Regulation of G1-specific gene expression in yeast

描述(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。这种调节是在细胞周期的G1期通过调节一大类G1特异基因的表达来实施的。我们之前已经描述了两个新的酵母中G1特异性基因表达的抑制因子。在G1期早期，Whi5结合并抑制两个G1特异性转录因子之一SBF，而当细胞退出G1期时，Nrm1与MBF共同抑制G1特异性转录。这两种调控因子在细胞周期检查点中都扮演着重要的角色，它们对细胞周期事件施加秩序：在G1期细胞大小检查点中的WHI5和在DNA复制检查点中的Nrm1。该应用程序有三个具体目标。首先，我们建议通过研究Swi6与Whi5和Nrm1相互作用的基础以及蛋白质磷酸化对这种相互作用的调节来表征Swi6作为转录调控平台的作用。Swi6是MBF和SBF的共同成分。其次，我们提出通过DNA复制检查点来确定MBF调控转录的机制和作用。Nrm1在检查点信号通路和细胞周期机制之间发挥作用。Checkpoint通过Checkpoint蛋白激酶的磷酸化来调节Nrm1/MBF的相互作用，对基因组的稳定性非常重要。第三，我们建议建立RAK基序的作用，RAK基序是一个在Nrm1、Whi5和其他蛋白质之间保守的氨基酸序列基序，它定义了Nrm1/Whi5超家族。我们预计，这种氨基酸序列的保守性掩盖了这些蛋白质对细胞周期调控的保守方面。我们预计，完成这些特定的目标将提供一个更广泛的理解调控的G1-特异性转录在细胞周期和反应激活 DNA复制检查点。在远缘关系较远的芽酵母酿酒酵母和裂殖酵母庞贝裂殖酵母中了解这种机制有望建立 在细胞增殖和人类DNA调控的背景下测试的范例 复制检查点响应。对这两个过程的不当监管与 人类癌症。我们希望对细胞周期调控转录的更全面的看法 机械及其监管机构将提供对人类生物学和医学的洞察。

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.