Regulation of Raf-1-dependent signaling during early Xenopus development.

The Raf-1 gene product is activated in response to cellular stimulation by a variety of growth factors and hormones. Raf-1 activity has been implicated in both cellular differentiation and proliferation. We have examined the regulation of the Raf-1/MEK/MAP kinase (MAPK) pathway during embryonic development in the frog Xenopus laevis. We report that Raf-1, MEK, and MAPK activities are turned off following fertilization and remain undetectable up until blastula stages (stage 8), some 4 h later. Tight regulation of the Raf-1/MEK/MAPK pathway following fertilization is crucial for embryonic cell cycle progression. Inappropriate reactivation of MAPK activity by microinjection of oncogenic Raf-1 RNA results in metaphase cell cycle arrest and, consequently, embryonic lethality. Our findings demonstrate an absolute requirement, in vivo, for inactivation of the MAPK signaling pathway to allow normal cell cycle progression during the period of synchronous cell divisions which occur following fertilization. Further, we show that cytostatic factor effects are mediated through MEK and MAPK.

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Excess histone H3 is a Chk1 inhibitor that controls embryonic cell cycle progression

10.1101/2020.06.09.142414 ◽

2020 ◽

Author(s):

Yuki Shindo ◽

Amanda A. Amodeo

Keyword(s):

Cell Cycle ◽

Cell Fate ◽

Cell Cycle Progression ◽

Histone H3 ◽

Embryonic Cell ◽

Cycle Progression ◽

Cell Cycles ◽

Embryonic Cell Cycle

AbstractThe early embryos of many species undergo a switch from rapid, reductive cleavage divisions to slower, cell fate-specific division patterns at the Mid-Blastula Transition (MBT). The maternally loaded histone pool is used to measure the increasing ratio of nuclei to cytoplasm (N/C ratio) to control MBT onset, but the molecular mechanism of how histones regulate the cell cycle has remained elusive. Here, we show that excess histone H3 inhibits the DNA damage checkpoint kinase Chk1 to promote cell cycle progression in the Drosophila embryo. We find that excess H3-tail that cannot be incorporated into chromatin is sufficient to shorten the embryonic cell cycle and reduce the activity of Chk1 in vitro and in vivo. Removal of the Chk1 phosphosite in H3 abolishes its ability to regulate the cell cycle. Mathematical modeling quantitatively supports a mechanism where changes in H3 nuclear concentrations over the final cell cycles leading up to the MBT regulate Chk1-dependent cell cycle slowing. We provide a novel mechanism for Chk1 regulation by H3, which is crucial for proper cell cycle remodeling during early embryogenesis.

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Pharmacodynamic Effects and Mechanisms of Resistance to Vemurafenib in Patients With Metastatic Melanoma

Journal of Clinical Oncology ◽

10.1200/jco.2012.44.7888 ◽

2013 ◽

Vol 31 (14) ◽

pp. 1767-1774 ◽

Cited By ~ 241

Author(s):

Kerstin Trunzer ◽

Anna C. Pavlick ◽

Lynn Schuchter ◽

Rene Gonzalez ◽

Grant A. McArthur ◽

...

Keyword(s):

