Regulatory mechanisms of lysosomal degradation in neurodegenerative disease

神经退行性疾病中溶酶体降解的调节机制

基本信息

批准号：
10354193
负责人：
MICHAEL X ZHU
金额：
$ 42.9万
依托单位：
UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-09-20 至 2025-02-28
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10354193
关键词：
Acceleration Adult Amino Acids Ammonium Anabolism Area Attention Autophagocytosis Autophagosome Biochemistry Brain Calmodulin Cell Death Cell Survival Cell membrane Cell physiology Cells Cessation of life Characteristics Core Protein Coupled Cytoplasm Digestion Endocytosis Endosomes Fostering Foundations Functional disorder Generations Glutaminase Glutamine Goals Growth Factor Hippocampus (Brain)Hydrolase Hydrolysis Image Imaging Techniques Intercellular Fluid Label Lipids Lumen of the Lysosome Lysosomes Mediating Membrane Microtubule-Associated Proteins Molecular Chaperones Multivesicular Body Mus Natural regeneration Nerve Degeneration Neurodegenerative Disorders Neurons Neurosciences Nutrient Organelles Pathway interactions Pharmacology Phase Phosphorylation Phosphotransferases Plasma Process Production Protein-Serine-Threonine Kinases Proteins Proteomics RIPK1 gene RIPK3 gene Recycling Regulation Regulatory Pathway Research Resolution Role Serum Slice Speed Starvation Stress Testing Withdrawal deprivation individual response knock-down knockout gene novel nutrient deprivation protein degradation receptor response sugar

Acceleration Adult Amino Acids Ammonium Anabolism Area Attention Autophagocytosis Autophagosome Biochemistry Brain Calmodulin Cell Death Cell Survival Cell membrane Cell physiology Cells Cessation of life Characteristics Core Protein Coupled Cytoplasm Digestion Endocytosis Endosomes Fostering Foundations Functional disorder Generations Glutaminase Glutamine Goals Growth Factor Hippocampus (Brain)Hydrolase Hydrolysis Image Imaging Techniques Intercellular Fluid Label Lipids Lumen of the Lysosome Lysosomes Mediating Membrane Microtubule-Associated Proteins Molecular Chaperones Multivesicular Body Mus Natural regeneration Nerve Degeneration Neurodegenerative Disorders Neurons Neurosciences Nutrient Organelles Pathway interactions Pharmacology Phase Phosphorylation Phosphotransferases Plasma Process Production Protein-Serine-Threonine Kinases Proteins Proteomics RIPK1 gene RIPK3 gene Recycling Regulation Regulatory Pathway Research Resolution Role Serum Slice Speed Starvation Stress Testing Withdrawal deprivation individual response knock-down knockout gene novel nutrient deprivation protein degradation receptor response sugar

