Mitochondrial inheritance and quality control

线粒体遗传和质量控制

• 批准号: 10604362
• 负责人: Liza A Pon
• 金额: $ 52.83万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-04-01 至 2027-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10604362
• 关键词: Aging; Autophagocytosis; Autophagosome; Cardiovascular Diseases; Cell model; Cell physiology; Cells; Complex; Cytoprotection; Disease; Endosomes; Excision; Funding; Future; Gene Delivery; Goals; In Vitro; Individual; Lead; Life; Link; Lipids; Lysosomes; Mammalian Cell; Mediating; Membrane; Membrane Proteins; Metabolic Diseases; Mitochondria; Mitochondrial Inheritance; Mitochondrial Matrix; Mitochondrial Proteins; Modeling; Myopathy; Neurodegenerative Disorders; Organelles; Outer Mitochondrial Membrane; Pathway interactions; Peptide Hydrolases; Physiological; Play; Premature aging syndrome; Process; Protein Biosynthesis; Protein Import; Proteins; Quality Control; Role; Shapes; Site; Sorting; Structure; TOM translocase; Vacuole; Yeasts; biological adaptation to stress; body system; congenital muscular dystrophy; endoplasmic reticulum stress; fitness; hatching; misfolded protein; multicatalytic endopeptidase complex; novel; protein aggregation; protein folding; protein misfolding; proteostasis; reconstitution; repaired; uptake

Protein homeostasis, or proteostasis, relies on precise control of protein synthesis, folding and degradation. Proteostatic errors lead to protein aggregates, which are toxic and linked to neurodegenerative, cardiovascular, muscular and metabolic disorders, and to premature aging. The ER and mitochondria are major sites for protein folding and are supported by quality control mechanisms that correct protein folding or eliminate proteins or organelles that are damaged beyond repair. ER-associated degradation (ERAD) and mitochondria-associated degradation (MAD) are functionally and mechanistically related mechanisms. In both, misfolded proteins are identified, ubiquitinated, extracted from organelles and degraded by the proteasome. However, both pathways have limitations. Previous studies suggested that MAD proteostasis was restricted to mitochondrial outer mem- brane (OM) proteins, <10% of mitochondrial proteins. Moreover, MAD and ERAD are inherently low-throughput because they act on individual proteins. This limitation is a particular concern for ER, where 1/3 of all proteins in the cell undergo folding, and protein entry into ER occurs at rates of 0.1-1 million proteins/minute. In the last funding period, we found that MAD functions in proteostatic control of mitochondrial matrix and inner membrane proteins. Consistent with this, we found that MAD and not chaperones, proteases or autophagy proteins, plays a major role in mitochondrial and cellular fitness in a model for aging and that loss of MAD function results in premature aging. We also reconstituted retrotranslocation of MAD substrates from the matrix in vitro and identi- fied a role for the TOM channel, which imports proteins into mitochondria, in retrotranslocation of MAD substrates out of the organelle. In complementary studies, we identified a novel ER proteostasis pathway that has overlap- ping function with ERAD, but has higher throughput and contributes to the ER stress response in yeast, mam- malian cells and cellular models for a newly identified congenital muscular dystrophy (CHKB CMD). In this path- way, lipid droplets (LDs), organelles that form at ER membranes, act as escape hatches for large-scale removal of unfolded ER proteins and degradation of those proteins and their LD carriers. Here, degradation occurs by microautophagy, a conserved but understudied form of autophagy that does not rely on autophagosomes or core ATG genes for delivery of cargoes to the vacuole (yeast lysosome). Rather, LD uptake occurs by direct contact with the vacuole at invaginations of the vacuolar membrane, and LDs are released into the vacuolar lumen by membrane scission mediated by the endosomal sorting complex required for transport (ESCRT). Important fu- ture goals are to understand the mechanism of MAD function within mitochondria, and the physiological conse- quences of MAD-mediated mitochondrial proteostasis. Another important goal is to identify components and functional consequences of ER-PERM, the pathway for ER proteostasis mediated by ESCRT and microlipoph- agy, in yeast and mammalian cells. These studies will reveal mechanisms and functions of ER-PERM and targets for treatment of CHKB CMD, a life-threatening disease for which there is no cure.

蛋白质稳态或蛋白抑制性依赖于蛋白质合成，折叠和降解的精确控制。 蛋白抑制导致蛋白质聚集体，这些蛋白质骨料有毒，与神经退行性，心血管相关， 肌肉和代谢性疾病，并过早衰老。 ER和线粒体是蛋白质的主要部位 折叠并受到质量控制机制的支持，这些机制纠正蛋白质折叠或消除蛋白质或 损坏的细胞器无法修复。 ER相关的降解（ERAD）和线粒体相关 降解（MAD）在功能和机械上相关的机制上。在这两者中，错误折叠的蛋白质是 从细胞器中鉴定，泛素化，从细胞器中提取并被蛋白酶体降解。但是，这两种途径 有局限性。先前的研究表明，疯狂的蛋白抑制剂仅限于线粒体外膜 Brane（OM）蛋白，<线粒体蛋白的10％。而且，疯狂和埃拉德本质上是低通量的 因为它们对单个蛋白质作用。这种限制是ER的特别关注，其中所有蛋白质的1/3 该细胞经历折叠，进入ER的蛋白质的发生率为0.1-1百万蛋白/分钟。在最后 资金期，我们发现疯狂在线粒体基质和内膜的蛋白抑制控制中起作用 蛋白质。与此一致，我们发现疯狂而不是伴侣，蛋白酶或自噬蛋白会发挥作用 在衰老模型中，在线粒体和细胞适应性中的主要作用和MAD功能的丧失导致 过早衰老。我们还在体外和鉴定中重新建立了来自基质的MAD底物的转递转换。 将蛋白质导入线粒体的汤姆通道（Tom Channel 从细胞器中出来。在互补研究中，我们确定了一种新型的ER蛋白抑制途径，该途径重叠 ERAD的PING功能，但具有更高的吞吐量，并有助于酵母中的ER应力反应，MAM- 新鉴定的先天性肌肉营养不良（CHKB CMD）的马里细胞和细胞模型。在这个路径中 - 方式，脂质液滴（LDS），在ER膜上形成的细胞器，充当大规模去除的逃生舱口 这些蛋白质及其LD携带者的展开的ER蛋白质和降解。在这里，降解是由 微自噬，一种保守但研究的自噬形式，不依赖自噬体或核心 ATG基因将货物传递到液泡（酵母溶酶体）。相反，LD吸收是通过直接接触而发生的 液泡在液泡膜的起伏处，LDS被释放到液泡腔中 由运输所需的内体分选复合物（ESCRT）介导的膜分裂。重要的fu- 目标的目标是了解线粒体中疯狂功能的机制，以及生理结构 疯狂介导的线粒体蛋白抑制剂的问题。另一个重要目标是确定组件和 ER-Perm的功能后果，Escrt和Microlipoph-介导的ER蛋白质量的途径 Agy，在酵母和哺乳动物细胞中。这些研究将揭示ER-Perm和目标的机制和功能 为了治疗CHKB CMD，这是一种危及生命的疾病，无法治愈。