scholarly journals A quantised cyclin-based cell cycle model

2020 ◽  
Author(s):  
Chris Emerson ◽  
Lindsey Bennie ◽  
Dermot Green ◽  
Fred Currell ◽  
Jonathan A. Coulter
Keyword(s):  
Cell Cycle ◽  
Gene Networks ◽  
Cell Cycle Progression ◽  
Tumour Growth ◽  
Computational Modelling ◽  
Cycle Progression ◽  
Mutational Status ◽  
Cyclin Protein ◽  
The Absolute ◽  
The Impact

AbstractComputational modelling is an important research tool, helping predict the outcome of proposed treatment plans or to illuminate the mechanics of tumour growth. In silico modelling has been used in every aspect of cancer research from DNA damage and repair, tumour growth, drug/tumour interactions, and mutational status. Indeed, modelling even holds potential in understanding the interactions between individual proteins on a single cell basis. Here, we present a computational model of the cell cycle network of the cyclin family of proteins (cyclin A, B, D and E). This model has been quantised using western blot and flow cytometry data from a synchronised HUVEC line to enable the determination of the absolute number of cyclin protein molecules per cell. This quantification allows the model to have stringent controls over the thresholds between transitions. The results show that the peak values obtained for the four cyclins are similar with cyclin B having a peak values of 5×106 to 9×106 molecules per cell. Comparing this value with the number of actin proteins, 5E8, shows that despite their importance, the level of cyclin family proteins are approximately 2 orders of magnitude lower. The efficiency of the model presented would also allow for its use as an internal component in more complex models such as a tumour growth model, in which each individual cell would have its own cell cycle calculated independently from neighbouring cells. Additionally, the model can also be used to help understand the impact of novel therapeutic interventions on cell cycle progression.Author SummaryProtein and gene networks control every physiological behaviour of cells, with the cell cycle being controlled by the network of genes that promote the cyclin family of proteins. These networks hold the key to creating accurate and relevant biological models. Normally these models are presented with relative protein concentrations without any real world counterpart to their outputs. The model presented within shows and advancement of this approach by calculating the absolute concentration of each cyclin protein in one cell as it progresses through the cell cycle. This model employs Boolean variables to represent the genetic network, either the gene is active or not, and continuous variables to represent the concentrations of the proteins. This hybridised approach allows for rapid calculations of the protein concentrations and of the cell cycle progression allowing for a model that could be easily incorporated into larger tumour models, allowing for the tracking of discrete cells within the tumour.

Life after meiosis: patterning the angiosperm male gametophyte

2010 ◽  
Vol 38 (2) ◽  
pp. 577-582 ◽  
Author(s):  
Michael Borg ◽  
David Twell
Keyword(s):  
Cell Cycle ◽  
Cell Fate ◽  
Cell Cycle Progression ◽  
Male Gametophyte ◽  
Cell Fate Determination ◽  
Double Fertilization ◽  
Cycle Progression ◽  
Fate Determination ◽  
Male Gametogenesis ◽  
The Impact

Pollen grains represent the highly reduced haploid male gametophyte generation in angiosperms. They play an essential role in plant fertility by generating and delivering twin sperm cells to the embryo sac to undergo double fertilization. The functional specialization of the male gametophyte and double fertilization are considered to be key innovations in the evolutionary success of angiosperms. The haploid nature of the male gametophyte and its highly tractable ontogeny makes it an attractive system to study many fundamental biological processes, such as cell fate determination, cell-cycle progression and gene regulation. The present mini-review encompasses key advances in our understanding of the molecular mechanisms controlling male gametophyte patterning in angiosperms. A brief overview of male gametophyte development is presented, followed by a discussion of the genes required at landmark events of male gametogenesis. The value of the male gametophyte as an experimental system to study the interplay between cell fate determination and cell-cycle progression is also discussed and exemplified with an emerging model outlining the regulatory networks that distinguish the fate of the male germline from its sister vegetative cell. We conclude with a perspective of the impact emerging data will have on future research strategies and how they will develop further our understanding of male gametogenesis and plant development.

scholarly journals P2Y2 purinergic receptor activation is essential for efficient hepatocyte proliferation in response to partial hepatectomy

2014 ◽  
Vol 307 (11) ◽  
pp. G1073-G1087 ◽  
Author(s):  
Bryan C. Tackett ◽  
Hongdan Sun ◽  
Yu Mei ◽  
Janielle P. Maynard ◽  
Sayuri Cheruvu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Partial Hepatectomy ◽  
Cell Cycle Progression ◽  
Purinergic Receptors ◽  
Purinergic Receptor ◽  
Receptor Activation ◽  
Hepatocyte Proliferation ◽  
Receptor Subtypes ◽  
Cycle Progression ◽  
The Impact

