scholarly journals Homeostatic control of meiotic G2/prophase checkpoint function by Pch2 and Hop1

2020 ◽  
Author(s):  
Vivek B. Raina ◽  
Gerben Vader
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Spindle Assembly Checkpoint ◽  
Cell Cycle Control ◽  
Cycle Progression ◽  
Aaa Atpase ◽  
Chromosome Synapsis ◽  
Cellular Context ◽  
The Face ◽  
Insight Into

SummaryCheckpoints cascades coordinate cell cycle progression with essential chromosomal processes. During meiotic G2/prophase, recombination and chromosome synapsis are monitored by what are considered distinct checkpoints [1–3]. In budding yeast, the AAA+ ATPase Pch2 is thought to specifically promote cell cycle delay in response to synapsis defects [4–6]. However, unperturbed pch2Δ cells are delayed in meiotic G2/prophase [6], suggesting paradoxical roles for Pch2 in cell cycle progression. Here, we provide insight into the checkpoint roles of Pch2 and its connection to Hop1, a HORMA domain-containing client protein. Contrary to current understanding, we find that the Pch2-Hop1 module is crucial for checkpoint function in response to both recombination and synapsis defects, thus revealing a shared meiotic checkpoint cascade. Meiotic checkpoint responses are transduced by DNA break-dependent phosphorylation of Hop1 [7, 8]. Based on our data and on the effect of Pch2 on HORMA topology [9–11], we propose that Pch2 promotes checkpoint proficiency by catalyzing the availability of signaling-competent Hop1. Conversely, we demonstrate that Pch2 can act as a checkpoint silencer, also in the face of persistent DNA repair defects. We establish a framework in which Pch2 and Hop1 form a homeostatic module that governs general meiotic checkpoint function. We show that this module can - depending on the cellular context - fuel or extinguish meiotic checkpoint function, which explains the contradictory roles of Pch2 in cell cycle control. Within the meiotic checkpoint, the Pch2-Hop1 module thus operates analogous to the Pch2/TRIP13-Mad2 module in the spindle assembly checkpoint that monitors chromosome segregation [12–16].

scholarly journals Limits and constraints on mechanisms of cell-cycle regulation imposed by cell sizehomeostasis measurements

2019 ◽  
Author(s):  
Lisa Willis ◽  
Henrik Jönsson ◽  
Kerwyn Casey Huang
Keyword(s):  
Cell Cycle ◽  
Cell Size ◽  
Cell Cycle Progression ◽  
Control Mechanism ◽  
Cell Cycle Control ◽  
Cycle Progression ◽  
Constant Size ◽  
Cycle Regulation ◽  
High Throughput Imaging ◽  
Insight Into

SummaryHigh-throughput imaging has led to an explosion of observations regarding cell-size homeostasis across the kingdoms of life. Among bacteria, “adder” behavior in which a constant size appears to be added during each cell cycle is ubiquitous, while various eukaryotes show other size-homeostasis behaviors. Since interactions between cell-cycle progression and growth ultimately determine size-homeostasis behaviors, we developed a general model of cell proliferation to: 1) discover how the requirement of cell-size homeostasis limits mechanisms of cell-cycle control; 2) predict how features of cell-cycle control translate into size-homeostasis measurements. Our analyses revealed plausible cell-cycle control scenarios that nevertheless fail to regulate cell size, conditions that generate apparent adder behavior without underlying adder mechanisms, cell-cycle features that play unintuitive roles in causing deviations from adder, and distinguishing predictions for extended size-homeostasis statistics according to the underlying control mechanism. The model thus provides holistic insight into the mechanistic implications of cell-size homeostasis measurements.

scholarly journals Circadian regulation of c-MYC in mice

2020 ◽  
Vol 117 (35) ◽  
pp. 21609-21617
Author(s):  
Zhenxing Liu ◽  
Christopher P. Selby ◽  
Yanyan Yang ◽  
Laura A. Lindsey-Boltz ◽  
Xuemei Cao ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Circadian Clock ◽  
Tumor Suppressors ◽  
Feedback Loop ◽  
Cell Cycle Progression ◽  
Regulatory Mechanism ◽  
Clock Genes ◽  
Circadian Regulation ◽  
Cycle Progression ◽  
Insight Into

The circadian clock is a global regulatory mechanism that controls the expression of 50 to 80% of transcripts in mammals. Some of the genes controlled by the circadian clock are oncogenes or tumor suppressors. Among theseMychas been the focus of several studies which have investigated the effect of clock genes and proteins onMyctranscription and MYC protein stability. Other studies have focused on effects ofMycmutation or overproduction on the circadian clock in comparison to their effects on cell cycle progression and tumorigenesis. Here we have used mice with mutations in the essential clock genesBmal1,Cry1,andCry2to gain further insight into the effect of the circadian clock on this important oncogene/oncoprotein and tumorigenesis. We find that mutation of bothCry1andCry2, which abolishes the negative arm of the clock transcription–translation feedback loop (TTFL), causes down-regulation of c-MYC, and mutation ofBmal1,which abolishes the positive arm of TTFL, causes up-regulation of the c-MYC protein level in mouse spleen. These findings must be taken into account in models of the clock disruption–cancer connection.

