Investigation into the mechanisms for generating interneuron diversity

描述（由申请人提供）：GABA能中间神经元是神经系统中抑制的主要来源，在每个脑回路中发挥关键作用。皮质中间神经元的异常发育和功能与许多神经系统疾病如精神分裂症、自闭症和癫痫的病理生物学有关。由于这些疾病的发病出现在成年期之前，因此需要更好地理解正常发育和疾病模型中的中间神经元分化和成熟。这个K99/R 00应用程序将支持博士蒂莫西彼得罗斯在他的追求发展创新战略和获得新的技能集研究中间神经元的发展。实验将在指导期间开始（在纽约大学Gord Fisell博士的实验室进行），并在获得独立职位后在彼得罗斯博士自己的实验室继续进行。彼得罗斯博士的长期职业目标是解开指导中间神经元命运决定和成熟的机制，希望开发用于治疗各种神经系统疾病的新治疗靶点。彼得罗斯博士先前的工作已经确定了一种调节由内侧神经节隆起（MGE）产生的最大的临床相关中间神经元群体的命运决定的新机制：表达小清蛋白（PV+）的细胞优先通过间接神经发生产生于中间神经元祖细胞（INP），而直接神经发生主要产生表达生长抑素（Sst+）的中间神经元。调节这一决定的分子机制仍然未知，但初步数据表明，Jagged 1和notch信号转导参与这一过程的潜力很大。具体目标1将利用多个 体外和体内方法来研究Jagged 1抑制MGE中的notch活性以促进直接神经发生和Sst+细胞形成的假设。MGE是产生许多不同细胞类型的祖细胞的异质群体，并且由于生长抑素和小清蛋白在MGE中不表达，我们目前缺乏细胞标记物和遗传策略来区分这些细胞。理想情况下，我们希望确定在MGE中经历命运决定的细胞的转录谱，同时保留鉴定其在出生后大脑中成为哪种类型的中间神经元（PV+或Sst+）的能力。为此，具体目标2将创建一个空间限制和时间诱导形式 Dam-鉴定（DamID）来“标记”MGE祖细胞的转录组以供将来分析。最初的实验将利用ESC技术，这将导致产生新的小鼠品系，以确定Sst+和PV+中间神经元中的新的命运决定基因。重要的是，拟议中的实验应该大大推进我们对中间神经元发育的理解，并为彼得罗斯博士在学术界获得独立地位铺平道路。

DESCRIPTION (provided by applicant): GABAergic interneurons are the primary source of inhibition in the nervous system and play critical roles in every brain circuit. The abnormal development and function of cortical interneurons has been implicated in the pathobiology of many neurological disorders such as schizophrenia, autism, and epilepsy. As the onset of these diseases presents prior to adulthood, a better understanding of interneuron differentiation and maturation in normal development and disease models is required. This K99/R00 application will support Dr. Timothy Petros in his pursuit of developing innovative strategies and acquiring new skill sets to study interneuron development. The experiments will be initiated during the mentored period (carried out in Dr. Gord Fishell's lab at NYU) and continue in Dr. Petros' own laboratory upon securing an independent position. Dr. Petros' long-term career goal is to unravel the mechanisms that direct interneuron fate determination and maturation, with the hope of developing new therapeutic targets for treating a variety of neurological diseases. Dr. Petros' previous work has identified a novel mechanism regulating fate decisions for the largest, clinically- relevant interneuron populations arising from the medial ganglionic eminence (MGE): parvalbumin-expressing (PV+) cells preferentially arise from intermediate neuronal progenitors (INPs) via indirect neurogenesis whereas direct neurogenesis primarily gives rise to somatostatin-expressing (Sst+) interneurons. The molecular mechanisms that regulate this decision remain unknown, but out preliminary data demonstrate a strong potential for involvement of Jagged1 and notch signaling in this process. Specific Aim 1 will utilize multiple in vitro and in vivo approaches to investigate the hypothesis that Jagged1 inhibits notch activity in the MGE to promote direct neurogenesis and formation of Sst+ cells. The MGE is a heterogeneous population of progenitors that gives rise to many different cell types, and since somatostatin and parvalbumin are not expressed in the MGE, we currently lack cell markers and genetic strategies to distinguish these cells. Ideally, we would like to determine the transcriptional profile of a cell undergoing fate decisions in the MGE while at the same time retain the ability to identify which type of interneuron (PV+ or Sst+) it becomes in the postnatal brain. To this end, Specific Aim 2 will create a spatially restricted and temporally inducible form of Dam-identification (DamID) to 'time-stamp' the transcriptome of MGE progenitors for future analysis. Initial experiments will utilize ESC technology that will lead to generation of new mouse strains to identify novel fate-determining genes in Sst+ and PV+ interneurons. Importantly, the proposed experiments should significantly advance our understanding of interneuron development and pave the way for Dr. Petros to secure an independent position in academia.