Extracellular nucleotides via activation of P2 purinergic receptors influence hepatocyte proliferation and liver regeneration in response to 70% partial hepatectomy (PH). Adult hepatocytes express multiple P2Y (G protein-coupled) and P2X (ligand-gated ion channels) purinergic receptor subtypes. However, the identity of key receptor subtype(s) important for efficient hepatocyte proliferation in regenerating livers remains unknown. To evaluate the impact of P2Y2 purinergic receptor-mediated signaling on hepatocyte proliferation in regenerating livers, wild-type (WT) and P2Y2 purinergic receptor knockout (P2Y2−/−) mice were subjected to 70% PH. Liver tissues were analyzed for activation of early events critical for hepatocyte priming and subsequent cell cycle progression. Our findings suggest that early activation of p42/44 ERK MAPK (5 min), early growth response-1 (Egr-1) and activator protein-1 (AP-1) DNA-binding activity (30 min), and subsequent hepatocyte proliferation (24–72 h) in response to 70% PH were impaired in P2Y2−/− mice. Interestingly, early induction of cytokines (TNF-α, IL-6) and cytokine-mediated signaling (NF-κB, STAT-3) were intact in P2Y2−/− remnant livers, uncovering the importance of cytokine-independent and nucleotide-dependent early priming events critical for subsequent hepatocyte proliferation in regenerating livers. Hepatocytes isolated from the WT and P2Y2−/− mice were treated with ATP or ATPγS for 5–120 min and 12–24 h. Extracellular ATP alone, via activation of P2Y2 purinergic receptors, was sufficient to induce ERK phosphorylation, Egr-1 protein expression, and key cyclins and cell cycle progression of hepatocytes in vitro. Collectively, these findings highlight the functional significance of P2Y2 purinergic receptor activation for efficient hepatocyte priming and proliferation in response to PH.

scholarly journals Genotypic and Phenotypic Variables Affect Meiotic Cell Cycle Progression, Tumor Ploidy, and Cancer-Associated Mortality in a brca2-Mutant Zebrafish Model

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
L. Mensah ◽  
J. L. Ferguson ◽  
H. R. Shive
Keyword(s):  
Cell Cycle ◽  
Cancer Cells ◽  
Germ Cells ◽  
Cell Cycle Progression ◽  
Chromosomal Abnormalities ◽  
Somatic Cells ◽  
Zebrafish Model ◽  
Cycle Progression ◽  
Human Cancers ◽  
The Impact

Successful cell replication requires both cell cycle completion and accurate chromosomal segregation. The tumor suppressor BRCA2 is positioned to influence both of these outcomes, and thereby influence genomic integrity, during meiotic and mitotic cell cycles. Accordingly, mutations in BRCA2 induce chromosomal abnormalities and disrupt cell cycle progression in both germ cells and somatic cells. Despite these findings, aneuploidy is not more prevalent in BRCA2-associated versus non-BRCA2-associated human cancers. More puzzlingly, diploidy in BRCA2-associated cancers is a negative prognostic factor, unlike non-BRCA2-associated cancers and many other human cancers. We used a brca2-mutant/tp53-mutant cancer-prone zebrafish model to explore the impact of BRCA2 mutation on cell cycle progression, ploidy, and cancer-associated mortality by performing DNA content/cell cycle analysis on zebrafish germ cells, somatic cells, and cancer cells. First, we determined that combined brca2/tp53 mutations uniquely disrupt meiotic progression. Second, we determined that sex significantly influences ploidy outcome in zebrafish cancers. Third, we determined that brca2 mutation and female sex each significantly reduce survival time in cancer-bearing zebrafish. Finally, we provide evidence to support a link between BRCA2 mutation, tumor diploidy, and poor survival outcome. These outcomes underscore the utility of this model for studying BRCA2-associated genomic aberrations in normal and cancer cells.

scholarly journals Kaempferol and Its Glycoside Derivatives as Modulators of Etoposide Activity in HL-60 Cells

2021 ◽  
Author(s):  
Magdalena Kluska ◽  
Michał Juszczak ◽  
Jerzy Żuchowski ◽  
Anna Stochmal ◽  
Katarzyna Woźniak
Keyword(s):  
Cell Cycle ◽  
Free Radicals ◽  
Lens Culinaris ◽  
Cell Cycle Progression ◽  
Opposite Effect ◽  
Cycle Progression ◽  
Aerial Parts ◽  
Proliferation And Apoptosis ◽  
Antitumor Properties ◽  
The Impact

