scholarly journals Fluctuation in radioresponse of HeLa cells during the cell cycle evaluated based on micronucleus frequency

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hiroaki Shimono ◽  
Atsushi Kaida ◽  
Hisao Homma ◽  
Hitomi Nojima ◽  
Yusuke Onozato ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Hela Cells ◽  
Time Lapse ◽  
S Phase ◽  
G1 Phase ◽  
M Phase ◽  
G2 Phase ◽  
The Difference ◽  
Time Lapse Imaging ◽  
First Time

AbstractIn this study, we examined the fluctuation in radioresponse of HeLa cells during the cell cycle. For this purpose, we used HeLa cells expressing two types of fluorescent ubiquitination-based cell cycle indicators (Fucci), HeLa-Fucci (CA)2 and HeLa-Fucci (SA), and combined this approach with the micronucleus (MN) assay to assess radioresponse. The Fucci system distinguishes cell cycle phases based on the colour of fluorescence and cell morphology under live conditions. Time-lapse imaging allowed us to further identify sub-positions within the G1 and S phases at the time of irradiation by two independent means, and to quantitate the number of MNs by following each cell through M phase until the next G1 phase. Notably, we found that radioresponse was low in late G1 phase, but rapidly increased in early S phase. It then decreased until late S phase and increased in G2 phase. For the first time, we demonstrated the unique fluctuation of radioresponse by the MN assay during the cell cycle in HeLa cells. We discuss the difference between previous clonogenic experiments using M phase-synchronised cell populations and ours, as well as the clinical implications of the present findings.

scholarly journals Lamin-binding Fragment of LAP2 Inhibits Increase in Nuclear Volume during the Cell Cycle and Progression into S Phase

1997 ◽  
Vol 139 (5) ◽  
pp. 1077-1087 ◽  
Author(s):  
Li Yang ◽  
Tinglu Guan ◽  
Larry Gerace
Keyword(s):  
Cell Cycle ◽  
Hela Cells ◽  
Nuclear Lamina ◽  
Normal Function ◽  
S Phase ◽  
Nuclear Volume ◽  
G1 Phase ◽  
Binding Region ◽  
Recombinant Polypeptide ◽  
Volume Increase

Lamina-associated polypeptide 2 (LAP2) is an integral membrane protein of the inner nuclear membrane that binds to both lamin B and chromatin and has a putative role in nuclear envelope (NE) organization. We found that microinjection of a recombinant polypeptide comprising the nucleoplasmic domain of rat LAP2 (residues 1–398) into metaphase HeLa cells does not affect the reassembly of transport-competent nuclei containing NEs and lamina, but strongly inhibits nuclear volume increase. This effect appears to be specifically due to lamin binding, because it also is caused by microinjection of the minimal lamin-binding region of LAP2 (residues 298–373) but not by the chromatin-binding domain (residues 1–88). Injection of the lamin-binding region of rat LAP2 into early G1 phase HeLa cells also strongly affects nuclear growth; it almost completely prevents the threefold nuclear volume increase that normally occurs during the ensuing 10 h. Moreover, injection of the fragment during early G1 phase strongly inhibits entry of cells into S phase, whereas injection during S phase has no apparent effect on ongoing DNA replication. Since the lamin-binding fragment of LAP2 most likely acts by inhibiting dynamics of the nuclear lamina, our results suggest that a normal function of LAP2 involves regulation of nuclear lamina growth. These data also suggest that lamina dynamics are required for growth of the NE and for nuclear volume increase during the cell cycle, and that progression into S phase is dependent on the acquisition of a certain nuclear volume.

