A murine replication protein accumulates temporarily in the heterochromatic regions of nuclei prior to initiation of DNA replication

1995 ◽  
Vol 108 (3) ◽  
pp. 927-934 ◽  
Author(s):  
M. Starborg ◽  
E. Brundell ◽  
K. Gell ◽  
C. Larsson ◽  
I. White ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Mammalian Cells ◽  
Mitotic Cell ◽  
Yeast Cells ◽  
Metaphase Chromosomes ◽  
Licensing Factor ◽  
Mammalian Homologue ◽  
Initiation Of Dna Replication

We have analyzed the expression of the murine P1 gene, the mammalian homologue of the yeast MCM3 protein, during the mitotic cell cycle. The MCM3 protein has previously been shown to be of importance for initiation of DNA replication in Saccharomyces cerevisiae. We found that the murine P1 protein was present in the nuclei of mammalian cells throughout interphase of the cell cycle. This is in contrast to the MCM3 protein, which is located in the nuclei of yeast cells only between the M and the S phase of the cell cycle. Detailed analysis of the intranuclear localization of the P1 protein during the cell cycle revealed that it accumulates transiently in the heterochromatic regions towards the end of G1. The accumulation of the P1 protein in the heterochromatic regions prior to activation of DNA replication suggests that the mammalian P1 protein is also of importance for initiation of DNA replication. The MCM2-3.5 proteins have been suggested to represent yeast equivalents of a hypothetical replication licensing factor initially described in Xenopus. Our data support this model and indicate that the murine P1 protein could function as replication licensing factor. The chromosomal localization of the P1 gene was determined by fluorescence in situ hybridization to region 6p12 in human metaphase chromosomes.

scholarly journals Cdc48p is required for the cell cycle commitment point at Start via degradation of the G1-CDK inhibitor Far1p

2003 ◽  
Vol 163 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Xinrong Fu ◽  
Christine Ng ◽  
Daorong Feng ◽  
Chun Liang
Keyword(s):  
Cell Cycle ◽  
Mammalian Cells ◽  
Kinase Inhibitor ◽  
Mitotic Cell ◽  
Cyclin Dependent Kinase ◽  
Restriction Point ◽  
Cyclin Dependent Kinase Inhibitor ◽  
Cell Cycle Reentry ◽  
Mammalian Homologue ◽  
Cycle Regulation

The budding yeast Cdc48p and its mammalian homologue p97 are involved in many important cellular activities. Because previous cdc48 mutants have exclusive G2/M arrest, Cdc48p was thought to play an essential role only during mitosis. We found that Cdc48p is required for the execution of Start (a yeast cell cycle commitment point equivalent to the restriction point in mammalian cells) in both a normal mitotic cell cycle and cell cycle reentry after mating pheromone withdrawal through degradation of the G1–cyclin-dependent kinase inhibitor Far1p. Our work is the first to uncover novel roles of Cdc48p as a critical cell cycle regulator in G1, and to shed new light on cell cycle regulation of Far1p, which is the first cyclin-dependent kinase inhibitor shown to be a substrate of an essential proteolysis event mediated by Cdc48p.

scholarly journals The cell cycle regulator p27Kip1interacts with MCM7, a DNA replication licensing factor, to inhibit initiation of DNA replication

FEBS Letters ◽  
2005 ◽  
Vol 579 (29) ◽  
pp. 6529-6536 ◽  
Author(s):  
Shriram Nallamshetty ◽  
Martin Crook ◽  
Manfred Boehm ◽  
Takanobu Yoshimoto ◽  
Michelle Olive ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Cell Cycle Regulator ◽  
Licensing Factor ◽  
Initiation Of Dna Replication

Cdc6p establishes and maintains a state of replication competence during G1 phase

1997 ◽  
Vol 110 (6) ◽  
pp. 753-763 ◽  
Author(s):  
C.S. Detweiler ◽  
J.J. Li
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Transcriptional Repression ◽  
Prolonged Exposure ◽  
S Phase ◽  
Restrictive Temperature ◽  
Yeast Saccharomyces Cerevisiae ◽  
Important Intermediate ◽  
Initiation Of Dna Replication ◽  
And Function