Abstract Kaempferol is a polyphenol found in a variety of plants. Kaempferol has antitumor properties by affecting proliferation and apoptosis of cancer cells. We investigated whether kaempferol and its glycoside derivatives: kaempferol 3-O-[(6-O-E-caffeoyl)-β-D-glucopyranosyl-(1→2)]-β-D-galactopyranoside-7-O-β-D -glucuropyranoside (P2), kaempferol 3-O-[(6-O-E-p-coumaroyl)-β-D-glucopyranosyl-(1→2)]-β-D-galactopyranoside-7-O-β-D-glucuropyranoside (P5) and kaempferol 3-O-[(6-O-E-feruloyl)-β-D-glucopyranosyl-(1→2)]-β-D-galactopyranoside-7-O-β-D-glucuropyranoside (P7) isolated from aerial parts of Lens culinaris Medik. affect the antitumor activity of etoposide in HL-60 cells. We analyzed the effect of kaempferol and its derivatives on cytotoxicity, DNA damage, apoptosis, cell cycle progression and free radicals induced by etoposide. We also studied the impact of kaempferol and its derivatives on the expression of HO-1 and Nrf-2 genes in HL-60 cells. We demonstrated that kaempferol increases the sensitivity of HL-60 cells to etoposide but does not affect apoptosis induced by this drug. Kaempferol also reduces the level of free radicals generated by etoposide. Unlike kaempferol, some of its derivatives reduce the apoptosis of HL-60 cells (P2 and P7) and increase the level of free radicals (P2 and P5) induced by etoposide. Our results indicate that kaempferol derivatives may have an opposite effect on the action of etoposide in HL-60 cells compared to kaempferol.

scholarly journals The contribution of lincRNAs at the interface between cell cycle regulation and cell state maintenance

2019 ◽  
Author(s):  
Adriano Biasini ◽  
Adam Alexander Thil Smith ◽  
Baroj Abdulkarim ◽  
Jennifer Yihong Tan ◽  
Maria Ferreira da Silva ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Stem Cell ◽  
Embryonic Stem Cell ◽  
Cell Cycle Progression ◽  
Embryonic Stem ◽  
Differentially Expressed ◽  
Cell Cycle Regulators ◽  
Cycle Progression ◽  
Cell State ◽  
The Impact

ABSTRACTCell cycle progression requires dynamic and tightly-regulated transitions between well-defined cell cycle stages. These transitions are controlled by the interplay of established cell cycle regulators. Changes in the activity of these regulators are thought to underpin differences in cell cycle kinetics between distinct cell types. Here, we investigate whether cell type-specific long intergenic noncoding RNAs (lincRNAs) contribute to embryonic stem cell adaptations, which have been shown to be essential for the maintenance of embryonic stem cell state.We used single cell RNA-sequencing data of mouse embryonic stem cells (mESC) staged as G1, S, or G2/M to identify genes differentially expressed between these phases. We found differentially expressed lincRNAs to be enriched amongst cell cycle regulated genes. These cell cycle associated lincRNAs (CC-lincRNAs) are co-expressed with protein-coding genes with established roles in cell cycle progression. Interestingly, 70% of CC-lincRNAs are differentially expressed between G1 and S, suggesting they may contribute to the maintenance of the short G1 phase that characterizes the embryonic stem cell cycle. Consistent with this hypothesis, the promoters of CC-lincRNAs are enriched in pluripotency transcription factor binding sites, and their transcripts are frequently co-regulated with genes involved in the maintenance of pluripotency. We tested the impact of 2 CC-lincRNA candidates and show that modulation of their expression is associated with impaired cell cycle progression, further underlining the contribution of mESC-specific lincRNAs to cell cycle modulation in these cells.

scholarly journals Flavin Oxidase-Induced ROS Generation Modulates PKC Biphasic Effect of Resveratrol on Endothelial Cell Survival

Biomolecules ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 209 ◽  
Author(s):  
Anna Maria Posadino ◽  
Roberta Giordo ◽  
Annalisa Cossu ◽  
Gheyath K. Nasrallah ◽  
Abdullah Shaito ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Dna Synthesis ◽  
Cell Survival ◽  
Cellular Response ◽  
Cell Cycle Progression ◽  
Natural Antioxidants ◽  
Cycle Progression ◽  
Protein Levels ◽  
The Impact

