scholarly journals An interaction between myosin-10 and the cell cycle regulator Wee1 links spindle dynamics to mitotic progression in epithelia

2018 ◽  
Vol 217 (3) ◽  
pp. 849-859 ◽  
Author(s):  
Joshua C. Sandquist ◽  
Matthew E. Larson ◽  
Sarah Woolner ◽  
Zhiwei Ding ◽  
William M. Bement
Keyword(s):  
Cell Cycle ◽  
Motor Protein ◽  
Cell Junctions ◽  
Dependent Manner ◽  
Cyclin Dependent Kinase ◽  
Mitotic Progression ◽  
Anaphase Onset ◽  
Spindle Dynamics ◽  
Position And Orientation ◽  
Spindle Position

Anaphase in epithelia typically does not ensue until after spindles have achieved a characteristic position and orientation, but how or even if cells link spindle position to anaphase onset is unknown. Here, we show that myosin-10 (Myo10), a motor protein involved in epithelial spindle dynamics, binds to Wee1, a conserved regulator of cyclin-dependent kinase 1 (Cdk1). Wee1 inhibition accelerates progression through metaphase and disrupts normal spindle dynamics, whereas perturbing Myo10 function delays anaphase onset in a Wee1-dependent manner. Moreover, Myo10 perturbation increases Wee1-mediated inhibitory phosphorylation on Cdk1, which, unexpectedly, concentrates at cell–cell junctions. Based on these and other results, we propose a model in which the Myo10–Wee1 interaction coordinates attainment of spindle position and orientation with anaphase onset.

Primitive Hematopoietic Cells Resist HIV-1 Infection Via P21Waf1/Cip1/Sdi1.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 490-490
Author(s):  
Jie Lin Zhang ◽  
Clyde S. Crumpacker ◽  
David T. Scadden
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Hematopoietic Cells ◽  
Surrogate Marker ◽  
Dependent Manner ◽  
Cyclin Dependent Kinase ◽  
Hematopoietic Stem ◽  
Hiv 1

Abstract Hematopoietic stem cells are resistant to HIV-1 infection. We have identified a novel mechanism by which the cyclin-dependent kinase inhibitor, p21Waf1/Cip1/Sdi1 (p21), known for its regulation of stem cell pool size (1,2), restricts HIV-1 infection of primitive hematopoietic cells in a non-cell cycle dependent manner. Knocking down p21 by siRNA increased HIV-1 infection and induction of p21 expression by phorbol ester (TPA) blocked HIV-1 replication. P21 did not affect the overall levels of cDNA synthesis, but significantly blocked viral integration and resulted in marked increase in 2-LTR circles, a surrogate marker of abortive integration. Consistent with these observations, p21 coimmunoprecipitated with viral integrase and both were detected in the preintegration complex (PIC). Furthermore, silencing p27Kip1 and p18INK4C, cyclin dependent kinase inhibitors related to p21 that affect cell cycle, revealed no impact on viral DNA integration. A closely related dual-tropic lentivirus with a distinct integrase, SIVmac-251 and the other cell-intrinsic inhibitors of HIV-1, Trim5a, PML, Murr1, and IFN-a were unaffected by p21. These results indicate a new function for p21, participating in prevention of HIV integration into the cellular genome. Therefore p21 is an endogenous cellular component in stem cells that provides a unique molecular barrier to HIV-1 infection and may explain the basis for these cells being an uninfected ‘sanctuary’ in HIV disease.

scholarly journals Opposite Transcriptional Effects of Cyclic AMP-Responsive Elements in Confluent or p27KIP-Overexpressing Cells versus Serum-Starved or Growing Cells

1998 ◽  
Vol 18 (1) ◽  
pp. 409-419 ◽  
Author(s):  
Laurent Deleu ◽  
François Fuks ◽  
Dimitry Spitkovsky ◽  
Rita Hörlein ◽  
Steffen Faisst ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Cyclic Amp ◽  
Dna Amplification ◽  
S Phase ◽  
Host Cells ◽  
Dependent Manner ◽  
Cyclin Dependent Kinase ◽  
Minute Virus Of Mice ◽  
Minute Virus

