Tumor Suppressor Function of Smad4 by Ubiquitin

泛素对 Smad4 的抑癌作用

• 批准号: 7120037
• 负责人: XIN-HUA FENG
• 金额: $ 23.15万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 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 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7120037
• 关键词: SDS polyacrylamide gel electrophoresis; biological signal transduction; breast neoplasms; cell growth regulation; cell proliferation; chemical stability; clinical research; female; gene expression; growth factor receptors; human tissue; immunoprecipitation; mutant; neoplastic cell; posttranslational modifications; protein metabolism; protein protein interaction; protein structure function; proteolysis; transforming growth factors; tumor suppressor proteins; ubiquitin; western blottings

DESCRIPTION (provided by applicant): Loss of the antiproliferative responsiveness to TGF-beta is often considered as a major step in tumor progression. The long-term objective of this application is to understand the molecular basis of how alterations in TGF-beta antiproliferative signaling pathways lead to deregulation of growth control in human diseases. The general strategy of this application is to focus on the ubiquitin and SUMO-1 modifications of tumor suppressor SMAD4 and the physiological functions of these modifications in the regulation of cell growth and tumorigenesis. SMAD4 is a tumor suppressor. It is an essential common mediator for all the SMAD-dependent responses, thus playing a central role in signaling of TGF-beta superfamily. SMAD4 inhibits cell proliferation through transcription-dependent mechanisms. However, the mechanism of how SMAD4 is regulated remains to be elucidated. The unifying hypothesis of this proposal is that the biological functions of SMAD4 are controlled by ubiquitin/proteasome pathway and SUMOylation pathway. To test this hypothesis, we will study the molecular mechanisms of SMAD4 ubiquitination and SUMOylation, their functions in the regulation of TGF-beta signaling, and the physiological outcomes in cell growth regulation in normal and cancer cells. Four Specific Aims are proposed: 1. Determine the molecular mechanisms for SMAD4-SKP2 interaction, SMAD4 ubiquitination and proteasome-mediated degradation. 2. Examine the effects of SKP2 gene silencing on SMAD4 stability and TGF-beta antiproliferative responses. 3. Investigate the opposing functions of SKP2 and SMAD4 in human cancers. 4. Understand the inter-relationship among ubiquitination, SUMOylation and stability of SMAD4 in human cancers. The proposed studies should help to establish a working theory for the posttranslational regulation of SMAD4 activity during TGF-beta-mediated cell growth control and development, and to understand the mechanisms of SMAD4 actions in malignant transformation and progression of human cancers. Finally, the results may provide a foundation for the rational design of novel therapeutic approaches for disease prevention and treatment.

描述（由申请人提供）：TGF-β抗增殖反应性的丧失通常被认为是肿瘤进展的一个主要步骤。该应用的长期目标是了解 TGF-β 抗增殖信号通路的改变如何导致人类疾病中生长控制失调的分子基础。本申请的总体策略是重点研究抑癌基因SMAD4的泛素和SUMO-1修饰以及这些修饰在调节细胞生长和肿瘤发生中的生理功能。 SMAD4 是一种肿瘤抑制因子。它是所有 SMAD 依赖性反应的重要共同介质，因此在 TGF-β 超家族的信号传导中发挥核心作用。 SMAD4 通过转录依赖性机制抑制细胞增殖。然而，SMAD4的调控机制仍有待阐明。该提议的统一假设是SMAD4的生物学功能由泛素/蛋白酶体途径和SUMO化途径控制。为了检验这一假设，我们将研究 SMAD4 泛素化和 SUMO 化的分子机制、它们在 TGF-β 信号传导调节中的功能，以及正常细胞和癌细胞中细胞生长调节的生理结果。提出了四个具体目标： 1. 确定 SMAD4-SKP2 相互作用、SMAD4 泛素化和蛋白酶体介导的降解的分子机制。 2. 检查 SKP2 基因沉默对 SMAD4 稳定性和 TGF-β 抗增殖反应的影响。 3. 研究人类癌症中SKP2和SMAD4的相反功能。 4.了解人类癌症中SMAD4的泛素化、SUMO化和稳定性之间的相互关系。拟议的研究应有助于建立TGF-β介导的细胞生长控制和发育过程中SMAD4活性翻译后调节的工作理论，并了解SMAD4在人类癌症恶性转化和进展中的作用机制。最后，研究结果可为合理设计疾病预防和治疗的新治疗方法提供基础。