Molecular cloning of G1 phase mRNAs from a subtractive G1 phase cDNA library

1993 ◽  
Vol 71 (7-8) ◽  
pp. 372-380 ◽  
Author(s):  
Gin Wu ◽  
Shiawhwa Su ◽  
Tzyy-Yun Tzeng Kung ◽  
R. Curtis Bird
Keyword(s):  
Cell Cycle ◽  
Cdna Library ◽  
Light Chain ◽  
Hela Cells ◽  
Subtractive Hybridization ◽  
S Phase ◽  
G1 Phase ◽  
Chain Gene ◽  
Centrifugal Elutriation ◽  
Light Chain Gene

Many G1-phase-specific mRNAs have been identified from various normal or transformed cells based on serum induction and re-entry into the cell cycle from quiescence. However, these mRNAs may not represent some important genes expressed during G1 phase in continuously cycling cells. The eukaryotic cell cycle possesses two cdk (cyclin-dependent kinase) dependent regulatory gates through which cells pass during late G1 phase and G2 phase of each cycle. Subtractive hybridization was employed to synthesize a high R0t fraction cDNA library enriched in sequences expressed during G1 phase prior to passage through the G1-phase gate. To prepare G1-phase cells from continuously cycling cell populations, G1-phase HeLa cells were collected by centrifugal elutriation and highly synchronous S phase cells were obtained by double thymidine block followed by centrifugal elutriation. A G1-phase subtractive cDNA library was prepared by subtracting G1-phase cDNA with a 10-fold excess of S-phase mRNA. Single-stranded, G1-phase cDNAs were isolated by oligo(dA) chromatography. The library was screened with a high R0t fraction subtractive probe population. Following two rounds of screening, 20 positive clones were obtained. Northern blot analysis indicated that six of these clones were enhanced in expression level during G1 phase when compared with S phase. Nucleotide sequence comparison of each clone with the GenBank data base revealed that hG1.11 was highly homologous (99%) to the apoferritin light chain gene and clones hG1.6, hG1.10, hG1.17, and hG1.18 represented new G1-phase-enriched members of four human ribosomal protein gene families (71–95% homology). The last clone, hG1.1, encoded a highly charged polypeptide not previously identified. Additional study of these G1-phase-enriched mRNAs will be required to determine their role in cell cycle progression and the G1-phase gateway through which cells transit as they proceed through the cell cycle.Key words: cell cycle, G1 phase, subtractive hybridization, cDNA cloning, ribosomal proteins, apoferritin light chain, HeLa cells.

scholarly journals Estrogen Receptor Beta Displays Cell Cycle-Dependent Expression and Regulates the G1 Phase through a Non-Genomic Mechanism in Prostate Carcinoma Cells

2008 ◽  
Vol 30 (4) ◽  
pp. 349-365 ◽  
Author(s):  
Antoni Hurtado ◽  
Tomàs Pinós ◽  
Anna Barbosa-Desongles ◽  
Sandra López-Avilés ◽  
Jordi Barquinero ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Cell Cycle ◽  
Estrogen Receptor ◽  
Estrogen Receptor Beta ◽  
Mechanisms Of Action ◽  
S Phase ◽  
G1 Phase ◽  
Over Expression ◽  
M Phase ◽  
Receptor Beta

Background: It is well known that estrogens regulate cell cycle progression, but the specific contributions and mechanisms of action of the estrogen receptor beta (ERβ) remain elusive.Methods: We have analyzed the levels of ERβ1 and ERβ2 throughout the cell cycle, as well as the mechanisms of action and the consequences of the over-expression of ERβ1 in the human prostate cancer LNCaP cell line.Results: Both ERβ1 mRNA and protein expression increased from the G1 to the S phase and decreased before entering the G2/M phase, whereas ERβ2 levels decreased during the S phase and increased in the G2/M phase. ERβ1 protein was detected in both the nuclear and non-nuclear fractions, and ERβ2 was found exclusively in the nucleus. Regarding the mechanisms of action, endogenous ERβ was able to activate transcription via ERE during the S phase in a ligand-dependent manner, whereas no changes in AP1 and NFκB transactivation were observed after exposure to estradiol or the specific inhibitor ICI 182,780. Over-expression of either wild type ERβ1 or ERβ1 mutated in the DNA-binding domain caused an arrest in early G1. This arrest was accompanied by the interaction of over-expressed ERβ1 with c-Jun N-terminal protein kinase 1 (JNK1) and a decrease in c-Jun phosphorylation and cyclin D1 expression. The administration of ICI impeded the JNK1–ERβ1 interaction, increased c-Jun phosphorylation and cyclin D1 expression and allowed the cells to progress to late G1, where they became arrested.Conclusions: Our results demonstrate that, in LNCaP prostate cancer cells, both ERβ isoforms are differentially expressed during the cell cycle and that ERβ regulates the G1 phase by a non-genomic mechanism.

