Mechanisms and significance of programmed cell death in hypothalamic CRH neurons

项目摘要/摘要 下丘脑表达促肾上腺皮质激素释放激素(CRH)的神经元是 神经内分泌应激反应。CRH神经元整合应激相关的神经输入，作为 下丘脑-垂体-肾上腺(HPA)轴，诱导ACTH释放，最终导致糖皮质激素释放 (皮质醇)。促肾上腺皮质激素释放激素神经元的发育具有重要的生物医学意义。 CRH神经元参与了与压力相关的疾病，如焦虑和抑郁。因此，这是至关重要的 鉴定促肾上腺皮质激素释放激素神经元发育的分子和细胞机制 发育变化如何影响压力反应。使用斑马鱼，斑马鱼是基因可及的， 在光学半透明的情况下，我们发现DSCAML1缺乏损害CRH的发育细胞死亡 并引起HPI轴(HPA轴的斑马鱼类似物)的过度激活。考虑到 DSCAML1是已知的中介细胞间的相互作用，我们假设，基于邻近和突触 CRH神经元之间的相互作用引发发育细胞死亡，从而调节神经内分泌的活动 应激反应系统。为了测试这一点，我们提出了以下目标。在目标1中，我们将测试 基于邻近的相互作用促进CRH神经元的细胞死亡。使用实时成像的强度 斑马鱼模型，我们将研究相邻CRH神经元之间的相互作用是否促进细胞死亡和 确定不同水平的DSCAML1如何调节细胞丢失的程度。在目标2中，我们将测试 突触相互作用影响CRH神经元死亡。突触活动对神经元的指导作用 生死存亡。鉴于DSCAML1的S已知在突触发生中的功能，我们将调查CRH神经元 存活依赖于神经元的活动以及DSCAML1介导的突触发生如何控制 CRH神经元的兴奋性。在目标3中，我们将测试DSCAML1如何在CRH神经元内触发细胞 死亡并建立HPI轴活动。使用CRH神经元特异性突变体，我们将确定DSCAML1如何 促肾上腺皮质激素释放激素神经元内的功能以及DSCAML1‘S在其他类型细胞中的功能是否也对HpI轴有贡献 发展。在目标4中，我们将检验CRH神经元数量调节HPI轴活动的假设。 虽然细胞死亡的重要性得到了广泛的认识，但CRH神经元细胞死亡的功能影响 没有被探索过。我们将使用基因工具来增加或减少CRH神经元的数量，并确定 细胞数量和HPI轴活动之间的因果关系。综合起来，这些目标将阐明如何 细胞间相互作用影响CRH神经元死亡并为未来提供分子框架 分子研究。

PROJECT SUMMARY/ABSTRACT Corticotropin-releasing hormone (CRH) expressing neurons in the hypothalamus are critical regulators of the neuroendocrine stress response. CRH neurons integrate stress-related neural inputs and, as part of the hypothalamic-pituitary-adrenal (HPA) axis, induce the release of ACTH and, ultimately, glucocorticoids (cortisol). The development of CRH neurons is of great biomedical interest, as developmental vulnerabilities of CRH neurons contribute to stress-associated disorders such as anxiety and depression. It is, therefore, critical to identify the molecular and cellular mechanisms mediating the development of CRH neurons and determine how developmental changes affect stress response. Using zebrafish, which are genetically accessible and optically translucent, we found that DSCAML1 deficiency impaired the developmental cell death of CRH neurons and caused hyperactivation of the HPI axis (the zebrafish analog of the HPA axis). Given that DSCAML1 is known to mediate intercellular interactions, we hypothesize that proximity-based and synaptic interactions in CRH neurons trigger developmental cell death, which tunes the activity of the neuroendocrine stress response system. To test this, we propose the following aims. In Aim 1, we will test whether proximity-based interactions promote cell death in CRH neurons. Using the live imaging strength of the zebrafish model, we will examine whether interactions between adjacent CRH neurons promote cell death and determine how varying levels of DSCAML1 modulate the extent of cell loss. In Aim 2, we will test whether synaptic interactions affect CRH neuron cell death. Synaptic activity plays an instructive role in neuronal survival. Given DSCAML1’s known functions in synaptogenesis, we will investigate whether CRH neuron survival is dependent on neuronal activity and how DSCAML1-mediated synaptogenesis controls the excitability of CRH neurons. In Aim 3, we will test how DSCAML1 acts within CRH neurons to trigger cell death and establish HPI-axis activity. Using CRH neuron-specific mutants, we will determine how DSCAML1 functions within CRH neurons and whether DSCAML1’s function in other cell types also contributes to HPI-axis development. In Aim 4, we will test the hypothesis that CRH neuron number tunes HPI-axis activity. While the significance of cell death is widely recognized, the functional impact of CRH neuron cell death has not been explored. We will use genetic tools to increase or decrease CRH neuron number and determine the causal relationship between cell number and HPI-axis activity. Together, these aims will shed light on how intercellular interactions influence CRH neuron cell death and provide a molecular framework for future molecular studies.