Lipid droplets as protein sequestration sites

脂滴作为蛋白质隔离位点

• 批准号: 8642196
• 负责人: MICHAEL Andreas WELTE
• 金额: $ 29.01万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2017-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8642196
• 关键词: Address; Affect; Anabolism; Atherosclerosis; Binding; Biochemical; Biochemistry; Biological; Biological Models; Biological Testing; Buffers; Cardiovascular Diseases; Caveolins; Cell Nucleus; Cell membrane; Cell physiology; Cessation of life; Characteristics; Complex; Core Protein; DNA Damage; Data; Development; Developmental Process; Diabetes Mellitus; Disease; Drosophila genus; Embryo; Embryonic Development; Ensure; Enzymes; Equilibrium; Fatty acid glycerol esters; Genetic; Goals; Health; Hepatitis; Histones; Homeostasis; Image; Lead; Life; Life Cycle Stages; Link; Lipids; Lipodystrophy; Liver; Macromolecular Complexes; Mammals; Mediating; Metabolism; Modeling; Mutation; Nuclear Proteins; Obesity; Organelles; Phenotype; Play; Production; Proteins; Publishing; Role; Severity of illness; Site; Structure; Surface; Testing; Time; Transplantation; Viral; Viral Proteins; Virus; Wasting Syndrome; Yeasts; design; fly; human disease; in vivo; insight; lipid metabolism; mutant; novel; overexpression; photoactivation; physical state; premature; public health relevance; research study; response

DESCRIPTION (provided by applicant): Lipid droplets are ubiquitous fat storage organelles and play central roles in lipid metabolism in both health and disease. These complex, dynamic organelles have been implicated in cellular functions well beyond lipid homeostasis. In particular, they have been proposed to serve as temporary storage sites for toxic or unstable proteins, as assembly platforms for macromolecular complexes, or as vehicles to deliver proteins intracellularly. Although lipid droplets clearly play an important role in the life cycle f several viruses and likely promote viral assembly, whether they act as transient protein sequestration site for endogenous proteins remains unresolved. A long list of proteins from other cellular compartments has been shown to relocate to lipid droplets in a regulated manner, but whether these proteins perform novel functions at the droplet surface or are indeed regulated by droplet association is unclear. A critical test of the sequestration model has important implications for our understanding of basic cellular and developmental processes as well as for the management of human diseases resulting from aberrant fat storage, including lipodystrophies and obesity. The goal of this project is to resolve this issue for one particularly provocative case of proposed protein sequestration, histone storage on lipid droplets in early Drosophila embryos. In this model system, it is possible to combine genetics, biochemistry and live imaging to address this general question. In these embryos, massive amounts of certain histones associate transiently with lipid droplets; this association is mediated by the novel protein Jabba, the putative histone anchor on droplets. In the absence of Jabba, histone levels in embryos are dramatically reduced and - when new histone synthesis is mildly compromised - embryos die with phenotypes indicating lack of sufficient histone supplies. These observations support a model that histones are stored on lipid droplets for later use in development. The goal of this project is to test central predictions of this model. Using a structure-function approach, the domains of Jabba that mediate droplet and histone binding will be identified and the physical state of histones on the droplets will be determined. This information will be employed to generate Jabba mutants lacking specific interactions or mislocalized to other cellular compartments; these mutants will be tested for their ability to rescue high histone levels and normal development. Live imaging and droplet transplantation will address how quickly histones are transferred from lipid droplets to nuclei and whether Jabba remains stably behind. Finally, histone overexpression will be employed to address if droplets normally buffer the histone supply and protect against histone overabundance. If successful, the proposed studies will provide novel insights into both histone metabolism and lipid-droplet function. Most importantly, these studies will provide a paradigm for how and why proteins from other compartments are transiently sequestered on lipid droplets.

描述（由申请方提供）：脂滴是普遍存在的脂肪储存细胞器，在健康和疾病的脂质代谢中发挥核心作用。这些复杂、动态的细胞器与细胞功能的关系远远超出了脂质体内平衡。特别是，它们已被提议用作毒性或不稳定蛋白质的临时储存位点，作为大分子复合物的组装平台，或作为细胞内递送蛋白质的载体。虽然脂滴在几种病毒的生命周期中发挥着重要作用，并可能促进病毒的组装，但它们是否作为内源性蛋白质的瞬时蛋白质螯合位点仍然没有得到解决。来自其他细胞区室的一长串蛋白质已被证明以受调节的方式重新定位到脂滴，但这些蛋白质是否在液滴表面发挥新功能或确实受到液滴结合的调节尚不清楚。隔离模型的关键测试对我们理解基本的细胞和发育过程以及管理异常脂肪储存导致的人类疾病（包括脂肪代谢障碍和肥胖症）具有重要意义。这个项目的目标是解决这个问题，特别是 提出蛋白质隔离，组蛋白储存在早期果蝇胚胎的脂滴中的挑衅性案例。在这个模型系统中，有可能将遗传学、生物化学和活体成像联合收割机来解决这个普遍问题。在这些胚胎中，大量的某些组蛋白与脂滴短暂结合;这种结合是由新型蛋白Jabba介导的，Jabba是液滴上假定的组蛋白锚。在没有贾巴的情况下，胚胎中的组蛋白水平急剧下降，当新的组蛋白合成受到轻微影响时，胚胎死亡的表型表明缺乏足够的组蛋白供应。这些观察结果支持了一个模型，即组蛋白储存在脂滴上，供以后在发育中使用。该项目的目标是测试该模型的核心预测。使用结构-功能方法，将鉴定介导液滴和组蛋白结合的Jabba结构域，并确定液滴上组蛋白的物理状态。这些信息将用于产生缺乏特异性相互作用或错误定位到其他细胞区室的Jabba突变体;这些突变体将被测试其拯救高组蛋白水平和正常发育的能力。实时成像和液滴移植将解决组蛋白从脂滴转移到细胞核的速度以及贾巴是否稳定地留在后面。最后，组蛋白过表达将用于解决液滴是否正常缓冲组蛋白供应并防止组蛋白过量。如果成功，这些研究将为组蛋白代谢和脂滴功能提供新的见解。最重要的是，这些研究将提供一个范例，如何以及为什么蛋白质从其他车厢暂时隔离的脂滴。