Background: Dietary intake of natural antioxidants is thought to impart protection against oxidative-associated cardiovascular diseases. Despite many in vivo studies and clinical trials, this issue has not been conclusively resolved. Resveratrol (RES) is one of the most extensively studied dietary polyphenolic antioxidants. Paradoxically, we have previously demonstrated that high RES concentrations exert a pro-oxidant effect eventually elevating ROS levels leading to cell death. Here, we further elucidate the molecular determinants underpinning RES-induced oxidative cell death. Methods: Using human umbilical vein endothelial cells (HUVECs), the effect of increasing concentrations of RES on DNA synthesis and apoptosis was studied. In addition, mRNA and protein levels of cell survival or apoptosis genes, as well as protein kinase C (PKC) activity were determined. Results: While high concentrations of RES reduce PKC activity, inhibit DNA synthesis and induce apoptosis, low RES concentrations elicit an opposite effect. This biphasic concentration-dependent effect (BCDE) of RES on PKC activity is mirrored at the molecular level. Indeed, high RES concentrations upregulate the proapoptotic Bax, while downregulating the antiapoptotic Bcl-2, at both mRNA and protein levels. Similarly, high RES concentrations downregulate the cell cycle progression genes, c-myc, ornithine decarboxylase (ODC) and cyclin D1 protein levels, while low RES concentrations display an increasing trend. The BCDE of RES on PKC activity is abrogated by the ROS scavenger Tempol, indicating that this enzyme acts downstream of the RES-elicited ROS signaling. The RES-induced BCDE on HUVEC cell cycle machinery was also blunted by the flavin inhibitor diphenyleneiodonium (DPI), implicating flavin oxidase-generated ROS as the mechanistic link in the cellular response to different RES concentrations. Finally, PKC inhibition abrogates the BCDE elicited by RES on both cell cycle progression and pro-apoptotic gene expression in HUVECs, mechanistically implicating PKC in the cellular response to different RES concentrations. Conclusions: Our results provide new molecular insight into the impact of RES on endothelial function/dysfunction, further confirming that obtaining an optimal benefit of RES is concentration-dependent. Importantly, the BCDE of RES could explain why other studies failed to establish the cardio-protective effects mediated by natural antioxidants, thus providing a guide for future investigation looking at cardio-protection by natural antioxidants.

Control of p21Cip by BRCA1-associated protein is critical for cardiomyocyte cell cycle progression and survival

2019 ◽  
Vol 116 (3) ◽  
pp. 592-604 ◽  
Author(s):  
Cornelia Volland ◽  
Peter Schott ◽  
Michael Didié ◽  
Jörg Männer ◽  
Bernhard Unsöld ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Cell Cycle Regulation ◽  
Cell Cycle Progression ◽  
Kinase Inhibitor ◽  
Ki 67 ◽  
Cycle Progression ◽  
Developmental Arrest ◽  
Cycle Regulation ◽  
The Impact

Abstract Aims Identifying the key components in cardiomyocyte cell cycle regulation is of relevance for the understanding of cardiac development and adaptive and maladaptive processes in the adult myocardium. BRCA1-associated protein (BRAP) has been suggested as a cytoplasmic retention factor for several proteins including Cyclin-dependent-kinase inhibitor p21Cip. We observed profound expressional changes of BRAP in early postnatal myocardium and investigated the impact of BRAP on cardiomyocyte cell cycle regulation. Methods and results General knockout of Brap in mice evoked embryonic lethality associated with reduced myocardial wall thickness and lethal cardiac congestion suggesting a prominent role for BRAP in cardiomyocyte proliferation. αMHC-Cre driven cardiomyocyte-specific knockout of Brap also evoked lethal cardiac failure shortly after birth. Likewise, conditional cardiomyocyte-specific Brap deletion using tamoxifen-induced knockout in adult mice resulted in marked ventricular dilatation and heart failure 3 weeks after induction. Several lines of evidence suggest that Brap deletion evoked marked inhibition of DNA synthesis and cell cycle progression. In cardiomyocytes with proliferative capacity, this causes developmental arrest, whereas in adult hearts loss of BRAP-induced apoptosis. This is explained by altered signalling through p21Cip which we identify as the link between BRAP and cell cycle/apoptosis. BRAP deletion enhanced p21Cip expression, while BRAP overexpression in cardiomyocyte-specific transgenic mice impeded p21Cip expression. That was paralleled by enhanced nuclear Ki-67 expression and DNA synthesis. Conclusion By controlling p21Cip activity BRAP expression controls cell cycle activity and prevents developmental arrest in developing cardiomyocytes and apoptosis in adult cardiomyocytes.

