scholarly journals A Novel Protein with Similarities to Rb Binding Protein 2 Compensates for Loss of Chk1 Function and Affects Histone Modification in Fission Yeast

2004 ◽  
Vol 24 (9) ◽  
pp. 3660-3669 ◽  
Author(s):  
Shakil Ahmed ◽  
Carmela Palermo ◽  
Shanhong Wan ◽  
Nancy C. Walworth

ABSTRACT The conserved protein kinase Chk1 mediates cell cycle progression and consequently the ability of cells to survive when exposed to DNA damaging agents. Cells deficient in Chk1 are hypersensitive to such agents and enter mitosis in the presence of damaged DNA, whereas checkpoint-proficient cells delay mitotic entry to permit time for DNA repair. In a search for proteins that can improve the survival of Chk1-deficient cells exposed to DNA damage, we identified fission yeast Msc1, which is homologous to a mammalian protein that binds to the tumor suppressor Rb (RBP2). Msc1 and RBP2 each possess three PHD fingers, domains commonly found in proteins that influence the structure of chromatin. Msc1 is chromatin associated and coprecipitates a histone deacetylase activity, a property that requires the PHD fingers. Cells lacking Msc1 have a dramatically altered histone acetylation pattern, exhibit a 20-fold increase in global acetylation of histone H3 tails, and are readily killed by trichostatin A, an inhibitor of histone deacetylases. We postulate that Msc1 plays an important role in regulating chromatin structure and that this function modulates the cellular response to DNA damage.

2001 ◽  
Vol 21 (21) ◽  
pp. 7150-7162 ◽  
Author(s):  
Ronjon K. Chakraverty ◽  
Jonathan M. Kearsey ◽  
Thomas J. Oakley ◽  
Muriel Grenon ◽  
Maria-Angeles de la Torre Ruiz ◽  
...  

ABSTRACT Deletion of the Saccharomyces cerevisiae TOP3gene, encoding Top3p, leads to a slow-growth phenotype characterized by an accumulation of cells with a late S/G2content of DNA (S. Gangloff, J. P. McDonald, C. Bendixen, L. Arthur, and R. Rothstein, Mol. Cell. Biol. 14:8391–8398, 1994). We have investigated the function of TOP3 during cell cycle progression and the molecular basis for the cell cycle delay seen in top3Δ strains. We show that top3Δ mutants exhibit a RAD24-dependent delay in the G2 phase, suggesting a possible role for Top3p in the resolution of abnormal DNA structures or DNA damage arising during S phase. Consistent with this notion,top3Δ strains are sensitive to killing by a variety of DNA-damaging agents, including UV light and the alkylating agent methyl methanesulfonate, and are partially defective in the intra-S-phase checkpoint that slows the rate of S-phase progression following exposure to DNA-damaging agents. This S-phase checkpoint defect is associated with a defect in phosphorylation of Rad53p, indicating that, in the absence of Top3p, the efficiency of sensing the existence of DNA damage or signaling to the Rad53 kinase is impaired. Consistent with a role for Top3p specifically during S phase, top3Δ mutants are sensitive to the replication inhibitor hydroxyurea, expression of the TOP3 mRNA is activated in late G1 phase, and DNA damage checkpoints operating outside of S phase are unaffected by deletion of TOP3. All of these phenotypic consequences of loss of Top3p function are at least partially suppressed by deletion of SGS1, the yeast homologue of the human Bloom's and Werner's syndrome genes. These data implicate Top3p and, by inference, Sgs1p in an S-phase-specific role in the cellular response to DNA damage. A model proposing a role for these proteins in S phase is presented.


1997 ◽  
Vol 17 (2) ◽  
pp. 742-750 ◽  
Author(s):  
T Matsumoto

Successful recovery from DNA damage requires coordination of several biological processes. Eukaryotic cell cycle progression is delayed when the cells encounter DNA-damaging agents. This cell cycle delay allows the cells to cope with DNA damage by utilizing DNA repair enzymes. Thus, at least two processes, induction of the cell cycle delay and repair of damaged DNA, are coordinately required for recovery. In this study, a fission yeast rad mutant (slp1-362) was genetically investigated. In response to radiation, slp1 stops cell division; however, it does not restart it. This defect is suppressed when slp1-362 is combined with wee1-50 or cdc2-3w; in these mutants, the onset of mitosis is advanced due to the premature activation of p34cdc2. In contrast, slp1 is synthetically lethal with cdc25, nim1/cdr1, or cdr2, all of which are unable to activate the p34cdc2 kinase correctly. These genetic interactions of slp1 with cdc2 and its modulators imply that slp1 is not defective in either "induction of cell cycle delay" or "DNA repair." slp1+ may be involved in a critical process which restarts cell cycle progression after the completion of DNA repair. Molecular cloning of slp1+ revealed that slp1+ encodes a putative 488-amino-acid polypeptide exhibiting significant homology to WD-domain proteins, namely, CDC20 (budding yeast), p55CDC (human), and Fizzy (fly). A possible role of slp1+ is proposed.


2019 ◽  
Vol 202 (2) ◽  
Author(s):  
Peter E. Burby ◽  
Lyle A. Simmons

ABSTRACT All organisms regulate cell cycle progression by coordinating cell division with DNA replication status. In eukaryotes, DNA damage or problems with replication fork progression induce the DNA damage response (DDR), causing cyclin-dependent kinases to remain active, preventing further cell cycle progression until replication and repair are complete. In bacteria, cell division is coordinated with chromosome segregation, preventing cell division ring formation over the nucleoid in a process termed nucleoid occlusion. In addition to nucleoid occlusion, bacteria induce the SOS response after replication forks encounter DNA damage or impediments that slow or block their progression. During SOS induction, Escherichia coli expresses a cytoplasmic protein, SulA, that inhibits cell division by directly binding FtsZ. After the SOS response is turned off, SulA is degraded by Lon protease, allowing for cell division to resume. Recently, it has become clear that SulA is restricted to bacteria closely related to E. coli and that most bacteria enforce the DNA damage checkpoint by expressing a small integral membrane protein. Resumption of cell division is then mediated by membrane-bound proteases that cleave the cell division inhibitor. Further, many bacterial cells have mechanisms to inhibit cell division that are regulated independently from the canonical LexA-mediated SOS response. In this review, we discuss several pathways used by bacteria to prevent cell division from occurring when genome instability is detected or before the chromosome has been fully replicated and segregated.


