Fission yeast Nda1 and Nda4, MCM homologs required for DNA replication, are constitutive nuclear proteins

1996 ◽  
Vol 109 (2) ◽  
pp. 319-326 ◽  
Author(s):  
N. Okishio ◽  
Y. Adachi ◽  
M. Yanagida

The nda1+ and nda4+ genes of the fission yeast Schizosaccharomyces pombe encode proteins similar to budding yeast MCM2 and MCM5/CDC46, respectively, which are required for the early stages of DNA replication. The budding yeast Mcm proteins display cell-cycle dependent localization. They are present in the nucleus specifically from late M phase until the beginning of S phase, so that they were suggested to be components of a replication licensing factor, a positive factor for the onset of replication, which is thought to be inactivated after use, thus restricting replication to only once in a cell cycle. In the present study, we raised antibodies against Nda1 or Nda4 and identified 115 kDa and 80 kDa proteins, respectively. Their immunolocalization was examined in wild-type cells and in various cell-cycle mutants. Both Nda1 and Nda4 proteins remained primarily in the nucleus throughout the cell cycle. In mutants arrested in G1, S, and G2 phases, these proteins were also enriched in the nucleus. These results indicate that the dramatic change in subcellular localization as seen in budding yeast is not essential in fission yeast for the functions of Nda1 and Nda4 proteins to be executed. The histidine-tagged nda1+ gene was constructed and integrated into the chromosome to replace the wild-type nda1+ gene. The resulting His-tagged Nda1 protein was adsorbed to the Ni-affinity column, and co-eluted with the untagged Nda4 protein, suggesting that they formed a complex.

1990 ◽  
Vol 10 (7) ◽  
pp. 3847-3851
Author(s):  
C H McGowan ◽  
P Russell ◽  
S I Reed

The product of the CDC2Hs gene is the protein kinase subunit of the M-phase promoting factor, which is required for entry into mitosis. The activity of this kinase is regulated in a cell cycle-dependent manner by reversible phosphorylation and through association with other proteins. We report here that in HeLa cells, the abundance of the CDC2Hs mRNA and the rate of synthesis of the encoded protein, p34, vary in a cell cycle-dependent manner.


1979 ◽  
Vol 39 (1) ◽  
pp. 215-233
Author(s):  
KIM NASMYTH ◽  
PAUL NURSE ◽  
R. S. S. FRASER

Request for reprints to Paul Nurse. Two isotopic methods for measuring DNA replication in the fission yeast Schizosaccharomyces pombe are described. The first is a method for measuring the total quantity of [3H]uracil incorporated into DNA after pulse labelling. The second is a means of detecting DNA replication in single cells by autoradiography. Both of these techniques have been used to investigate the timing and duration of S-phase in a series of mutant strains whose cell mass at division varies over a 3-fold range. The results support the hypothesis that in S. pombe there are 2 different controls over the timing of S-phase: an attainment of a critical cell mass and a dependency upon the completion of the previous mitosis coupled with a short minimum time in G1. Strains whose cell mass at birth is above this critical level initiate DNA replication almost immediately after septation, that is, very soon after the previous mitosis. Strains whose cell mass at birth is below the critical level do not initiate replication until the critical cell mass is attained. The duration of S-phase has been estimated from the proportion of cells whose nuclei are labelled after a pulse of given duration. S-phase is short in S. pombe, lasting only about 0.1 of a cell cycle in wild type. Cell mass at S-phase does not have any consistent effect on this length. We have also investigated the degree of synchrony of S-phase initiation in daughter cells, and have found that, in a cell cycle 240 min long, their S-phases are initiated within 1–2 min of each other. This result indicates that between sisters variability in the duration of the G1 phase is small compared with variability in the total cell cycle time, and argues against the hypothesis that the rate of cell cycle traverse is determined by a random transition in G1.


