Nicotinic Acetylcholine Receptors in Neural Development

神经发育中的烟碱乙酰胆碱受体

• 批准号: 7429773
• 负责人: Rae Nishi
• 金额: $ 31.78万
• 依托单位: UNIVERSITY OF VERMONT & ST AGRIC COLLEGE
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-15 至 2010-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7429773
• 关键词: Abbreviations; Adverse effects; Apoptosis; Binding; Biological Models; Bungarotoxins; CREB1 gene; Calcium; Cell Death; Cell surface; Cells; Cessation of life; Chickens; Cholinergic Agents; Chromosome Pairing; Ciliary Neurotrophic Factor; Co-Immunoprecipitations; Cyclic AMP-Responsive DNA-Binding Protein; Daily; Development; Developmental Process; Embryo; Epitopes; Exposure to; Genetic Transcription; Genus Lynx; Heterogeneity; Image; In Vitro; Link; Localized; Mediating; Messenger RNA; Monoclonal Antibodies; Mutation; Neurons; Neurotoxins; Nicotine; Nicotinic Receptors; Numbers; Pattern; Peripheral; Pharmaceutical Preparations; Play; Population; Principal Investigator; Protein Overexpression; RNA Interference; Relative (related person); Retroviral Vector; Role; Signal Transduction; Structure of ciliary ganglion; Surface; Synapses; Testing; Tissues; Transcript; Western Blotting; cholinergic; day; density; desensitization; immunocytochemistry; in vivo; nAChR alpha7 subunit; nervous system development; neurodevelopment; neuron loss; patch clamp; prenatal exposure; prevent; programs; response; transmission process

DESCRIPTION (provided by applicant): In addition to their traditional function of mediating rapid cholinergic transmission, nicotinic acetylcholine receptors (nAChRs) are poised to serve non-traditional functions such as regulating gene transcription through calcium-dependent signaling. Therefore, studying the role that nicotinic signaling plays in guiding the development of the nervous system provides a means for assessing the potential adverse effects of prenatal exposure to drugs such as nicotine. We propose to use the chicken ciliary ganglion as a simple model system in which the role of nicotinic signaling in programmed cell death in vivo can be studied in detail. Programmed cell death normally reduces the total number of neurons in the ciliary ganglion by 50% between embryonic days (E)8 and E14, and embryonic neurons express two functionally distinct populations of nAChRs: homomeric alpha7 containing nAChRs that become extrasynaptically localized by E14, and heteromeric nAChRs containing alpha3, alpha5, Beta2 and Beta4 subunits (alpha3 * nAChRs). Our previous studies suggested that activation of neuronal alpha7 subunit containing nAChRs caused neuronal cell death. We propose that between E6-9, neurons that express a high density of alpha7 nAChRs on their surfaces allow calcium influx that exceeds the set point for survival, thereby inducing apoptosis. After E9, target interactions act to prevent cell death through alpha7 by upregulating an endogenous abtx-like molecule, lynx, that "silences" alpha7 nAChRs. Thus, the central hypothesis of this proposal is that an overabundance of signaling through alpha7 subunit containing nAChRs induces calcium-dependent cell death during normal ciliary ganglion development. To test this hypothesis, the aims of our project are: 1. To determine whether embryonic neurons express more heterogeneity with respect to the levels of alpha7 mRNA prior to cell death and whether neurons expressing elevated alpha7 remain after rescue by MLA and abtx; 2. To determine whether overexpression of alpha7 nAChR subunits causes enhanced levels of intracellular calcium in response to nicotinic stimulation and exacerbates cell death in vivo; 3. To determine whether reducing alpha7 nAChR expression or locally blocking alpha7 nAChRs in ciliary ganglion neurons promotes survival; 4. To test the hypothesis that target- interactions prevent cell death by inducing the expression of lynx, a cell surface molecule with homology to abtx that silences cell surface alpha7 nAChRs. These studies will make a significant contribution towards the detailed understanding of how nicotinic signaling contributes to the development of the nervous system.

描述（由申请人提供）：除了介导快速胆碱能传递的传统功能外，烟碱乙酰胆碱受体（nAChR）还具有非传统功能，例如通过钙依赖性信号传导调节基因转录。因此，研究烟碱信号在指导神经系统发育中的作用，为评估产前暴露于尼古丁等药物的潜在不良影响提供了一种手段。我们建议使用鸡睫状神经节作为一个简单的模型系统，其中烟碱信号在体内细胞程序性死亡中的作用可以详细研究。程序性细胞死亡通常使睫状神经节中的神经元总数在胚胎日（E）8和E14之间减少50%，并且胚胎神经元表达两种功能不同的nAChR群体：含有nAChR的同源α 7，其通过E14变得突触外定位，以及含有α 3、α 5、β 2和β 4亚基（α 3 * nAChR）的异源nAChR。我们以前的研究表明，激活神经元α 7亚单位含有nAChRs引起神经元细胞死亡。我们提出，E6-9之间，神经元表达高密度的α 7 nAChR在其表面上允许钙流入超过设定点的生存，从而诱导凋亡。在E9之后，靶相互作用通过上调内源性abtx样分子lynx来防止通过α 7的细胞死亡，所述内源性abtx样分子lynx“沉默”α 7 nAChR。因此，该提议的中心假设是，通过含有nAChR的α 7亚基的过度信号传导在正常睫状神经节发育期间诱导钙依赖性细胞死亡。为了验证这一假设，我们的项目的目标是：1。确定胚胎神经元在细胞死亡前是否表达相对于α 7 mRNA水平的更多异质性，以及表达升高的α 7的神经元在通过MLA和abtx拯救后是否仍然存在; 2.确定是否过表达α 7 nAChR亚基导致响应烟碱刺激的细胞内钙水平升高并加剧体内细胞死亡; 3.确定降低睫状神经节神经元中的α 7 nAChR表达或局部阻断α 7 nAChR是否促进存活; 4.为了检验靶相互作用通过诱导lynx的表达来防止细胞死亡的假设，lynx是一种与abtx具有同源性的细胞表面分子，其使细胞表面α 7 nAChR沉默。这些研究将为详细了解烟碱信号如何促进神经系统的发育做出重大贡献。