scholarly journals Ectopic cyclin E expression induces premature entry into S phase and disrupts pattern formation in the Drosophila eye imaginal disc

Development ◽  
1995 ◽  
Vol 121 (10) ◽  
pp. 3371-3379 ◽  
Author(s):  
H. Richardson ◽  
L.V. O'Keefe ◽  
T. Marty ◽  
R. Saint
Keyword(s):  
Phase Transition ◽  
Imaginal Disc ◽  
Cyclin E ◽  
Ectopic Expression ◽  
S Phase ◽  
G1 Phase ◽  
Mammalian Tissue ◽  
Culture Cells ◽  
Tissue Culture Cells ◽  
Eye Imaginal Disc

During animal development, cell proliferation is controlled in many cases by regulation of the G1 to S phase transition. Studies of mammalian tissue culture cells have shown that the G1-specific cyclin, cyclin E, can be rate limiting for progression from G1 to S phase. During Drosophila development, down-regulation of cyclin E is required for G1 arrest in terminally differentiating embryonic epidermal cells. Whether cyclin E expression limits progression into S phase in proliferating, as opposed to differentiating, cells during development has not been investigated. Here we show that Drosophila cyclin E (DmcycE) protein is absent in G1 phase cells but appears at the onset of S phase in proliferating cells of the larval optic lobe and eye imaginal disc. We have examined cells in the eye imaginal epithelium, where a clearly defined developmentally regulated G1 to S phase transition occurs. Ectopic expression of DmcycE induces premature entry of most of these G1 cells into S phase. Thus in these cells, control of DmcycE expression is required for regulated entry into S phase. Significantly, a band of eye imaginal disc cells in G1 phase was not induced to enter S phase by ectopic expression of DmcycE. This provides evidence for additional regulatory mechanisms that operate during G1 phase to limit cell proliferation during development. These results demonstrate that the role of cyclin E in regulating progression into S phase in mammalian tissue culture cells applies to some, but not all, cells during Drosophila development.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Ectopic expression of human p53 inhibits entry into S phase and induces apoptosis in the Drosophila eye imaginal disc

Oncogene ◽  
1999 ◽  
Vol 18 (48) ◽  
pp. 6767-6775 ◽  
Author(s):  
Masamitsu Yamaguchi ◽  
Fumiko Hirose ◽  
Yoshihiro H Inoue ◽  
Michina Shiraki ◽  
Yuko Hayashi ◽  
...  
Keyword(s):  
Imaginal Disc ◽  
Ectopic Expression ◽  
S Phase ◽  
Drosophila Eye ◽  
Eye Imaginal Disc

scholarly journals Ectopic Expression of Cdc25A Accelerates the G1/S Transition and Leads to Premature Activation of Cyclin E- and Cyclin A-Dependent Kinases

1999 ◽  
Vol 19 (9) ◽  
pp. 6183-6194 ◽  
Author(s):  
Ida Blomberg ◽  
Ingrid Hoffmann
Keyword(s):  
Phase Transition ◽  
Cyclin E ◽  
Ectopic Expression ◽  
Cyclin A ◽  
S Phase ◽  
Important Regulator ◽  
Cycle Regulation ◽  
Cdc25a Phosphatase ◽  
Rate Limiting

ABSTRACT Human Cdc25 phosphatases play important roles in cell cycle regulation by removing inhibitory phosphates from tyrosine and threonine residues of cyclin-dependent kinases. Three human Cdc25 isoforms, A, B, and C, have been discovered. Cdc25B and Cdc25C play crucial roles at the G2/M transition. In the present study, we have investigated the function of human Cdc25A phosphatase. Cell lines that express human Cdc25A in an inducible manner have been generated. Ectopic expression of Cdc25A accelerates the G1/S-phase transition, indicating that Cdc25A controls an event(s) that is rate limiting for entry into S phase. Furthermore, we carried out a detailed analysis of the expression and activation of human Cdc25A. Activation of endogenous Cdc25A occurs during late G1 phase and increases in S and G2 phases. We further demonstrate that Cdc25A is activated at the same time as cyclin E- and cyclin A-dependent kinases. In vitro, Cdc25A dephosphorylates and activates the cyclin-Cdk complexes that are active during G1. Overexpression of Cdc25A in the inducible system, however, leads to a premature activation of both cyclin E-Cdk2 and cyclin A-Cdk2 complexes, while no effect of cyclin D-dependent kinases is observed. Furthermore, Cdc25A overexpression induces a tyrosine dephosphorylation of Cdk2. These results suggest that Cdc25A is an important regulator of the G1/S-phase transition and that cyclin E- and cyclin A-dependent kinases act as direct targets.

A Drosophila G1-specific cyclin E homolog exhibits different modes of expression during embryogenesis

Development ◽  
1993 ◽  
Vol 119 (3) ◽  
pp. 673-690 ◽  
Author(s):  
H.E. Richardson ◽  
L.V. O'Keefe ◽  
S.I. Reed ◽  
R. Saint
Keyword(s):  
Phase Transition ◽  
Cell Cycle ◽  
Nervous System ◽  
Peripheral Nervous System ◽  
Cyclin E ◽  
S Phase ◽  
G1 Phase ◽  
Cycle Phase ◽  
E Gene ◽  
G1 Cyclin