Cell Cycle ◽

Metastatic Melanoma ◽

Cell Cycle Progression ◽

Mapk Pathway ◽

Objective Response ◽

Acquired Resistance ◽

Braf Inhibitor ◽

Mapk Signaling ◽

Cycle Progression ◽

Pharmacodynamic Effects

Purpose To assess pharmacodynamic effects and intrinsic and acquired resistance mechanisms of the BRAF inhibitor vemurafenib in BRAFV600-mutant melanoma, leading to an understanding of the mechanism of action of vemurafenib and ultimately to optimization of metastatic melanoma therapy. Methods In the phase II clinical study NP22657 (BRIM-2), patients received oral doses of vemurafenib (960 mg twice per day). Serial biopsies were collected to study changes in mitogen-activated protein kinase (MAPK) signaling, cell-cycle progression, and factors causing intrinsic or acquired resistance by immunohistochemistry, DNA sequencing, or somatic mutation profiling. Results Vemurafenib inhibited MAPK signaling and cell-cycle progression. An association between the decrease in extracellular signal-related kinase (ERK) phosphorylation and objective response was observed in paired biopsies (n = 22; P = .013). Low expression of phosphatase and tensin homolog showed a modest association with lower response. Baseline mutations in MEK1P124 coexisting with BRAFV600 were noted in seven of 92 samples; their presence did not preclude objective tumor responses. Acquired resistance to vemurafenib associated with reactivation of MAPK signaling as observed by elevated ERK1/2 phosphorylation levels in progressive lesions and the appearance of secondary NRASQ61 mutations or MEK1Q56P or MEK1E203K mutations. These two activating MEK1 mutations had not previously been observed in vivo in biopsies of progressive melanoma tumors. Conclusion Vemurafenib inhibits tumor proliferation and oncogenic BRAF signaling through the MAPK pathway. Acquired resistance results primarily from MAPK reactivation driven by the appearance of secondary mutations in NRAS and MEK1 in subsets of patients. The data suggest that inhibition downstream of BRAF should help to overcome acquired resistance.

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Whole-genome sequencing of recurrent neuroblastoma reveals somatic mutations that affect key players in cancer progression and telomere maintenance

Scientific Reports ◽

10.1038/s41598-020-78370-7 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Susanne Fransson ◽

Angela Martinez-Monleon ◽

Mathias Johansson ◽

Rose-Marie Sjöberg ◽

Caroline Björklund ◽

...

Keyword(s):

Cell Cycle ◽

Whole Genome Sequencing ◽

Genome Sequencing ◽

Cancer Progression ◽

Cell Cycle Progression ◽

Mapk Signaling ◽

Telomere Maintenance ◽

Whole Genome ◽

Genomic Alterations ◽

Cycle Progression

AbstractNeuroblastoma is the most common and deadly childhood tumor. Relapsed or refractory neuroblastoma has a very poor prognosis despite recent treatment advances. To investigate genomic alterations associated with relapse and therapy resistance, whole-genome sequencing was performed on diagnostic and relapsed lesions together with constitutional DNA from seven children. Sequencing of relapsed tumors indicates somatic alterations in diverse genes, including those involved in RAS-MAPK signaling, promoting cell cycle progression or function in telomere maintenance and immortalization. Among recurrent alterations, CCND1-gain, TERT-rearrangements, and point mutations in POLR2A, CDK5RAP, and MUC16 were shown in ≥ 2 individuals. Our cohort contained examples of converging genomic alterations in primary-relapse tumor pairs, indicating dependencies related to specific genetic lesions. We also detected rare genetic germline variants in DNA repair genes (e.g., BARD1, BRCA2, CHEK2, and WRN) that might cooperate with somatically acquired variants in these patients with highly aggressive recurrent neuroblastoma. Our data indicate the importance of monitoring recurrent neuroblastoma through sequential genomic characterization and that new therapeutic approaches combining the targeting of MAPK signaling, cell cycle progression, and telomere activity are required for this challenging patient group.

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To Divide or Not to Divide? How Deuterium Affects Growth and Division of Chlamydomonas reinhardtii

Biomolecules ◽

10.3390/biom11060861 ◽

2021 ◽

Vol 11 (6) ◽

pp. 861

Author(s):

Veronika Kselíková ◽

Vilém Zachleder ◽

Kateřina Bišová

Keyword(s):

