CYCLIN B EXPRESSION IN HELA CELLS DURING THE G2 BLOCK INDUCED BY IONIZING RADIATION

1991 ◽  
pp. 172 ◽  
Author(s):  
Ruth J. Muschel ◽  
Hong Bing Zhang ◽  
George Iliakis ◽  
W. Gillies McKenna
Keyword(s):  
Ionizing Radiation ◽  
Hela Cells ◽  
Cyclin B ◽  
G2 Block

scholarly journals A complex containing p34cdc2 and cyclin B phosphorylates the nuclear lamin and disassembles nuclei of clam oocytes in vitro.

1991 ◽  
Vol 112 (4) ◽  
pp. 523-533 ◽  
Author(s):  
G Dessev ◽  
C Iovcheva-Dessev ◽  
J R Bischoff ◽  
D Beach ◽  
R Goldman
Keyword(s):  
Protein Kinase ◽  
Hela Cells ◽  
Kinase Activity ◽  
Nuclear Lamina ◽  
Cyclin B ◽  
Protein Kinase Activity ◽  
Nuclear Lamin ◽  
Single Protein ◽  
M Phase

Cell-free extracts prepared from activated clam oocytes contain factors which induce phosphorylation of the single 67-kD lamin (L67), disassemble clam oocyte nuclei, and cause chromosome condensation in vitro (Dessev, G., R. Palazzo, L. Rebhun, and R. Goldman. 1989. Dev. Biol. 131:469-504). To identify these factors, we have fractionated the oocyte extracts. The nuclear lamina disassembly (NLD) activity, together with a protein kinase activity specific for L67, appear as a single peak throughout a number of purification steps. This peak also contains p34cdc2, cyclin B, and histone H1-kinase activity, which are components of the M-phase promoting factor (MPF). The NLD/L67-kinase activity is depleted by exposure of this purified material to Sepharose conjugated to p13suc1, and is restored upon addition of a p34cdc2/p62 complex from HeLa cells. The latter complex phosphorylates L67 and induces NLD in the absence of other clam oocyte proteins. Our results suggest that a single protein kinase activity (p34cdc2-H1 kinase, identical with MPF) phosphorylates the lamin and is involved in the meiotic breakdown of the nuclear envelope in clam oocytes.

scholarly journals Cytoplasmic accumulation of cdc25B phosphatase in mitosis triggers centrosomal microtubule nucleation in HeLa cells

1996 ◽  
Vol 109 (5) ◽  
pp. 1081-1093 ◽  
Author(s):  
B.G. Gabrielli ◽  
C.P. De Souza ◽  
I.D. Tonks ◽  
J.M. Clark ◽  
N.K. Hayward ◽  
...  
Keyword(s):  
Functional Status ◽  
Hela Cells ◽  
Mitotic Spindle ◽  
Dominant Negative ◽  
Cyclin B ◽  
Wild Type ◽  
Microtubule Nucleation ◽  
Cytoplasmic Accumulation ◽  
Low Levels ◽  
Essential Prerequisite

The formation of the mitotic spindle is an essential prerequisite for successful mitosis. The dramatic changes in the level of microtubule (Mt) nucleation at the centrosomes and Mt dynamics that occur in prophase are presumed to be initiated through the activity of cdc2/cyclin B. Here we present data that the cdc25B isoform functions to activate the cytoplasmic pool of cdc2/cyclin B responsible for these events. In contrast to cdc25C, cdc25B is present at low levels in HeLa cells during interphase, but sharply increases in prophase, when cdc25B accumulation in the cytoplasm correlates with prophase spindle formation. Overexpression of wild type and dominant negative mutants of cdc25B and cdc25C shows that prophase Mt nucleation is a consequence of cytoplasmic cdc25B activity, and that cdc25C regulates nuclear G2/M events. Our data also suggest that the functional status of the centrosome can regulate nuclear mitotic events.

scholarly journals Combined Treatment of Ionizing Radiation With Genistein on Cervical Cancer HeLa Cells

2006 ◽  
Vol 102 (1) ◽  
pp. 129-135 ◽  
Author(s):  
Bei Zhang ◽  
Jia-yin Liu ◽  
Jin-shun Pan ◽  
Su-ping Han ◽  
Xiao-xing Yin ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Ionizing Radiation ◽  
Hela Cells ◽  
Combined Treatment

scholarly journals Inactivation of Rho GTPases withClostridium difficileToxin B Impairs Centrosomal Activation of Aurora-A in G2/M Transition of HeLa Cells