Author(s):  
Supriya G. Prasanth ◽  
Juan Méndez ◽  
Kannanganattu V. Prasanth ◽  
Bruce Stillman

Replication of the human genome every time a cell divides is a highly coordinated process that ensures accurate and efficient inheritance of the genetic information. The molecular mechanism that guarantees that many origins of replication fire only once per cell–cycle has been the area of intense research. The origin recognition complex (ORC) marks the position of replication origins in the genome and serves as the landing pad for the assembly of a multiprotein, pre–replicative complex (pre–RC) at the origins, consisting of ORC, cell division cycle 6 (Cdc6), Cdc10–dependent transcript (Cdt1) and mini–chromosome maintenance (MCM) proteins. The MCM proteins serve as key participants in the mechanism that limits eukaryotic DNA replication to once–per–cell–cycle and its binding to the chromatin marks the final step of pre–RC formation, a process referred to as ‘replication licensing’. We present data demonstrating how the MCM proteins associate with the chromatin during the G1 phase, probably defining pre–RCs and then anticipate replication fork movement in a precisely coordinated manner during the S phase of the cell cycle. The process of DNA replication must also be carefully coordinated with other cell–cycle processes including mitosis and cytokinesis. Some of the proteins that control initiation of DNA replication are likely to interact with the pathways that control these important cell–cycle transitions. Herein, we discuss the participation of human ORC proteins in other vital functions, in addition to their bona fide roles in replication.


1993 ◽  
Vol 341 (1298) ◽  
pp. 449-454 ◽  

Genetic analysis using the fission yeast has provided a powerful methodology to investigate the eukaryotic cell cycle and its control. The onset of M -phase in fission yeast is controlled by a regulatory gene network which activates the p34 cdc2 protein kinase encoded by the cdc 2 + gene. The coupling of M -phase to the completion of S-phase also works through p34 cdc2 . A similar network is operative in vertebrate cells. Future work will focus on the controls regulating onset of S-phase and on the mechanisms by which a cell duplicates itself in space during division.


1990 ◽  
Vol 10 (7) ◽  
pp. 3847-3851 ◽  
Author(s):  
C H McGowan ◽  
P Russell ◽  
S I Reed

The product of the CDC2Hs gene is the protein kinase subunit of the M-phase promoting factor, which is required for entry into mitosis. The activity of this kinase is regulated in a cell cycle-dependent manner by reversible phosphorylation and through association with other proteins. We report here that in HeLa cells, the abundance of the CDC2Hs mRNA and the rate of synthesis of the encoded protein, p34, vary in a cell cycle-dependent manner.


Open Biology ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 190259
Author(s):  
Simon Gemble ◽  
Géraldine Buhagiar-Labarchède ◽  
Rosine Onclercq-Delic ◽  
Gaëlle Fontaine ◽  
Sarah Lambert ◽  
...  

Topoisomerase IIα (Topo IIα), a well-conserved double-stranded DNA (dsDNA)-specific decatenase, processes dsDNA catenanes resulting from DNA replication during mitosis. Topo IIα defects lead to an accumulation of ultrafine anaphase bridges (UFBs), a type of chromosome non-disjunction. Topo IIα has been reported to resolve DNA anaphase threads, possibly accounting for the increase in UFB frequency upon Topo IIα inhibition. We hypothesized that the excess UFBs might also result, at least in part, from an impairment of the prevention of UFB formation by Topo IIα. We found that Topo IIα inhibition promotes UFB formation without affecting the global disappearance of UFBs during mitosis, but leads to an aberrant UFB resolution generating DNA damage within the next G1. Moreover, we demonstrated that Topo IIα inhibition promotes the formation of two types of UFBs depending on cell cycle phase. Topo IIα inhibition during S-phase compromises complete DNA replication, leading to the formation of UFB-containing unreplicated DNA, whereas Topo IIα inhibition during mitosis impedes DNA decatenation at metaphase–anaphase transition, leading to the formation of UFB-containing DNA catenanes. Thus, Topo IIα activity is essential to prevent UFB formation in a cell-cycle-dependent manner and to promote DNA damage-free resolution of UFBs.