ABSTRACT The minute virus of mice, an autonomous parvovirus, requires entry of host cells into the S phase of the cell cycle for its DNA to be amplified and its genes expressed. This work focuses on the P4 promoter of this parvovirus, which directs expression of the transcription unit encoding the parvoviral nonstructural polypeptides. These notably include protein NS1, necessary for the S-phase-dependent burst of parvoviral DNA amplification and gene expression. The activity of the P4 promoter is shown to be regulated in a cell cycle-dependent manner. At the G1/S-phase transition, the promoter is activated via a cis-acting DNA element which interacts with phase-specific complexes containing the cellular transcription factor E2F. It is inhibited, on the other hand, in cells arrested in G1 due to contact inhibition. This inhibitory effect is not observed in serum-starved cells. It is mediated in cis by cyclic AMP response elements (CREs). Unlike serum-starved cells, confluent cells accumulate the cyclin-dependent kinase inhibitor p27, suggesting that the switch from CRE-mediated activation to CRE-mediated repression involves the p27 protein. Accordingly, plasmid-driven overexpression of p27 causes down-modulation of promoter P4 in growing cells, depending on the presence of at least two functional CREs. No such effect is observed with two other cyclin-dependent kinase inhibitors, p16 and p21. Given the importance of P4-driven synthesis of protein NS1 in parvoviral DNA amplification and gene expression, the stringent S-phase dependency of promoter P4 is likely a major determinant of the absolute requirement of the minute virus of mice for host cell proliferation.

scholarly journals Seliciclib (CYC202 or R-roscovitine), a small-molecule cyclin-dependent kinase inhibitor, mediates activity via down-regulation of Mcl-1 in multiple myeloma

Blood ◽  
2005 ◽  
Vol 106 (3) ◽  
pp. 1042-1047 ◽  
Author(s):  
Noopur Raje ◽  
Shaji Kumar ◽  
Teru Hideshima ◽  
Aldo Roccaro ◽  
Kenji Ishitsuka ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Kinase Inhibitor ◽  
Dependent Manner ◽  
Cyclin Dependent Kinase ◽  
Down Regulation ◽  
Induce Cell Cycle Arrest ◽  
Caspase Cleavage ◽  
Stat3 Phosphorylation

AbstractCyclin-dependent kinase (CDK) inhibitors have the potential to induce cell-cycle arrest and apoptosis in cancer cells. Seliciclib (CYC202 or R-roscovitine) is a potent CDK inhibitor currently undergoing phase-2 clinical testing in lung and B-cell malignancies. Here we studied the in vitro cytotoxic activity of seliciclib against multiple myeloma (MM) cells. Our data demonstrate that seliciclib has potent cytotoxicity against MM cells that are both sensitive and resistant to conventional therapy as well as primary MM cells from patients. Cell-cycle and Western blot analysis confirmed apoptosis. Importantly, seliciclib triggered a rapid down-regulation of Mcl-1 transcription and protein expression independent of caspase cleavage. Adherence of MM cells to bone marrow stromal cells (BMSCs) induced increased Mcl-1 expression associated with signal transducer and activator of transcription 3 (STAT3) phosphorylation, which was inhibited in a time- and dose-dependent manner by seliciclib. Furthermore, seliciclib inhibited interleukin 6 (IL-6) transcription and secretion triggered by tumor cell binding to BMSCs. Up-regulation of Mcl-1 expression in cocultures was only partially blocked by neutralizing antibody to IL-6, suggesting alternative mechanisms of Mcl-1 modulation by seliciclib. Finally, combination studies of seliciclib with doxorubicin and bortezomib show in vitro synergism, providing the rationale for testing these drug combinations to improve patient outcome in MM.

scholarly journals Separase cooperates with Zds1 and Zds2 to activate Cdc14 phosphatase in early anaphase

2008 ◽  
Vol 182 (5) ◽  
pp. 873-883 ◽  
Author(s):  
Ethel Queralt ◽  
Frank Uhlmann
Keyword(s):  
Cell Cycle ◽  
Budding Yeast ◽  
Mitotic Exit ◽  
Interacting Proteins ◽  
Cyclin Dependent Kinase ◽  
Down Regulation ◽  
Anaphase Onset ◽  
Early Anaphase ◽  
Key Enzyme ◽  
Mitotic Cyclin