CDC6 is essential for the initiation of DNA replication in the budding yeast Saccharomyces cerevisiae. Here we examine the timing of Cdc6p expression and function during the cell cycle. Cdc6p is expressed primarily between mitosis and Start. This pattern of expression is due in part to posttranscriptional controls, since it is maintained when CDC6 is driven by a constitutively induced promoter. Transcriptional repression of CDC6 or exposure of cdc6-1(ts) cells to the restrictive temperature at mitosis blocks subsequent S phase, demonstrating that the activity of newly synthesized Cdc6p is required each cell cycle for DNA replication. In contrast, similar perturbations imposed on cells arrested in G(1) before Start have moderate or no effects on DNA replication. This suggests that, between mitosis and Start, Cdc6p functions in an early step of initiation, effectively making cells competent for replication. Prolonged exposure of cdc6-1(ts) cells to the restrictive temperature at the pre-Start arrest eventually does cripple S phase, indicating that Cdc6p also functions to maintain this initiation competence during G(1). The requirement for Cdc6p to establish and maintain initiation competence tightly correlates with the requirement for Cdc6p to establish and maintain the pre-replicative complex at a replication origin, strongly suggesting that the pre-replicative complex is an important intermediate for the initiation of DNA replication. Confining assembly of the complex to G(1) by restricting expression of Cdc6p to this period may be one way of ensuring precisely one round of replication per cell cycle.

Temporal order of DNA replication in the H-2 major histocompatibility complex of the mouse

1992 ◽  
Vol 12 (11) ◽  
pp. 5174-5188
Author(s):  
E G Spack ◽  
E D Lewis ◽  
B Paradowski ◽  
R T Schimke ◽  
P P Jones
Keyword(s):  
Dna Replication ◽  
Mammalian Cells ◽  
Temporal Order ◽  
Chromosomal Region ◽  
S Phase ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
T Lymphoma Cells ◽  
Initiation Of Dna Replication ◽  
T Lymphoma

As an approach to mapping replicons in an extended chromosomal region, the temporal order of DNA replication was analyzed in the murine major histocompatibility gene complex (MHC). Replicating DNA from T-lymphoma and myelomonocyte cell lines was density labeled with bromodeoxyuridine and extracted from cells which had been fractionated into different stages of S phase by centrifugal elutriation. The replicating DNA from each fraction of S phase was separated from nonreplicating DNA on density gradients, blotted, and hybridized with 34 specific MHC probes. The earliest replication occurred in the vicinity of transcribed genes K, HAM1 and HAM2, RD, B144, D, L, T18, and T3. The temporal order of replication of groups of DNA segments suggests the location of five or six replicons within the H-2 complex, some of which appear to be either unidirectional or markedly asymmetric. The rates of replication through each of these apparent replicons appear to be similar. The TL region of the S49.1 T-lymphoma cells, which contains at least three transcribed genes, replicates earlier than the inactive TL region of WEHI-3 myelomonocytic cells. These results provide further evidence of a relationship between transcription and the initiation of DNA replication in mammalian cells. The mouse MHC examined in this study is the largest chromosomal region (> 2,000 kb) measured for timing of replication to date.

Yeast Mutants That Produce a Novel Type of Ascus Containing Asci Instead of Spores

Genetics ◽  
1996 ◽  
Vol 144 (3) ◽  
pp. 979-989 ◽  
Author(s):  
Zhixiong Xue ◽  
Xiaoyin Shan ◽  
Alex Sinelnikov ◽  
Teri Melese
Keyword(s):  
Cell Cycle ◽  
Essential Gene ◽  
Mitotic Cell ◽  
Yeast Cells ◽  
Mitotic Cell Cycle ◽  
Spindle Formation ◽  
Bud Formation ◽  
Yeast Mutants ◽  
Two Hybrid

Abstract Tetraploid yeast cells lacking BFR1 or overexpressing an essential gene BBPl produce a novel type of ascus that contains asci instead of spores. We show here that the asci within an ascus likely arise because a/α spores undergo a second round of meiosis. Cells depleted of Bbplp or lacking Bfr1p are defective in a number of processes such as nuclear segregation, bud formation, cytokinesis and nuclear spindle formation. Furthermore, deletion of BFR1 or overexpression of BBP1 leads to an increase in cell ploidy, indicating that Bfr1p and Bbplp play roles in both the mitotic cell cycle and meiosis. Bfr1p and Bbp1p interact with each other in a two hybrid assay, further suggesting that they might form a complex important for cell cycle coordination.

scholarly journals Yeast Ppz1 protein phosphatase toxicity involves the alteration of multiple cellular targets

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Diego Velázquez ◽  
Marcel Albacar ◽  
Chunyi Zhang ◽  
Carlos Calafí ◽  
María López-Malo ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Transcription Factor ◽  
Protein Phosphatase ◽  
Mitotic Cell ◽  
Yeast Cells ◽  
Growth Defect ◽  
Cellular Targets ◽  
Major Mechanism ◽  
Bud Emergence ◽  
Phosphorylation Pattern

