scholarly journals The Centrosomal Protein C-Nap1 Is Required for Cell Cycle–Regulated Centrosome Cohesion

2000 ◽  
Vol 151 (4) ◽  
pp. 837-846 ◽  
Author(s):  
Thibault Mayor ◽  
York-Dieter Stierhof ◽  
Kayoko Tanaka ◽  
Andrew M. Fry ◽  
Erich A. Nigg
Keyword(s):  
Cell Cycle ◽  
Protein C ◽  
Function Analysis ◽  
Cell Cycle Phase ◽  
Cycle Phase ◽  
Detailed Structure ◽  
Centrosomal Protein ◽  
Spindle Poles ◽  
Dynamic Cell ◽  
A Cell

Duplicating centrosomes are paired during interphase, but are separated at the onset of mitosis. Although the mechanisms controlling centrosome cohesion and separation are important for centrosome function throughout the cell cycle, they remain poorly understood. Recently, we have proposed that C-Nap1, a novel centrosomal protein, is part of a structure linking parental centrioles in a cell cycle–regulated manner. To test this model, we have performed a detailed structure–function analysis on C-Nap1. We demonstrate that antibody-mediated interference with C-Nap1 function causes centrosome splitting, regardless of the cell cycle phase. Splitting occurs between parental centrioles and is not dependent on the presence of an intact microtubule or microfilament network. Centrosome splitting can also be induced by overexpression of truncated C-Nap1 mutants, but not full-length protein. Antibodies raised against different domains of C-Nap1 prove that this protein dissociates from spindle poles during mitosis, but reaccumulates at centrosomes at the end of cell division. Use of the same antibodies in immunoelectron microscopy shows that C-Nap1 is confined to the proximal end domains of centrioles, indicating that a putative linker structure must contain additional proteins. We conclude that C-Nap1 is a key component of a dynamic, cell cycle–regulated structure that mediates centriole–centriole cohesion.

scholarly journals Heterogeneous Nuclear Ribonucleoprotein C Modulates Translation of c-myc mRNA in a Cell Cycle Phase-Dependent Manner

2003 ◽  
Vol 23 (2) ◽  
pp. 708-720 ◽  
Author(s):  
Jong Heon Kim ◽  
Ki Young Paek ◽  
Kobong Choi ◽  
Tae-Don Kim ◽  
Bumsuk Hahm ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Phase ◽  
In Vitro Translation ◽  
Cycle Phase ◽  
Dependent Manner ◽  
Heterogeneous Nuclear Ribonucleoprotein ◽  
M Phase ◽  
Hnrnp C ◽  
A Cell ◽  
Nuclear Ribonucleoprotein

ABSTRACT The c-myc proto-oncogene plays a key role in the proliferation, differentiation, apoptosis, and regulation of the cell cycle. Recently, it was demonstrated that the 5′ nontranslated region (5′ NTR) of human c-myc mRNA contains an internal ribosomal entry site (IRES). In this study, we investigated cellular proteins interacting with the IRES element of c-myc mRNA. Heterogeneous nuclear ribonucleoprotein C (hnRNP C) was identified as a cellular protein that interacts specifically with a heptameric U sequence in the c-myc IRES located between two alternative translation initiation codons CUG and AUG. Moreover, the addition of hnRNP C1 in an in vitro translation system enhanced translation of c-myc mRNA. Interestingly, hnRNP C was partially relocalized from the nucleus, where most of the hnRNP C resides at interphase, to the cytoplasm at the G2/M phase of the cell cycle. Coincidently, translation mediated through the c-myc IRES was increased at the G2/M phase when cap-dependent translation was partially inhibited. On the other hand, a mutant c-myc mRNA lacking the hnRNP C-binding site, showed a decreased level of translation at the G2/M phase compared to that of the wild-type message. Taken together, these findings suggest that hnRNP C, via IRES binding, modulates translation of c-myc mRNA in a cell cycle phase-dependent manner.