Phosphatidylcholine catabolism in the MCF-7 cell cycle

2006 ◽  
Vol 84 (5) ◽  
pp. 737-744 ◽  
Author(s):  
Weiyang Lin ◽  
Gilbert Arthur
Keyword(s):  
Cell Cycle ◽  
S Phase ◽  
Specific Cell ◽  
Synchronized Cells ◽  
M Phase ◽  
G2 Phase ◽  
Cell Cycle Phases ◽  
Kinetics Of ◽  
Mcf 7

The catabolism of phosphatidylcholine (PtdCho) appears to play a key role in regulating the net accumulation of the lipid in the cell cycle. Current protocols for measuring the degradation of PtdCho at specific cell-cycle phases require prolonged periods of incubation with radiolabelled choline. To measure the degradation of PtdCho at the S and G2 phases in the MCF-7 cell cycle, protocols were developed with radiolabelled lysophosphatidylcholine (lysoPtdCho), which reduces the labelling period and minimizes the recycling of labelled components. Although most of the incubated lysoPtdCho was hydrolyzed to glycerophosphocholine (GroPCho) in the medium, the kinetics of the incorporation of label into PtdCho suggests that the labelled GroPCho did not contribute significantly to cellular PtdCho formation. A protocol which involved exposing the cells twice to hydroxyurea, was also developed to produce highly synchronized MCF-7 cells with a profile of G1:S:G2/M of 90:5:5. An analysis of PtdCho catabolism in the synchronized cells following labelling with lysoPtdCho revealed that there was increased degradation of PtdCho in early to mid-S phase, which was attenuated in the G2/M phase. The results suggest that the net accumulation of PtdCho in MCF-7 cells may occur in the G2 phase of the cell cycle.

scholarly journals hPOC5 is a centrin-binding protein required for assembly of full-length centrioles

2009 ◽  
Vol 185 (1) ◽  
pp. 101-114 ◽  
Author(s):  
Juliette Azimzadeh ◽  
Polla Hergert ◽  
Annie Delouvée ◽  
Ursula Euteneuer ◽  
Etienne Formstecher ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Drosophila Melanogaster ◽  
Hela Cells ◽  
Binding Protein ◽  
Distal Portion ◽  
S Phase ◽  
G1 Phase ◽  
Evolutionary Divergence ◽  
Distal Half

Centrin has been shown to be involved in centrosome biogenesis in a variety of eukaryotes. In this study, we characterize hPOC5, a conserved centrin-binding protein that contains Sfi1p-like repeats. hPOC5 is localized, like centrin, in the distal portion of human centrioles. hPOC5 recruitment to procentrioles occurs during G2/M, a process that continues up to the full maturation of the centriole during the next cell cycle and is correlated with hyperphosphorylation of the protein. In the absence of hPOC5, RPE1 cells arrest in G1 phase, whereas HeLa cells show an extended S phase followed by cell death. We show that hPOC5 is not required for the initiation of procentriole assembly but is essential for building the distal half of centrioles. Interestingly, the hPOC5 family reveals an evolutionary divergence between vertebrates and organisms like Drosophila melanogaster or Caenorhabditis elegans, in which the loss of hPOC5 may correlate with the conspicuous differences in centriolar structure.

scholarly journals Novel phase I study combining G1 phase, S phase, and G2/M phase cell cycle inhibitors in patients with advanced malignancies

Cell Cycle ◽  
2015 ◽  
Vol 14 (21) ◽  
pp. 3434-3440
Author(s):  
Rajul K Jain ◽  
David S Hong ◽  
Aung Naing ◽  
Jennifer Wheler ◽  
Thorunn Helgason ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Phase I ◽  
Phase I Study ◽  
S Phase ◽  
Phase Cell ◽  
G1 Phase ◽  
Advanced Malignancies ◽  
M Phase ◽  
Cell Cycle Inhibitors

scholarly journals Cdc25b and Cdc25c Differ Markedly in Their Properties as Initiators of Mitosis