Completion of mitotic exit and cytokinesis requires the inactivation of mitotic cyclin-dependent kinase (Cdk) activity. A key enzyme that counteracts Cdk during budding yeast mitotic exit is the Cdc14 phosphatase. Cdc14 is inactive for much of the cell cycle, sequestered by its inhibitor Net1 in the nucleolus. At anaphase onset, separase-dependent down-regulation of PP2ACdc55 allows phosphorylation of Net1 and consequent Cdc14 release. How separase causes PP2ACdc55 down-regulation is not known. Here, we show that two Cdc55-interacting proteins, Zds1 and Zds2, contribute to timely Cdc14 activation during mitotic exit. Zds1 and Zds2 are required downstream of separase to facilitate nucleolar Cdc14 release. Ectopic Zds1 expression in turn is sufficient to down-regulate PP2ACdc55 and promote Net1 phosphorylation. These findings identify Zds1 and Zds2 as new components of the mitotic exit machinery, involved in activation of the Cdc14 phosphatase at anaphase onset. Our results suggest that these proteins may act as separase-regulated PP2ACdc55 inhibitors.

scholarly journals Plk1- and β-TrCP–dependent degradation of Bora controls mitotic progression

2008 ◽  
Vol 181 (1) ◽  
pp. 65-78 ◽  
Author(s):  
Akiko Seki ◽  
Judith A. Coppinger ◽  
Haining Du ◽  
Chang-Young Jang ◽  
John R. Yates ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Mitotic Progression ◽  
Cell Cycle Protein ◽  
Cycle Progression ◽  
Microtubule Polymerization ◽  
Anaphase Onset ◽  
Chromatid Segregation ◽  
Spindle Stability ◽  
Synthesis And Degradation

Through a convergence of functional genomic and proteomic studies, we identify Bora as a previously unknown cell cycle protein that interacts with the Plk1 kinase and the SCF–β-TrCP ubiquitin ligase. We show that the Bora protein peaks in G2 and is degraded by proteasomes in mitosis. Proteolysis of Bora requires the Plk1 kinase activity and is mediated by SCF–β-TrCP. Plk1 phosphorylates a conserved DSGxxT degron in Bora and promotes its interaction with β-TrCP. Mutations in this degron stabilize Bora. Expression of a nondegradable Bora variant prolongs the metaphase and delays anaphase onset, indicating a physiological requirement of Bora degradation. Interestingly, the activity of Bora is also required for normal mitotic progression, as knockdown of Bora activates the spindle checkpoint and delays sister chromatid segregation. Mechanistically, Bora regulates spindle stability and microtubule polymerization and promotes tension across sister kinetochores during mitosis. We conclude that tight regulation of the Bora protein by its synthesis and degradation is critical for cell cycle progression.

scholarly journals Automated mitotic spindle tracking suggests a link between spindle dynamics, spindle orientation, and anaphase onset in epithelial cells

2017 ◽  
Vol 28 (6) ◽  
pp. 746-759 ◽  
Author(s):  
Matthew E. Larson ◽  
William M. Bement
Keyword(s):  
Mitotic Spindle ◽  
Spindle Positioning ◽  
Tissue Organization ◽  
Anaphase Onset ◽  
Spindle Dynamics ◽  
And Function ◽  
Spindle Position ◽  
The Relationship ◽  
Rotational Oscillations ◽  
Final Orientation

Proper spindle positioning at anaphase onset is essential for normal tissue organization and function. Here we develop automated spindle-tracking software and apply it to characterize mitotic spindle dynamics in the Xenopus laevis embryonic epithelium. We find that metaphase spindles first undergo a sustained rotation that brings them on-axis with their final orientation. This sustained rotation is followed by a set of striking stereotyped rotational oscillations that bring the spindle into near contact with the cortex and then move it rapidly away from the cortex. These oscillations begin to subside soon before anaphase onset. Metrics extracted from the automatically tracked spindles indicate that final spindle position is determined largely by cell morphology and that spindles consistently center themselves in the XY-plane before anaphase onset. Finally, analysis of the relationship between spindle oscillations and spindle position relative to the cortex reveals an association between cortical contact and anaphase onset. We conclude that metaphase spindles in epithelia engage in a stereotyped “dance,” that this dance culminates in proper spindle positioning and orientation, and that completion of the dance is linked to anaphase onset.