2007 ◽  
Vol 18 (10) ◽  
pp. 3752-3763 ◽  
Author(s):  
Yoshikazu Ando ◽  
Shingo Yasuda ◽  
Fabian Oceguera-Yanez ◽  
Shuh Narumiya
Keyword(s):  
Signaling Pathways ◽  
Hela Cells ◽  
Rho Gtpases ◽  
Mammalian Cells ◽  
Cyclin B ◽  
Aurora A ◽  
Toxin B ◽  
Mitotic Kinases ◽  
H3 Phosphorylation ◽  
G2 Phase

During G2 phase of cell cycle, centrosomes function as a scaffold for activation of mitotic kinases. Aurora-A is first activated at late G2 phase at the centrosome, facilitates centrosome maturation, and induces activation of cyclin B-Cdk1 at the centrosome for mitotic entry. Although several molecules including HEF1 and PAK are implicated in centrosomal activation of Aurora-A, signaling pathways leading to Aurora-A activation at the centrosome, and hence mitotic commitment in vertebrate cells remains largely unknown. Here, we have used Clostridium difficile toxin B and examined the role of Rho GTPases in G2/M transition of HeLa cells. Inactivation of Rho GTPases by the toxin B treatment delayed by 2 h histone H3 phosphorylation, Cdk1/cyclin B activation, and Aurora-A activation. Furthermore, PAK activation at the centrosome that was already present before the toxin addition was significantly attenuated for 2 h by the addition of toxin B, and HEF1 accumulation at the centrosome that occurred in late G2 phase was also delayed. These results suggest that Rho GTPases function in G2/M transition of mammalian cells by mediating multiple signaling pathways converging to centrosomal activation of Aurora-A.

scholarly journals Nanoscale insight into chromatin remodeling and DNA repair complex in HeLa cells after ionizing radiation

DNA Repair ◽  
2020 ◽  
Vol 96 ◽  
pp. 102974
Author(s):  
Ruqun Wu ◽  
Wenjing Liu ◽  
Yujie Sun ◽  
Cheng Shen ◽  
Jinlong Guo ◽  
...  
Keyword(s):  
Dna Repair ◽  
Ionizing Radiation ◽  
Chromatin Remodeling ◽  
Hela Cells ◽  
Insight Into

scholarly journals Clostridium botulinum C2 Toxin Delays Entry into Mitosis and Activation of p34cdc2Kinase and cdc25-C Phosphatase in HeLa cells

1999 ◽  
Vol 67 (10) ◽  
pp. 5083-5090 ◽  
Author(s):  
Holger Barth ◽  
Manuela Klingler ◽  
Klaus Aktories ◽  
Volker Kinzel
Keyword(s):  
Cell Cycle ◽  
Protein Kinase ◽  
Hela Cells ◽  
Clostridium Botulinum ◽  
Focal Adhesions ◽  
Cyclin B ◽  
Phase Cell ◽  
Synchronized Cells ◽  
Clostridium Botulinum C2 Toxin ◽  
C2 Toxin

ABSTRACT The Clostridium botulinum C2 toxin ADP-ribosylates monomeric actin, thereby inducing disassembly of actin filaments, alteration of focal adhesions, and rounding of cells. After treatment with C2 toxin, cells stop to proliferate but remain viable for about 2 days. In view of reported correlations between the structure of the actin cytoskeleton and cell cycle transition, the effects of C2 toxin on the G2/M phase transition of the cell division cycle were studied. Since C2 toxin delayed entry into mitosis in HeLa cells, those enzymes which control entry into mitosis, the cyclin-dependent protein kinase mitosis-promoting factor (MPF) and the phosphatase cdc25-C were examined after treatment of synchronized cells with C2 toxin. MPF is composed of the regulatory cyclin B and the enzymatic p34 cdc2 kinase subunits. For its activation at the G2/M border, p34 cdc2 needs to be associated with cyclin B and additionally dephosphorylated at Tyr-15 by the specific phosphatase cdc25-C. Treatment of synchronized cells in S or G2 phase with C. botulinum C2 toxin prevented p34 cdc2 protein kinase activation by inhibiting its tyrosine dephosphorylation at the G2/M border. Furthermore, the activity of cdc25-C phosphatase was decreased after treatment of cells with C2 toxin. Our results suggest that the prevented activation of the mitotic inducers p34 cdc2 kinase and cdc25-C phosphatase represents the final downstream events in the action of C2 toxin resulting in a G2 phase cell cycle delay in synchronized HeLa cells.

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