Cell Cycle regulation of the yeast HO Gene

描述（由申请人提供）：控制细胞周期的机制在所有真核生物中都非常保守。在大多数生物体中，进行一轮细胞分裂的决定发生在G1期，而致癌过程通过干扰G1进程的调节因子发挥最大的影响。我们的研究重点是在生长和静止细胞中控制进入有丝分裂细胞周期的分子机制。细胞周期蛋白依赖性激酶（Cdks）控制G1到S的转变。在出芽酵母中，有三个G1周期蛋白在两个连续的波中被转录调节。第一波转录产生Cln3细胞周期蛋白和转录因子Swi4。在G1早期，Cln3激活周期蛋白依赖性激酶（Cdk），进而激活晚期G1转录复合物Swi6/Swi4和Swi6/Mbp1。这些复合物调节超过200个转录本，包括周期蛋白产生的G1后期波，这是过渡到S期的关键。现在，晚期G1转录的机制比以往任何时候都更类似于后生动物途径，因为酵母相当于视网膜母细胞瘤（Rb）已经被确定。该蛋白名为wh5，抑制G1晚期转录，可被Cln3/Cdk磷酸化并从转录复合体中释放。我们建议建立G1晚期转录复合物组分与wh5之间的关系，并确定这些组分的活性如何受到影响Start的信号通路的影响，以响应内在和外在的线索。这对快速生长的细胞很重要，但同样重要的是要了解Start程序的修改，使细胞能够进入，维持并从静止状态中恢复，因为这是实验室外更普遍的过渡。大多数细胞从G1开始退出循环。要做到这一点，有丝分裂启动机制必须稳定地失活，然后在条件改善时重新激活。我们首次能够从氧化石墨烯中纯化出同步进入S期的氧化石墨烯细胞。我们将使用这种方法来测试一系列解除有丝分裂开始程序的突变体，以了解GO到S和G1到S有何不同。

DESCRIPTION (provided by applicant): The mechanisms that control the cell cycle are remarkably conserved among all eukaryotes. The decision to commit to a round of cell division occurs in G1 in most organisms and oncogenic processes exert their greatest impact by interfering with regulators of G1 progression. Our research is focused on the molecular mechanisms that control the decision to enter the mitotic cell cycle in growing and quiescent cells. The control of the G1 to S transition is governed by cyclin-dependent kinases (Cdks). In budding yeast, there are three G1 cyclins that are transcriptionally regulated in two consecutive waves. The first wave of transcription produces components the Cln3 cyclin and the transcription factor Swi4. During early G1, Cln3 activates the cyclin-dependent kinase (Cdk), which, in turn activates the Iate-G1 transcription complexes, Swi6/Swi4 and Swi6/Mbp1. These complexes regulate over 200 transcripts, including the late G1 wave of cyclin production, which is key to the transition to S phase. Now more than ever, the mechanism of late G1 transcription resembles the metazoan pathway, in that the yeast equivalent of Retinoblastoma (Rb) has been identified. This protein, Whi5, represses late G1 transcription and can be phosphorylated and released from the transcription complex by Cln3/Cdk phosphorylation. We propose to establish the relationships between the late G1 transcription complex components and Whi5 and to identify how the activities of these components are affected by the signaling pathways that influence Start in response to intrinsic and extrinsic cues. This is important in rapidly growing cells, but it is equally important to understand the modifications of the Start program that enable cells to enter, maintain and recover from quiescence, because this is the more prevalent transition outside the laboratory. Most cells exit the cycle from G1. To do so, the mitotic Start machinery must be stably inactivated and then reactivated when conditions improve. For the first time, we are able to purify a uniform population of GO cells that synchronously enter S phase from GO. We will use this method to test a series of mutants that deregulate the mitotic start program to see how GO to S and G1 to S differ.