2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Lionel Condé ◽  
Yulemi Gonzalez Quesada ◽  
Florence Bonnet-Magnaval ◽  
Rémy Beaujois ◽  
Luc DesGroseillers

AbstractBackgroundStaufen2 (STAU2) is an RNA binding protein involved in the posttranscriptional regulation of gene expression. In neurons, STAU2 is required to maintain the balance between differentiation and proliferation of neural stem cells through asymmetric cell division. However, the importance of controlling STAU2 expression for cell cycle progression is not clear in non-neuronal dividing cells. We recently showed that STAU2 transcription is inhibited in response to DNA-damage due to E2F1 displacement from theSTAU2gene promoter. We now study the regulation of STAU2 steady-state levels in unstressed cells and its consequence for cell proliferation.ResultsCRISPR/Cas9-mediated and RNAi-dependent STAU2 depletion in the non-transformed hTERT-RPE1 cells both facilitate cell proliferation suggesting that STAU2 expression influences pathway(s) linked to cell cycle controls. Such effects are not observed in the CRISPR STAU2-KO cancer HCT116 cells nor in the STAU2-RNAi-depleted HeLa cells. Interestingly, a physiological decrease in the steady-state level of STAU2 is controlled by caspases. This effect of peptidases is counterbalanced by the activity of the CHK1 pathway suggesting that STAU2 partial degradation/stabilization fines tune cell cycle progression in unstressed cells. A large-scale proteomic analysis using STAU2/biotinylase fusion protein identifies known STAU2 interactors involved in RNA translation, localization, splicing, or decay confirming the role of STAU2 in the posttranscriptional regulation of gene expression. In addition, several proteins found in the nucleolus, including proteins of the ribosome biogenesis pathway and of the DNA damage response, are found in close proximity to STAU2. Strikingly, many of these proteins are linked to the kinase CHK1 pathway, reinforcing the link between STAU2 functions and the CHK1 pathway. Indeed, inhibition of the CHK1 pathway for 4 h dissociates STAU2 from proteins involved in translation and RNA metabolism.ConclusionsThese results indicate that STAU2 is involved in pathway(s) that control(s) cell proliferation, likely via mechanisms of posttranscriptional regulation, ribonucleoprotein complex assembly, genome integrity and/or checkpoint controls. The mechanism by which STAU2 regulates cell growth likely involves caspases and the kinase CHK1 pathway.


2021 ◽  
Author(s):  
Kerry Silva McPherson ◽  
Dmitry Korzhnev

Cellular DNA damage response (DDR) is an extensive signaling network that orchestrates DNA damage recognition, repair and avoidance, cell cycle progression and cell death. DDR alternation is a hallmark of...


2010 ◽  
Vol 29 (18) ◽  
pp. 3130-3139 ◽  
Author(s):  
Sophie E Polo ◽  
Abderrahmane Kaidi ◽  
Linda Baskcomb ◽  
Yaron Galanty ◽  
Stephen P Jackson

2015 ◽  
Vol 16 (1) ◽  
Author(s):  
Jing Song ◽  
Ping Hong ◽  
Chengeng Liu ◽  
Yueqi Zhang ◽  
Jinling Wang ◽  
...  

2014 ◽  
Vol 307 (9) ◽  
pp. C878-C892 ◽  
Author(s):  
Jennifer T. Durham ◽  
Howard K. Surks ◽  
Brian M. Dulmovits ◽  
Ira M. Herman

Microvascular stability and regulation of capillary tonus are regulated by pericytes and their interactions with endothelial cells (EC). While the RhoA/Rho kinase (ROCK) pathway has been implicated in modulation of pericyte contractility, in part via regulation of the myosin light chain phosphatase (MLCP), the mechanisms linking Rho GTPase activity with actomyosin-based contraction and the cytoskeleton are equivocal. Recently, the myosin phosphatase-RhoA-interacting protein (MRIP) was shown to mediate the RhoA/ROCK-directed MLCP inactivation in vascular smooth muscle. Here we report that MRIP directly interacts with the β-actin-specific capping protein βcap73. Furthermore, manipulation of MRIP expression influences pericyte contractility, with MRIP silencing inducing cytoskeletal remodeling and cellular hypertrophy. MRIP knockdown induces a repositioning of βcap73 from the leading edge to stress fibers; thus MRIP-silenced pericytes increase F-actin-driven cell spreading twofold. These hypertrophied and cytoskeleton-enriched pericytes demonstrate a 2.2-fold increase in contractility upon MRIP knockdown when cells are plated on a deformable substrate. In turn, silencing pericyte MRIP significantly affects EC cycle progression and angiogenic activation. When MRIP-silenced pericytes are cocultured with capillary EC, there is a 2.0-fold increase in EC cycle entry. Furthermore, in three-dimensional models of injury and repair, silencing pericyte MRIP results in a 1.6-fold elevation of total tube area due to EC network formation and increased angiogenic sprouting. The pivotal role of MRIP expression in governing pericyte contractile phenotype and endothelial growth should lend important new insights into how chemomechanical signaling pathways control the “angiogenic switch” and pathological angiogenic induction.


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