Sortilin-dependent traffic to dense core secretory granules - Resubmission 01

致密核心分泌颗粒的分拣蛋白依赖性交通 - 重新提交 01

• 批准号: 8695899
• 负责人: AARON P TURKEWITZ
• 金额: $ 32.24万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-05-01 至 2018-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8695899
• 关键词: Binding; Biochemical Genetics; Biogenesis; C-terminal; Cell membrane; Cells; Chimera organism; Clathrin; Complex; Cryoelectron Microscopy; Crystallins; Cytoplasmic Granules; Cytoplasmic Tail; Data; Databases; Defect; Diabetes Mellitus; Drosophila genus; Dynamin; Endocytosis; Enzymes; Equilibrium; Eukaryota; Family; Gene Expression; Genes; Homologous Gene; Human; Insulin; Kinetics; Ligand Binding; Ligands; Light; Lysosomes; Maintenance; Mass Spectrum Analysis; Measures; Mediating; Memory; Modeling; Molecular Profiling; Neuroendocrine Cell; Neurons; Organelles; Organism; Pathway interactions; Peptides; Play; Process; Protein Secretion; Proteins; Regulation; Risk Factors; Role; Sampling; Secretory Vesicles; Site-Directed Mutagenesis; Sorting - Cell Movement; Structural Protein; Surface Plasmon Resonance; System; Testing; Tetrahymena; Tetrahymena thermophila; Tissues; Variant; Vesicle; Work; adapter protein; base; bone; member; neurotrophic factor; neurotropic; novel; novel strategies; promoter; public health relevance; receptor; research study; sortilin; tool; trafficking

DESCRIPTION (provided by applicant): Dense core granules are vesicles that store and release bioactive peptides, and are found throughout most eukaryotes. Over the past two decades, detailed models have been developed to explain protein targeting to secretory granules. The most fundamental aspect of these models is that protein sorting in this pathway does not rely on canonical transmembrane receptors or receptor adaptors. However, recent experiments in mammalian neurons led to the surprising finding that bone-derived neurotropic factor (BDNF), a peptide important for neuronal maintenance, is targeted to secretory granules in a pathway, as yet undescribed, that involves a classical lysosomal sorting receptor, sortilin. Moreover, sortilin-family receptor variants have been identified as risk factors for diabetes, and recent work suggests they play a direct role in formation of insulin-containing granules. Another challenge came from recent studies in Drosophila, and in mammalian neuroendocrine cells, which implicated the AP-3 adaptor complex in secretory granule formation. No current model explains the sortilin or AP-3 data. Secretory granules are a prominent feature in the ciliate Tetrahymena thermophila. By studying gene expression during periods of active granule synthesis, it was recently discovered that the Tetrahymena sortilin homologs are highly upregulated under these conditions, in combination with a set of genes that are proposed to underlie secretory granule formation. Those gene products include putative sortilin ligands as well as AP-3 adaptors and other cytoplasmic machinery that is likely to be involved in sortilin trafficking. Preliminary data validate the value of this gene expression-based approach to uncovering mechanisms involved in granulogenesis, and demonstrate that sorting of major classes of granule proteins in Tetrahymena requires sortilins. The proposal is therefore aimed at understanding how sortilins facilitate protein targeting to granules, and what other cellular machinery is involved. To that end, the aims of this proposal include the analysis of sortilin ligands and of adapter proteins that interact with sortilin cytoplasmic domains.

描述（由申请人提供）：致密核心颗粒是储存和释放生物活性肽的囊泡，并且在大多数真核生物中发现。在过去的二十年中，详细的模型已经开发出来，以解释蛋白质靶向分泌颗粒。这些模型最基本的方面是，在这个途径中的蛋白质分选不依赖于典型的跨膜受体或受体衔接子。然而，最近在哺乳动物神经元中的实验导致了令人惊讶的发现，骨源性神经营养因子（BDNF），一种对神经元维持重要的肽，在涉及经典溶酶体分选受体分拣蛋白的通路中靶向于分泌颗粒，尚未描述。此外，分拣蛋白家族受体变体已被确定为糖尿病的危险因素，最近的研究表明它们在含胰岛素颗粒的形成中发挥直接作用。另一个挑战来自最近在果蝇和哺乳动物神经内分泌细胞中的研究，这些研究涉及AP-3适配器复合物在分泌颗粒形成中的作用。目前没有模型解释分拣蛋白或AP-3数据。分泌颗粒是四膜虫的一个显著特征。通过研究活跃颗粒合成期间的基因表达，最近发现，四膜虫分拣蛋白同源物在这些条件下高度上调，与一组被提出为分泌颗粒形成的基础的基因相结合。这些基因产物包括推定的分拣蛋白配体以及AP-3衔接子和其他可能参与分拣蛋白运输的细胞质机制。初步的数据验证了这种基于基因表达的方法的价值，以揭示参与颗粒形成的机制，并表明，分选的主要类别的颗粒蛋白在四膜虫需要分拣蛋白。因此，该提案旨在了解分拣蛋白如何促进蛋白质靶向颗粒，以及涉及哪些其他细胞机制。为此，本提案的目的包括分析分拣蛋白配体和与分拣蛋白胞质结构域相互作用的衔接蛋白。