Cell Fate Determination in the Cerebellum

描述（由申请人提供）：神经发育需要以紧密订阅的时间序列产生一系列细胞类型。在这方面，小脑菱形唇是特别感兴趣的。虽然最初被认为只产生颗粒细胞，但现在已知它也有助于各种后脑核团以及小脑深部核团。我们以前的工作表明，通过Notch和BMP信号之间的相互作用，小脑脑室区细胞依次招募成为表达Mathl的菱形唇祖细胞。值得注意的是，遗传命运作图揭示了菱形唇内表达Mathl的祖细胞是高度瞬时的，使得线性不同的Mathl群体在E10和E12之间顺序地产生后脑和小脑深部核，并且在E12和E16之间产生小脑颗粒细胞。在本研究的第一部分中，我们将探索小脑脑室区的哪些群体产生了Mathl阳性菱形唇祖细胞的连续队列。此外，在该渐进诱导期期间，我们将检查来源于Notch与BMP响应性前体的身份和后代。在本研究的最后部分，我们将探讨菱形唇内是否存在隐性谱系区室。具体来说，我们将确定是否特定的后脑亚型（如聊天+ve后脑神经元）内产生的菱形唇的一个特定的内侧域。在本研究的第二部分中，我们验证了我们的假设，即Mathl与三种转录因子Id4、Tbr 2和Pax6一起控制菱形唇产生离散神经元亚型的能力。我们将首先研究是否Mathl的持久性在后期，但不是早期的菱形唇后代影响他们的能力。我们接下来将对Id4、Tbr 2和Pax6的无效或条件无效等位基因进行功能丧失分析。最后，我们将使用一种诱导性功能获得的方法来测试这些基因是否足以自主影响菱形唇祖细胞的命运。总之，这些研究不仅可以揭示Mathl如何塑造后脑和小脑的发育，而且还可以深入了解所研究的下游转录因子如何指导该区域的细胞命运。与公共卫生的相关性：小脑和后脑的功能障碍是导致广泛的神经系统疾病的原因，包括运动障碍、共济失调和自闭症。这些疾病状态中涉及的关键神经元群体在菱形唇内产生。我们的研究将揭示这些人群产生的机制，从而为找到治疗这些疾病的方法迈出第一步。

DESCRIPTION (provided by applicant): Neural development requires that a series of cell types be produced in a tightly subscribed temporal sequence. In this regard the cerebellar rhombic lip is of particular interest. While originally considered to give rise only to granule cells, it is now known to also contribute to a variety of hindbrain nuclei, as well as the deep cerebellar nuclei. Our previous work demonstrated that through an interplay between Notch and BMP signaling, cerebellar ventricular zone cells are sequentially recruited to become Mathl-expressing rhombic lip progenitors. Remarkably, genetic fate mapping has revealed that the Mathl expressing progenitors within the rhombic lip are highly transient, such that lineally distinct Mathl populations sequentially give rise to hindbrain and deep cerebellar nuclei between E10 and E12 and cerebellar granule cells between E12 and E16. In the first part of this grant we will explore which populations within the cerebellar ventricular zone give rise to the sequential cohorts of Mathl positive rhombic lip progenitors. Furthermore during this progressive induction period, we will examine the identity and progeny derived from Notch versus BMP responsive precursors. In the final part of this aim we will examine whether there exists covert lineage compartments within the rhombic lip. Specifically, we will determine whether specific hindbrain subtypes (e.g. Chat-+ve hindbrain neurons) are produced within a particular medio-lateral domain of the rhombic lip. In the second section of this grant, we test our hypothesis that Mathl acts in conjunction with three transcription factors, Id4, Tbr2 and Pax6 to control the competence of the rhombic lip to produce discrete neuronal subtypes. We will first examine whether the persistence of Mathl in late but not early rhombic lip progeny affects their competence. We will next do a loss of function analysis of either null or conditionally null alleles of Id4, Tbr2 and Pax6. Finally we will use an inducible gain of function approach to test the sufficiency of these genes to cell autonomously affect the fate of rhombic lip progenitors. Together these studies will not only be informative in revealing how Mathl shapes development in the hindbrain and cerebellum but will also provide insight into how the examined downstream transcription factors direct cell fate in this region. Relevance to Public Health: Disfunction in the cerebellum and hindbrain is responsible for a wide spectrum of neurological disorders including dyskinesia, ataxia and autism. Key neuronal populations implicated in these disease states are generated within the rhombic lip. Our studies will reveal the mechanisms by which these populations are generated and thus provide the first step towards finding a cure to these disorders.