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.

蛋白质稳态依赖于蛋白质合成、折叠和降解的精确控制。 蛋白质抑制错误导致蛋白质聚集，这是有毒的，并与神经退行性疾病，心血管疾病， 肌肉和代谢紊乱，以及过早衰老。内质网和线粒体是蛋白质的主要场所 折叠，并得到质量控制机制的支持，这些机制可以纠正蛋白质折叠或消除蛋白质， 受损无法修复的细胞器ER相关降解（ERAD）和ERAD相关 降解（MAD）是功能和机制相关的机制。在这两种情况下，错误折叠的蛋白质 鉴定、泛素化、从细胞器中提取并被蛋白酶体降解。然而，这两种途径 有局限性。先前的研究表明，MAD蛋白酶抑制作用仅限于线粒体外膜。 膜（OM）蛋白，<10%的线粒体蛋白。此外，MAD和ERAD固有地是低吞吐量的 因为它们作用于单个蛋白质。这种限制对于ER是一个特别的问题，其中ER中所有蛋白质的1/3在ER中。 细胞经历折叠，蛋白质以每分钟0.1 - 1百万蛋白质的速率进入ER。在过去 研究期间，我们发现MAD在线粒体基质和内膜的蛋白质稳定控制中发挥作用 proteins.与此一致，我们发现MAD而不是伴侣蛋白，蛋白酶或自噬蛋白， 在衰老模型中线粒体和细胞适应性的主要作用，MAD功能的丧失导致 过早衰老我们还重建了MAD底物从体外基质中的逆转位，并鉴定了 证明了TOM通道在MAD底物的逆向转运中的作用，TOM通道将蛋白质输入线粒体 从细胞器中分离出来在补充研究中，我们发现了一种新的ER蛋白抑制途径， ping功能与ERAD，但具有更高的吞吐量，并有助于ER应激反应在酵母，mam- 马里细胞和新鉴定的先天性肌营养不良症（CHKB CMD）的细胞模型。在这条路上- 另一方面，在内质网膜上形成的细胞器--脂滴（LDs），作为大规模清除的逃逸舱口， 未折叠的ER蛋白和这些蛋白及其LD载体的降解。在这里，降解通过以下方式发生 微自噬，一种保守但研究不足的自噬形式，不依赖于自噬体或核心 将货物运送到液泡（酵母溶酶体）的ATG基因。相反，LD吸收通过直接接触发生 在液泡膜的内陷处有液泡，LD通过 由内体转运所需的分选复合物（ESCRT）介导的膜断裂。重要的福- 真正的目标是了解线粒体内MAD功能的机制，以及其生理后果。 序列的MAD介导的线粒体蛋白质稳态。另一个重要目标是确定组件， ER-PERM的功能后果，ESCRT和microlipoph介导的ER蛋白酶抑制途径， AGY，存在于酵母和哺乳动物细胞中。这些研究将揭示ER-PERM的作用机制和作用靶点 用于治疗CHKB CMD，一种无法治愈的危及生命的疾病。