scholarly journals Cyclin F-Chk1 synthetic lethality mediated by E2F1 degradation

2019 ◽  
Author(s):  
Kamila Burdova ◽  
Hongbin Yang ◽  
Roberta Faedda ◽  
Samuel Hume ◽  
Daniel Ebner ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Cell Cycle Progression ◽  
Kinase Inhibitors ◽  
Synthetic Lethality ◽  
Checkpoint Inhibitors ◽  
Dependent Manner ◽  
Cycle Progression ◽  
Multiple Substrates ◽  
Cyclin F

SummaryCyclins are central engines of cell cycle progression when partnered with Cyclin Dependent Kinases (CDKs). Among the different cyclins controlling cell cycle progression, cyclin F does not partner with a CDK, but forms an E3 ubiquitin ligase, assembling through the F-box domain, an Skp1-Cul1-F-box (SCF) module. Although multiple substrates of cyclin F have been identified the vulnerabilities of cells lacking cyclin F are not known. Thus, we assessed viability of cells lacking cyclin F upon challenging cells with more than 200 kinase inhibitors. The screen revealed a striking synthetic lethality between Chk1 inhibition and cyclin F loss. Chk1 inhibition in cells lacking cyclin F leads to DNA replication catastrophe. The DNA replication catastrophe depends on the accumulation of E2F1 in cyclin F depleted cells. We observe that SCFcyclin F promotes E2F1 degradation after Chk1 inhibitors in a CDK dependent manner. Thus, Cyclin F restricts E2F1 activity during cell cycle and upon checkpoint inhibition to prevent DNA replication stress. Our findings pave the way for patient selection in the clinical use of checkpoint inhibitors.

scholarly journals Local inhibition of PRC2 activity by H3.3K27M drives DNA replication defects through misregulation of the JNK pathway

2019 ◽  
Author(s):  
Kamila Delaney ◽  
Maude Strobino ◽  
Joanna M. Wenda ◽  
Andrzej Pankowski ◽  
Florian A. Steiner
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Drug Targets ◽  
Cell Cycle Progression ◽  
Human Tumor ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Cycle Progression ◽  
Jnk Pathway ◽  
Local Inhibition

AbstractSubstitution of lysine 27 with methionine in histone H3.3 is a recently discovered driver mutation of pediatric high-grade gliomas. Mutant tumor cells show decreased levels and altered distribution of H3K27me3. How these chromatin changes are established genome-wide and lead to tumorigenesis only in specific tissues remains unclear. Here we show that H3.3K27M-mediated alterations in H3K27me3 distribution result in ectopic DNA replication and cell cycle progression of germ cells in Caenorhabditis elegans. By genetically inducing changes in the H3.3 distribution, we demonstrate that both H3.3K27M oncohistone incorporation and pre-existing H3K27me3 act locally and antagonistically on Polycomb Repressive Complex 2 (PRC2) in a concentration-dependent manner, explaining the observed H3K27me3 distribution in mutant cells. The altered heterochromatin patterns lead to extensive misregulation of gene expression. Through unbiased genetic screening, we found that inhibiting JNK pathway components, which are overexpressed in H3.3K27M cells, suppresses the ectopic DNA replication and cell cycle progression without rescuing the altered H3K27me3 distribution. Moreover, we show that JNK inhibition suppresses the replicative fate in human tumor-derived H3.3K27M cells, thus establishing C. elegans as a powerful model for the identification of potential drug targets for treatment of H3.3K27M tumors.

scholarly journals Regulation of Cell Division in Bacteria by Monitoring Genome Integrity and DNA Replication Status

2019 ◽  
Vol 202 (2) ◽  
Author(s):  
Peter E. Burby ◽  
Lyle A. Simmons
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Division ◽  
Dna Replication ◽  
Cell Cycle Progression ◽  
Genome Instability ◽  
Sos Response ◽  
Bacterial Cells ◽  
Cycle Progression ◽  
Content Type

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.

Deregulated expression of the RanBP1 gene alters cell cycle progression in murine fibroblasts

1997 ◽  
Vol 110 (19) ◽  
pp. 2345-2357 ◽  
Author(s):  
A. Battistoni ◽  
G. Guarguaglini ◽  
F. Degrassi ◽  
C. Pittoggi ◽  
A. Palena ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Cell Cycle Progression ◽  
Protein Import ◽  
Proliferating Cells ◽  
Cycle Progression ◽  
Ran Gtpase ◽  
Genes Encoding ◽  
Active Transcription ◽  
Gtpase Cycle