Phenotypic Characterization of Targeted Knockdown of Cyclin-Dependent Kinases in the Intestinal Epithelial Cells

2020 ◽  
Vol 177 (1) ◽  
pp. 226-234 ◽  
Author(s):  
Shuyan Lu ◽  
Tae Sung ◽  
Marina Amaro ◽  
Brad Hirakawa ◽  
Bart Jessen ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Epithelial Cells ◽  
Cell Cycle Progression ◽  
Intestinal Epithelial Cells ◽  
Intestinal Cell ◽  
Cdk Inhibitors ◽  
Intestinal Epithelial ◽  
Cycle Progression ◽  
Cyclin Dependent Kinases ◽  
The Impact

Abstract Cyclin-dependent kinases (CDKs) are serine/threonine kinases that regulate cell cycle and have been vigorously pursued as druggable targets for cancer. There are over 20 members of the CDK family. Given their structural similarity, selective inhibition by small molecules has been elusive. In addition, collateral damage to highly proliferative normal cells by CDK inhibitors remains a safety concern. Intestinal epithelial cells are highly proliferative and the impact of individual CDK inhibition on intestinal cell proliferation has not been well studied. Using the rat intestinal epithelial (IEC6) cells as an in vitro model, we found that the selective CDK4/6 inhibitor palbociclib lacked potent anti-proliferative activity in IEC6 relative to the breast cancer cell line MCF7, indicating the absence of intestinal cell reliance on CDK4/6 for cell cycle progression. To further illustrate the role of CDKs in intestinal cells, we chose common targets of CDK inhibitors (CDK 1, 2, 4, 6, and 9) for targeted gene knockdown to evaluate phenotypes. Surprisingly, only CDK1 and CDK9 knockdown demonstrated profound cell death or had moderate growth effects, respectively. CDK2, 4, or 6 knockdowns, whether single, double, or triple combinations, did not have substantial impact. Studies evaluating CDK1 knockdown under various cell seeding densities indicate direct effects on viability independent of proliferation state and imply a potential noncanonical role for CDK1 in intestinal epithelial biology. This research supports the concept that CDK1 and CDK9, but not CDKs 2, 4, or 6, are essential for intestinal cell cycle progression and provides safety confidence for interphase CDK inhibition.

scholarly journals Impact of overexpression of metallothionein-1 on cell cycle progression and zinc toxicity

2008 ◽  
Vol 295 (5) ◽  
pp. C1399-C1408 ◽  
Author(s):  
Paul J. Smith ◽  
Marie Wiltshire ◽  
Emeline Furon ◽  
John H. Beattie ◽  
Rachel J. Errington
Keyword(s):  
Cell Cycle ◽  
Steady State ◽  
Cell Cycle Progression ◽  
Cellular Stress ◽  
Zinc Homeostasis ◽  
Zinc Toxicity ◽  
Cycle Progression ◽  
Intracellular Zinc ◽  
Endogenous Expression ◽  
The Impact

Metallothioneins (MTs) have an important role in zinc homeostasis and may counteract the impact of oversupply. Both intracellular zinc and MT expression have been implicated in proliferation control and resistance to cellular stress, although the interdependency is unclear. The study addresses the consequences of a steady-state overexpression of MT-1 for intracellular zinc levels, cell cycle progression, and protection from zinc toxicity using a panel of cell lines with differential expression of MT-1. The panel comprised parental Chinese hamster ovary-K1 cells with low endogenous expression of MT and transfectants with enhanced expression of mouse MT-1 on an autonomously replicating expression vector with a noninducible promoter. Cell cycle progression, determined by flow cytometry and time-lapse microscopy, revealed that enhanced cytoplasmic expression of MT-1 does not impact on normal cell cycle operation, suggesting that basal levels of MT-1 expression are not limiting for background levels of oxidative stress. MT-1 overexpression correlated with a steady-state increase in cytoplasmic free Zn2+, assessed using the fluorescent zinc-sensor Zinquin, particularly at high levels of overexpression, further suggesting that zinc availability is normally not limiting for cell cycle progression. Enhanced MT-1 expression, over a 10-fold range, had a clear impact on resistance to Cd2+ and Zn2+ toxicity. In the case of Zn2+, the degree of protection afforded was less, indicating that MT-1 has a limited range and saturable capacity for effecting resistance. The results have implications for the use of cellular stress responses to exogenously supplied zinc and zinc-based systemic therapies.

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