scholarly journals Centrosome Clustering in the Development of Bovine Binucleate Trophoblast Giant Cells

2016 ◽  
Vol 203 (5) ◽  
pp. 287-294 ◽  
Author(s):  
Karl Klisch ◽  
Elisabeth M. Schraner ◽  
Alois Boos
Keyword(s):  
Cell Cycle ◽  
Tumor Cells ◽  
Molecular Mechanisms ◽  
Giant Cells ◽  
Cell Nuclei ◽  
Pericentriolar Material ◽  
A Cell ◽  
Pass Through ◽  
Diploid Cells ◽  
Trophoblast Giant Cells

Binucleate trophoblast giant cells (BNC) are the characteristic feature of the ruminant placenta. During their development, BNC pass through 2 acytokinetic mitoses and become binucleate with 2 tetraploid nuclei. In this study, we investigate the number and location of centrosomes in bovine BNC. Centrosomes typically consist of 2 centrioles surrounded by electron-dense pericentriolar material. Duplication of centrosomes is tightly linked to the cell cycle, which ensures that the number of centrosomes remains constant in proliferating diploid cells. Alterations of the cell cycle, which affect the number of chromosome sets, also affect the number of centrosomes. In this study, we use placentomal tissue from pregnant cows (gestational days 80-230) for immunohistochemical staining of γ-tubulin (n = 3) and transmission electron microscopy (n = 3). We show that mature BNC have 4 centrosomes with 8 centrioles, clustered in the angle between the 2 cell nuclei. During the second acytokinetic mitosis, the centrosomes must be clustered to form the poles of a bipolar spindle. In rare cases, centrosome clustering fails and tripolar mitosis leads to the formation of trinucleate “BNC”. Generally, centrosome clustering occurs in polyploid tumor cells, which have an increased number of centrioles, but it is absent in proliferating diploid cells. Thus, inhibition of centrosome clustering in tumor cells is a novel promising strategy for cancer treatment. BNC are a cell population in which centrosome clustering occurs as part of the normal life history. Thus, they might be a good model for the study of the molecular mechanisms of centrosome clustering.

scholarly journals Repurposing of KLF5 activates a cell cycle signature during the progression from a precursor state to Oesophageal Adenocarcinoma

2020 ◽  
Author(s):  
Connor Rogerson ◽  
Samuel Ogden ◽  
Edward Britton ◽  
Yeng Ang ◽  
Andrew D. Sharrocks ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Prognostic Significance ◽  
Gene Expression Signature ◽  
Chromatin Accessibility ◽  
Oesophageal Adenocarcinoma ◽  
Cell Cycle Gene ◽  
A Cell

AbstractOesophageal adenocarcinoma (OAC) is one of the most common causes of cancer deaths and yet compared to other common cancers, we know relatively little about the underlying molecular mechanisms. Barrett’s oesophagus (BO) is the only known precancerous precursor to OAC, but our understanding about the specific events leading to OAC development is limited. Here, we have integrated gene expression and chromatin accessibility profiles of human biopsies of BO and OAC and identified a strong cell cycle gene expression signature in OAC compared to BO. Through analysing associated chromatin accessibility changes, we have implicated the transcription factor KLF5 in the transition from BO to OAC. Importantly, we show that KLF5 expression is unchanged during this transition, but instead, KLF5 is redistributed across chromatin in OAC cells to directly regulate cell cycle genes specifically in OAC. Our findings have potential prognostic significance as the survival of patients with high expression of KLF5 target genes is significantly lower. We have provided new insights into the gene expression networks in OAC and the mechanisms behind progression to OAC, chiefly the repurposing of KLF5 for novel regulatory activity in OAC.

scholarly journals Tumor quiescence: elevating SOX2 in diverse tumor cell types downregulates a broad spectrum of the cell cycle machinery and inhibits tumor growth

BMC Cancer ◽  
2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Ethan P. Metz ◽  
Erin L. Wuebben ◽  
Phillip J. Wilder ◽  
Jesse L. Cox ◽  
Kaustubh Datta ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Tumor Growth ◽  
Tumor Cell ◽  
Tumor Cells ◽  
Molecular Mechanisms ◽  
Cell Types ◽  
Cell Cycle Machinery

