Gβγ regulates mitotic Golgi fragmentation and G2/M cell cycle progression

Heterotrimeric G proteins (αβγ) function at the cytoplasmic surface of a cell's plasma membrane to transduce extracellular signals into cellular responses. However, numerous studies indicate that G proteins also play non-canonical roles at unique intracellular locations. Previous work has established that G protein βγ subunits (Gβγ) regulate a signaling pathway on the cytoplasmic surface of Golgi membranes that controls the exit of select protein cargo. Now, we demonstrate a novel role for Gβγ in regulating mitotic Golgi fragmentation, a key checkpoint of the cell cycle that occurs in the late G2 phase. We show that siRNA-mediated depletion of Gβ1 and Gβ2 in synchronized cells causes a decrease in cells with fragmented Golgi in late G2 and a delay in entry into mitosis and progression through G2/M. We also demonstrate that during G2/M Gβγ acts upstream of protein kinase D and regulates the phosphorylation of the Golgi structural protein Grasp55. Expression of Golgi-targeted GRK2ct, a Gβγ-sequestering protein used to inhibit Gβγ signaling, also causes a decrease in Golgi fragmentation and a delay in mitotic progression. These results highlight a novel role for Gβγ in regulation of Golgi structure.

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Advantages of Tyrosine Kinase Anti-Angiogenic Cediranib over Bevacizumab: Cell Cycle Abrogation and Synergy with Chemotherapy

Pharmaceuticals ◽

10.3390/ph14070682 ◽

2021 ◽

Vol 14 (7) ◽

pp. 682

Author(s):

Jianling Bi ◽

Garima Dixit ◽

Yuping Zhang ◽

Eric J. Devor ◽

Haley A. Losh ◽

...

Keyword(s):

Cell Cycle ◽

Endometrial Cancer ◽

Tyrosine Kinase ◽

Cell Viability ◽

Cell Lines ◽

Cell Cycle Progression ◽

Kinase Inhibitor ◽

Cell Cycle Checkpoint ◽

Mitotic Catastrophe ◽

M Cell

Angiogenesis plays a crucial role in tumor development and metastasis. Both bevacizumab and cediranib have demonstrated activity as single anti-angiogenic agents in endometrial cancer, though subsequent studies of bevacizumab combined with chemotherapy failed to improve outcomes compared to chemotherapy alone. Our objective was to compare the efficacy of cediranib and bevacizumab in endometrial cancer models. The cellular effects of bevacizumab and cediranib were examined in endometrial cancer cell lines using extracellular signal-related kinase (ERK) phosphorylation, ligand shedding, cell viability, and cell cycle progression as readouts. Cellular viability was also tested in eight patient-derived organoid models of endometrial cancer. Finally, we performed a phosphoproteomic array of 875 phosphoproteins to define the signaling changes related to bevacizumab versus cediranib. Cediranib but not bevacizumab blocked ligand-mediated ERK activation in endometrial cancer cells. In both cell lines and patient-derived organoids, neither bevacizumab nor cediranib alone had a notable effect on cell viability. Cediranib but not bevacizumab promoted marked cell death when combined with chemotherapy. Cell cycle analysis demonstrated an accumulation in mitosis after treatment with cediranib + chemotherapy, consistent with the abrogation of the G2/M checkpoint and subsequent mitotic catastrophe. Molecular analysis of key controllers of the G2/M cell cycle checkpoint confirmed its abrogation. Phosphoproteomic analysis revealed that bevacizumab and cediranib had both similar and unique effects on cell signaling that underlie their shared versus individual actions as anti-angiogenic agents. An anti-angiogenic tyrosine kinase inhibitor such as cediranib has the potential to be superior to bevacizumab in combination with chemotherapy.

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Loss of Melanopsin (OPN4) Leads to a Faster Cell Cycle Progression and Growth in Murine Melanocytes

Current Issues in Molecular Biology ◽

10.3390/cimb43030101 ◽

2021 ◽

Vol 43 (3) ◽

pp. 1436-1450

Author(s):

Leonardo Vinícius Monteiro de Assis ◽

Maria Nathália Moraes ◽

Davi Mendes ◽

Matheus Molina Silva ◽

Carlos Frederico Martins Menck ◽

...

Keyword(s):

Cell Cycle ◽

Cell Cycle Progression ◽

Population Analysis ◽

Cell Populations ◽

Specific Cell ◽

Significant Modification ◽

M Cell ◽

Cycle Progression ◽

Gene And Protein Expression ◽

Independent Functions

Skin melanocytes harbor a complex photosensitive system comprised of opsins, which were shown, in recent years, to display light- and thermo-independent functions. Based on this premise, we investigated whether melanopsin, OPN4, displays such a role in normal melanocytes. In this study, we found that murine Opn4KO melanocytes displayed a faster proliferation rate compared to Opn4WT melanocytes. Cell cycle population analysis demonstrated that OPN4KO melanocytes exhibited a faster cell cycle progression with reduced G0–G1, and highly increased S and slightly increased G2/M cell populations compared to the Opn4WT counterparts. Expression of specific cell cycle-related genes in Opn4KO melanocytes exhibited alterations that corroborate a faster cell cycle progression. We also found significant modification in gene and protein expression levels of important regulators of melanocyte physiology. PER1 protein level was higher while BMAL1 and REV-ERBα decreased in Opn4KO melanocytes compared to Opn4WT cells. Interestingly, the gene expression of microphthalmia-associated transcription factor (MITF) was upregulated in Opn4KO melanocytes, which is in line with a higher proliferative capability. Taken altogether, we demonstrated that OPN4 regulates cell proliferation, cell cycle, and affects the expression of several important factors of the melanocyte physiology; thus, arguing for a putative tumor suppression role in melanocytes.