Dynamically-enhanced retention of gold nanoclusters in HeLa cells following X-rays exposure: A cell cycle phase-dependent targeting approach

2016 ◽  
Vol 119 (3) ◽  
pp. 544-551 ◽  
Author(s):  
Yan Liu ◽  
Weiqiang Chen ◽  
Pengcheng Zhang ◽  
Xiaodong Jin ◽  
Xinguo Liu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Hela Cells ◽  
Gold Nanoclusters ◽  
Cell Cycle Phase ◽  
Cycle Phase ◽  
X Rays ◽  
A Cell

scholarly journals The mechanism regulating the dissociation of the centrosomal protein C-Nap1 from mitotic spindle poles

2002 ◽  
Vol 115 (16) ◽  
pp. 3275-3284 ◽  
Author(s):  
Thibault Mayor ◽  
Ulrike Hacker ◽  
York-Dieter Stierhof ◽  
Erich A. Nigg
Keyword(s):  
Cell Cycle ◽  
Protein C ◽  
Proteasome Inhibitors ◽  
Full Length ◽  
Centrosomal Protein ◽  
Large Structures ◽  
Spindle Poles ◽  
M Phase ◽  
Nucleation Activity ◽  
Cycle Regulation

The centrosomal protein C-Nap1 is thought to play an important role in centrosome cohesion during interphase of the cell cycle. At the onset of mitosis, when centrosomes separate for bipolar spindle formation, C-Nap1 dissociates from centrosomes. Here we report the results of experiments aimed at determining whether the dissociation of C-Nap1 from mitotic centrosomes is triggered by proteolysis or phosphorylation. Specifically, we analyzed both the cell cycle regulation of endogenous C-Nap1 and the fate of exogenously expressed full-length C-Nap1. Western blot analyses suggested a reduction in the endogenous C-Nap1 level during M phase, but studies using proteasome inhibitors and destruction assays performed in Xenopus extracts argue against ubiquitin-dependent degradation of C-Nap1. Instead, our data indicate that the mitotic C-Nap1 signal is reduced as a consequence of M-phase-specific phosphorylation. Overexpression of full-length C-Nap1 in human U2OS cells caused the formation of large structures that embedded the centrosome and impaired its microtubule nucleation activity. Remarkably, however, these centrosome-associated structures did not interfere with cell division. Instead, centrosomes were found to separate from these structures at the onset of mitosis, indicating that a localized and cell-cycle-regulated activity can dissociate C-Nap1 from centrosomes. A prime candidate for this activity is the centrosomal protein kinase Nek2, as the formation of large C-Nap1 structures was substantially reduced upon co-expression of active Nek2. We conclude that the dissociation of C-Nap1 from mitotic centrosomes is regulated by localized phosphorylation rather than generalized proteolysis.

scholarly journals Dependence of cell-type proportioning and sorting on cell cycle phase in Dictyostelium discoideum

1984 ◽  
Vol 70 (1) ◽  
pp. 133-145 ◽  
Author(s):  
C.J. Weijer ◽  
G. Duschl ◽  
C.N. David
Keyword(s):  
Cell Cycle ◽  
Stationary Phase ◽  
Dictyostelium Discoideum ◽  
Cell Cycle Phase ◽  
Cycle Phase ◽  
Cell Type ◽  
Slime Mould ◽  
Synchronous Cell ◽  
A Cell ◽  
The Relationship

