Cell cycle control in the mammalian retina

描述(由申请人提供)：某些人类基因的突变会导致中枢神经系统(CNS)特定区域的细胞数量缺陷。这些变化会导致发育异常，严重损害中枢神经系统的功能。越来越多的证据表明，这些突变中有几个存在于控制增殖的基因中。然而，人们对它们的作用机制知之甚少。为了解决这个问题，我们正在研究小鼠视网膜发育过程中增殖的调节。发育中的小鼠视网膜是研究中枢神经系统发育的模型系统，已经确定了导致视网膜神经上皮特有的增殖缺陷的基因突变。识别这些突变是如何改变视网膜增殖的，可能有助于我们理解如何在整个中枢神经上皮细胞中发生区域特异性的增殖调控。Chx10是一种在视网膜祖细胞中表达的同源框基因，零突变会导致人类和小鼠的先天性小眼球。在视网膜中，细胞数量严重不足，这在很大程度上是由于发育期间增殖减少所致。两个细胞周期基因Cyclin D1和p27(Kip1)在Chx10突变的视网膜中调控错误，而p27(Kip1)的基因失活显著恢复了细胞数量，减轻了小眼球的严重程度。这些发现建立了Chx10与视网膜前体细胞的细胞周期之间的联系。 我们的假设是，Chx10可能在视网膜前体细胞的增殖中具有多种功能。在目标1中，我们将确定Chx10是否调节G1进程所需的蛋白质。在目标2中，我们将确定细胞周期的哪些阶段依赖于Chx10。为了达到这些目的，Chx10缺失的小鼠将与含有关键细胞周期基因零等位基因的小鼠交配，以产生组合突变。在目标3中，我们将使用原代细胞培养来确定视网膜前体细胞中的有丝分裂原信号是否需要Chx10。这些研究有可能确定Chx10在调节视网膜前体细胞增殖中的功能，这些信息可以应用于中枢神经系统的其他区域，在那里，增殖是发育和功能的关键决定因素。

DESCRIPTION (provided by applicant): Mutations in certain human genes cause cell number defects in specific regions of the central nervous system (CNS). These changes cause developmental anomalies that severely compromise CNS function. Evidence is starting to emerge that several of these mutations are in genes that regulate proliferation. However, the mechanisms by which they function are poorly understood. To address this, we are studying the regulation of proliferation during murine retinal development. The developing mouse retina is well established as a model system for studying CNS development, and genetic mutations have been identified that cause proliferation defects specific to the retinal neuroepithelium. Identifying how these mutations alter retinal proliferation may help us to understand how region specific regulation of proliferation occurs throughout the CNS neuroepithelium. Chx10 is a homeobox gene expressed in retinal progenitor cells and null mutations cause congenital microphthalmia in humans and mice. In the retina, there is a severe deficit in cell number, and this is due in large part to a reduction in proliferation during development. Two cell cycle genes, Cyclin D1 and p27(Kip1), are misregulated in the Chx10 mutant retina, and genetic inactivation of p27(Kip1) significantly restores cell number and alleviates the severity of the microphthalmia. These findings establish a link between Chx10 and the cell cycle in retinal progenitor cells. Our hypothesis is that Chx10 could have multiple functions in retinal progenitor proliferation. In Aim 1 we will determine if Chx10 regulates proteins required for G 1 progression. In Aim 2, we will determine which phases of the cell cycle are dependent on Chx10. For these Aims, Chx10 null mice will be mated with mice containing null alleles of critical cell cycle genes to produce combinatorial mutants. In Aim 3, we will determine if Chx10 is required for mitogen signaling in retinal progenitor cells using primary cell culture. These studies have the potential to identify the functions of Chx10 in regulating retinal progenitor proliferation, and this information can be applied to other areas of the CNS where proliferation is a key determinant of development and function.