Tuberin and hamartin in rapamycin-sensitive & rapamycin-insensitive smooth muscle

雷帕霉素敏感的马铃薯蛋白和错构瘤蛋白

• 批准号: 7736421
• 负责人: GERALDINE A FINLAY
• 金额: $ 35.78万
• 依托单位: TUFTS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7736421
• 关键词: Address; Apoptosis; Asthma; Blood Vessels; Cell Proliferation; Complex; Data; Development; Diagnosis; Disease; Evaluation; Functional disorder; GTP-Binding Proteins; Generations; Growth; Guanosine Triphosphate; Hypertrophy; Knock-out; Lead; Lung; Lymphangioleiomyomatosis; Measurement; Mediating; Mitochondria; Modeling; Mus; Oxidation-Reduction; Pathway interactions; Phenotype; Production; Proteins; Pulmonary Hypertension; Pulmonary Vascular Resistance; Pulmonary artery structure; Quantitative Evaluations; Ras homolog enriched in brain; Rattus; Regulation; Signal Transduction; Sirolimus; Small Interfering RNA; Smooth Muscle; Smooth Muscle Myocytes; Source; Superoxides; Systolic Pressure; TSC1 gene; TSC1/2 gene; TSC2 gene; Techniques; Tuberous sclerosis protein complex; Tumor Suppressor Genes; Tumor Suppressor Proteins; Vascular Smooth Muscle; Ventricular; Woman; cell growth; functional loss; human TSC1 protein; human TSC2 protein; improved; in vivo; mTOR protein; overexpression; pressure; public health relevance; response; rho; vasoconstriction

DESCRIPTION (provided by applicant): Smooth muscle cell proliferation is the hallmark of many diseases, including pulmonary hypertension, asthma, lymphangioleiomyomatosis, and tuberous sclerosis complex (TSC). Hamartin and tuberin are highly expressed in smooth muscle and are encoded by the tumor suppressor genes, Tuberous Sclerosis Complex-1 and -2 respectively (TSC1; TSC2). Tumor suppressor function is dependent upon complex formation between hamartin and tuberin. Functional loss of either hamartin or tuberin leads to identical cellular effects: Increased levels of the G protein, GTP-Rheb (Ras homolog enriched in brain), with downstream constitutive activation of mTOR (mammalian target of rapamycin), S6Kinase (S6K) and S6, leading to increased cellular growth. We show that independent of S6K-S6 activation, the cellular hyperproliferation observed in pulmonary artery vascular smooth muscle cells (PaVSMCs), where the TSC1/TSC2 complex is disrupted, is also associated with (i) rapamycin-sensitive effects that involve mitochondrial-derived superoxide anion (O2.-) production and reduced mitochondrial-mediated apoptosis and (ii) rapamycin-insensitive activation and co-localization of the G proteins, Rheb and Rho A. Recent data suggests that low grade pulmonary hypertension occurs in women diagnosed with pulmonary LAM, a disease where TSC2 is functionally deficient and we have observed increased pulmonary pressures in a murine model where TSC1 is conditionally knocked out in vascular smooth muscle. Our hypothesis is that in PaVSMCs, TSC1/TSC2 complex dysfunction results in: (i) rapamycin- sensitive altered mitochondrial function that promotes redox-regulated apoptosis, (ii) rapamycin- insensitive activation of Rheb and RhoA that also promotes growth, and (iii) a phenotype that promotes the development of pulmonary hypertension. To address this hypothesis , our Specific Aims are: 1) To study the regulation by the TSC1/TSC2 complex of the rapamycin-sensitive generation of mitochondrial O2.- and the downstream effectors that are pertinent to PaVSMC growth; 2) To study the regulation by the TSC1/TSC2 complex of the rapamycin-insensitive activation of the G proteins Rheb and RhoA and their downstream effectors pertinent to PaVSMC growth and 3) To study the effect of TSC1/TSC2 complex disruption on the development of pulmonary hypertension in vivo. These studies will lead to a new understanding of how the TSC1/TSC2 complex controls the proliferation of pulmonary vascular smooth muscle. We hope that our studies will lead to the development of new therapies for diseases characterized by SMC proliferation like pulmonary hypertension. PUBLIC HEALTH RELEVANCE: Smooth muscle cell (SMC) growth is the hallmark of pulmonary hypertension. We plan to study the regulation of SMC growth by two SMC proteins, hamartin and tuberin. The purpose of the proposed studies is to improve our understanding of the mechanisms that lead to uncontrolled growth in smooth muscle and to develop new targets for the treatment of pulmonary hypertension.

描述（由申请人提供）：平滑肌细胞增殖是许多疾病的标志，包括肺动脉高压、哮喘、淋巴管平滑肌瘤病和结节性硬化症（TSC）。Hamartin和tuberin在平滑肌中高表达，分别由肿瘤抑制基因Tuberous Sclerosis Complex-1和-2 （TSC1; TSC2）编码。肿瘤抑制功能依赖于错构体和tuberin之间形成的复合物。无论是错构体还是tuberin的功能缺失都会导致相同的细胞效应：G蛋白、GTP-Rheb（在大脑中富集的Ras同源物）水平升高，并伴随mTOR（哺乳动物雷帕霉素靶点）、s6激酶（S6K）和S6的下游组成性激活，导致细胞生长增加。我们发现，独立于S6K-S6激活，在肺动脉血管平滑肌细胞（PaVSMCs）中观察到的细胞过度增殖，其中TSC1/TSC2复合物被破坏，也与(i)雷帕霉素敏感效应有关，包括线粒体来源的超氧阴离子（O2.-）的产生和线粒体介导的细胞凋亡的减少，以及（ii）雷帕霉素不敏感的激活和G蛋白的共定位。最近的数据表明，低级别肺动脉高压发生在被诊断为肺性LAM的女性中，这种疾病中TSC2功能缺陷，我们在血管平滑肌中TSC1有条件地被敲除的小鼠模型中观察到肺压力增加。我们的假设是，在PaVSMCs中，TSC1/TSC2复合物功能障碍导致：(i)雷帕霉素敏感的线粒体功能改变，促进氧化还原调节的细胞凋亡；（ii）雷帕霉素不敏感的Rheb和RhoA激活，也促进生长；（iii）一种促进肺动脉高压发展的表型。为了解决这一假设，我们的具体目标是：1)研究TSC1/TSC2复合物对雷帕霉素敏感的线粒体O2生成的调控。-以及与PaVSMC生长相关的下游效应物；2)研究TSC1/TSC2复合体对与PaVSMC生长相关的G蛋白Rheb和RhoA及其下游效应物的雷帕霉素不敏感活化的调控作用；3)研究TSC1/TSC2复合体破坏对体内肺动脉高压发展的影响。这些研究将导致对TSC1/TSC2复合物如何控制肺血管平滑肌增殖的新认识。我们希望我们的研究将导致以SMC增生为特征的疾病如肺动脉高压的新疗法的发展。