RanBP1 is a molecular partner of the Ran GTPase, which is implicated in the control of several processes, including DNA replication, mitotic entry and exit, cell cycle progression, nuclear structure, protein import and RNA export. While most genes encoding Ran-interacting partners are constitutively active, transcription of the RanBP1 mRNA is repressed in non proliferating cells, is activated at the G1/S transition in cycling cells and peaks during S phase. We report here that forced expression of the RanBP1 gene disrupts the orderly execution of the cell division cycle at several stages, causing inhibition of DNA replication, defective mitotic exit and failure of chromatin decondensation during the telophase-to-interphase transition in cells that achieve nuclear duplication and chromosome segregation. These results suggest that deregulated RanBP1 activity interferes with the Ran GTPase cycle and prevents the functioning of the Ran signalling system during the cell cycle.

scholarly journals Microarray gene expression profiling in colorectal (HCT116) and hepatocellular (HepG2) carcinoma cell lines treated withMelicope ptelefolialeaf extract reveals transcriptome profiles exhibiting anticancer activity

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5203 ◽  
Author(s):  
Mohammad Faujul Kabir ◽  
Johari Mohd Ali ◽  
Onn Haji Hashim
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Dna Replication ◽  
Cell Lines ◽  
Microarray Data ◽  
Expression Profiling ◽  
Cell Cycle Progression ◽  
Anticancer Activities ◽  
Microarray Gene Expression ◽  
Cycle Progression

BackgroundWe have previously reported anticancer activities ofMelicope ptelefolia(MP) leaf extracts on four different cancer cell lines. However, the underlying mechanisms of actions have yet to be deciphered. In the present study, the anticancer activity of MP hexane extract (MP-HX) on colorectal (HCT116) and hepatocellular carcinoma (HepG2) cell lines was characterized through microarray gene expression profiling.MethodsHCT116 and HepG2 cells were treated with MP-HX for 24 hr. Total RNA was extracted from the cells and used for transcriptome profiling using Applied Biosystem GeneChip™ Human Gene 2.0 ST Array. Gene expression data was analysed using an Applied Biosystems Expression Console and Transcriptome Analysis Console software. Pathway enrichment analyses was performed using Ingenuity Pathway Analysis (IPA) software. The microarray data was validated by profiling the expression of 17 genes through quantitative reverse transcription PCR (RT-qPCR).ResultsMP-HX induced differential expression of 1,290 and 1,325 genes in HCT116 and HepG2 cells, respectively (microarray data fold change, MA_FC ≥ ±2.0). The direction of gene expression change for the 17 genes assayed through RT-qPCR agree with the microarray data. In both cell lines, MP-HX modulated the expression of many genes in directions that support antiproliferative activity. IPA software analyses revealed MP-HX modulated canonical pathways, networks and biological processes that are associated with cell cycle, DNA replication, cellular growth and cell proliferation. In both cell lines, upregulation of genes which promote apoptosis, cell cycle arrest and growth inhibition were observed, while genes that are typically overexpressed in diverse human cancers or those that promoted cell cycle progression, DNA replication and cellular proliferation were downregulated. Some of the genes upregulated by MP-HX include pro-apoptotic genes (DDIT3, BBC3, JUN), cell cycle arresting (CDKN1A, CDKN2B), growth arrest/repair (TP53, GADD45A) and metastasis suppression (NDRG1). MP-HX downregulated the expression of genes that could promote anti-apoptotic effect, cell cycle progression, tumor development and progression, which include BIRC5, CCNA2, CCNB1, CCNB2, CCNE2, CDK1/2/6, GINS2, HELLS, MCM2/10 PLK1, RRM2 and SKP2. It is interesting to note that all six top-ranked genes proposed to be cancer-associated (PLK1, MCM2, MCM3, MCM7, MCM10 and SKP2) were downregulated by MP-HX in both cell lines.DiscussionThe present study showed that the anticancer activities of MP-HX are exerted through its actions on genes regulating apoptosis, cell proliferation, DNA replication and cell cycle progression. These findings further project the potential use of MP as a nutraceutical agent for cancer therapeutics.

scholarly journals Carvedilol Inhibits Angiotensin II-Induced Proliferation and Contraction in Hepatic Stellate Cells through the RhoA/Rho-Kinase Pathway

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Ying Wu ◽  
Zhen Li ◽  
Sining Wang ◽  
Aiyuan Xiu ◽  
Chunqing Zhang
Keyword(s):  
Cell Cycle ◽  
Angiotensin Ii ◽  
Liver Fibrosis ◽  
Cell Cycle Progression ◽  
Rho Kinase ◽  
Cell Counting ◽  
Type I ◽  
Dependent Manner ◽  
Ang Ii ◽  
Cycle Progression