Abstract Background Quiescent tumor cells pose a major clinical challenge due to their ability to resist conventional chemotherapies and to drive tumor recurrence. Understanding the molecular mechanisms that promote quiescence of tumor cells could help identify therapies to eliminate these cells. Significantly, recent studies have determined that the function of SOX2 in cancer cells is highly dose dependent. Specifically, SOX2 levels in tumor cells are optimized to promote tumor growth: knocking down or elevating SOX2 inhibits proliferation. Furthermore, recent studies have shown that quiescent tumor cells express higher levels of SOX2 compared to adjacent proliferating cells. Currently, the mechanisms through which elevated levels of SOX2 restrict tumor cell proliferation have not been characterized. Methods To understand how elevated levels of SOX2 restrict the proliferation of tumor cells, we engineered diverse types of tumor cells for inducible overexpression of SOX2. Using these cells, we examined the effects of elevating SOX2 on their proliferation, both in vitro and in vivo. In addition, we examined how elevating SOX2 influences their expression of cyclins, cyclin-dependent kinases (CDKs), and p27Kip1. Results Elevating SOX2 in diverse tumor cell types led to growth inhibition in vitro. Significantly, elevating SOX2 in vivo in pancreatic ductal adenocarcinoma, medulloblastoma, and prostate cancer cells induced a reversible state of tumor growth arrest. In all three tumor types, elevation of SOX2 in vivo quickly halted tumor growth. Remarkably, tumor growth resumed rapidly when SOX2 returned to endogenous levels. We also determined that elevation of SOX2 in six tumor cell lines decreased the levels of cyclins and CDKs that control each phase of the cell cycle, while upregulating p27Kip1. Conclusions Our findings indicate that elevating SOX2 above endogenous levels in a diverse set of tumor cell types leads to growth inhibition both in vitro and in vivo. Moreover, our findings indicate that SOX2 can function as a master regulator by controlling the expression of a broad spectrum of cell cycle machinery. Importantly, our SOX2-inducible tumor studies provide a novel model system for investigating the molecular mechanisms by which elevated levels of SOX2 restrict cell proliferation and tumor growth.

scholarly journals Gcn5-mediated acetylation at MBF-regulated promoters induces the G1/S transcriptional wave

2019 ◽  
Vol 47 (16) ◽  
pp. 8439-8451 ◽  
Author(s):  
Alberto González-Medina ◽  
Elena Hidalgo ◽  
José Ayté
Keyword(s):  
Cell Cycle ◽  
Molecular Mechanisms ◽  
Histone H3 ◽  
Dependent Manner ◽  
Saga Complex ◽  
Lysine Residues ◽  
Physical Barriers ◽  
A Cell ◽  
Cycle Dependent ◽  
Regulated Promoters

Abstract In fission yeast, MBF-dependent transcription is inactivated at the end of S phase through a negative feedback loop that involves the co-repressors, Yox1 and Nrm1. Although this repression system is well known, the molecular mechanisms involved in MBF activation remain largely unknown. Compacted chromatin constitutes a barrier to activators accessing promoters. Here, we show that chromatin regulation plays a key role in activating MBF-dependent transcription. Gcn5, a part of the SAGA complex, binds to MBF-regulated promoters through the MBF co-activator Rep2 in a cell cycle-dependent manner and in a reverse correlation to the binding of the MBF co-repressors, Nrm1 or Yox1. We propose that the co-repressors function as physical barriers to SAGA recruitment onto MBF promoters. We also show that Gcn5 acetylates specific lysine residues on histone H3 in a cell cycle-regulated manner. Furthermore, either in a gcn5 mutant or in a strain in which histone H3 is kept in an unacetylated form, MBF-dependent transcription is downregulated. In summary, Gcn5 is required for the full activation and correct timing of MBF-regulated gene transcription.