Induction of Growth Inhibition and Apoptosis by TZD18, a Novel Dual Ligand for PPAR alpha/gamma, in Human Ph-Positive ALL Cells In Vitro.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2088-2088
Author(s):  
Elena Elstner ◽  
Hongyu Liu ◽  
Chuanbing Zang ◽  
Dachuan Liu ◽  
Shunnan Xu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Growth Inhibition ◽  
Cell Cycle Arrest ◽  
Cell Lines ◽  
Hormone Receptors ◽  
Therapeutic Agent ◽  
Dependent Manner ◽  
Cyclin Dependent Kinase ◽  
Apoptosis Induction ◽  
Cycle Arrest

Abstract Peroxisome proliferator-activated receptors (PPARs) are ligand activated nuclear hormone receptors which play key roles in the differentiation and lipid metabolism of adipocytes. Recent data frequently indicated that PPAR ligands are also implicated in the growth inhibition, differentiation and apoptosis induction of several human cancers with diverse tissues. We previously showed that Pioglitazone (PGZ), a specific PPARgamma ligand and a member of the approved thiazolidinedione (TZD) class of anti-diabetic drugs, inhibited growth and induced apoptosis of human ALL cell lines including Ph-positive ALL cells (Zang et. al., Leukemia Research, 28:387, 2004). In this study, effects of a novel dual ligand specific for PPARalpha/gamma, TZD18 (MERCK, NJ, USA), on Ph-positive ALL cell lines, BV173, SD1 and Sup-B15 were examined. We noted that treatment of these cells with TZD18 resulted in growth inhibition in a dose-dependent manner which was associated with a G1 to S cell cycle arrest. This growth inhibition was much stronger than that of PGZ. However, this effect seemed not to be meditated through activation of PPARalpha or PPARgamma, since antagonists of PPARalpha or gamma could not reverse it. By studying the key regulators of cell cycle progression, we found that the expression of the cyclin dependent kinase inhibitor (CDKI) p27kip1, but not that of p21cip1, was enhanced whereas the expression of c-myc, cyclin D2, and cyclin dependent kinase 2 and 4 (CDK2 and CDK4) was decreased when these cells were treated with TZD18. Therefore, upregulation of p27kip1 and downregulation of cyclin Ds and CDKs may account for the G1 cell cycle arrest. Furthermore, a remarkable apoptosis induction was found in Ph-positive ALL cells treated with this dual ligand as measured by cell-death ELISA. No obvious alteration of bcl-2 levels but an upregulation of bax were observed in apoptotic cells. An activation of caspase-8 and caspase-9 by this ligand was also noticed. Of clinical importance, TZD18 enhanced the cytotoxic effect of Imatinib, a specific therapeutic agent for Ph-positive ALL. Overall, our findings strongly suggest that TZD18 may offer a new therapeutic agent for treatment of Ph-positive ALL in an adjuvant setting. (This study was supported by grants from Deutsche Jose Carreras Leukaemie-Stiftung and Deutsche Forschungsgemeinschaft to EE)

scholarly journals Anti-proliferation Effect on Human Breast Cancer Cells via Inhibition of pRb Phosphorylation by Taiwanin E Isolated from Eleutherococcus trifoliatus

2014 ◽  
Vol 9 (9) ◽  
pp. 1934578X1400900
Author(s):  
Hui-Chun Wang ◽  
Yen-Hsueh Tseng ◽  
Hui-Rong Wu ◽  
Fang-Hua Chu ◽  
Yueh-Hsiung Kuo ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Kinase Inhibitors ◽  
Folk Medicine ◽  
Breast Adenocarcinoma ◽  
Cyclin D ◽  
Dependent Manner ◽  
Cyclin Dependent Kinase ◽  
Human Breast ◽  
Mcf 7

Eleutherococcus trifoliatus has been used as a folk medicine since ancient times, especially as refreshing qi medicines. In our current study, taiwanin E, which possesses strong cytotoxicity, was isolated from the branches of E. trifoliatus by using a bioactivity guided fractionation procedure. Taiwanin E presented a potent anti-proliferation activity on the growth of a human breast adenocarcinoma cell line (MCF-7), with an IC50 value for cytotoxicity of 1.47 μM. Cell cycle analysis revealed that the proportion of cells in the G0/G1 phase increased in a dose-dependent manner (from 79.4% to 90.2%) after 48 h exposure to taiwanin E at a dosage range from 0.5 to 4μM. After treatment with taiwanin E, phosphorylation of retinoblastoma protein (pRb) in MCF-7 cells was inhibited, accompanied by a decrease in the levels of cyclin D1, cyclin D3 and cyclin-dependent kinase 4 (cdk4) and cdk6; in addition, there was an increase in the expression of cyclin-dependent kinase inhibitors p21WAF-1/Cip1 and p27Kip1. The results suggest that taiwanin E inhibits cell cycle progression of MCF-7 at the G0/G1 transition.