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Akt/Protein Kinase B-Dependent Phosphorylation and Inactivation of WEE1Hu Promote Cell Cycle Progression at G2/M Transition

Molecular and Cellular Biology ◽

10.1128/mcb.25.13.5725-5737.2005 ◽

2005 ◽

Vol 25 (13) ◽

pp. 5725-5737 ◽

Cited By ~ 97

Author(s):

Kazuhiro Katayama ◽

Naoya Fujita ◽

Takashi Tsuruo

Keyword(s):

Cell Cycle ◽

Cell Cycle Progression ◽

Kinase Inhibitor ◽

Phosphorylation Site ◽

Cytoplasmic Localization ◽

M Cell ◽

Serine Threonine Kinase ◽

Cycle Progression ◽

M Phase ◽

Promote Cell Cycle Progression

ABSTRACT The serine/threonine kinase Akt is known to promote cell growth by regulating the cell cycle in G1 phase through activation of cyclin/Cdk kinases and inactivation of Cdk inhibitors. However, how the G2/M phase is regulated by Akt remains unclear. Here, we show that Akt counteracts the function of WEE1Hu. Inactivation of Akt by chemotherapeutic drugs or the phosphatidylinositide-3-OH kinase inhibitor LY294002 induced G2/M arrest together with the inhibitory phosphorylation of Cdc2. Because the increased Cdc2 phosphorylation was completely suppressed by wee1hu gene silencing, WEE1Hu was associated with G2/M arrest induced by Akt inactivation. Further analyses revealed that Akt directly bound to and phosphorylated WEE1Hu during the S to G2 phase. Serine-642 was identified as an Akt-dependent phosphorylation site. WEE1Hu kinase activity was not affected by serine-642 phosphorylation. We revealed that serine-642 phosphorylation promoted cytoplasmic localization of WEE1Hu. The nuclear-to-cytoplasmic translocation was mediated by phosphorylation-dependent WEE1Hu binding to 14-3-3θ but not 14-3-3β or -σ. These results indicate that Akt promotes G2/M cell cycle progression by inducing phosphorylation-dependent 14-3-3θ binding and cytoplasmic localization of WEE1Hu.

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c-Myc regulates the CDK1/cyclin B1 dependent‑G2/M cell cycle progression by histone H4 acetylation in Raji cells

International Journal of Molecular Medicine ◽

10.3892/ijmm.2018.3519 ◽

2018 ◽

Cited By ~ 3

Author(s):

Yan Yang ◽

Kai Xue ◽

Zhi Li ◽

Wei Zheng ◽

Weijie Dong ◽

...

Keyword(s):

Cell Cycle ◽

Cell Cycle Progression ◽

Cyclin B1 ◽

Histone H4 ◽

M Cell ◽

Cycle Progression ◽

Raji Cells ◽

Histone H4 Acetylation

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Cdc6 disruption leads to centrosome abnormalities and chromosome instability in pancreatic cancer cells

Scientific Reports ◽

10.1038/s41598-020-73474-6 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Yuna Youn ◽

Jong-chan Lee ◽

Jaihwan Kim ◽

Jae Hyeong Kim ◽

Jin-Hyeok Hwang

Keyword(s):

Cell Cycle ◽

Pancreatic Cancer ◽

Dna Replication ◽

Cell Cycle Progression ◽

Chromosome Instability ◽

The Cancer Genome Atlas ◽

M Cell ◽

Pancreatic Cancer Cells ◽

Potential Biomarker ◽

Cancer Genome Atlas

Abstract Cell division cycle 6 (Cdc6) plays key roles in regulating DNA replication, and activation and maintenance of cell cycle check points. In addition, Cdc6 exerts oncogenic properties via genomic instability associated with incomplete DNA replication. This study aimed to examine the effects of Cdc6 on pancreatic cancer (PC) cells. Our results showed that Cdc6 expression was higher in clinical PC specimens (based on analysis of the GEPIA database) and cell lines, and the high Cdc6 expression was associated with poorer survival in The Cancer Genome Atlas-PC cohort. In addition, Cdc6-depleted PC cells significantly inhibited cell proliferation and colony formation, delayed G2/M cell cycle progression, and increased expression of p-histone H3 and cyclin A2 levels. These observations could be explained by Cdc6 depletion leading to multipolar and split spindles via centrosome amplification and microtubule disorganization which eventually increases chromosome missegregation. Furthermore, Cdc6-depleted PC cells showed significantly increased apoptosis, which was consistent with increased caspase-9 and caspase-3 activation. Collectively, our results demonstrated that Cdc6-depleted PC cells are arrested in mitosis and eventually undergo cell death by induced multipolar spindles, centrosome aberrations, microtubule disorganization, and chromosome instability. In conclusion, Cdc6 may be a potential biomarker and therapeutic target for PC.