S-phase-specific expression of the Mad3 gene in proliferating and differentiating cells

2001 ◽  
Vol 359 (2) ◽  
pp. 361-367 ◽  
Author(s):  
Elizabeth J. FOX ◽  
Stephanie C. WRIGHT
Keyword(s):  
Cell Cycle ◽  
Cellular Proliferation ◽  
Cultured Cells ◽  
S Phase ◽  
Proliferating Cells ◽  
Specific Expression ◽  
Related Function ◽  
Erythroleukemia Cells ◽  
A Cell ◽  
Pass Through

The Myc/Max/Mad transcription factor network plays a central role in the control of cellular proliferation, differentiation and apoptosis. In order to elucidate the biological function of Mad3, we have analysed the precise temporal patterns of Mad3 mRNA expression during the cell cycle and differentiation in cultured cells. We show that Mad3 is induced at the G1/S transition in proliferating cells; expression persists throughout S-phase, and then declines as cells pass through G2 and mitosis. The expression pattern of Mad3 is coincident with that of Cdc2 throughout the cell cycle. In contrast, the expression of Mad3 during differentiation of cultured mouse erythroleukemia cells shows two transient peaks of induction. The first of these occurs at the onset of differentiation, and does not correlate with the S-phase of the cell cycle, whereas the second is coincident with the S-phase burst that precedes the terminal stages of differentiation. Our results therefore suggest that Mad3 serves a cell-cycle-related function in both proliferating and differentiating cells, and that it may also have a distinct role at various stages of differentiation.

Hydrogen peroxide regulates angiogenesis-related factors in tumor cells

2017 ◽  
Vol 95 (6) ◽  
pp. 679-685 ◽  
Author(s):  
Ana Jerónimo ◽  
Gonçalo Rodrigues ◽  
Filipe Vilas-Boas ◽  
Gabriel G. Martins ◽  
Ana Bagulho ◽  
...  
Keyword(s):  
Tumor Cells ◽  
Tumor Angiogenesis ◽  
Molecular Mechanisms ◽  
Tumor Development ◽  
Angiogenic Factors ◽  
Related Factors ◽  
Tumor Neovascularization ◽  
A Cell ◽  
Vessel Network ◽  
Xenografted Tumor

Tumor angiogenesis is required for tumor development and growth, and is regulated by several factors including ROS. H2O2 is a ROS with an important role in cell signaling, but how H2O2 regulates tumor angiogenesis is still poorly understood. We have xenografted tumor cells with altered levels of H2O2 by catalase overexpression into zebrafish embryos to study redox-induced tumor neovascularization. We found that vascular recruitment and invasion were impaired if catalase was overexpressed. In addition, the overexpression of catalase altered the transcriptional levels of several angiogenesis-related factors in tumor cells, including TIMP-3 and THBS1. These two anti-angiogenic factors were found to be H2O2-regulated by two different mechanisms: TIMP-3 expression in a cell-autonomous manner; and, THBS1 expression that was non-cell-autonomous. Our work shows that intracellular H2O2 regulates the expression of angiogenic factors and the formation of a vessel network. Understanding the molecular mechanisms that govern this multifunctional effect of H2O2 on tumor angiogenesis could be important for the development of more efficient anti-angiogenic therapies.

scholarly journals Neurogenic decisions require a cell cycle independent function of the CDC25B phosphatase

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Frédéric Bonnet ◽  
Angie Molina ◽  
Mélanie Roussat ◽  
Manon Azais ◽  
Sophie Bel-Vialar ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Molecular Mechanisms ◽  
Neural Progenitors ◽  
Apical Surface ◽  
Independent Function ◽  
M Cell ◽  
Stem Cell Maintenance ◽  
A Cell ◽  
Cell Cycle Dynamics ◽  
Cell Cycle Length

