Mechanisms of Degenerative Cell Death in C. elegans

线虫退行性细胞死亡的机制

• 批准号: 7848537
• 负责人: MONICA A. DRISCOLL
• 金额: $ 0.77万
• 依托单位: RUTGERS, THE STATE UNIV OF N.J.
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-01 至 2009-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7848537
• 关键词: Acidosis; Affect; Alleles; Animal Model; Animals; Apoptotic; Biological; Biological Models; Brain; Caenorhabditis elegans; Calcium; Calcium Binding; Calcium-Binding Proteins; Calpain; Cathepsins; Cations; Cell Death; Cell membrane; Cessation of life; Clinical; Clinical Treatment; Development; Disease; Dissection; EF Hand Motifs; Enhancers; Experimental Models; Family; Foundations; Functional disorder; Genes; Genetic; Genetic Models; Genetic Screening; Goals; Homeostasis; Homologous Gene; Human; Human Identifications; Image; Individual; Injury; Intervention; Investigation; Ion Channel; Ischemia; Life; Mammals; Maps; Modeling; Molecular; Molecular Genetics; Monitor; Mus; Mutation; Necrosis; Nematoda; Neurodegenerative Disorders; Neuronal Injury; Neurons; Neurotic Disorders; Organism; Outcome; Pathology; Pathway interactions; Peptide Hydrolases; Phenotype; Physiological; Positioning Attribute; Process; Proteins; RNA Interference; Relative (related person); Reporter; Role; Signal Transduction; Societies; Stimulus; Stroke; System; Testing; Toxic effect; Translating; Work; combat; design; effective intervention; effective therapy; epithelial Na+ channel; genome-wide; in vivo; mutant; nervous system disorder; neuron loss; neurotoxicity; novel; novel strategies; parallel processing; public health relevance; research study

DESCRIPTION (provided by applicant): Necrotic neuronal death underlies the pathology of many neurodegenerative diseases and is an incapacitating outcome of stroke, ischemia, acidosis, and physical injury. Currently, there are no effective clinical treatments that protect against necrotic neuronal loss and understanding of necrosis mechanisms lags far behind understanding of apoptotic death. Extending mechanistic understanding of necrosis is an essential first step toward design of effective interventions. In the facile genetic model C. elegans, hyper-activated mutant plasma membrane ion channels of the DEG/ENAC superfamily conduct excess Na+ and Ca+2 to initiate necrotic neuronal death. Our genetic dissection of this process in nematodes suggests that Ca+2 influx through the MEC DEG/ENaC channel is critical in necrosis initiation, and that the neurotoxicity mechanism requires ER Ca+2 release. The resultant rise in intracellular Ca+2 promotes necrotic demise, acting in part through specific Ca+2-activated calpain proteases and cathepsin proteases associated with lysosomal dysfunction. Although we have made much progress in establishing a genetic pathway for neuronal necrosis, there are major gaps in our mechanistic understanding of necrosis, including the perplexing problem of how MEC channel hyperactivation can circumvent Ca+2 homeostasis mechanisms to signal for toxic ER Ca+2 release. This mechanism appears directly relevant to parallel toxicity mechanisms operative in higher organisms--the MEC channel-related mammalian ASIC1a channel of the DEG/ENaC family can be hyperactivated in stroke to conduct excess Ca+2 influx, inducing acidosis and substantial brain neuron loss. Intracellular Ca+2 rise and activation of calpain proteases are features of human necrosis, suggesting death mechanisms are conserved from nematodes to humans. Our experimental plan is to combine genetic, molecular biological and Ca+2 imaging approaches to define key conserved players in neuronal necrosis, and to determine where and how they act in the necrotic pathway. We have identified novel necrosis-enhancing mutants (normal activity protects against necrosis) and calcium binding protein genes that modulate necrosis outcomes-- these constitute the foundation for our planned mechanistic investigations. Overall, we expect to exploit unique advantages of the C. elegans experimental model to generate a detailed mechanistic description of necrosis, including identification of novel genetic factors that may suggest new strategies for limiting devastating effects of necrosis in human injury and disease. PUBLIC HEALTH RELEVANCE: Stroke, ischemia, acidosis, physical injury to neurons, and neurodegenerative disease can induce a type of neuronal death called necrosis. Necrotic neuronal loss is a thus major clinical problem--yet there are currently no effective treatments that combat neuronal necrosis, in part because necrosis mechanisms are not well defined. We work with a simple genetic animal model for channel hyperactivation-induced necrosis to identify genes that are essential for, promote, or diminish neuronal necrosis. There is strong evidence that necrosis mechanisms are conserved from simple animals to humans (for example, the mammalian homolog of the channel we study is a major contributor to neuronal loss in mouse stroke models). Molecularly identifying necrosis modulator genes and determining how they work to affect necrosis outcomes will provide much needed understanding of basic necrosis mechanisms and should inspire novel approaches toward potential anti-necrosis therapies.