Cell Cycle ◽

Chlamydomonas Reinhardtii ◽

Cell Cycle Progression ◽

Model Organism ◽

Cycle Progression ◽

Synchronous Cultures ◽

Multiple Fission ◽

First Choice ◽

High Doses

Extensive in vivo replacement of hydrogen by deuterium, a stable isotope of hydrogen, induces a distinct stress response, reduces cell growth and impairs cell division in various organisms. Microalgae, including Chlamydomonas reinhardtii, a well-established model organism in cell cycle studies, are no exception. Chlamydomonas reinhardtii, a green unicellular alga of the Chlorophyceae class, divides by multiple fission, grows autotrophically and can be synchronized by alternating light/dark regimes; this makes it a model of first choice to discriminate the effect of deuterium on growth and/or division. Here, we investigate the effects of high doses of deuterium on cell cycle progression in C. reinhardtii. Synchronous cultures of C. reinhardtii were cultivated in growth medium containing 70 or 90% D2O. We characterize specific deuterium-induced shifts in attainment of commitment points during growth and/or division of C. reinhardtii, contradicting the role of the “sizer” in regulating the cell cycle. Consequently, impaired cell cycle progression in deuterated cultures causes (over)accumulation of starch and lipids, suggesting a promising potential for microalgae to produce deuterated organic compounds.

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Spirulina Crude Protein Promotes the Migration and Proliferation in IEC-6 Cells by Activating EGFR/MAPK Signaling Pathway

Marine Drugs ◽

10.3390/md17040205 ◽

2019 ◽

Vol 17 (4) ◽

pp. 205

Author(s):

Su-Jin Jeong ◽

Jeong-Wook Choi ◽

Min-Kyeong Lee ◽

Youn-Hee Choi ◽

Taek-Jeong Nam

Keyword(s):

Cell Cycle ◽

Epithelial Cells ◽

Signaling Pathway ◽

Crude Protein ◽

Cell Cycle Progression ◽

Intestinal Epithelial Cells ◽

Mapk Signaling ◽

S Phase ◽

Intestinal Epithelial ◽

Cycle Progression

Spirulina is a type of filamentous blue-green microalgae known to be rich in nutrients and to have pharmacological effects, but the effect of spirulina on the small intestine epithelium is not well understood. Therefore, this study aims to investigate the proliferative effects of spirulina crude protein (SPCP) on a rat intestinal epithelial cells IEC-6 to elucidate the mechanisms underlying its effect. First, the results of wound-healing and cell viability assays demonstrated that SPCP promoted migration and proliferation in a dose-dependent manner. Subsequently, when the mechanisms of migration and proliferation promotion by SPCP were confirmed, we found that the epidermal growth factor receptor (EGFR) and mitogen-activated protein (MAPK) signaling pathways were activated by phosphorylation. Cell cycle progression from G0/G1 to S phase was also promoted by SPCP through upregulation of the expression levels of cyclins and cyclin-dependent kinases (Cdks), which regulate cell cycle progression to the S phase. Meanwhile, the expression of cyclin-dependent kinase inhibitors (CKIs), such as p21 and p27, decreased with SPCP. In conclusion, our results indicate that activation of EGFR and its downstream signaling pathway by SPCP treatment regulates cell cycle progression. Therefore, these results contribute to the research on the molecular mechanism for SPCP promoting the migration and proliferation of rat intestinal epithelial cells.

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Analysis of Cell Cycle and Replication of Mouse Macrophages afterIn VivoandIn VitroCryptococcus neoformans Infection Using Laser Scanning Cytometry

Infection and Immunity ◽

10.1128/iai.06332-11 ◽

2012 ◽

Vol 80 (4) ◽

pp. 1467-1478 ◽

Cited By ~ 12

Author(s):

Carolina Coelho ◽

Lydia Tesfa ◽

Jinghang Zhang ◽

Johanna Rivera ◽

Teresa Gonçalves ◽

...

