Tumor Suppressor Function of Smad4 by Ubiquitin

泛素对 Smad4 的抑癌作用

• 批准号: 6775397
• 负责人: XIN-HUA FENG
• 金额: $ 26.27万
• 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/6775397
• 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）：对TGF-β的抗增殖反应性的丧失通常被认为是肿瘤进展的主要步骤。本申请的长期目标是了解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的失调的分子基础。本申请的总体策略是关注肿瘤抑制因子SMAD 4的泛素和SUMO-1修饰以及这些修饰在细胞生长和肿瘤发生调节中的生理功能。SMAD 4是一种肿瘤抑制因子。它是所有SMAD依赖性反应的必需共同介质，因此在TGF-β超家族的信号传导中发挥核心作用。SMAD 4通过转录依赖性机制抑制细胞增殖。然而，SMAD 4如何调节的机制仍有待阐明。该假说的统一假设是SMAD 4的生物学功能受泛素/蛋白酶体途径和SUMO化途径控制。为了验证这一假设，我们将研究SMAD 4泛素化和SUMO化的分子机制，它们在调节TGF-β信号传导中的功能，以及在正常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SMAD 4-SKP 2相互作用、SMAD 4泛素化和蛋白酶体介导的降解的分子机制。2.检查SKP 2基因沉默对SMAD 4稳定性和TGF-β抗增殖反应的影响。3.研究SKP 2和SMAD 4在人类癌症中的相反功能。4.了解SMAD 4在人类癌症中的泛素化、SUMO化和稳定性之间的相互关系。这些研究将有助于建立TGF-β介导的细胞生长控制和发育过程中SMAD 4活性的翻译后调节的工作理论，并了解SMAD 4在人类癌症恶性转化和进展中的作用机制。最后，这些结果可能为合理设计新的疾病预防和治疗方法提供基础。