚胎致死性，不可能使用全身基因缺失来研究这些酶的生物学作用。为了克服这个实验问题，产生了其中两个PI 3 K基因可以在特定组织中选择性缺失的小鼠品系。利用这些动物，这项提议解决了四个研究问题。目的1确定胰腺特异性消融p110 a或p110 <$是否阻断由组成性活性KrasG 12 D诱导的胰腺肿瘤的形成。胰腺特异性表达KrasG 12 D的小鼠发展出人类胰腺癌中常见的全谱恶性上皮内病变。此外，荧光光谱技术用于测量激活的Kras和含有p110 a或p110？的PI 3 K复合物之间的结合亲和力，这可能为两种敲除菌株中观察到的表型提供机理性见解。目的2研究胰岛素样生长因子-1（IGF-1）如何激活肌肉特异性p110 a基因敲除小鼠肌管中雷帕霉素靶蛋白（mTOR）信号通路。IGF-1激活PI 3 K，然后mTOR被认为是刺激肌肉生长的中心调节信号。这些研究追求的分子机制解释了在p110 a缺失肌肉中响应IGF-1增强mTOR信号传导的意外发现，即使Akt激活大大降低。目的3：研究p110 a或p110 <$的消融是否影响由后肢卸载或肌肉再生引起的骨骼肌萎缩。该动物模型模拟了住院期间可能发生的肌肉卸载和重新加载的过程。肌肉萎缩的程度和随后的再生长通过同一动物中肌肉质量的microCT扫描来监测。Aim 4还使用microCT扫描来确定克伦特罗（一种已知可促进人类和啮齿动物肌肉生长的肾上腺素能受体激动剂）是否仍能刺激肌肉特异性p110 a或p110 <$敲除小鼠的肌肉肥大。还在从敲除小鼠制备的肌管中研究了克伦特罗向mTOR的信号传导。从这些实验中获得的知识很重要，因为抑制PI 3 K的药物已经在临床试验中进行了癌症治疗的测试。识别对这种靶向信号转导治疗有反应的癌症患者仍然是一个重大挑战。此外，如果这些酶在调节器官功能（包括维持肌肉质量）中起重要作用，则对PI 3 K的全身性抑制有不良副作用的风险。 公共卫生相关性：胰腺癌是一种几乎没有有效治疗的致命疾病。该项目的一个目标是了解磷脂酰肌醇-3激酶（PI 3 K）是否在这种癌症的发展中发挥作用。肌肉萎缩是一个主要的健康问题，其影响范围从减少体力活动到严重损害活动能力，可能对患者及其家人造成严重的医疗和经济后果。该项目的另一个目标是了解PI 3 K是否在控制肌肉萎缩和生长中发挥作用。这些研究将增加我们对PI 3 K信号传导的改变如何促进这些健康问题的发展的认识，并导致更好地治疗这些疾病。