Keyword(s):

Cell Cycle ◽

Cell Division ◽

Cytotoxic Effect ◽

Laser Scanning ◽

Cell Cycle Progression ◽

Cycle Progression ◽

Content Type ◽

Cycle Arrest ◽

Laser Scanning Cytometry

ABSTRACTWe investigated the outcome of the interaction ofCryptococcus neoformanswith murine macrophages using laser scanning cytometry (LSC). Previous results in our lab had shown that phagocytosis ofC. neoformanspromoted cell cycle progression. LSC allowed us to simultaneously measure the phagocytic index, macrophage DNA content, and 5-ethynyl-2′-deoxyuridine (EdU) incorporation such that it was possible to study host cell division as a function of phagocytosis. LSC proved to be a robust, reliable, and high-throughput method for quantifying phagocytosis. Phagocytosis ofC. neoformanspromoted cell cycle progression, but infected macrophages were significantly less likely to complete mitosis. Hence, we report a new cytotoxic effect associated with intracellularC. neoformansresidence that manifested itself in impaired cell cycle completion as a consequence of a block in the G2/M stage of the mitotic cell cycle. Cell cycle arrest was not due to increased cell membrane permeability or DNA damage. We investigated alveolar macrophage replicationin vivoand demonstrated that these cells are capable of low levels of cell division in the presence or absence ofC. neoformansinfection. In summary, we simultaneously studied phagocytosis, the cell cycle state of the host cell and pathogen-mediated cytotoxicity, and our results demonstrate a new cytotoxic effect ofC. neoformansinfection on murine macrophages: fungus-induced cell cycle arrest. Finally, we provide evidence for alveolar macrophage proliferationin vivo.

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A bulky glycocalyx fosters metastasis formation by promoting G1 cell cycle progression

eLife ◽

10.7554/elife.25752 ◽

2017 ◽

Vol 6 ◽

Cited By ~ 27

Author(s):

Elliot C Woods ◽

FuiBoon Kai ◽

J Matthew Barnes ◽

Kayvon Pedram ◽

Michael W Pickup ◽

...

Keyword(s):

Cell Cycle ◽

Tumor Cells ◽

Cell Cycle Progression ◽

Disseminated Tumor Cells ◽

Metastatic Potential ◽

Cancer Cell Growth ◽

Cycle Progression ◽

Growth And Survival ◽

Syngeneic Mouse Model

Metastasis depends upon cancer cell growth and survival within the metastatic niche. Tumors which remodel their glycocalyces, by overexpressing bulky glycoproteins like mucins, exhibit a higher predisposition to metastasize, but the role of mucins in oncogenesis remains poorly understood. Here we report that a bulky glycocalyx promotes the expansion of disseminated tumor cells in vivo by fostering integrin adhesion assembly to permit G1 cell cycle progression. We engineered tumor cells to display glycocalyces of various thicknesses by coating them with synthetic mucin-mimetic glycopolymers. Cells adorned with longer glycopolymers showed increased metastatic potential, enhanced cell cycle progression, and greater levels of integrin-FAK mechanosignaling and Akt signaling in a syngeneic mouse model of metastasis. These effects were mirrored by expression of the ectodomain of cancer-associated mucin MUC1. These findings functionally link mucinous proteins with tumor aggression, and offer a new view of the cancer glycocalyx as a major driver of disease progression.

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SCL-mediated regulation of the cell-cycle regulator p21 is critical for murine megakaryopoiesis

Blood ◽

10.1182/blood-2011-01-328765 ◽

2011 ◽

Vol 118 (3) ◽

pp. 723-735 ◽

Cited By ~ 28

Author(s):

Hedia Chagraoui ◽

Mira Kassouf ◽

Sreemoti Banerjee ◽

Nicolas Goardon ◽

Kevin Clark ◽

...