A fundamental issue in developmental biology and in organ homeostasis is understanding the molecular mechanisms governing the balance between stem cell maintenance and differentiation into a specific lineage. Accumulating data suggest that cell cycle dynamics play a major role in the regulation of this balance. Here we show that the G2/M cell cycle regulator CDC25B phosphatase is required in mammals to finely tune neuronal production in the neural tube. We show that in chick neural progenitors, CDC25B activity favors fast nuclei departure from the apical surface in early G1, stimulates neurogenic divisions and promotes neuronal differentiation. We design a mathematical model showing that within a limited period of time, cell cycle length modifications cannot account for changes in the ratio of the mode of division. Using a CDC25B point mutation that cannot interact with CDK, we show that part of CDC25B activity is independent of its action on the cell cycle.

scholarly journals The Nanovirus-Encoded Clink Protein Affects Plant Cell Cycle Regulation through Interaction with the Retinoblastoma-Related Protein

2007 ◽  
Vol 81 (8) ◽  
pp. 4177-4185 ◽  
Author(s):  
Sébastien Lageix ◽  
Olivier Catrice ◽  
Jean-Marc Deragon ◽  
Bruno Gronenborn ◽  
Thierry Pélissier ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Plant Viruses ◽  
Cell Nuclei ◽  
Ploidy Levels ◽  
Link Protein ◽  
Additional Cell ◽  
Pass Through ◽  
Unique Cell

ABSTRACT Nanoviruses, multicomponent single-stranded DNA plant viruses, encode a unique cell cycle link protein, Clink, that interacts with retinoblastoma-related proteins (RBR). We have established transgenic Arabidopsis thaliana lines that conditionally express Clink or a Clink variant deficient in RBR binding. By controlled induction of Clink expression, we demonstrated the capacity of the Clink protein to alter RBR function in vivo. We showed that transcription of both S-phase-specific and G2/M-phase-specific genes was up-regulated depending on the RBR-binding proficiency of Clink. Concomitantly, ploidy levels increased in a substantial fraction of leaf cell nuclei. Also, leaf epidermis cells of transgenic plants producing Clink were smaller and more numerous, indicating additional cell divisions in this tissue. Furthermore, cytogenetic analyses following induction of Clink expression in mature leaves revealed the presence of metaphasic and anaphasic nuclei, clear evidence that Clink-mediated RBR inactivation is sufficient to induce quiescent cells to reenter cell cycle progression and, for at least a fraction of them, to pass through mitosis. Expression of Clink had no effect on genes transcribed by RNA polymerases I and III, suggesting that, in contrast to its mammalian homologue, A. thaliana RBR is not involved in the repression of polymerase I and polymerase III transcription. The results of these in vivo analyses firmly establish Clink as a member of the diverse class of multifunctional cell cycle modulator proteins encoded by small DNA viruses.

scholarly journals Gains of 12p13.31 delay WNT-mediated initiation of hPSC differentiation and promote residual pluripotency in a cell cycle dependent manner

2021 ◽  
Author(s):  
Alexander Keller ◽  
Yingnan Lei ◽  
Nuša Krivec ◽  
Edouard Couvreu De Deckersberg ◽  
Dominika Dziedzicka ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Wnt Signaling ◽  
Feedback Loop ◽  
Molecular Mechanisms ◽  
Physical Interaction ◽  
Dependent Manner ◽  
Pluripotent Cells ◽  
Primary Driver ◽  
A Cell ◽  
Cycle Dependent

Though gains of chromosome 12p13.31 are highly recurrent in hPSC, their impact on differentiation is poorly understood. We identify a reduction in differentiation capacity towards all three germ layers and a subpopulation of residual pluripotent cells that appear during hepatic specification. These cells form as a result of the overexpression of NANOG and GDF3, whereby NANOG as the primary driver delays activation of WNT signaling, partly as a result of a direct physical interaction with TCF7. Entry into the residual state is determined by cell cycle position at the onset of differentiation and is maintained by a feedback loop between NANOG and GDF3. These findings highlight the ability of genetically abnormal hPSC to escape correct differentiation and to form residual pluripotent cells, an important risk in the safe clinical translation of hPSC. Our results further refine the molecular mechanisms that underpin the exit from pluripotency and onset of differentiation.

scholarly journals The BUD4 protein of yeast, required for axial budding, is localized to the mother/BUD neck in a cell cycle-dependent manner.

