Analysis of Drosophila cyclin EI and II function during development: identification of an inhibitory zone within the morphogenetic furrow of the eye imaginal disc that blocks the function of cyclin EI but not cyclin EII.
The Drosophila cyclin E (DmcycE) gene gives rise to two transcripts encoding proteins that differ at their N termini, DmcycEII and DmcycEI. This study presents the first in vivo dissection of Cyclin E function. Ectopic expression studies using N- and C-terminal deletions of DmcycEI revealed that a region of 322 residues surrounding the cyclin box is sufficient to induce entry of G1-arrested larval eye imaginal disc cells into S phase. Ectopic expression of DmcycEI in the eye disc has been previously shown to drive anterior, but not posterior, G1-phase cells within the morphogenetic furrow (MF) into S phase. Significantly, ectopic expression of DmcycEII and N-terminal deletions of DmcycEI were able to drive all G1 cells within the morphogenetic furrow into S phase, while a C-terminal deletion of DmcycEI could not. The p21 homolog Dacapo was shown by yeast two-hybrid, coimmunolocalization, and in vivo functional studies not to be the mediator of the DmcycEI inhibition in posterior part of the MF. Taken together, these results reveal a novel zone within the posterior region of the MF where DmcycEI but not DmcycEII function is inhibited, and suggest that DmcycEII is a more potent inducer of S phase.
Crack
Donna
D
Center for the Molecular Genetics of Development and Department of Molecular Biosciences, University of Adelaide, Adelaide, South Australia, 5005, Australia.
Secombe
Julie
J
Coombe
Michelle
M
Brumby
Anthony
A
Saint
Robert
R
Richardson
Helena
H
D000818:Animals; D030801:Animals, Genetically Modified; D019927:Cyclin E / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D016213:Cyclins / Q000235:genetics / Q000502:physiology*; D004330:Drosophila / Q000235:genetics / Q000254:growth & development* / Q000502:physiology*; D029721:Drosophila Proteins; D005123:Eye / Q000166:cytology / Q000254:growth & development*; D016193:G1 Phase / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D007763:Lac Operon; D009687:Nuclear Proteins / Q000502:physiology; D016196:S Phase / Q000502:physiology; D017384:Sequence Deletion; D020798:Two-Hybrid System Techniques
D019927:Cyclin E; D016213:Cyclins; D029721:Drosophila Proteins; D018840:HSP70 Heat-Shock Proteins; D009687:Nuclear Proteins; C103336:dap protein, Drosophila