Investigating molecular mechanisms and function of tanycyte-derived neurogenesis in the postnatal hypothalamus

项目总结 近年来，有证据表明，张力细胞具有在大脑中产生神经元的能力。 出生后的下丘脑。张力细胞是放射状胶质细胞，在两种细胞中都与神经前体细胞非常相似 形态和基因表达谱。而饮食和荷尔蒙暗示可以调节tanycell来源 神经发生、黑素细胞增殖和黑素细胞来源的神经再生的总体水平较低， 在成年小鼠身上几乎检测不到。神经原性功能的分子调控机制 张力性细胞来源的神经元的确切生理功能仍不清楚。 识别刺激Tanycell来源的神经发生的分子机制，以促进分化 调节体重和新陈代谢的Tanycell来源的神经元是一种新的潜在的治疗方法 肥胖和代谢紊乱，如II型糖尿病。 最近，布莱克肖实验室的研究已经确定了核因子1(NFI)家族的转录 在调节下丘脑的神经源性能力中起关键作用的因子(TF)，Nfia/b/x 柔韧细胞。在正常饮食条件下，雄性小鼠缺乏nfia/b/x的伸缩细胞表现出增强。 增殖和神经发生。NfiA/b/x缺陷伸缩细胞的单细胞RNA序列分析 Tanycell来源的细胞表明，相当一部分Tanycell来源的神经元是GABA能的 子类型。这些GABA能神经元的一部分表达瘦素受体(Lepr)，并对Leptin做出反应。 布莱克肖实验室还表明，柔韧细胞衍生的神经元存活下来，整合到下丘脑回路中， 和火的自发动作电位。通过分析对照和对照之间差异表达的基因 NFIA/b/x缺陷的Tanycell，我们已经证明Shh和Wnt信号在以下Tanycell中上调 Nfia/b/x缺失。我们还观察到在Nfia/b/x缺陷的张力细胞中Notch通路的下调。 在发育过程中，Shh和Wnt通路促进下丘脑的神经发生。While Notch 信号通路促进视网膜Müler胶质细胞和皮质星形胶质细胞的静止。鉴于这些发现，我 假设柔韧细胞的神经源性能力在出生后受到积极抑制 神经发生后的下丘脑和Tanycell来源的神经元调节身体的假说 体重平衡和新陈代谢。为了解决这些假设，我提出了以下两个目标： 目的1：研究正向或负向控制Tanycell来源的外源性调节因子 青少年和青壮年下丘脑的神经发生。这项工作将确定分子机制 和基因调控网络，对Tanycell来源的神经发生进行积极或消极的调控 出生后的下丘脑。 目的2：研究Tanycell来源的神经元对体重、动态平衡和代谢的影响。 这些研究将为深入了解Tanycell来源的神经元在控制 体重动态平衡和新陈代谢。

PROJECT SUMMARY In recent years, evidence now shows that tanycytes possess the ability to generate neurons in the postnatal hypothalamus. Tanycytes are radial glial cells that closely resemble neural progenitors in both morphology and gene expression profiles. While dietary and hormonal cues can regulate tanycyte-derived neurogenesis, the overall levels of tanycyte proliferation and tanycyte-derived neurogenesis are low and virtually undetectable in adult mice. The molecular mechanisms controlling neurogenic competence in tanycytes, and the precise physiological function of tanycyte-derived neurons remains poorly defined. Identifying molecular mechanisms that stimulate tanycyte-derived neurogenesis, to promote differentiation of tanycyte-derived neurons that modulate body weight and metabolism, is a new potential therapeutic for treating obesity and metabolic disorders such as type II diabetes. Recently, studies from the Blackshaw lab have identified the Nuclear Factor One (Nfi) family transcription factors (TFs), Nfia/b/x, as playing a critical role in regulating neurogenic competence in hypothalamic tanycytes. Under normal dietary conditions in male mice, Nfia/b/x-deficient tanycytes show enhanced proliferation and neurogenesis. Single-cell RNA-sequencing analysis of Nfia/b/x-deficient tanycytes and tanycyte-derived cells indicates that a substantial fraction of all tanycyte-derived neurons are GABAergic subtypes. A subset of these GABAergic neurons expresses the Leptin receptor (Lepr) and responds to leptin. The Blackshaw lab has also shown that tanycyte-derived neurons survive, integrate into hypothalamic circuits, and fire spontaneous action potentials. By analyzing genes differentially expressed between control and Nfia/b/x-deficient tanycytes, we have shown that Shh and Wnt signaling is upregulated in tanycytes following loss of Nfia/b/x. We also observed the downregulation of the Notch pathway in Nfia/b/x-deficient tanycytes. During development, Shh and Wnt pathways promotes neurogenesis in the hypothalamus. While Notch signaling pathway promote quiescence in retinal Müller glia and cortical astrocytes. Given these findings, I hypothesize that neurogenic competence in tanycytes is actively suppressed in the postnatal hypothalamus after neurogenesis and, hypothesize that tanycyte-derived neurons regulate body weight homeostasis and metabolism. To address these hypotheses, I propose the following two Aims: AIM 1: To investigate extrinsic regulators that positively or negatively control tanycyte-derived neurogenesis in the juvenile and young adult hypothalamus. This work will identify molecular mechanisms and gene regulatory networks that positively or negatively regulate tanycyte-derived neurogenesis in the postnatal hypothalamus. AIM 2: To determine the role of tanycyte-derived neurons on bodyweight homeostasis and metabolism. These studies will provide key insights into the physiological function of tanycyte-derived neurons in controlling body weight homeostasis and metabolism.