Cdk1-Dependent Phosphorylation ofNPM Overrides G2/M Checkpoint and Increases Leukemic Blasts in Mice

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1322-1322
Author(s):  
Wei Du ◽  
Yun Zhou ◽  
Suzette Pike ◽  
Qishen Pang
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Cell Cycle Control ◽  
Xenograft Model ◽  
Phosphorylation Sites ◽  
M Cell ◽  
Cycle Progression ◽  
Hematopoietic Stem ◽  
Cycle Arrest ◽  
Regulation Of Cell Cycle

Abstract An elevated level of nucleophosmin (NPM) is often found in actively proliferative cells including human tumors. To identify the regulatory role for NPM phosphorylation in proliferation and cell cycle control, a series of mutants targeting the consensus cyclin-dependent kinase (CKD) phosphorylation sites was created to mimic or abrogate either single-site or multi-site phosphorylation. Cells expressing the phosphomimetic NPM mutants showed enhanced proliferation and G2/M cell-cycle transition; whereas nonphosphorylatable mutants induced G2/M cell-cycle arrest. Simultaneous inactivation of two CKD phosphorylation sites at Ser10 and Ser70 (S10A/S70A, NPM-AA) induced phosphorylation of Cdk1 at Tyr15 (Cdc2Tyr15) and increased cytoplasmic accumulation of Cdc25C. Strikingly, stress-induced Cdk1Tyr15 and Cdc25C sequestration were completely suppressed by expression of a double phosphomimetic NPM mutant (S10E/S70E, NPM-EE). Further analysis revealed that phosphorylation of NPM at both Ser10 and Ser70 sites were required for proper interaction between Cdk1 and Cdc25C in mitotic cells. Moreover, the NPM-EE mutant directly bound to Cdc25C and prevented phosphorylation of Cdc25C at Ser216 during mitosis. Finally, NPM-EE overrided stress-induced G2/M arrest, increased peripheral-blood blasts and splenomegaly in a NOD/SCID xenograft model, and promoted leukemia development in Fanconi mouse hematopoietic stem/progenitor cells. Thus, these findings reveal a novel function of NPM on regulation of cell-cycle progression, in which Cdk1-dependent phosphorylation of NPM controls cell-cycle progression at G2/M transition through modulation of Cdc25C activity.

scholarly journals The Multiple Roles of the Cdc14 Phosphatase in Cell Cycle Control

2020 ◽  
Vol 21 (3) ◽  
pp. 709
Author(s):  
Javier Manzano-López ◽  
Fernando Monje-Casas
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Current Knowledge ◽  
Cell Cycle Control ◽  
Multiple Roles ◽  
Special Focus ◽  
Cyclin Dependent Kinase ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cycle Progression

The Cdc14 phosphatase is a key regulator of mitosis in the budding yeast Saccharomyces cerevisiae. Cdc14 was initially described as playing an essential role in the control of cell cycle progression by promoting mitotic exit on the basis of its capacity to counteract the activity of the cyclin-dependent kinase Cdc28/Cdk1. A compiling body of evidence, however, has later demonstrated that this phosphatase plays other multiple roles in the regulation of mitosis at different cell cycle stages. Here, we summarize our current knowledge about the pivotal role of Cdc14 in cell cycle control, with a special focus in the most recently uncovered functions of the phosphatase.

scholarly journals Functional Differentiation of SWI/SNF Remodelers in Transcription and Cell Cycle Control

2006 ◽  
Vol 27 (2) ◽  
pp. 651-661 ◽  
Author(s):  
Yuri M. Moshkin ◽  
Lisette Mohrmann ◽  
Wilfred F. J. van Ijcken ◽  
C. Peter Verrijzer
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Target Genes ◽  
Structural Integrity ◽  
Function Analysis ◽  
Cell Cycle Control ◽  
Functional Differentiation ◽  
Transcription Control ◽  
Cycle Progression ◽  
The Core