Keyword(s):

Cell Cycle ◽

Transcriptional Control ◽

Cell Cycle Progression ◽

Cellular Proliferation ◽

Loss Of Function ◽

Cycle Progression ◽

Cell Cycle Regulator ◽

Nuclear Changes ◽

Cytoplasmic Maturation

Abstract Megakaryopoiesis is a complex process that involves major cellular and nuclear changes and relies on controlled coordination of cellular proliferation and differentiation. These mechanisms are orchestrated in part by transcriptional regulators. The key hematopoietic transcription factor stem cell leukemia (SCL)/TAL1 is required in early hematopoietic progenitors for specification of the megakaryocytic lineage. These early functions have, so far, prevented full investigation of its role in megakaryocyte development in loss-of-function studies. Here, we report that SCL critically controls terminal megakaryocyte maturation. In vivo deletion of Scl specifically in the megakaryocytic lineage affects all key attributes of megakaryocyte progenitors (MkPs), namely, proliferation, ploidization, cytoplasmic maturation, and platelet release. Genome-wide expression analysis reveals increased expression of the cell-cycle regulator p21 in Scl-deleted MkPs. Importantly, p21 knockdown-mediated rescue of Scl-mutant MkPs shows full restoration of cell-cycle progression and partial rescue of the nuclear and cytoplasmic maturation defects. Therefore, SCL-mediated transcriptional control of p21 is essential for terminal maturation of MkPs. Our study provides a mechanistic link between a major hematopoietic transcriptional regulator, cell-cycle progression, and megakaryocytic differentiation.

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Roquin1 Suppresses Breast Cancer Growth by Inducing Cell Cycle Arrest via Selectively Destabilizing Cell Cycle–Promoting Gene mRNAs

10.21203/rs.3.rs-53499/v1 ◽

2020 ◽

Author(s):

Wenbao Lu ◽

Meicen Zhou ◽

Bing Wang ◽

Xueting Liu ◽

Bingwei Li

Keyword(s):

Breast Cancer ◽

Cell Cycle ◽

Cell Proliferation ◽

Cell Cycle Arrest ◽

Breast Cancer Cell ◽

Breast Tumor ◽

Cell Cycle Progression ◽

Cycle Progression ◽

Cycle Arrest

Abstract Background: Dysregulation of cell cycle progression is one of the common features of human cancer cells, however, its mechanism remains unclear. This study aims to clarify the role and the underlying mechanisms of Roquin1 in cell cycle arrest induction in breast cancer.Methods: Public cancer databases were analyzed to identify the expression pattern of Roquin1 in human breast cancers and the significant association with patient survival. Quantitative real-time PCR and western blots were performed to detect the expression of Roquin1 in breast cancer samples and cell lines. Cell counting, MTT assay, flow cytometry, and in vivo study were conducted to investigate the effects of Roquin1 on cell proliferation, cell cycle progression and tumor progression. RNA-sequencing was applied to identify the differential genes and pathways regulated by Roquin1. RNA immunoprecipitation assay, luciferase reporter assay, mRNA half-life detection, RNA affinity binding assay, and RIP-ChIP were used to explore the molecular mechanisms of Roquin1.Results: We showed that Roquin1 expression in breast cancer tissues and cell lines was inhibited, and the reduction in Roquin1 expression was associated with poor overall survival and relapse free survival of patients with breast cancer. Roquin1 overexpression inhibited breast cancer cell proliferation and induced G1/S cell cycle arrest without causing significant apoptosis. In contrast, knockdown of Roquin1 promoted breast cancer cell growth and cycle progression. Moreover, in vivo induction of Roquin1 by adenovirus significantly suppressed breast tumor growth and metastasis. Mechanistically, Roquin1 selectively destabilizing cell cycle–promoting genes, including Cyclin D1, Cyclin E1, cyclin dependent kinase 6 (CDK6) and minichromosome maintenance 2 (MCM2) through targeting the stem–loop structure in the 3’untranslated region (3’UTR) of mRNAs via its ROQ domain, leading to the downregulation of cell cycle–promoting mRNAs.Conclusions: Our findings demonstrated that Roquin1 was a novel breast tumor suppressor and could induce G1/S cell cycle arrest by selectively downregulating the expression of cell cycle–promoting genes, which might as a potential molecular target for breast cancer treatment.

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