Role of PMEL 17 in melanosome biogenesis

PMEL 17 在黑素体生物发生中的作用

• 批准号: 7322336
• 负责人: Brenda Watt
• 金额: $ 4.1万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-06 至 2009-07-05
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7322336
• 关键词: Address; Affect; Alzheimer' s Disease; Amyloid; Animal Model; Biochemical; Biogenesis; Biological Assay; Cells; Characteristics; Cholesterol; Color; Defect; Deposition; Disease; Disruption; Early Endosome; Electron Microscopy; Event; Eye; Fractionation; Functional disorder; Genetic; Goals; Golgi Apparatus; Health; Human; Hypopigmentation; Integral Membrane Protein; Length; Maintenance; Mediating; Melanins; Melanosomes; Membrane Microdomains; Morphology; Mutation; Neurodegenerative Disorders; Organelles; Pathway interactions; Phenotype; Pigmentation physiologic function; Pigments; Prions; Process; Protein Precursors; Proteins; Range; Role; Skin; Sorting - Cell Movement; Staging; Structure of retinal pigment epithelium; Sucrose; Testing; Transmembrane Domain; Ultraviolet Rays; Vesicle; Work; amyloid formation; base; fibrillogenesis; melanocyte; mutant; pMel17 antigen; trafficking

DESCRIPTION (provided by applicant): The overall goals of this proposal are to understand how the transmembrane domain (TMD) of Pmel17 regulates its sorting to melanosomes and its ability to form the fibrillar melanosome matrix, and how mutations in this domain result in the melanosome dysfunction underlying pigmentation defects. Melanosomes are pigment-cell specific organelles in which melanins, which protect the skin and eyes from UV radiation, are synthesized and stored. Within melanosomes, melanins are deposited on a fibrillar amyloid-like matrix of which the highly conserved pigment cell-specific protein Pmel17 is the main component. To form fibrils, Pmel17 - like several pathological amyloid precursors - must first be sorted within endosomal intermediates to intralumenal vesicles (ILVs), but the mechanisms responsible for this sorting are unclear. Natural occurring mutations in the unusually long Pmel17 TMD cause hypopigmentation in model organisms; although similar mutations in human Pmel17 have not been identified in pigmentary diseases, they likely exist given the high degree of homology among vertebrate Pmel17 orthologues and the similar phenotypes associated with Pmel17 mutations in a broad range of species. The hypopigmentation phenotypes associated with these mutations suggest that the TMD is critical to Pmel17 function. This proposal poses the hypothesis that the Pmel17 TMD mediates partitioning into lipid rafts and that this partitioning is required for sorting of Pmel17 to ILVs for subsequent fibril formation because long TMDs tend to partition in lipid rafts and ILVs are enriched in lipid raft components. This hypothesis will be addressed with the following specific aims: 1) Determine if Pmel17 associates to lipid rafts using classical biochemical fractionation and test whether cholesterol depletion affects Pmel17 lipid raft association, sorting, and/or fibril formation. 2) Determine if mutations in the Pmel17 TMD affects sorting to ILVs and/or fibrillogenesis. The proposed work is relevant as it relates to understanding the mechanisms that control the targeting of Pmel17 to melanosomes and the formation of the amyloid-like matrix, essential to PrneM 7 function and melanosome integrity. The results may also be relevant to understanding how amyloid forms in neurodegenerative diseases.

描述（由申请人提供）：本提案的总体目标是了解 Pmel17 的跨膜结构域 (TMD) 如何调节其对黑素体的分选及其形成纤维状黑素体基质的能力，以及该结构域的突变如何导致色素沉着缺陷背后的黑素体功能障碍。黑素体是色素细胞特异性细胞器，其中合成和储存黑色素，保护皮肤和眼睛免受紫外线辐射。在黑素体内，黑色素沉积在纤维状淀粉样蛋白基质上，其中高度保守的色素细胞特异性蛋白 Pmel17 是主要成分。为了形成原纤维，Pmel17 与几种病理性淀粉样蛋白前体一样，必须首先在内体中间体中分选为腔内囊泡 (ILV)，但负责这种分选的机制尚不清楚。异常长的 Pmel17 TMD 中自然发生的突变会导致模型生物体色素沉着不足；尽管人类 Pmel17 中的类似突变尚未在色素性疾病中被发现，但鉴于脊椎动物 Pmel17 直系同源物之间的高度同源性以及与广泛物种中 Pmel17 突变相关的相似表型，它们很可能存在。与这些突变相关的色素沉着不足表型表明 TMD 对 Pmel17 功能至关重要。该提议提出了这样的假设：Pmel17 TMD 介导脂筏的分配，并且这种分配是 Pmel17 分选至 ILV 以便随后形成原纤维所必需的，因为长 TMD 倾向于分配在脂筏中，而 ILV 富含脂筏成分。该假设将通过以下具体目标来解决： 1) 使用经典生化分级分离确定 Pmel17 是否与脂筏结合，并测试胆固醇消耗是否影响 Pmel17 脂筏结合、排序和/或原纤维形成。 2) 确定 Pmel17 TMD 中的突变是否影响 ILV 的分选和/或原纤维形成。 拟议的工作具有相关性，因为它涉及了解控制 Pmel17 靶向黑素体的机制以及淀粉样蛋白样基质的形成，这对于 PrneM 7 功能和黑素体完整性至关重要。研究结果也可能与了解淀粉样蛋白在神经退行性疾病中的形成方式有关。