1999 ◽  
Vol 146 (3) ◽  
pp. 573-584 ◽  
Author(s):  
Christina Karlsson ◽  
Stephanie Katich ◽  
Anja Hagting ◽  
Ingrid Hoffmann ◽  
Jonathon Pines
Keyword(s):  
Cell Cycle ◽  
Nuclear Export ◽  
Time Lapse ◽  
Cyclin B1 ◽  
S Phase ◽  
Cell Cycle Checkpoints ◽  
Culture Cells ◽  
Tissue Culture Cells ◽  
G2 Phase ◽  
Dna Synthesis Inhibitors

We have used time-lapse fluorescence microscopy to study the properties of the Cdc25B and Cdc25C phosphatases that have both been implicated as initiators of mitosis in human cells. To differentiate between the functions of the two proteins, we have microinjected expression constructs encoding Cdc25B or Cdc25C or their GFP-chimeras into synchronized tissue culture cells. This assay allows us to express the proteins at defined points in the cell cycle. We have followed the microinjected cells by time-lapse microscopy, in the presence or absence of DNA synthesis inhibitors, and assayed whether they enter mitosis prematurely or at the correct time. We find that overexpressing Cdc25B alone rapidly causes S phase and G2 phase cells to enter mitosis, whether or not DNA replication is complete, whereas overexpressing Cdc25C does not cause premature mitosis. Overexpressing Cdc25C together with cyclin B1 does shorten the G2 phase and can override the unreplicated DNA checkpoint, but much less efficiently than overexpressing Cdc25B. These results suggest that Cdc25B and Cdc25C do not respond identically to the same cell cycle checkpoints. This difference may be related to the differential localization of the proteins; Cdc25C is nuclear throughout interphase, whereas Cdc25B is nuclear in the G1 phase and cytoplasmic in the S and G2 phases. We have found that the change in subcellular localization of Cdc25B is due to nuclear export and that this is dependent on cyclin B1. Our data suggest that although both Cdc25B and Cdc25C can promote mitosis, they are likely to have distinct roles in the controlling the initiation of mitosis.

CD4+ Lymphocytes in Asymptomatic HTLV-1 Carriers Present Cell Cycle Arrest in G0/G1-Phase

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 5377-5377 ◽  
Author(s):  
Mari Cleia Martins Rodrigues Ferreira ◽  
Renata Kikuchi Foltran ◽  
Rodrigo Santucci ◽  
Luis Alberto de Padua Covas Lage ◽  
Debora Levy ◽  
...  
Keyword(s):  
Cell Cycle ◽  
S Phase ◽  
High Rate ◽  
G1 Phase ◽  
Control Group ◽  
Dna Index ◽  
Asymptomatic Carriers ◽  
M Phase ◽  
And Control ◽  
Cd4 Lymphocytes