描述（由申请人提供）：坏死神经元死亡是许多神经退行性疾病的病理构成的，是中风，缺血，酸中毒和身体损伤的无能力结果。目前，没有有效的临床治疗方法可以防止坏死神经元丧失和对坏死机制的理解，这远远落后于对凋亡死亡的理解。扩展对坏死的机理理解是设计有效干预措施的重要第一步。在秀丽的秀丽隐杆线虫中，DEG/ENAC超家族的过度激活的突变质膜离子通道进行了多余的Na+和Ca+ 2，以引发坏死神经元死亡。我们对线虫中此过程的遗传解剖表明，通过MEC DEG/ENAC通道的Ca+2涌入对于坏死开始至关重要，并且神经毒性机制需要ER Ca+2释放。最终的细胞内Ca+2的升高促进了坏死的灭绝，部分作用于特定的Ca+2个激活的钙蛋白酶蛋白酶和与溶酶体功能障碍相关的组织蛋白酶蛋白酶。尽管我们在建立神经元坏死的遗传途径方面取得了很大进展，但我们对坏死的机械理解存在主要差距，包括MEC通道过度激活如何绕过CA+2稳态机制的令人困惑的问题，以信号有毒ER CA+2释放。该机制似乎与较高生物体中的平行毒性机制直接相关 - 与MEC通道相关的DEG/ENAC家族的MEC通道相关的ASIC1A通道可以在中风中过度激活，以进行多余的Ca+2膨胀，诱导酸中毒和实质性脑神经元丧失。细胞内Ca+2的升高和钙蛋白酶蛋白酶的激活是人类坏死的特征，这表明死亡机制是从线虫到人类的保守的。我们的实验计划是结合遗传，分子生物学和Ca+2成像方法，以定义神经元坏死中的关键保守参与者，并确定它们在坏死途径中的何处以及如何作用。我们已经确定了新的坏死增强突变体（正常活性预防坏死）和钙结合蛋白基因，这些基因调节坏死结局 - 这些构成了我们计划的机械研究的基础。总体而言，我们希望利用秀丽隐杆线虫实验模型的独特优势来产生对坏死的详细机理描述，包括鉴定新的遗传因素，这些因素可能暗示了可能限制坏死对人类伤害和疾病的毁灭性影响的新策略。公共卫生相关性：中风，缺血，酸中毒，神经元的身体损伤以及神经退行性疾病可诱导一种称为坏死的神经元死亡。坏死性神经元丧失是一个主要的临床问题 - 但目前尚无有效治疗可抵抗神经元坏死的治疗方法，部分原因是坏死机制尚未很好地定义。我们与一个简单的遗传动物模型合作，用于通道过度激活诱导的坏死，以识别对神经元坏死必不可少的基因。有充分的证据表明，坏死机制是从简单动物到人类的保守的（例如，我们研究的通道的哺乳动物同源物是小鼠卒中模型中神经元丧失的主要贡献者）。分子鉴定坏死调节剂基因并确定它们如何工作以影响坏死结局将提供对基本坏死机制的急需理解，并应激发潜在的抗疾病疗法的新方法。