1996 ◽  
Vol 134 (2) ◽  
pp. 413-427 ◽  
Author(s):  
S L Sanders ◽  
I Herskowitz
Keyword(s):  
Cell Cycle ◽  
Binding Motif ◽  
Temperature Sensitive ◽  
Dependent Manner ◽  
Alpha Cells ◽  
Yeast Saccharomyces Cerevisiae ◽  
Bud Neck ◽  
A Cell ◽  
Cycle Dependent ◽  
Diploid Cells

A and alpha cells of the yeast Saccharomyces cerevisiae exhibit an axial budding pattern, whereas a/alpha diploid cells exhibit a bipolar pattern. Mutations in BUD3, BUD4, and AXL1 cause a and alpha cells to exhibit the bipolar pattern, indicating that these genes are necessary to specify the axial budding pattern (Chant, J., and I. Herskowitz. 1991. Cell. 65:1203-1212; Fujita, A., C. Oka, Y. Arikawa, T. Katagi, A. Tonouchi, S. Kuhara, and Y. Misumi. 1994. Nature (Lond.). 372:567-570). We cloned and sequenced BUD4, which codes for a large, novel protein (Bud4p) with a potential GTP-binding motif. Bud4p is expressed and localized to the mother/bud neck in all cell types. Most mitotic cells contain two apparent rings of Bud4 immunoreactive staining, as observed for Bud3p (Chant, J., M. Mischke, E. Mitchell, I. Herskowitz, and J.R. Pringle. 1995. J. Cell Biol. 129: 767-778). Early G1 cells contain a single ring of Bud4p immunoreactive staining, whereas cells at START and in S phase lack these rings. The level of Bud4p is also regulated in a cell cycle-dependent manner. Bud4p is inefficiently localized in bud3 mutants and after a temperature shift of a temperature-sensitive mutant, cdc12, defective in the neck filaments. These observations suggest that Bud4p and Bud3p cooperate to recognize a spatial landmark (the neck filaments) during mitosis and support the hypothesis that they subsequently become a landmark for establishing the axial budding pattern in G1.

scholarly journals Genome-Wide Studies Reveal that H3K4me3 Modification in Bivalent Genes Is Dynamically Regulated during the Pluripotent Cell Cycle and Stabilized upon Differentiation

2015 ◽  
Vol 36 (4) ◽  
pp. 615-627 ◽  
Author(s):  
Rodrigo A. Grandy ◽  
Troy W. Whitfield ◽  
Hai Wu ◽  
Mark P. Fitzgerald ◽  
Jennifer J. VanOudenhove ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Histone Modifications ◽  
Molecular Mechanisms ◽  
Embryonic Stem ◽  
Gene Promoters ◽  
Transition Analysis ◽  
Differentiated Cells ◽  
A Cell ◽  
Cycle Dependent ◽  
Cell Phenotypes

Stem cell phenotypes are reflected by posttranslational histone modifications, and this chromatin-related memory must be mitotically inherited to maintain cell identity through proliferative expansion. In human embryonic stem cells (hESCs), bivalent genes with both activating (H3K4me3) and repressive (H3K27me3) histone modifications are essential to sustain pluripotency. Yet, the molecular mechanisms by which this epigenetic landscape is transferred to progeny cells remain to be established. By mapping genomic enrichment of H3K4me3/H3K27me3 in pure populations of hESCs in G2, mitotic, and G1phases of the cell cycle, we found striking variations in the levels of H3K4me3 through the G2-M-G1transition. Analysis of a representative set of bivalent genes revealed that chromatin modifiers involved in H3K4 methylation/demethylation are recruited to bivalent gene promoters in a cell cycle-dependent fashion. Interestingly, bivalent genes enriched with H3K4me3 exclusively during mitosis undergo the strongest upregulation after induction of differentiation. Furthermore, the histone modification signature of genes that remain bivalent in differentiated cells resolves into a cell cycle-independent pattern after lineage commitment. These results establish a new dimension of chromatin regulation important in the maintenance of pluripotency.

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