Abstract Introduction: Adult T-cell leukemia/lymphoma (ATLL) is an aggressive and incurable disease caused by human T-lymphotropic virus 1 (HTLV-1) that infects CD4+ and CD8+ lymphocytes, but most commonly the malignant cell present a CD4+ phenotype. However, clonal expansion and cell cycle abnormalities have been demonstrated in CD4+ and in CD8+ lymphocytes of HTLV-1 carriers. Objectives: This study compared DNA content and G0/G1, G2/M and “S”-phases of CD4+ and CD8+ lymphocytes among asymptomatic HTLV-1 carriers, ATLL and health subjects. Methods: Werestudied 38 HTLV-1 carriers, 20 ATLL and 35 health subjects pared by sex and age at the Hematology Department of the Faculty of Medicine, University of São Paulo. Peripheral blood mononuclear cells (PBMCs) were isolated on Ficoll-Paque® and lymphocytes subtypes were obtained by positive selection in a magnetic column. Cell-cycle distribution and DNA index (DI) was assessed by flow cytometry after propidium iodide staining. Results: In ATLL, themedian age was 53.5 years (24 to 72) and 50% were female, in HTLV-1 carriers was 55.5 years (33 to 80) with 63.2% of female and in control group was 50 years (24 to 80) with 54.3% of female. In the CD4+ lymphocyte a % of cells in G0/G1 (98.32%) in HTLV-1 carriers was higher than in control group (97.14%) (p=0.041) and in ATLL (97.25%) (p=0.023). S-phase was not statistically different in asymptomatic carriers (0.34%) and control group (0.63%) (p=0.073), but was higher in ATLL (1.80%) than in asymptomatic carriers (0.34%) (p<0.001) and in control group (0.63%) (p=0.02). G2/M-phase was not significantly different among all groups (p=0.960) (Table 1). The CD4+ lymphocytes were aneuploidy in 39.5% (18.4% DI > 1.05 and 21.5% < 0.95) of asymptomatic carriers and in 26.7% (20% > 1.05 and 6.7% < 0.95) of ATLL patients (p=0.557). All control groups were diploid. Table 1.Comparison of the cell cycle by flow cytometry of T lymphocytes CD4+CD4+ cellsAsymptomatic carriersATLLControl groupp-ValueG0/G1mean(dp)97.78 (2.182)95.69 (3.557)96.55 (2.964)0.0351º; median;3ºq97.03;98.32;99.6491.40;97.25;98.3295.01;97.14;98.64G2/Mmean(dp)1.55(1.848)1.91(2.798)2.03(2.902)0.961º; median;3ºq0.00;0.88;2.670.12;0.99;1.990.00;0.56;2.97S-phasemean(dp)0.68(1.207)2.80(3.372)1.43(1.780)0.0031º; median;3ºq0.00;0.34;0.650.65;1.80;3.510.04;0.63;2.55 In CD8+ there was no found significantly difference in whole groups for G0/G1-phase (p=0.138) and G2/M-phase (p=0.374). ATLL presented higher S-phase (median 1.54%) than asymptomatic carriers (median 0.45%) (p=0.003) and control group. S-phase in asymptomatic carriers was not significantly different in comparison to control group (p=0.712). CD8+ were aneuploidy in 23.7% (5.3% DI > 1.05 and 18.4% < 0.95) of asymptomatic carriers and in 21% (10.5% > 1.05 and 10.5% < 0.95) of ATLL (p=0.603). In ATLL the median of DI was 1.01 (1.0; 1.05) in CD4+ and higher than in CD8+ median 0.99 (0.98; 1.0) (p=0.007). Aneuploidia was seen in 47.7% of ATLL, 26,7% (20% DI > 1.05 and 6,7% < 0.95) in CD4+ and 21,0% in CD8+ (10,5% > 1.05 and10,5% < 0.95) (p=0.625). Figure 1: Dna index of CD4+ and CD8+. Aneuploidia was found in HTLV I carriers in both CD4+ and CD8+. Figure 1:. Dna index of CD4+ and CD8+. Aneuploidia was found in HTLV I carriers in both CD4+ and CD8+. Figure 2. Comparison of DI between CD4+ and CD8+ of asymptomatic carriers and ATLL Figure 2. Comparison of DI between CD4+ and CD8+ of asymptomatic carriers and ATLL Figure 3 Figure 3. Conclusion: We demonstrated for the first time “in vivo” that asymptomatic HTLV-1 carriers display cell cycle arrest in G0/G1-phase in CD4+ lymphocytes and high rate of aneuploidia in both CD4+ and CD8+. ATLL showed high rate of hiperdiploidia in CD4+ and hipodiploidia in CD8+ and high rate of S-phase in CD4+. Genetic instability and proliferative disturbs are a hallmark not only in ATLL but also in HTLV-1 carriers and in both CD4+ and CD8+ lymphocytes. Disclosures No relevant conflicts of interest to declare.

scholarly journals Transforming growth factor β decreases the rate of proliferation of rat vascular smooth muscle cells by extending the G2 phase of the cell cycle and delays the rise in cyclic AMP before entry into M phase

1994 ◽  
Vol 299 (1) ◽  
pp. 227-235 ◽  
Author(s):  
D J Grainger ◽  
P R Kemp ◽  
C M Witchell ◽  
P L Weissberg ◽  
J C Metcalfe
Keyword(s):  
Cell Cycle ◽  
Smooth Muscle ◽  
Growth Factor ◽  
Cyclic Amp ◽  
Vascular Smooth Muscle Cells ◽  
Transforming Growth Factor ◽  
S Phase ◽  
Tgf Beta ◽  
M Phase ◽  
G2 Phase