scholarly journals SOX7 is involved in polyphyllin D-induced G0/G1 cell cycle arrest through down-regulation of cyclin D1

2020 ◽  
Vol 70 (2) ◽  
pp. 191-200 ◽  
Author(s):  
Bin Zheng ◽  
Gang Wang ◽  
Wenbo Gao ◽  
Qiquan Wu ◽  
Weizhi Zhu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cyclin D1 ◽  
Cell Cycle Arrest ◽  
Complete Medium ◽  
Dependent Manner ◽  
Cyclin Dependent Kinase ◽  
Down Regulation ◽  
Cycle Arrest ◽  
G1 Cell Cycle Arrest ◽  
Polyphyllin D

AbstractThe incidence of mortality of prostate cancer (PCa) has been an uptrend in recent years. Our previous study showed that the sex-determining region Y-box 7 (SOX7) was low-expressed and served as a tumor suppressor in PCa cells. Here, we describe the effects of polyphyllin D (PD) on proliferation and cell cycle modifications of PCa cells, and whether SOX7 participates in this process. PC-3 cells were cultured in complete medium containing PD for 12, 24, and 48 h. MTT assay was used to investigate the cytotoxic effects of PD. Cell cycle progression was analyzed using propidium iodide (PI) staining, and protein levels were assayed by Western blot analysis. Our results showed low expression of SOX7 in PCa tissues/cells compared to their non-tumorous counterparts/RWPE-1 cells. Moreover, PD inhibited the proliferation of PC-3 cells in a dose- and time-dependent manner. PD induced G0/G1 cell cycle arrest, while co-treatment with short interfering RNA targeting SOX7 (siSOX7) had reversed this effect. PD downregulated SOX7, cyclin D1, cyclin-dependent kinase 4 (CDK4), and cyclin-dependent kinase 6 (CDK6) expressions in a dose-dependent manner, whereas co-treatment of siSOX7 and PD rescued the PD-inhibited cyclin D1 expression. However, no obvious changes were observed in CDK4 or CDK6 expression. These results indicate that SOX7 is involved in PD-induced PC-3 cell cycle arrest through down-regulation of cyclin D1.

scholarly journals DDA3 recruits microtubule depolymerase Kif2a to spindle poles and controls spindle dynamics and mitotic chromosome movement

2008 ◽  
Vol 181 (2) ◽  
pp. 255-267 ◽  
Author(s):  
Chang-Young Jang ◽  
Jim Wong ◽  
Judith A. Coppinger ◽  
Akiko Seki ◽  
John R. Yates ◽  
...  
Keyword(s):  
Mitotic Spindle ◽  
Substantial Reduction ◽  
Genomic Analysis ◽  
Dependent Manner ◽  
Mitotic Progression ◽  
Spindle Poles ◽  
Functional Genomic Analysis ◽  
Chromosome Congression ◽  
Spindle Dynamics ◽  
Steady State Levels

Dynamic turnover of the spindle is a driving force for chromosome congression and segregation in mitosis. Through a functional genomic analysis, we identify DDA3 as a previously unknown regulator of spindle dynamics that is essential for mitotic progression. DDA3 depletion results in a high frequency of unaligned chromosomes, a substantial reduction in tension across sister kinetochores at metaphase, and a decrease in the velocity of chromosome segregation at anaphase. DDA3 associates with the mitotic spindle and controls microtubule (MT) dynamics. Mechanistically, DDA3 interacts with the MT depolymerase Kif2a in an MT-dependent manner and recruits Kif2a to the mitotic spindle and spindle poles. Depletion of DDA3 increases the steady-state levels of spindle MTs by reducing the turnover rate of the mitotic spindle and by increasing the rate of MT polymerization, which phenocopies the effects of partial knockdown of Kif2a. Thus, DDA3 represents a new class of MT-destabilizing protein that controls spindle dynamics and mitotic progression by regulating MT depolymerases.

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