ABSTRACT Drosophila BAP and PBAP represent two evolutionarily conserved subclasses of SWI/SNF chromatin remodelers. The two complexes share the same core subunits, including the BRM ATPase, but differ in a few signature subunits: OSA defines BAP, whereas Polybromo (PB) and BAP170 specify PBAP. Here, we present a comprehensive structure-function analysis of BAP and PBAP. An RNA interference knockdown survey revealed that the core subunits BRM and MOR are critical for the structural integrity of both complexes. Whole-genome expression profiling suggested that the SWI/SNF core complex is largely dysfunctional in cells. Regulation of the majority of target genes required the signature subunit OSA, PB, or BAP170, suggesting that SWI/SNF remodelers function mostly as holoenzymes. BAP and PBAP execute similar, independent, or antagonistic functions in transcription control and appear to direct mostly distinct biological processes. BAP, but not PBAP, is required for cell cycle progression through mitosis. Because in yeast the PBAP-homologous complex, RSC, controls cell cycle progression, our finding reveals a functional switch during evolution. BAP mediates G2/M transition through direct regulation of string/cdc25. Its signature subunit, OSA, is required for directing BAP to the string/cdc25 promoter. Our results suggest that the core subunits play architectural and enzymatic roles but that the signature subunits determine most of the functional specificity of SWI/SNF holoenzymes in general gene control.

Cell cycle control

2016 ◽  
pp. 31-41
Author(s):  
Simon M. Carr ◽  
Nicholas B. La Thangue
Keyword(s):  
Cell Cycle ◽  
Final Stage ◽  
Cell Cycle Progression ◽  
Cell Cycle Control ◽  
Control Mechanisms ◽  
Chromosomal Dna ◽  
Cycle Progression ◽  
M Phase ◽  
Cellular Components ◽  
Regulate Cell Cycle Progression

All cells arise by the division of existing cells in a highly regulated series of events known as the cell cycle. Whilst duplication of other cellular contents occurs throughout all stages of the cycle, chromosomal DNA is replicated only once at a stage known as S phase. Once this is complete, distribution of chromosomes and other cellular components occurs during the final stage of the cell cycle, known as M phase, or mitosis. The cell cycle is therefore regulated in a temporal fashion, so that entry into subsequent cell cycle stages only occurs once the previous stage has been completed. A number of signalling mechanisms monitor the integrity of cell cycle progression, and later cell cycle stages can be delayed if any errors need correction. This chapter gives an overview of the major control mechanisms that regulate cell cycle progression, and how these are circumvented during the onset of cancer.

scholarly journals Ubiquitin signaling in cell cycle control and tumorigenesis

2020 ◽  
Author(s):  
Fabin Dang ◽  
Li Nie ◽  
Wenyi Wei
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Regulation ◽  
Cell Cycle Progression ◽  
Kinase Inhibitors ◽  
Cell Cycle Control ◽  
Ubiquitin Ligases ◽  
E3 Ubiquitin Ligases ◽  
Cycle Progression ◽  
Precise Control ◽  
Cycle Regulation

Abstract Cell cycle progression is a tightly regulated process by which DNA replicates and cell reproduces. The major driving force underlying cell cycle progression is the sequential activation of cyclin-dependent kinases (CDKs), which is achieved in part by the ubiquitin-mediated proteolysis of their cyclin partners and kinase inhibitors (CKIs). In eukaryotic cells, two families of E3 ubiquitin ligases, anaphase-promoting complex/cyclosome and Skp1-Cul1-F-box protein complex, are responsible for ubiquitination and proteasomal degradation of many of these CDK regulators, ensuring cell cycle progresses in a timely and precisely regulated manner. In the past couple of decades, accumulating evidence have demonstrated that the dysregulated cell cycle transition caused by inefficient proteolytic control leads to uncontrolled cell proliferation and finally results in tumorigenesis. Based upon this notion, targeting the E3 ubiquitin ligases involved in cell cycle regulation is expected to provide novel therapeutic strategies for cancer treatment. Thus, a better understanding of the diversity and complexity of ubiquitin signaling in cell cycle regulation will shed new light on the precise control of the cell cycle progression and guide anticancer drug development.

scholarly journals Inhibition of Cellular DNA Synthesis by the Human Cytomegalovirus IE86 Protein Is Necessary for Efficient Virus Replication

2006 ◽  
Vol 80 (8) ◽  
pp. 3872-3883 ◽  
Author(s):  
Dustin T. Petrik ◽  
Kimberly P. Schmitt ◽  
Mark F. Stinski
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Human Cytomegalovirus ◽  
Cell Cycle Progression ◽  
Cell Cycle Control ◽  
Single Amino Acid ◽  
Cycle Progression ◽  
Artificial Chromosomes ◽  
Early Genes ◽  
Cellular Dna