Transforming growth factor beta 1 (TGF-beta 1) decreased the rate of proliferation of rat aortic vascular smooth muscle cells (VSMCs) stimulated with serum showing a maximal effect at > 5 ng/ml (200 pM). However, it did not reduce the proportion of cells which passed through S phase (> 90%) and entry into S phase was delayed by less than 3 h. The proportion of cells passing through M phase (> 90%) was also unaffected, but entry into mitosis was delayed by approx. 24 h. This increase in cell cycle time was therefore due mainly to an increase in the G2 to mitotic metaphase period. Addition of TGF-beta 1 late in G1 or late in S phase failed to delay the onset of mitosis, but the presence of TGF-beta 1 between 0 and 12 h after the addition of serum to quiescent cells was sufficient to cause the maximal delay in mitosis of approx. 24 h. The role of cyclic AMP in the mechanism of the TGF-beta 1 effects on the cell cycle was examined. Entry into mitosis was preceded by a transient 2-fold increase in cyclic AMP concentration and TGF-beta 1 delayed both this increase in cyclic AMP and entry into mitosis to the same extent. Addition of forskolin or 8-(4-chlorophenylthio)-cyclic AMP to cells 30 h after stimulation with serum completely reversed the increase in duration of G2 in the presence of TGF-beta 1, suggesting that the rise in cyclic AMP levels which precedes mitosis might trigger entry of the VSMCs into M phase. Addition of forskolin late in S phase (26 h after stimulation with serum) advanced the entry of the cells into M phase and they divided prematurely. This effect was unaffected by the addition of cycloheximide with the forskolin; however, the effect of forskolin on cell division was completely inhibited when cycloheximide was added late in G1. TGF-beta 1 prevented the loss of smooth-muscle-specific myosin heavy chain (SM-MHC), which occurs in primary VSMC cultures in the presence or absence of serum, and the cells proliferated while maintaining a differentiated phenotype. However, TGF-beta 1 did not cause re-differentiation of subcultured VSMCs which contained very low amounts of SM-MHC and the effect of TGF-beta 1 in extending the G2 phase of the cell cycle is exerted independently of its effect on differentiation.

scholarly journals S-Phase Synchronization Facilitates the Early Progression of Induced-Cardiomyocyte Reprogramming through Enhanced Cell-Cycle Exit

2018 ◽  
Author(s):  
Emre Bektik ◽  
Adrienne Dennis ◽  
Gary Pawlowski ◽  
Danielle Maleski ◽  
Satoru Takahashi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Phase Synchronization ◽  
Time Lapse ◽  
S Phase ◽  
Great Promise ◽  
Cell Cycle Exit ◽  
Early Progression ◽  
Fundamental Biological Process ◽  
Time Lapse Imaging ◽  
Cycle Regulation

Direct reprogramming of fibroblasts into induced cardiomyocytes (iCMs) holds a great promise for regenerative medicine and has been studied in several major directions. However, cell-cycle regulation, a fundamental biological process, has not been investigated during iCM-reprogramming. Here, our time-lapse imaging on iCMs, reprogrammed by Gata4, Mef2c, and Tbx5 (GMT) monocistronic retroviruses, revealed that iCM-reprogramming was majorly initiated at late-G1- or S-phase and nearly half of GMT-reprogrammed iCMs divided soon after reprogramming. iCMs exited cell cycle along the process of reprogramming with decreased percentage of EdU+/&alpha;MHC-GFP+ cells. S-phase synchronization post-GMT-infection could enhance cell-cycle exit of reprogrammed iCMs and yield more GFPhigh iCMs, which achieved an advanced reprogramming with more expression of cardiac genes than GFPlow cells; however, S-phase synchronization didn&rsquo;t enhance the polycistronic-MGT reprogramming, in which cell-cycle exit had been accelerated. In conclusion, post-infection synchronization of S-phase facilitated the early progression of GMT-reprogramming through a mechanism of enhanced cell-cycle exit.

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