How are necrotic neurons recognized by their phagocytes

坏死的神经元如何被吞噬细胞识别

基本信息

批准号：
10708976
负责人：
Zheng Zhou
金额：
$ 40万
依托单位：
BAYLOR COLLEGE OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-09-22 至 2027-08-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10708976
关键词：
ATP-Binding Cassette Transporters Alleles Alzheimer&apos s Disease Animals Apoptosis Apoptotic Area Autoimmune Diseases Autoimmune Responses Axon Biochemical Caenorhabditis elegans Cell Death Cell Death Process Cell Separation Cell membrane Cells Cytoplasm Deterioration Development Digestion Disease Eating Endoplasmic Reticulum Endosomes Event Evolution Excision Family Gene Mutation Genes Genetic Epistasis Genetic Screening Goals Health Homeostasis Homologous Gene Human Induced Mutation Inflammatory Response Injury Ion Channel Protein Learning Life Malignant Neoplasms Mediating Microglia Molecular Morphology Natural regeneration Necrosis Necrosis Induction Nematoda Nerve Degeneration Nervous System Neurodegenerative Disorders Neurons Outcome Pathologic Pathway interactions Phagocytes Phagocytosis Phenotype Phosphatidylserines Phospholipids Physiological Prealbumin Process Protein Family Proteins Recovery Recycling Role Side Signal Transduction Stress Stroke Surface Synapses Testing Therapeutic Touch sensation Translating age related axon injury cell suicide chronic inflammatory disease dominant genetic mutation epithelial Na+ channel fighting gene product genetic analysis in vitro Assay member model organism mutant novel phospholipid scramblase prevent receptor repaired response stroke recovery tat Protein tissue injury tissue repair

项目摘要

In an animal’s life, a large number of cells undergo apoptosis – cell suicide, to support development and maintain body homeostasis. In addition, during stroke, cancer, and other traumatic situations, a large number of cells undergo necrosis after injury. These cells are rapidly internalized by other cells via phagocytosis (engulfment) and degraded inside engulfing cells. The swift removal of dying cells prevents tissue injury, inflammatory responses, and auto-immune responses, clears the wounded area, and promotes tissue repair. Necrosis is also closely associated with neuron degeneration. The phagocytosis of necrotic neurons and axon debris facilitates the repair and recovery of neuron functions. Phagocytic activity by the microglia also contribute to the loss of synapses in Alzheimer’s disease. My long-term goal is to understand how dying cells are specifically recognized, internalized, and degraded by engulfing cells, using the nematode Caenorhabditis elegans as a model organism. As many physiological mechanisms are highly conserved throughout evolution, what we learn from C. elegans can be translated to humans. This proposal investigates the mechanisms that promote the exposure of phosphatidylserine (PS), an “eat me” signal, on the surfaces of necrotic and apoptotic cells to attract engulfing cells. In C. elegans, the necrosis of six mechanosensory neurons (also called touch neurons) is induced by mutations in a particular group of plasma membrane ion channel proteins, including the dominant mutations in MEC-4, a subunit of the mechanosensory Na+ channel. We found that two proteins, the ABC transporter CED-7, and ANOH-1, the worm homolog of the mammalian phospholipid scramblase TMEM16F, act in parallel to promote PS exposure on the surfaces of necrotic cells. Recently, we have identified that the exposure of PS on necrotic cells is mediated by cytoplasmic Ca2+. Furthermore, we discovered two alternative mechanisms that increase Ca2+ level in the cytoplasm, one dependent on the release of Ca2+ from the endoplasmic reticulum (ER), the other independent of the ER. In addition, we have identified multiple genes that act to regulate PS exposure. To further investigate the molecular mechanism(s) of PS exposure, I propose to determine the novel functions of a transthyretin-like protein and a proposed PS flippase in promoting the exposure of PS on the surfaces of necrotic cells in response to the Ca2+ signaling (Aims 1 and 2), and to identify new PS-exposure genes from mutants defective in the exposure of PS on dying cells that we isolated in a forward genetic screen (Aim 3). Together, the outcomes will allow us to establish pathways that promote PS exposure in response to upstream signals. They will also reveal novel molecular mechanisms regulating each step of the process, some of which are anticipated to be unique to necrotic or apoptotic cells.

在动物的一生中，大量细胞会发生凋亡——细胞自杀，以支持发育并维持身体稳态此外，在中风、癌症和其他创伤情况下，会产生很大的影响。损伤后大量细胞发生坏死，这些细胞通过其他细胞迅速内化。吞噬作用（吞噬）和吞噬细胞内的降解可防止死亡细胞的快速清除。组织损伤、炎症反应和自身免疫反应，清除受伤区域，促进组织的修复也与神经元变性的吞噬作用密切相关。神经元和轴突碎片促进神经元吞噬活性的修复和恢复。小胶质细胞也会导致阿尔茨海默病中突触的丧失。我的长期目标是了解。垂死细胞如何被线虫吞噬细胞特异性识别、内化和降解秀丽隐杆线虫作为模式生物，许多生理机制是高度保守的。在整个进化过程中，我们从秀丽隐杆线虫中学到的东西可以转化为人类。促进磷脂酰丝氨酸（PS）暴露在物体表面的机制，这是一种“吃我”信号坏死和凋亡细胞吸引吞噬细胞。在线虫中，六个机械感觉细胞坏死。神经元（也称为触摸神经元）是由特定质膜离子组的突变诱导的通道蛋白，包括 MEC-4（机械感觉 Na+ 通道的一个亚基）中的显性突变。我们发现两种蛋白质，ABC 转运蛋白 CED-7 和 ANOH-1（哺乳动物的蠕虫同源物）磷脂扰乱酶 TMEM16F 并行作用，促进坏死细胞表面的 PS 暴露。最近，我们发现坏死细胞上PS的暴露是由细胞质Ca2+介导的。此外，我们发现了两种增加细胞质中 Ca2+ 水平的替代机制，一种是依赖于内质网（ER）释放的Ca2+，另一个独立于ER。此外，我们还发现了多个调节 PS 暴露的基因，以进一步研究。 PS暴露的分子机制，我建议确定转甲状腺素蛋白样的新功能蛋白质和提出的 PS 翻转酶促进 PS 在坏死细胞表面的暴露对 Ca2+ 信号传导的响应（目标 1 和 2），并从缺陷突变体中鉴定新的 PS 暴露基因将 PS 暴露在我们在正向遗传筛选中分离出的垂死细胞中（目标 3）。结果将使我们能够建立促进 PS 暴露以响应上游信号的途径。还将揭示调节该过程每个步骤的新分子机制，其中一些是预计是坏死或凋亡细胞所特有的。