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
Date
2002
Authors
Denton, D.
Secombe, J.
Coombe, M.
Brumby, A.
Saint, R.
Richardson, H.
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Journal article
Citation
Developmental Biology, 2002; 241(1):157-171
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Abstract
The Drosophilacyclin 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.