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. ? ? ?

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
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Molecular Genetics B Study Section (MGB)
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Zatz, Marion M
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Scripps Research Institute
La Jolla
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Haase, Steven B; Wittenberg, Curt (2014) Topology and control of the cell-cycle-regulated transcriptional circuitry. Genetics 196:65-90
Ma, Hui; Han, Bong-Kwan; Guaderrama, Marisela et al. (2014) Psy2 targets the PP4 family phosphatase Pph3 to dephosphorylate Mth1 and repress glucose transporter gene expression. Mol Cell Biol 34:452-63
Travesa, Anna; Kalashnikova, Tatyana I; de Bruin, Robertus A M et al. (2013) Repression of G1/S transcription is mediated via interaction of the GTB motifs of Nrm1 and Whi5 with Swi6. Mol Cell Biol 33:1476-86
Bertoli, Cosetta; Klier, Steffi; McGowan, Clare et al. (2013) Chk1 inhibits E2F6 repressor function in response to replication stress to maintain cell-cycle transcription. Curr Biol 23:1629-37
Travesa, Anna; Wittenberg, Curt (2012) Turned on by genotoxic stress. Cell Cycle 11:3145-6
Travesa, Anna; Kuo, Dwight; de Bruin, Robertus A M et al. (2012) DNA replication stress differentially regulates G1/S genes via Rad53-dependent inactivation of Nrm1. EMBO J 31:1811-22
Spielewoy, Nathalie; Guaderrama, Marisela; Wohlschlegel, James A et al. (2010) Npr2, yeast homolog of the human tumor suppressor NPRL2, is a target of Grr1 required for adaptation to growth on diverse nitrogen sources. Eukaryot Cell 9:592-601
de Bruin, Robertus A M; Kalashnikova, Tatyana I; Wittenberg, Curt (2008) Stb1 collaborates with other regulators to modulate the G1-specific transcriptional circuit. Mol Cell Biol 28:6919-28
de Bruin, R A M; Kalashnikova, T I; Aslanian, A et al. (2008) DNA replication checkpoint promotes G1-S transcription by inactivating the MBF repressor Nrm1. Proc Natl Acad Sci U S A 105:11230-5
Ashe, Mabelle; de Bruin, Robertus A M; Kalashnikova, Tatyana et al. (2008) The SBF- and MBF-associated protein Msa1 is required for proper timing of G1-specific transcription in Saccharomyces cerevisiae. J Biol Chem 283:6040-9

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