The Role of Astrocytes in Cortical Interneuron Development

描述(申请人提供)：GABA能抑制中间神经元的丢失或功能障碍，特别是表达小白蛋白(PV)的中间神经元，与严重的精神障碍有关，包括精神分裂症、双相抑郁和多发性抽动症。PV中间神经元调节兴奋性神经元的输出，对协调大脑节律非常重要，因此兴奋性神经元可以同步放电--这一特性被认为对它们在认知和行为控制中的功能至关重要。本提案描述了卡伦·莫勒·史密斯博士在接受指导的职业发展培训期间将实现的职业发展计划和研究目标。这项建议的直接目标是为Smith博士的独立研究生涯做好准备，通过神经科学、神经发育障碍和统计学的正规课程工作，以及通过在原代组织培养、细胞移植、转基因小鼠的行为分析、使用翻译核糖体亲和纯化(TRAP)方法的基因表达微阵列实验以及使用体内沉默RNA(SiRNA)构建的靶向验证实验等方面的指导性研究培训，为Smith博士提供精神疾病神经生物学方面的理论和知识培训。长期的目标是了解在出生后大脑中突触整合和细胞成熟的关键时期，有助于皮质中间神经元成熟和存活的发育事件。史密斯博士通过对注意力缺陷多动障碍(ADHD)的多巴胺能系统基因进行候选基因分析，获得了遗传学博士学位。在耶鲁大学儿童研究中心(YCSC)的博士后培训期间，Smith博士参加了儿童神经精神障碍的T32神经生物学培训项目，在转基因小鼠的发育神经生物学、解剖分析和行为表征方面获得了专业知识，同时进行了多项研究，以阐明成纤维细胞生长因子(成纤维细胞生长因子)信号在皮质发育和行为中的作用。史密斯博士将在弗洛拉·瓦卡里诺博士的主要指导下，在由精神病学、神经生物学和分子遗传学专家组成的杰出科学顾问小组的协助下，继续在YCSC学习，他们将为她的研究设计、实验表现和数据分析提供指导。耶鲁大学多样化的研究环境提供了许多机会，让他们向精神病学、神经生物学和发育生物学领域的国际公认专家学习，并参加由各系举办的神经生物学和精神病学研究研讨会。史密斯博士将利用这些资源参加课程、研讨会系列、期刊俱乐部和核心设施的动手培训。史密斯博士将通过参加科学会议和神经科学方法论的密集研讨会课程来加强这些活动。在这项研究计划中，史密斯博士将利用缺乏成纤维细胞生长因子受体1(FGFR1)基因的小鼠，这种基因表现出与多动行为相关的PV皮质抑制中间神经元的减少，以更好地了解参与行为抑制的神经元电路是如何建立的。FGFR1突变体的中间神经元的丢失发生在出生后，当FGFR1在皮质的神经胶质细胞，特别是星形胶质细胞表达时。史密斯博士将通过体外共培养以及将中间神经元细胞移植到对照和FGFR1突变的大脑皮层中，来研究FGFR1突变的星形胶质细胞是否支持皮质间神经元的存活和成熟能力降低。她将产生星形胶质细胞特有的FGFR1突变，以检验星形胶质细胞中的FGFR1信号对抑制性中间神经元的正常成熟至关重要的假设。史密斯博士将利用TRAP和微阵列分析来确定星形胶质细胞中FGFR1突变破坏的途径，并将通过体内沉默RNA的电穿孔来测试候选基因对神经元间成熟的影响。这些研究将使史密斯博士能够确定FGFR1在建立皮质中PV中间神经元的适当比例方面所起的作用，并将有助于揭示PV中间神经元的出生后发育，这是一个与精神分裂症和双相抑郁直接相关的问题。这项研究的结果将为未来旨在促进皮质中间神经元健康和成熟的研究提供参考。 公共卫生相关性： 该项目将探讨一种重要的神经元亚型--皮质抑制中间神经元的出生后发育，这种神经元在精神分裂症和双相抑郁以及缺乏FGFR1基因的小鼠中会减少。这项研究将集中在胶质细胞，即大脑中表达FGFR1的支持细胞，在中间神经元整合到大脑电路中的时候，在维持抑制性中间神经元的健康和成熟方面所起的作用。这项研究的最终目标是确定有助于神经元间成熟和存活的机制，可能导致旨在预防或逆转精神疾病神经元间干扰的新疗法。

DESCRIPTION (provided by applicant): The loss or dysfunction of GABAergic inhibitory interneurons, particularly parvalbumin (PV) expressing interneurons, is implicated in severe psychiatric disorders including schizophrenia, bipolar depression, and Tourette syndrome. PV+ interneurons regulate excitatory neuron output and are important for coordinating brain rhythms so that excitatory neurons can fire in synchrony- properties deemed to be critical for their function in cognition and behavioral control. This proposal describes the career development plan and research aims that Karen M|ller Smith, Ph.D. will achieve during her mentored career development training. The immediate goal of this proposal is to prepare Dr. Smith for an independent research career by providing her with theoretical and knowledge-based training in the neurobiology of psychiatric disorders through formal course work in neuroscience, neurodevelopmental disorders and statistics, and through mentored research training in primary tissue culture, cell transplantation, behavioral analysis of transgenic mice, gene expression microarray experiments using the translating ribosome affinity purification (TRAP) method, and target validation experiments using in vivo electroporation of silencing RNA (siRNA) constructs. The long-term goal is to gain an understanding of the developmental events contributing to the maturation and survival of cortical interneurons during the critical period of their synaptic integration and cell maturation in the postnatal brain. Dr. Smith obtained her Ph.D. in genetics by performing candidate gene analysis of dopaminergic system genes in Attention Deficit Hyperactivity Disorder (ADHD). During her postdoctoral training at the Yale Child Study Center (YCSC), Dr. Smith participated in the T32 Neurobiology of Childhood Neuropsychiatric Disorders