Aim. Carvedilol is a nonselective beta-blocker used to reduce portal hypertension. This study investigated the effects and potential mechanisms of carvedilol in angiotensin II- (Ang II-) induced hepatic stellate cell (HSC) proliferation and contraction. Methods. The effect of carvedilol on HSC proliferation was measured by Cell Counting Kit-8 (CCK-8). Cell cycle progression and apoptosis in HSCs were determined by flow cytometry. A collagen gel assay was used to confirm HSC contraction. The extent of liver fibrosis in mice was evaluated by hematoxylin-eosin (H&E) and Sirius Red staining. Western blot analyses were performed to detect the expression of collagen I, collagen III, α-smooth muscle actin (α-SMA), Ang II type I receptor (AT1R), RhoA, Rho-kinase 2 (ROCK2), and others. Results. The results showed that carvedilol inhibited HSC proliferation and arrested the cell cycle at the G0/G1 phase in a dose-dependent manner. Carvedilol also modulated Bcl-2 family proteins and increased apoptosis in Ang II-treated HSCs. Furthermore, carvedilol inhibited HSC contraction induced by Ang II, an effect that was associated with AT1R-mediated RhoA/ROCK2 pathway interference. In addition, carvedilol reduced α-SMA expression and collagen deposition and attenuated liver fibrosis in carbon tetrachloride (CCl4)-treated mice. The in vivo data further confirmed that carvedilol inhibited the expression of angiotensin-converting enzyme (ACE), AT1R, RhoA, and ROCK2. Conclusions. The results indicated that carvedilol dose-dependently inhibited Ang II-induced HSC proliferation by impeding cell cycle progression, thus alleviating hepatic fibrosis. Furthermore, carvedilol could inhibit Ang II-induced HSC contraction by interfering with the AT1R-mediated RhoA/ROCK2 pathway.

scholarly journals Evidence for a dual role for TC4 protein in regulating nuclear structure and cell cycle progression.

1994 ◽  
Vol 125 (4) ◽  
pp. 705-719 ◽  
Author(s):  
S Kornbluth ◽  
M Dasso ◽  
J Newport
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Nuclear Structure ◽  
Cell Cycle Progression ◽  
Cycle Progression ◽  
Nuclear Assembly ◽  
Egg Extracts ◽  
A Cell ◽  
Xenopus Egg Extracts

TC4, a ras-like G protein, has been implicated in the feedback pathway linking the onset of mitosis to the completion of DNA replication. In this report we find distinct roles for TC4 in both nuclear assembly and cell cycle progression. Mutant and wild-type forms of TC4 were added to Xenopus egg extracts capable of assembling nuclei around chromatin templates in vitro. We found that a mutant TC4 protein defective in GTP binding (GDP-bound form) suppressed nuclear growth and prevented DNA replication. Nuclear transport under these conditions approximated normal levels. In a separate set of experiments using a cell-free extract of Xenopus eggs that cycles between S and M phases, the GDP-bound form of TC4 had dramatic effects, blocking entry into mitosis even in the complete absence of nuclei. The effect of this mutant TC4 protein on cell cycle progression is mediated by phosphorylation of p34cdc2 on tyrosine and threonine residues, negatively regulating cdc2 kinase activity. Therefore, we provide direct biochemical evidence for a role of TC4 in both maintaining nuclear structure and in the signaling pathways that regulate entry into mitosis.

scholarly journals Identification of DHX9 as a cell cycle regulated nucleolar recruitment factor for CIZ1

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Urvi Thacker ◽  
Tekle Pauzaite ◽  
James Tollitt ◽  
Maria Twardowska ◽  
Charlotte Harrison ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Cell Cycle Progression ◽  
Zinc Finger Protein ◽  
S Phase ◽  
Cycle Progression ◽  
Inactive X Chromosome ◽  
Functional Characterisation ◽  
Interaction Partners

Abstract CIP1-interacting zinc finger protein 1 (CIZ1) is a nuclear matrix associated protein that facilitates a number of nuclear functions including initiation of DNA replication, epigenetic maintenance and associates with the inactive X-chromosome. Here, to gain more insight into the protein networks that underpin this diverse functionality, molecular panning and mass spectrometry are used to identify protein interaction partners of CIZ1, and CIZ1 replication domain (CIZ1-RD). STRING analysis of CIZ1 interaction partners identified 2 functional clusters: ribosomal subunits and nucleolar proteins including the DEAD box helicases, DHX9, DDX5 and DDX17. DHX9 shares common functions with CIZ1, including interaction with XIST long-non-coding RNA, epigenetic maintenance and regulation of DNA replication. Functional characterisation of the CIZ1-DHX9 complex showed that CIZ1-DHX9 interact in vitro and dynamically colocalise within the nucleolus from early to mid S-phase. CIZ1-DHX9 nucleolar colocalisation is dependent upon RNA polymerase I activity and is abolished by depletion of DHX9. In addition, depletion of DHX9 reduced cell cycle progression from G1 to S-phase in mouse fibroblasts. The data suggest that DHX9-CIZ1 are required for efficient cell cycle progression at the G1/S transition and that nucleolar recruitment is integral to their mechanism of action.

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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