1999 ◽  
Vol 2 (3) ◽  
pp. 178-184 ◽  
Author(s):  
R. Cenamor ◽  
J. Jiménez ◽  
V.J. Cid ◽  
C. Nombela ◽  
M. Sánchez

2019 ◽  
Author(s):  
Simon Gemble ◽  
Géraldine Buhagiar-Labarchède ◽  
Rosine Onclercq-Delic ◽  
Sarah Lambert ◽  
Mounira Amor-Guéret

AbstractTopoisomerase IIα (Topo IIα), a well-conserved double-stranded DNA (dsDNA)-specific decatenase, processes dsDNA catenanes resulting from DNA replication during mitosis. Topo IIα defects lead to an accumulation of ultrafine anaphase bridges (UFBs), a type of chromosome non-disjunction. Topo IIα has been reported to resolve DNA anaphase threads, possibly accounting for the increase in UFB frequency upon Topo IIα inhibition. We hypothesized that the excess UFBs might also result, at least in part, from an impairment of the prevention of UFB formation by Topo IIα. We found that Topo IIα inhibition promotes UFB formation without affecting UFB resolution during anaphase. Moreover, we showed that Topo IIα inhibition promotes the formation of two types of UFBs depending on cell-cycle phase. Topo IIα inhibition during S-phase compromises complete DNA replication, leading to the formation of UFB-containing unreplicated DNA, whereas Topo IIα inhibition during mitosis impedes DNA decatenation at metaphase-anaphase transition, leading to the formation of UFB-containing DNA catenanes. Thus, Topo IIα activity is essential to prevent UFB formation in a cell-cycle dependent manner, but dispensable for UFB resolution during anaphase.


2000 ◽  
Vol 11 (2) ◽  
pp. 543-554 ◽  
Author(s):  
Cristina Martı́n-Castellanos ◽  
Miguel A. Blanco ◽  
José M. de Prada ◽  
Sergio Moreno

Eukaryotic cells coordinate cell size with cell division by regulating the length of the G1 and G2 phases of the cell cycle. In fission yeast, the length of the G1 phase depends on a precise balance between levels of positive (cig1, cig2, puc1, and cdc13 cyclins) and negative (rum1 and ste9-APC) regulators of cdc2. Early in G1, cyclin proteolysis and rum1 inhibition keep the cdc2/cyclin complexes inactive. At the end of G1, the balance is reversed and cdc2/cyclin activity down-regulates both rum1 and the cyclin-degrading activity of the APC. Here we present data showing that the puc1 cyclin, a close relative of the Cln cyclins in budding yeast, plays an important role in regulating the length of G1. Fission yeast cells lacking cig1 and cig2 have a cell cycle distribution similar to that of wild-type cells, with a short G1 and a long G2. However, when thepuc1 + gene is deleted in this genetic background, the length of G1 is extended and these cells undergo S phase with a greater cell size than wild-type cells. This G1 delay is completely abolished in cells lacking rum1. Cdc2/puc1 function may be important to down-regulate the rum1 Cdk inhibitor at the end of G1.


2005 ◽  
Vol 280 (23) ◽  
pp. 22060-22069 ◽  
Author(s):  
Jonathan D. Stallings ◽  
Edward G. Tall ◽  
Srinivas Pentyala ◽  
Mario J. Rebecchi

Nuclear phosphoinositides, especially phosphatidylinositol 4,5-bisphosphate, fluctuate throughout the cell cycle and are linked to proliferation and differentiation. Here we report that phospholipase C-δ1 accumulates in the nucleus at the G1/S boundary and in G0 phases of the cell cycle. Furthermore, as wild-type protein accumulated in the nucleus, nuclear phosphatidylinositol 4,5-bisphosphate levels were elevated 3–5-fold, whereas total levels were decreased compared with asynchronous cultures. To test whether phosphatidylinositol 4,5-bisphosphate binding is important during this process, we introduced a R40D point mutation within the pleckstrin homology domain of phospholipase C-δ1, which disables high affinity phosphatidylinositol 4,5-bisphosphate binding, and found that nuclear translocation was significantly reduced at G1/S and in G0. These results demonstrate a cell cycle-dependent compartmentalization of phospholipase C-δ1 and support the idea that relative levels of phosphoinositides modulate the portioning of phosphoinositide-binding proteins between the nucleus and other compartments.


Sign in / Sign up

Export Citation Format

Share Document