training program and has gained expertise in developmental neurobiology, anatomical analysis and behavioral characterization of transgenic mice while performing several studies to elucidate the role of fibroblast growth factor (Fgf) signaling in cortical development and behavior. Dr. Smith will continue her studies at YCSC, under the primary mentorship of Dr. Flora Vaccarino, with the assistance of a distinguished group of scientific advisors consisting of experts in psychiatry, neurobiology, and molecular genetics, who will provide guidance with her research design, performance of experiments, and data analysis. The diverse research environment at Yale offers numerous opportunities to learn from internationally recognized experts in the fields of psychiatry, neurobiology, and developmental biology and to attend seminars hosted by the various departments in neurobiology and psychiatric research. Dr. Smith will take advantage of these resources in order to attend courses, seminar series, journal clubs, and hands on training at core facilities. Dr. Smith will enhance these activities by attending scientific conferences and an intense workshop course in neuroscience methodologies. In the research proposal, Dr. Smith will utilize mice lacking the fibroblast growth factor receptor 1 (Fgfr1) gene, which exhibit a decrease in PV+ cortical inhibitory interneurons that is correlated with hyperactive behavior, in order to gain a better understanding of how the neuronal circuitry involved in behavioral inhibition is established. The loss of interneurons in Fgfr1 mutants occurs postnatally, when Fgfr1 is expressed in glial cells of the cortex, particularly astrocytes. Dr. Smith will investigate whether the astrocytes of Fgfr1 mutants are less capable of supporting the survival and maturation of cortical interneurons by in vitro co-culture, and by cell transplantation of interneurons into control and Fgfr1 mutant cerebral cortices. She will generate astrocyte specific mutations of Fgfr1 to test the hypothesis that Fgfr1 signaling in astrocytes is essential for proper maturation of inhibitory interneurons. Dr. Smith will utilize TRAP and microarray analysis to identify pathways that are disrupted by Fgfr1 mutations in astrocytes, and will test the effects of candidate genes upon interneuron maturation by in vivo electroporation of silencing RNAs. These studies will allow Dr. Smith to determine the role of Fgfr1 in establishing the proper proportion of PV+ interneurons in the cortex, and will shed light into the postnatal development of PV+ interneurons, a problem with direct relevance to schizophrenia and bipolar depression. Results from this research will inform future studies aimed at promoting the health and maturation cortical interneurons. PUBLIC HEALTH RELEVANCE: This project will address the postnatal development of an important subtype of neurons, cortical inhibitory interneurons, which are diminished in schizophrenia and bipolar depression, and in mice lacking the Fgfr1 gene. The research will focus on the role of glia, supportive cells of the brain that express Fgfr1, in maintaining the health and maturation of inhibitory interneurons at a time when interneurons are integrating into the brain circuitry. The ultimate goal of this research is to identify mechanisms that contribute to interneuron maturation and survival, possibly leading to novel therapies aimed at preventing or reversing interneuron disruption in psychiatric illnesses.