Mechanisms Regulating GPCR Trafficking

GPCR 贩运的监管机制

基本信息

批准号：
8209041
负责人：
Joann Trejo
金额：
$ 32.5万
依托单位：
UNIVERSITY OF CALIFORNIA, SAN DIEGO
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-01-01 至 2013-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8209041
关键词：
Adaptor Protein Complex 3 Arrestins Back Binding Biochemical Biological Assay Biological Models Cardiovascular Diseases Cell surface Cells Ceramides Clathrin Clathrin Adaptors Complex Cytoplasmic Tail Degradation Pathway Disease Drug usage Dynamin Endosomes Family G Protein-Coupled Receptor Signaling G-Protein-Coupled Receptors GTP-Binding Proteins Gastrointestinal Diseases Human Immune System Diseases Immunoelectron Microscopy Kidney Diseases Life Lung diseases Lysosomes Mediating Mental disorders Molecular Multivesicular Body Nerve Degeneration PAR-1 Receptor PAR-2 Receptor Pathway interactions Phosphorylation Physiological Prevention strategy Process Proteins Receptor Signaling Recycling Regulation Signal Transduction Small Interfering RNA Sorting - Cell Movement Stimulus System Tyrosine Ubiquitin Ubiquitination Vesicle base coated pit desensitization fluorescence imaging human disease inhibitor/antagonist insight mammalian genome mutant nexin novel public health relevance receptor research study response trafficking tumor progression

项目摘要

DESCRIPTION (provided by applicant): G protein-coupled receptors (GPCRs) comprise the largest family of cell surface signaling receptors in the mammalian genome, mediate cellular responses to diverse stimuli and control a vast physiological responses. Dysregulated GPCR signaling has been implicated in multiple human pathological conditions, making this receptor class the target of nearly half the drugs used clinically. In addition to rapid desensitization, GPCR trafficking is crucial for the temporal and spatial control of receptor signaling. However, the mechanisms responsible for trafficking of GPCRs through the endocytic system remains poorly understood. Internalization of activated GPCRs occurs through a clathrin- and dynamin-dependent pathway that requires arrestins. However, arrestins are not essential for internalization of all GPCRs. Several GPCRs including protease- activated receptor-1 (PAR1) internalize through a clathrin- and dynamin-dependent pathway independent of arrestins, suggesting that distinct mechanisms regulate internalization of different GPCRs. Once internalized, GPCRs are dephosphorylated and recycled back to the cell surface in a resensitized state competent to signal again or sorted to a lysosomal degradation pathway, a process critical for termination of receptor signaling. Other GPCRs remain in endocytic compartments and signal independent of G-proteins. We previously showed that unlike most GPCRs, which internalize and recycle, activated PAR1 is internalized, sorted directly to lysosomes and degraded; a process critical for shutting-off activated PAR1 signaling. The efficiency with which PARs are degraded makes this receptor class an excellent model system to investigate the molecular basis of GPCR lysosomal degradation. Many GPCRs including protease-activated receptor-2 (PAR2) are modified with ubiquitin, which facilitates lysosomal trafficking through the endosomal-sorting complex required for transport (ESCRT) pathway. However, several GPCRs sort to lysosomes independent of ubiquitination and some components of the ESCRT complex. Remarkably, we found that activated PAR1 trafficks from endosomes to lysosomes independent of ubiquitination and ubiquitin-binding ESCRT components. The molecular mechanism by which PAR1 and other GPCRs sort to lysosomes independent of ubiquitination is not known. This proposal is focused on delineating the molecular mechanisms that regulate ubiquitin-independent lysosomal sorting of GPCRs. The specific aims of the proposal are to: 1) determine whether GPCRs that sort through ubiquitin- dependent versus -independent lysosomal pathways internalize through the same or distinct clathrin-coated pits, and sort through the same or distinct early or late endosomal compartments, 2) define the sorting signals and mechanism for the novel ubiquitin-independent endosome-to-lysosome sorting of GPCRs, and 3) delineate the molecular pathway by which GPCRs uniquely sort to intralumenal vesicles (ILVs) of multivesicular bodies (MVBs) independent of ubiquitination and the ubiquitin-binding ESCRT components. PUBLIC HEALTH RELEVANCE: G protein-coupled receptors (GPCRs) signal in response to diverse stimuli, control vast physiological responses and are implicated in multiple human pathological diseases. In addition to rapid GPCR desensitization, GPCR trafficking is important for the spatial and temporal control of receptor signaling and dysregulated trafficking contributes to aberrant signaling and disease. Thus, understanding the mechanisms that control trafficking of GPCRs, and developing the ability to manipulate it, may provide new strategies for the prevention and treatment of a wide range of human diseases.

