Regulation of G1-specific gene expression in yeast

描述（由申请人提供）：忠实复制的能力是生命系统的标志之一。我们研究计划的总体目标是了解真核生物中细胞增殖的控制。该调节通过调节G1特异性基因的大家族的表达在细胞周期的G1期期间施加。我们以前已经描述了两个新的阻遏物G1特异性基因表达的酵母。Whi 5在G1期早期结合并抑制两种G1特异性转录因子之一的SBF，而Nrm 1在细胞退出G1期时作为MBF的共抑制物抑制G1特异性转录。这两种调节剂在细胞周期检查点中发挥关键作用，这些检查点对细胞周期事件施加顺序：G1细胞大小检查点中的Whi 5和DNA复制检查点中的Nrm 1。该应用程序提出了三个具体目标。首先，我们建议的特点Swi 6，MBF和SBF的共享组件，作为一个平台，通过研究其与Whi 5和NRM 1的相互作用和蛋白磷酸化的相互作用的调节的基础上调节转录的作用。其次，我们建议确定DNA复制检查点控制MBF调节转录的机制和作用。nrm 1在检查点信号通路和细胞周期机制之间的联系中起作用。检查点通过检查点蛋白激酶磷酸化调节Nrm 1/MBF相互作用，对基因组稳定性很重要。第三，我们建议建立RAK基序的作用，RAK基序是Nrm 1，Whi 5和其他定义Nrm 1/Whi 5超家族的蛋白质之间保守的氨基酸序列基序。我们预计，这种氨基酸序列的保守性掩盖了这些蛋白质的细胞周期调控的保守方面。我们预计，这些特定目标的完成将提供一个更广泛的理解G1特异性转录的调控，无论是在细胞周期中，并在响应激活的细胞周期。 DNA复制检查点。在远亲芽殖酵母、酿酒酵母和裂殖酵母中了解这种机制，有望建立 在调节细胞增殖和人类DNA的背景下进行测试的范例 复制检查点响应。这两个过程的失调与 人类癌症我们希望对细胞周期调控的转录调控有一个更普遍的看法， 机器及其调节器将提供对人类生物学和医学的深入了解。

DESCRIPTION (provided by applicant): The capacity to faithfully replicate is one of the hallmarks of living systems. The overall goal of our research program is to understand the control of cell proliferation in eukaryotes. That regulation is imposed during G1 phase of the cell cycle via the regulation of the expression of a large family of G1- specific genes. We have previously described two novel repressors of G1-specific gene expression in yeast. Whi5 binds and represses SBF, one of two G1-specific transcription factors, during early G1 phase whereas Nrm1 acts as a co-repressor with MBF to repress G1 specific transcription as cells exit G1 phase. Both regulators play critical roles in cell cycle checkpoints that impose order on cell cycle events: Whi5 in the G1 cell size checkpoint and Nrm1 in the DNA replication checkpoint. The application is presented in three specific aims. First, we propose to characterize the role of Swi6, a shared component of MBF and SBF, as a platform for regulation of transcription by studying the basis for its interaction with Whi5 and Nrm1 and the regulation of that interaction by protein phosphorylation. Second, we propose to determine the mechanism and role of control of MBF regulated transcription by the DNA replication checkpoint. Nrm1 acts at the nexus between the checkpoint signaling pathway and the cell cycle machinery. The checkpoint regulates the Nrm1/MBF interaction via phosphorylation by checkpoint protein kinases and is important for genomic stability. Third, we propose to establish the role of the RAK motif, an amino acid sequence motif conserved between Nrm1, Whi5 and other proteins that defines a Nrm1/Whi5 superfamily. We expect that this amino acid sequence conservation belies a conserved aspect of cell cycle regulation by those proteins. We anticipate that completion of these specific aims will provide a broader understanding of the regulation of G1-specific transcription both during the cell cycle and in response to activation of the DNA replication checkpoint. Understanding this mechanism in the distantly related budding yeast, Saccharomyces cerevisiae, and fission yeast, Schizosaccharomyces pombe, promises to establish paradigms to be tested in the context of the regulation of cell proliferation and the human DNA replication checkpoint response. Misregulation of both of those processes has been associated with human cancer. We are hopeful that a more general view of the cell cycle-regulated transcriptional machinery and its regulators will offer insight into human biology and medicine.