Novel functions for gp78 in ER-associated degradation

gp78 在 ER 相关降解中的新功能

• 批准号: 7263002
• 负责人: Shengyun Fang
• 金额: $ 28.16万
• 依托单位: UNIVERSITY OF MD BIOTECHNOLOGY INSTITUTE
• 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/7263002
• 关键词: Adopted; Angioplasty; Apoptosis; Binding; Biological Assay; CD3 Antigens; Cell Extracts; Cell Fractionation; Cell physiology; Cellular biology; Co-Immunoprecipitations; Complex; Condition; Confocal Microscopy; Couples; Coupling; Cues; Cultured Cells; Cystic Fibrosis; Cytosol; Disease; Endoplasmic Reticulum; Environment; Event; Faculty; Family; Fingers; Functional disorder; Goals; Hong Kong; Immunoblot Analysis; Immunofluorescence Immunologic; In Vitro; Iowa; Laboratories; Maryland; Mediating; Membrane Fusion; Modeling; Molecular; Molecular and Cellular Biology; Nature; Neoplasm Metastasis; Parkinson Disease; Pathogenesis; Pathway interactions; Physiologic pulse; Play; Polyubiquitin; Post-Translational Protein Processing; Process; Protein C Inhibitor; Proteins; Publishing; Pulse taking; RNA Interference; Recombinant Proteins; Recombinants; Regulation; Research; Role; Schools; Scientist; Stress; Students; TP53 gene; Techniques; Testing; Transfection; Ubiquitin; Ubiquitination; Universities; Variant; Work; bindin; cell motility; experience; ilium; in vitro Assay; in vivo; inhibitor-of-apoptosis protein; insight; medical schools; member; multicatalytic endopeptidase complex; mutant; novel; peer; post-doctoral training; programs; protein activation; protein degradation; protein expression; protein folding; protein protein interaction; protein transport; restenosis; thymocyte; tumor autocrine motility factor receptor; ubiquitin ligase; ubiquitin-protein ligase; valosin-containing protein

DESCRIPTION (provided by applicant): Endoplasmic reticulum-associated degradation (ERAD) is a process by which misfolded, unassembled, and some normal proteins are targeted for degradation by the ubiquitin proteasome pathway. ERAD is essential for many normal cellular processes and its dysfunctions contribute to the pathological conditions associated with Alzheimers' and Parkinson's diseases, cystic fibrosis, and al-antitrypsin-deficiency. While it is known that ERAD involves substrate ubiquitination, retrotranslocation, and proteasomal degradation, the molecular mechanisms for these events are not clear. To begin elucidating these molecular mechanisms, we have discovered that autocrine motility factor receptor, also known as gp78, is an ER-resident ubiquitin ligase (E3) required for ERAD and have now identified two additional gp78-interacting proteins: valosin-containing protein (VCP) and ubiquitin. Interaction of VCP with gp78 appears to activate VCP-polyubiquitin binding and facilitate polyubiquitinated protein degradation. Previous studies by others have shown that VCP is an essential factor for retrotranslocation. The finding of gp78 interactions with VCP and ubiquitin provides a novel avenue for elucidating the molecular mechanisms in ERAD. We hypothesize that gp78-acivated VCPpolyubiquitin binding couples substrate ubiquitination, retrotranslocation, and degradation during ERAD. To test the hypothesis, we propose the following specific aims: (1) to characterize gp78 interaction with VCP, ubc7, ubiquitin, and sec61 channel; (2) to elucidate the mechanisms by which gp78 activates VCPpolyubiquitin interaction; and (3) to evaluate the roles of gp78-activated VCP-polyubiquitin interaction in retrotranslocation and degradation of ERAD substrates. These studies will advance the current understanding of how gp78 and VCP is involved in substrate ubiquitination, retrotranslocation, and degradation during ERAD. The proposed work is consistent with this laboratory's long-term goal of understanding the molecular mechanisms of ERAD and its implications for disease pathogenesis.

描述（由申请人提供）： 内质网相关降解 (ERAD) 是错误折叠、未组装和一些正常蛋白质被泛素蛋白酶体途径靶向降解的过程。 ERAD 对于许多正常细胞过程至关重要，其功能障碍会导致与阿尔茨海默病和帕金森病、囊性纤维化和α-抗胰蛋白酶缺乏相关的病理状况。虽然已知 ERAD 涉及底物泛素化、逆转录转位和蛋白酶体降解，但这些事件的分子机制尚不清楚。为了开始阐明这些分子机制，我们发现自分泌运动因子受体（也称为 gp78）是 ERAD 所需的 ER 驻留泛素连接酶 (E3)，并且现已鉴定出另外两种 gp78 相互作用蛋白：含缬氨肽蛋白 (VCP) 和泛素。 VCP 与 gp78 的相互作用似乎激活 VCP-多聚泛素结合并促进多聚泛素化蛋白降解。其他人之前的研究表明VCP是逆转录转位的一个重要因素。 gp78 与 VCP 和泛素相互作用的发现为阐明 ERAD 的分子机制提供了新的途径。我们假设 gp78 激活的 VCP 多聚泛素结合偶联底物泛素化、逆转录转位和 ERAD 过程中的降解。为了检验这一假设，我们提出以下具体目标：（1）表征gp78与VCP、ubc7、泛素和sec61通道的相互作用； (2)阐明gp78激活VCP多泛素相互作用的机制； (3)评估gp78激活的VCP-多聚泛素相互作用在ERAD底物逆向易位和降解中的作用。这些研究将增进目前对 gp78 和 VCP 如何参与 ERAD 过程中底物泛素化、逆转录转位和降解的理解。拟议的工作与该实验室了解 ERAD 分子机制及其对疾病发病机制的影响的长期目标一致。