描述（由申请人提供）：G蛋白偶联受体（GPCR）包含哺乳动物基因组中最大的细胞表面信号传导受体家族，介导细胞对不同刺激的反应并控制大量的生理反应。失调的 GPCR 信号传导与多种人类病理状况有关，使得该受体类别成为临床使用的近一半药物的靶标。除了快速脱敏之外，GPCR 运输对于受体信号传导的时间和空间控制也至关重要。然而，对于通过内吞系统运输 GPCR 的机制仍然知之甚少。激活的 GPCR 的内化通过需要抑制蛋白的网格蛋白和动力依赖性途径发生。然而，抑制蛋白并不是所有 GPCR 内化所必需的。包括蛋白酶激活受体 1 (PAR1) 在内的几种 GPCR 通过独立于抑制蛋白的网格蛋白和动力依赖性途径内化，表明不同的机制调节不同 GPCR 的内化。一旦内化，GPCR 就会被去磷酸化并以重新敏感状态再循环回细胞表面，从而能够再次发出信号或分类到溶酶体降解途径，这是终止受体信号传导的关键过程。其他 GPCR 保留在内吞区室中，并且信号独立于 G 蛋白。我们之前表明，与大多数内化和回收的 GPCR 不同，激活的 PAR1 被内化，直接分类到溶酶体并降解；对于关闭激活的 PAR1 信号传导至关重要的过程。 PAR 的降解效率使该受体类成为研究 GPCR 溶酶体降解分子基础的优秀模型系统。许多 GPCR 包括蛋白酶激活受体 2 (PAR2) 均经过泛素修饰，从而促进通过运输所需的内体分选复合物 (ESCRT) 途径进行溶酶体运输。然而，一些 GPCR 对溶酶体进行排序，与泛素化和 ESRT 复合物的某些成分无关。值得注意的是，我们发现激活的 PAR1 从内体运输到溶酶体，不依赖于泛素化和泛素结合 ESCRT 成分。 PAR1 和其他 GPCR 不依赖于泛素化而分选到溶酶体的分子机制尚不清楚。该提案的重点是描述调节 GPCR 的不依赖于泛素的溶酶体分选的分子机制。该提案的具体目标是：1) 确定对泛素依赖性与非依赖性溶酶体途径进行分类的 GPCR 是否通过相同或不同的网格蛋白包被的凹坑内化，并通过相同或不同的早期或晚期内体区室进行分类，2 ) 定义了新型不依赖于泛素的内体到溶酶体 GPCR 分选的分选信号和机制，以及 3) 描绘了其中的分子途径GPCR 独特地对多囊泡体 (MVB) 的腔内囊泡 (ILV) 进行分类，与泛素化和泛素结合 ESCRT 成分无关。公共健康相关性：G 蛋白偶联受体 (GPCR) 发出响应不同刺激的信号，控制大量的生理反应，并与多种人类病理疾病有关。除了快速 GPCR 脱敏之外，GPCR 转运对于受体信号传导的空间和时间控制也很重要，而转运失调会导致异常信号传导和疾病。因此，了解控制 GPCR 贩运的机制并开发操纵它的能力，可能为预防和治疗多种人类疾病提供新策略。