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Plant hormone perception and action: a role for G–protein signal transduction?

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.1998.0297 ◽

1998 ◽

Vol 353 (1374) ◽

pp. 1425-1430 ◽

Cited By ~ 13

Author(s):

Richard Hooley

Keyword(s):

Signal Transduction ◽

G Protein ◽

G Proteins ◽

Plant Hormone ◽

Higher Plants ◽

Signalling Pathways ◽

Heterotrimeric G Proteins ◽

Extracellular Signals ◽

G Protein Signalling ◽

Auxin Signalling

Plants perceive and respond to a profusion of environmental and endogenous signals that influence their growth and development. The G–protein signalling pathway is a mechanism for transducing extracellular signals that is highly conserved in a range of eukaryotes and prokaryotes. Evidence for the existence of G–protein signalling pathways in higher plants is reviewed, and their potential involvement in plant hormone signal transduction evaluated. A range of biochemical and molecular studies have identified potential components of G–protein signalling in plants, most notably a homologue of the G–protein coupled receptor superfamily ( GCR1 ) and the G α and G β subunits of heterotrimeric G–proteins. G–protein agonists and antagonists are known to influence a variety of signalling events in plants and have been used to implicate heterotrimeric G–proteins in gibberellin and possibly auxin signalling. Antisense suppression of GCR1 in Arabidopsis leads to a phenotype which supports a role for this receptor in cytokinin signalling. These observations suggest that higher plants have at least some of the components of G–protein signalling pathways and that these might be involved in the action of certain plant hormones.

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SD-208, a Novel Protein Kinase D Inhibitor, Blocks Prostate Cancer Cell Proliferation and Tumor Growth In Vivo by Inducing G2/M Cell Cycle Arrest

PLoS ONE ◽

10.1371/journal.pone.0119346 ◽

2015 ◽

Vol 10 (3) ◽

pp. e0119346 ◽

Cited By ~ 20

Author(s):

Manuj Tandon ◽

Joseph M. Salamoun ◽

Evan J. Carder ◽

Elisa Farber ◽

Shuping Xu ◽

...

Keyword(s):

Prostate Cancer ◽

Cell Cycle ◽

Cell Proliferation ◽

Prostate Cancer Cell ◽

Protein Kinase D ◽

Cancer Cell Proliferation ◽

M Cell ◽

Cycle Arrest ◽

Novel Protein

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Cdk1-Dependent Phosphorylation ofNPM Overrides G2/M Checkpoint and Increases Leukemic Blasts in Mice

Blood ◽

10.1182/blood.v112.11.1322.1322 ◽

2008 ◽

Vol 112 (11) ◽

pp. 1322-1322

Author(s):

Wei Du ◽

Yun Zhou ◽

Suzette Pike ◽

Qishen Pang

Keyword(s):

Cell Cycle ◽

Cell Cycle Progression ◽

Cell Cycle Control ◽

Xenograft Model ◽

Phosphorylation Sites ◽

M Cell ◽

Cycle Progression ◽

Hematopoietic Stem ◽

Cycle Arrest ◽

Regulation Of Cell Cycle

Abstract An elevated level of nucleophosmin (NPM) is often found in actively proliferative cells including human tumors. To identify the regulatory role for NPM phosphorylation in proliferation and cell cycle control, a series of mutants targeting the consensus cyclin-dependent kinase (CKD) phosphorylation sites was created to mimic or abrogate either single-site or multi-site phosphorylation. Cells expressing the phosphomimetic NPM mutants showed enhanced proliferation and G2/M cell-cycle transition; whereas nonphosphorylatable mutants induced G2/M cell-cycle arrest. Simultaneous inactivation of two CKD phosphorylation sites at Ser10 and Ser70 (S10A/S70A, NPM-AA) induced phosphorylation of Cdk1 at Tyr15 (Cdc2Tyr15) and increased cytoplasmic accumulation of Cdc25C. Strikingly, stress-induced Cdk1Tyr15 and Cdc25C sequestration were completely suppressed by expression of a double phosphomimetic NPM mutant (S10E/S70E, NPM-EE). Further analysis revealed that phosphorylation of NPM at both Ser10 and Ser70 sites were required for proper interaction between Cdk1 and Cdc25C in mitotic cells. Moreover, the NPM-EE mutant directly bound to Cdc25C and prevented phosphorylation of Cdc25C at Ser216 during mitosis. Finally, NPM-EE overrided stress-induced G2/M arrest, increased peripheral-blood blasts and splenomegaly in a NOD/SCID xenograft model, and promoted leukemia development in Fanconi mouse hematopoietic stem/progenitor cells. Thus, these findings reveal a novel function of NPM on regulation of cell-cycle progression, in which Cdk1-dependent phosphorylation of NPM controls cell-cycle progression at G2/M transition through modulation of Cdc25C activity.

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