Analysis of Clustered Protocadherin Function in Mammalian Neurodevelopment

哺乳动物神经发育中簇状原钙粘蛋白功能分析

• 批准号: 8369364
• 负责人: LINDSAY A SCHWARZ
• 金额: $ 5.22万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-12-01 至 2014-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8369364
• 关键词: Adhesives; Adult; Animals; Area; Autistic Disorder; Axon; Bipolar Disorder; Birth; Brain; Brain region; Breeding; Cell Adhesion Molecules; Cells; Centromere; Chromosomes, Human, Pair 18; Cluster Analysis; Comprehension; Cues; Dendrites; Development; Disease; Distal; Epilepsy; Fiber; Future; Gene Cluster; Gene Family; Genes; Heart Diseases; Human Genome; Individual; Integral Membrane Protein; Knock-in Mouse; Knock-out; Knockout Mice; Knowledge; Label; Malignant Neoplasms; Mediating; Mental Depression; Methods; Molecular; Morphology; Mus; Mutant Strains Mice; Nervous system structure; Neurodevelopmental Disorder; Neurons; Patients; Phenotype; Play; Population; Predisposition; Process; Protein Isoforms; Proteins; Purkinje Cells; Research; Research Personnel; Role; Schizophrenia; Synapses; Techniques; Tissues; Transgenic Mice; genetic linkage analysis; insight; interest; knockout animal; knockout gene; mutant; nervous system development; nervous system disorder; neural circuit; neurodevelopment; neuron development; neuropsychiatry; novel; public health relevance; research study; synaptogenesis; tool

DESCRIPTION (provided by applicant): For proper function of the mature nervous system, neurons send processes out during development that must choose their correct synaptic partners from an enormous population of cells. The importance of this process in the mammalian brain is underscored by the growing knowledge that many neurodevelopmental disorders, such as autism and epilepsy, as well as adult disorders like bipolar disorder and schizophrenia, may result from improper formation of neuronal circuits. Therefore, a full understanding of the molecules mediating synaptic partner choice is crucial for make advancements in our comprehension and treatment of these diseases. While many guidance cues have been identified that assist outgrowing axons to reach an area of the brain, it's less clear how an axon chooses its exact synaptic partner. The clustered protocadherin family of genes (Pcdhs) show great potential to fill this role in mammalian brain development. The Pcdh gene family consists of 58 genes in three gene clusters (1, 2, and 3), each encoding for a unique adhesive transmembrane protein. It has been shown that individual neurons express a wide diversity of Pcdh isoforms, and studies have suggested their importance for synapse formation and axon targeting in certain classes of neurons. Furthermore, linkage analyses of schizophrenia and bipolar disorder patients have uncovered susceptibility loci for both disorders in the human genome near the clustered protocadherin gene family. Yet progress in understanding the function of Pcdhs has been limited by lethality in Pcdh-3 knockout animals, while studies of the other clusters are few (for Pcdh-1) or non-existent (for Pcdh-2). However, by using Mosaic Analysis with Double Markers (MADM), it should be possible to gain novel insight into the mechanisms by which Pcdhs contribute to neural development. Briefly, MADM allows for simultaneous labeling and gene knockout in individual cells. By inserting the appropriate labeling cassettes into chromosome 18 and breeding these mice (called MADM18 mice) with various Pcdh heterozygous mutant mice (1, 2, and 3 mutants, or a mutant mouse where all three clusters have been deleted), it will be possible to analyze axonal projections, dendritic arborizations, and synapse formation of Pcdh-lacking neurons next to wildtype-labeled neurons in a variety of brain regions where these proteins are known to be expressed. Compared to previous Pcdh-knockout studies, this strategy has several benefits: it avoids the lethality associated with complete loss of Pcdh-3, and should provide a more accurate assessment of Pcdh function through single cell knockout of the genes. Characterizing the role of the clustered protocadherins in neuronal development may also have value for understanding the molecular mechanisms of several neurological diseases, such as autism and schizophrenia, where it's thought that improper synapse formation may be involved. Finally, the MADM mouse produced for this study could be used in the future to analyze any gene distal to the MADM cassettes on the chromosome 18, which may be a useful tool for researchers in a variety of scientific fields.

描述（由申请人提供）：为了成熟神经系统的正常功能，神经元在发育过程中发出的过程必须从大量细胞中选择正确的突触伙伴。越来越多的人认识到，许多神经发育障碍，如自闭症和癫痫，以及成人障碍，如双相情感障碍和精神分裂症，可能是由于神经元回路形成不当造成的，这一过程在哺乳动物大脑中的重要性得到了强调。因此，充分了解介导突触伴侣选择的分子对于提高我们对这些疾病的理解和治疗至关重要。虽然已经确定了许多引导线索来帮助生长的轴突到达大脑的某个区域，但轴突是如何选择它确切的突触伙伴的还不太清楚。簇状原钙粘蛋白家族基因（Pcdhs）在哺乳动物大脑发育中具有填补这一角色的巨大潜力。Pcdh基因家族由三个基因簇（1、2和3）中的58个基因组成，每个基因簇编码一种独特的粘附跨膜蛋白。研究表明，单个神经元表达多种Pcdh亚型，研究表明它们对某些神经元的突触形成和轴突靶向很重要。此外，对精神分裂症和双相情感障碍患者的连锁分析发现了人类基因组中靠近簇状原钙粘蛋白基因家族的两种疾病的易感位点。然而，了解Pcdhs功能的进展受到pcdh3敲除动物的致死率的限制，而对其他簇的研究很少（pcdh1）或不存在（pcdh2）。然而，通过使用双标记镶嵌分析（MADM），应该有可能对Pcdhs促进神经发育的机制获得新的见解。简而言之，MADM允许在单个细胞中同时标记和基因敲除。通过将适当的标记盒插入18号染色体，并将这些小鼠（称为MADM18小鼠）与各种Pcdh杂合突变小鼠（1、2和3个突变体，或所有三个簇都被删除的突变小鼠）一起繁殖，将有可能分析在各种已知表达这些蛋白质的大脑区域中，缺乏Pcdh的神经元旁边的轴突投射、树突状树突和突触形成。与之前的Pcdh敲除研究相比，这种策略有几个好处：它避免了与Pcdh-3完全缺失相关的致命性，并且应该通过基因的单细胞敲除提供更准确的Pcdh功能评估。描述簇状原钙粘蛋白在神经元发育中的作用也可能对理解一些神经系统疾病的分子机制有价值，如自闭症和精神分裂症，人们认为这些疾病可能涉及不适当的突触形成。最后，为本研究生产的MADM小鼠可以在未来用于分析18号染色体上MADM磁带的任何远端基因，这可能是各种科学领域研究人员的有用工具。