Abstract Control of the protein phosphorylation status is a major mechanism for regulation of cellular processes, and its alteration often lead to functional disorders. Ppz1, a protein phosphatase only found in fungi, is the most toxic protein when overexpressed in Saccharomyces cerevisiae. To investigate the molecular basis of this phenomenon, we carried out combined genome-wide transcriptomic and phosphoproteomic analyses. We have found that Ppz1 overexpression causes major changes in gene expression, affecting ~ 20% of the genome, together with oxidative stress and increase in total adenylate pools. Concurrently, we observe changes in the phosphorylation pattern of near 400 proteins (mainly dephosphorylated), including many proteins involved in mitotic cell cycle and bud emergence, rapid dephosphorylation of Snf1 and its downstream transcription factor Mig1, and phosphorylation of Hog1 and its downstream transcription factor Sko1. Deletion of HOG1 attenuates the growth defect of Ppz1-overexpressing cells, while that of SKO1 aggravates it. Our results demonstrate that Ppz1 overexpression has a widespread impact in the yeast cells and reveals new aspects of the regulation of the cell cycle.

scholarly journals PR48, a Novel Regulatory Subunit of Protein Phosphatase 2A, Interacts with Cdc6 and Modulates DNA Replication in Human Cells

2000 ◽  
Vol 20 (3) ◽  
pp. 1021-1029 ◽  
Author(s):  
Zhen Yan ◽  
Sergei A. Fedorov ◽  
Marc C. Mumby ◽  
R. Sanders Williams
Keyword(s):  
Dna Replication ◽  
Protein Phosphatase ◽  
Mammalian Cells ◽  
Cell Cycle Progression ◽  
Protein Phosphatase 2A ◽  
Specific Interaction ◽  
Regulatory Subunit ◽  
Amino Terminal ◽  
Phosphatase 2A ◽  
Initiation Of Dna Replication

ABSTRACT Initiation of DNA replication in eukaryotes is dependent on the activity of protein phosphatase 2A (PP2A), but specific phosphoprotein substrates pertinent to this requirement have not been identified. A novel regulatory subunit of PP2A, termed PR48, was identified by a yeast two-hybrid screen of a human placental cDNA library, using human Cdc6, an essential component of prereplicative complexes, as bait. PR48 binds specifically to an amino-terminal segment of Cdc6 and forms functional holoenzyme complexes with A and C subunits of PP2A. PR48 localizes to the nucleus of mammalian cells, and its forced overexpression perturbs cell cycle progression, causing a G1 arrest. These results suggest that dephosphorylation of Cdc6 by PP2A, mediated by a specific interaction with PR48, is a regulatory event controlling initiation of DNA replication in mammalian cells.

scholarly journals Polar Remodeling and Histidine Kinase Activation, Which Is Essential for Caulobacter Cell Cycle Progression, Are Dependent on DNA Replication Initiation

2010 ◽  
Vol 192 (15) ◽  
pp. 3893-3902 ◽  
Author(s):  
Antonio A. Iniesta ◽  
Nathan J. Hillson ◽  
Lucy Shapiro
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Histidine Kinase ◽  
Cell Cycle Progression ◽  
Caulobacter Crescentus ◽  
Replication Initiation ◽  
Cycle Progression ◽  
Dna Replication Initiation ◽  
Flagellar Biosynthesis ◽  
Initiation Of Dna Replication

ABSTRACT Caulobacter crescentus initiates a single round of DNA replication during each cell cycle. Following the initiation of DNA replication, the essential CckA histidine kinase is activated by phosphorylation, which (via the ChpT phosphotransferase) enables the phosphorylation and activation of the CtrA global regulator. CtrA∼P then blocks the reinitiation of replication while regulating the transcription of a large number of cell cycle-controlled genes. It has been shown that DNA replication serves as a checkpoint for flagellar biosynthesis and cell division and that this checkpoint is mediated by the availability of active CtrA. Because CckA∼P promotes the activation of CtrA, we addressed the question of what controls the temporal activation of CckA. We found that the initiation of DNA replication is a prerequisite for remodeling the new cell pole, which includes the localization of the DivL protein kinase to that pole and, consequently, the localization, autophosphorylation, and activation of CckA at that pole. Thus, CckA activation is dependent on polar remodeling and a DNA replication initiation checkpoint that is tightly integrated with the polar phospho-signaling cascade governing cell cycle progression.

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