The relationship between the cell cycle phase of vegetative amoebae and prestalk and prespore differentiation in the slug stage were investigated in the slime mould Dictyostelium discoideum. Cells were synchronized by release from the stationary phase. Samples were taken at various times during the course of a synchronous cell doubling, fluorescently labelled and mixed with cells of random cell cycle phase from exponentially growing cultures. The fate of the fluorescently labelled cells was recorded at the slug stage. Cells early in the cycle exhibit strong prestalk sorting; cells taken later in the cycle exhibit strong prespore sorting. The period of prestalk sorting occurs immediately following mitosis and lasts about 1 h in a cell cycle of about 7 h duration. Accompanying the altered sorting behaviour is a marked changed in the prestalk-prespore proportions in slugs formed from synchronized populations of cells. Cells synchronized early in the cycle form slugs with 55% prespore cells; cells synchronized late in the cycle form slugs with 90% prespore. The results are discussed in terms of models for the formation of the prestalk-prespore pattern in slugs.

scholarly journals Visualizing Cell Cycle Phase Organization and Control During Neural Lineage Elaboration

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 2112
Author(s):  
Fatma Rabia Urun ◽  
Adrian W Moore
Keyword(s):  
Cell Cycle ◽  
Cell Fate ◽  
Cell Types ◽  
Cell Cycle Phase ◽  
Cycle Phase ◽  
Cell Cycle Regulators ◽  
Neural Lineage ◽  
Fate Control ◽  
A Cell ◽  
Cell Fate Control

In neural precursors, cell cycle regulators simultaneously control both progression through the cell cycle and the probability of a cell fate switch. Precursors act in lineages, where they transition through a series of cell types, each of which has a unique molecular identity and cellular behavior. Thus, investigating links between cell cycle and cell fate control requires simultaneous identification of precursor type and cell cycle phase, as well as an ability to read out additional regulatory factor expression or activity. We use a combined FUCCI-EdU labelling protocol to do this, and then apply it to the embryonic olfactory neural lineage, in which the spatial position of a cell correlates with its precursor identity. Using this integrated model, we find the CDKi p27KIP1 has different regulation relative to cell cycle phase in neural stem cells versus intermediate precursors. In addition, Hes1, which is the principle transcriptional driver of neural stem cell self-renewal, surprisingly does not regulate p27KIP1 in this cell type. Rather, Hes1 indirectly represses p27KIP1 levels in the intermediate precursor cells downstream in the lineage. Overall, the experimental model described here enables investigation of cell cycle and cell fate control linkage from a single precursor through to a lineage systems level.

scholarly journals TRF2 Controls Telomeric Nucleosome Organization in a Cell Cycle Phase-Dependent Manner

PLoS ONE ◽  
2012 ◽  
Vol 7 (4) ◽  
pp. e34386 ◽  
Author(s):  
Alessandra Galati ◽  
Frédérique Magdinier ◽  
Valentina Colasanti ◽  
Serge Bauwens ◽  
Sébastien Pinte ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Phase ◽  
Cycle Phase ◽  
Dependent Manner ◽  
Nucleosome Organization ◽  
A Cell

scholarly journals A cell-cycle-phase-specific mutant of amoeba

1984 ◽  
Vol 68 (1) ◽  
pp. 95-111
Author(s):  
A. Gangopadhyay ◽  
S. Chatterjee
Keyword(s):  
Cell Cycle ◽  
Cell Size ◽  
Size Structure ◽  
S Phase ◽  
Cell Cycle Phase ◽  
Membrane Properties ◽  
Cycle Phase ◽  
Mutagenic Action ◽  
A Cell ◽  
Characteristic Features

The treatment of Amoeba indica with ethylmethanesulphonate (EMS) at early S, late S and late G2 phases of the cell cycle leads to the production of mini amoeba cells in the G2 period. Among them, only a few of the mini cells that originated from EMS treatment at early S phase have been found to be viable and to give rise to stable clones. These mini amoebae show stable and altered characteristic features in cell size, structure, membrane properties, cell-cycle timing and the patterns of macromolecular syntheses as compared to the parental cells. It is suggested that the mini amoeba cell is a size mutant that has a cell-cycle-phase-specific origin. The finding is discussed in relation to preferential mutagenic action involving the functional state of DNA leading to the production of viable mutant amoebae.

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