ABSTRACT Human cytomegalovirus (HCMV) expresses several proteins that manipulate normal cellular functions, including cellular transcription, apoptosis, immune response, and cell cycle control. The IE2 gene, which is expressed from the HCMV major immediate-early (MIE) promoter, encodes the IE86 protein. IE86 is a multifunctional protein that is essential for viral replication. The functions of IE86 include transactivation of cellular and viral early genes, negative autoregulation of the MIE promoter, induction of cell cycle progression from G0/G1 to G1/S, and arresting cell cycle progression at the G1/S transition in p53-positive human foreskin fibroblast (HFF) cells. Mutations were introduced into the IE2 gene in the context of the viral genome using bacterial artificial chromosomes (BACs). From these HCMV BACs, a recombinant virus (RV) with a single amino acid substitution in the IE86 protein was isolated that replicates slower and to lower titers than wild-type HCMV. HFF cells infected with the Q548R RV undergo cellular DNA synthesis and do not arrest at any point in the cell cycle. The Q548R RV is able to negatively autoregulate the MIE promoter, transactivate viral early genes, activate cellular E2F-responsive genes, and produce infectious virus. This is the first report of a viable recombinant HCMV that is unable to inhibit cellular DNA synthesis in infected HFF cells.

E2f4 regulates fetal erythropoiesis through the promotion of cellular proliferation

Blood ◽  
2006 ◽  
Vol 108 (3) ◽  
pp. 886-895 ◽  
Author(s):  
Kathryn M. Kinross ◽  
Allison J. Clark ◽  
Rosa M. Iazzolino ◽  
Patrick Orson Humbert
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Cellular Proliferation ◽  
Cell Cycle Control ◽  
Macrocytic Anemia ◽  
Cycle Progression ◽  
Promote Cell Cycle Progression ◽  
Regulation Of Cell Cycle ◽  
Fetal Erythropoiesis

Abstract The E2F proteins are major regulators of the transcriptional program required to coordinate cell cycle progression and exit. In particular, E2f4 has been proposed to be the principal family member responsible for the regulation of cell cycle exit chiefly through its transcriptional repressive properties. We have previously shown that E2f4–/– mice display a marked macrocytic anemia implicating E2f4 in the regulation of erythropoiesis. However, these studies could not distinguish whether E2f4 was required for differentiation, survival, or proliferation control. Here, we describe a novel function for E2f4 in the promotion of erythroid proliferation. We show that loss of E2f4 results in an impaired expansion of the fetal erythroid compartment in vivo that is associated with impaired cell cycle progression and decreased erythroid proliferation. Consistent with these observations, cDNA microarray analysis reveals cell cycle control genes as one of the major class of genes down-regulated in E2f4–/– FLs, and we provide evidence that E2f4 may directly regulate the transcriptional expression of a number of these genes. We conclude that the macrocytic anemia of E2f4–/– mice results primarily from impaired cellular proliferation and that the major role of E2f4 in fetal erythropoiesis is to promote cell cycle progression and cellular proliferation.

scholarly journals Regulatory networks integrating cell cycle control with DNA damage checkpoints and double-strand break repair

2011 ◽  
Vol 366 (1584) ◽  
pp. 3562-3571 ◽  
Author(s):  
Petra Langerak ◽  
Paul Russell
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Division ◽  
Regulatory Networks ◽  
Cell Cycle Progression ◽  
Cell Cycle Control ◽  
Strand Break ◽  
Dsb Repair ◽  
Cycle Progression ◽  
Non Homologous End Joining

Double-strand breaks (DSBs), arising from exposure to exogenous clastogens or as a by-product of endogenous cellular metabolism, pose grave threats to genome integrity. DSBs can sever whole chromosomes, leading to chromosomal instability, a hallmark of cancer. Healing broken DNA takes time, and it is therefore essential to temporarily halt cell division while DSB repair is underway. The seminal discovery of cyclin-dependent kinases as master regulators of the cell cycle unleashed a series of studies aimed at defining how the DNA damage response network delays cell division. These efforts culminated with the identification of Cdc25, the protein phosphatase that activates Cdc2/Cdk1, as a critical target of the checkpoint kinase Chk1. However, regulation works both ways, as recent studies have revealed that Cdc2 activity and cell cycle position determine whether DSBs are repaired by non-homologous end-joining or homologous recombination (HR). Central to this regulation are the proteins that initiate the processing of DNA ends for HR repair, Mre11–Rad50–Nbs1 protein complex and Ctp1/Sae2/CtIP, and the checkpoint kinases Tel1/ATM and Rad3/ATR. Here, we review recent findings and provide insight on how proteins that regulate cell cycle progression affect DSB repair, and, conversely how proteins that repair DSBs affect cell cycle progression.

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