Understanding the role of Fezl in adult neural stem cell maintenance and fate

神经发生，或新神经元的诞生，在包括人类在内的哺乳动物的前脑（脑室下区和海马）的离散区域中持续整个成年生活。成人神经发生对大脑正常运作的能力起着至关重要的作用。这一过程的干扰与情感障碍（包括焦虑和抑郁）以及与学习和记忆有关的问题有关。了解神经干细胞的基本生物学以及神经发生的分子和细胞调控机制将对修复这些疾病状态和促进健康脑组织的维持产生潜在的重大影响。最近，具有增殖能力和表达神经干细胞标志物的细胞已被发现在整个脑脑室区的斑马鱼，脊椎动物的遗传模式生物，与哺乳动物有相当大的相似性，是适合遗传/化学筛选和体内成像。我感兴趣的是通过分析一种进化上保守的含锌指蛋白Fezl的功能，研究调节斑马鱼成体神经干细胞的特化、维持和分化的分子机制。Fezl在发育早期的前脑胚胎祖细胞中表达，并在胚胎后和成人脑的脑室区中检测到。我们的实验室分离出一种名为too few的突变体，它在大脑多巴胺神经元中的缺陷，后来发现它破坏了fezl基因。具体目的如下：1）测试Fezl划分斑马鱼前脑中成体神经干细胞的个体发育的假设，2）确定Fezl是否在成体神经干细胞维持或分化中起功能作用，以及3）确定在正常条件下以及响应于损伤时表达Fezl的成体心室祖细胞对成体脑的分化细胞的贡献。我们以前的研究已经确定，Fezl表达于成年斑马鱼端脑的自我更新心室祖细胞。为了确定这些表达Fezl的细胞是否是多能的，并且可以产生神经元和神经胶质细胞，我将进行体内谱系追踪。为了研究Fezl在成体神经干细胞和神经发生中的功能，将结合BrdU脉冲追踪研究，在野生型和太少（Fezl）突变体中检查神经干细胞和神经元的标志物。我还建议，以确定这些Fezl表达细胞的成人端脑分化细胞在正常条件下，以及在响应损伤的贡献，通过进行病变的研究，结合谱系追踪。

Neurogenesis, or the birth of new neurons, continues throughout adult life in discrete regions of the forebrain (the sub-ventricular zone and hippocampus) in mammals including humans. Adult neurogenesis contributes in a crucial way to the ability of the brain to function normally. Perturbations of this process have been implicated in affective disorders including anxiety and depression, as well as in problems related to learning and memory. Understanding the basic biology of neural stem cells and the molecular and cellular regulatory mechanisms of neurogenesis will potentially have a significant impact on repairing these disease states and promoting the maintenance of healthy brain tissues. Recently, cells with proliferative abilities and expressing neural stem cell markers have been found throughout the brain ventricular zone in zebrafish, a vertebrate genetic model organism that shares considerable similarity with mammals and is amenable to genetic/chemical screening and in vivo imaging. I am interested in investigating molecular mechanisms that regulate the specification, maintenance, and differentiation of adult neural stem cells in zebrafish, through analyzing the function of an evolutionarily conserved zinc finger-containing protein named Fezl. Fezl is expressed in forebrain embryonic progenitor cells early in development and is detected in the ventricular zone of post-embryonic and adult brains. A mutant named too few was isolated in our laboratory for its deficit in brain dopamine neurons and was later found to disrupt the fezl gene. The specific aims are as follows: 1) Test the hypothesis that Fezl demarcates the ontogeny of adult neural stem cells in the zebrafish forebrain, 2) Determine whether Fezl plays a functional role in adult neural stem cell maintenance or differentiation, and 3) Determine the contribution of Fezl-expressing adult ventricular progenitor cells to differentiated cells of the adult brain under normal conditions as well as in response to injury. Our previous studies have established that Fezl is expressed in self-renewing ventricular progenitor cells of the adult zebrafish telencephalon. To determine whether these Fezl-expressing cells are multipotent and can give rise to both neurons and glial cells, I will perform in vivo lineage tracing. To then investigate Fezl function in adult neural stem cells and neurogenesis, markers of neural stem cells and neurons will be examined in the wildtype and too few (Fezl) mutant, in conjunction with BrdU pulse-chase studies. I also propose to determine the contribution of these Fezl-expressing cells to differentiated cells of the adult telencephalon under normal conditions as well as in response to injury by performing lesion studies in conjunction with lineage tracing.