We have isolated a Drosophila homolog of the human G1-specific cyclin E gene. Cyclin E proteins thus constitute an evolutionarily conserved subfamily of metazoan cyclins. The Drosophila cyclin E gene, DmcycE, encodes two proteins with a common C-terminal region and unique N-terminal regions. Unlike other Drosophila cyclins, DmcycE exhibits a dynamic pattern of expression during development. DmcycE is supplied maternally, but at the completion of the cleavage divisions and prior to mitosis 14, the maternal transcripts are rapidly degraded in all cells except the pole (germ) cells. Two modes of DmcycE expression are observed in the subsequent divisions. During cycles 14, 15 and 16 in non-neural cells, DmcycE mRNA levels show no cell-cycle-associated variation. DmcycE expression in these cells is therefore independent of the cell cycle phase. In contrast, expression in proliferating embryonic peripheral nervous system cells occurs during interphase as a brief pulse that initiates before and overlaps with S phase, demonstrating the presence of a G1 phase in these embryonic neural cell cycles. DmcycE appears not to be expressed in cells that undergo endoreplication cycles during polytenization. The structural homology to human cyclin E, the ability of DmcycE to rescue a G1 cyclin-deficient yeast strain, the presence of multiple PEST sequences characteristic of G1-specific cyclins and expression during G1 phase in proliferating peripheral nervous system cells all argue that Drosophila cyclin E is a G1 cyclin. Constitutive DmcycE expression in embryonic cycles lacking a G1 phase, in contrast to expression during the G1-S phase transition in cycles exhibiting a G1 phase, implicates DmcycE expression in the regulation of the G1 to S phase transition during Drosophila embryogenesis.

scholarly journals Analysis of a Drosophila cyclin E Hypomorphic Mutation Suggests a Novel Role for Cyclin E in Cell Proliferation Control During Eye Imaginal Disc Development

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 1867-1882 ◽  
Author(s):  
Julie Secombe ◽  
Johanna Pispa ◽  
Robert Saint ◽  
Helena Richardson
Keyword(s):  
Imaginal Disc ◽  
Cyclin E ◽  
Cyclin A ◽  
Cyclin B1 ◽  
S Phase ◽  
P Element ◽  
Pigment Cells ◽  
Hypomorphic Mutation ◽  
Eye Imaginal Disc ◽  
Number Of Cells

Abstract We have generated and characterized a Drosophila cyclin E hypomorphic mutation, DmcycEJP, that is homozygous viable and fertile, but results in adults with rough eyes. The mutation arose from an internal deletion of an existing P[w+lacZ] element inserted 14 kb upstream of the transcription start site of the DmcycE zygotic mRNA. The presence of this deleted P element, but not the P[w+lacZ] element from which it was derived, leads to a decreased level of DmcycE expression during eye imaginal disc development. Eye imaginal discs from DmcycEJP larvae contain fewer S phase cells, both anterior and posterior to the morphogenetic furrow. This results in adults with small rough eyes, largely due to insufficient numbers of pigment cells. Altering the dosage of the Drosophila cdk2 homolog, cdc2c, retinoblastoma, or p21CIP1 homolog dacapo, which encode proteins known to physically interact with Cyclin E, modified the DmcycEJP rough eye phenotype as expected. Decreasing the dosage of the S phase transcription factor gene, dE2F, enhanced the DmcycEJP rough eye phenotype. Surprisingly, mutations in G2/M phase regulators cyclin A and string (cdc25), but not cyclin B1, B3, or cdc2, enhanced the DmcycE JP phenotype without affecting the number of cells entering S phase, but by decreasing the number of cells entering mitosis. Our analysis establishes the DmcycE JP allele as an excellent resource for searching for novel cyclin E genetic interactors. In addition, this analysis has identified cyclin A and string as DmcycEJP interactors, suggesting a novel role for cyclin E in the regulation of Cyclin A and String function during eye development.

Sulfhydryl bond formation is a prerequisite for proper cycling of centrosomes and chromosomes in mammalian tissue culture cells

1993 ◽  
Vol 51 ◽  
pp. 342-343
Author(s):  
Heide Schatten ◽  
Neidhard Paweletz ◽  
Ron Balczon
Keyword(s):  
Tissue Culture ◽  
Cell Cycle Progression ◽  
Group Formation ◽  
Sulfhydryl Group ◽  
Mammalian Tissue ◽  
Mitotic Chromosomes ◽  
Microtubule Network ◽  
Culture Cells ◽  
Tissue Culture Cells ◽  
Transmission Electron

To study the role of sulfhydryl group formation during cell cycle progression, mammalian tissue culture cells (PTK2) were exposed to 100¼M 2-mercaptoethanol for 2 to 6 h during their exponential phase of growth. The effects of 2-mercaptoethanol on centrosomes, chromosomes, microtubules, membranes and intermediate filaments were analyzed by transmission electron microscopy (TEM) and by immunofluorescence microscopy (IFM) methods using a human autoimmune antibody directed against centrosomes (SPJ), and a mouse monoclonal antibody directed against tubulin (E7). Chromosomes were affected most by this treatment: premature chromosome condensation was detected in interphase nuclei, and the structure in mitotic chromosomes was altered compared to control cells. This would support previous findings in dividing sea urchin cells in which chromosomes are arrested at metaphase while the centrosome splitting cycle continues. It might also support findings that certairt-sulfhydryl-blocking agents block cyclin destruction. The organization of the microtubule network was scattered probably due to a looser organization of centrosomal material at the interphase centers and at the mitotic poles.

scholarly journals Screens Using RNAi and cDNA Expression as Surrogates for Genetics in Mammalian Tissue Culture Cells

2005 ◽  
Vol 70 (0) ◽  
pp. 449-459 ◽  
Author(s):  
J. PEARLBERG ◽  
S. DEGOT ◽  
W. ENDEGE ◽  
J. PARK ◽  
J. DAVIES ◽  
...  
Keyword(s):  
Tissue Culture ◽  
Mammalian Tissue ◽  
Culture Cells ◽  
Tissue Culture Cells ◽  
Cdna Expression
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