展开

项目摘要

PROJECT SUMMARY Cells respond to nutrient shortage by activating autophagy, regulated processes of removing unnecessary or dysfunctional cellular components that allow orderly degradation and recycling of proteins, sugars, and lipids. While it is well known that starvation induces macroautophagy (often simply referred to as just autophagy), a process involving the formation of double-membraned structure called autophagosomes, other autophagic pathways, e.g., endosomal microautophagy, also occur as integral parts of the starvation response to help the cell cope with the stress caused by the nutrient deficiency. As a key step of autophagy, protein degradation in the lysosomes is crucial for regeneration of amino acids needed for the synthesis of essential core proteins that support survival of nutrient-deprived cells. However, how lysosomal degradation is regulated in response to nutrient deprivation is not clear. We have uncovered a novel regulatory pathway of lysosomal degradation centered around glutamine hydrolysis by glutaminases and the production of ammonium. Under fed conditions, the abundance of glutamine supports the ammonium production and in turn alkalization of the lysosome lumen, which slows down protein degradation by keeping lysosomal hydrolases in suboptimal conditions. Upon amino acid or glutamine withdrawal, the loss of ammonium production immediately causes acidification of the lysosomes and acceleration of protein degradation. We further found that this increase in lysosomal degradation following starvation is facilitated by accelerated autolysosome formation through activation of Mixed Lineage Kinase Domain Like Pseudokinase (MLKL), a protein previously mainly known for its role in necroptotic cell death downstream of death receptors and receptor-interacting serine/threonine-protein kinases 1 and 3 (RIPK1 and RIPK3). We show that starvation activates MLKL through Ca2+-calmodulin-dependent kinase II (CaMKII) independently of RIPK3 and this pathway targets the oligomerized MLKL to autophagosomes, instead of plasma membrane, where it supports phagophore closure, a key step required for the maturation of autophagosomes before they fuse with lysosomes to form autolysosomes where the breakdown of autophagosome cargoes occurs. We aim to define the functional significance of this new pathway in neurons where autophagy, including lysosomal degradation, strongly impacts neuronal cell survival and death (Aim I) and further elucidate how multiple regulatory mechanisms orchestrate the early response of the cells to amino acid shortage in order to cope with the stress of starvation (Aim II). Because of the critical involvement of autophagy and lysosomal dysfunction in many types of neurodegenerative diseases, this exploratory and foundational research, fostering the early and conceptual stages of a novel regulatory mechanism of autophagy and lysosomal regulation, will likely lead to breakthroughs in important areas of neuroscience.

项目摘要细胞通过激活自噬的，被调节的过程来响应营养短缺，以消除不必要的或功能失调的细胞成分，允许有序降解和回收蛋白质，糖和回收脂质。虽然众所周知，饥饿会诱导大型自噬（通常简单地称为自噬），一个涉及形成双膜结构的过程称为自噬体，其他自噬途径，例如内体微自噬，也作为饥饿的组成部分出现响应以帮助细胞应对由营养缺乏症引起的压力。作为自噬的关键步骤，溶酶体中的蛋白质降解对于合成所需的氨基酸的再生至关重要支持营养剥夺细胞存活的必需核心蛋白质。但是，如何溶酶体降解响应营养剥夺而受到调节。我们发现了一种新颖的监管途径通过谷氨酰胺酶围绕谷氨酰胺水解为中心的溶酶体降解和产生铵。在美联储条件下，丰富的谷氨酰胺支持铵产生和转动溶酶体腔的碱化，该溶酶体通过保持溶酶体的降低而减慢蛋白质降解在次优条件下的水解酶。在氨基酸或谷氨酰胺提取时，铵的损失产生立即导致溶酶体的酸化和蛋白质降解的加速度。我们进一步发现，饥饿后溶酶体降解的增加是通过加速促进的通过激活混合谱系激酶结构域（如假子酶（MLKL）），A的自体溶液体形成蛋白质以前主要以其在死亡受体下游的坏死细胞死亡中的作用而闻名受体相互作用的丝氨酸/苏氨酸 - 蛋白激酶1和3（RIPK1和RIPK3）。我们证明了饥饿通过Ca2+-calmodulin依赖性激酶II（CAMKII）激活MLKL，独立于RIPK3，这是途径将寡聚的MLKL靶向自噬体，而不是质膜支持吞噬封闭，这是自噬体融合之前成熟所需的关键步骤随着溶酶体形成自噬体货物故障的自体溶液体。我们的目标定义该新途径在自噬（包括溶酶体）的神经元中的功能意义降解，强烈影响神经元细胞的存活和死亡（目标I），并进一步阐明多个调节机制策划了细胞对氨基酸短缺的早期反应，以应对带有饥饿的压力（AIM II）。由于自噬和溶酶体的关键参与多种类型的神经退行性疾病的功能障碍，这项探索性和基础研究，促进自噬和溶酶体的新型调节机制的早期和概念阶段法规，可能会导致神经科学重要领域的突破。