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Gene Review

CycA  -  Cyclin A

Drosophila melanogaster

Synonyms: 0033/02, 0040/24, 0046/23, 0104/07, 0245/34, ...
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Disease relevance of CycA


High impact information on CycA


Biological context of CycA

  • Surprisingly, nuclear accumulation was not required, and even a membrane-tethered form of CycA was able to induce mitosis [5].
  • Cyclin A (CycA), the only essential mitotic cyclin in Drosophila, is cytoplasmic during interphase and accumulates in the nucleus during prophase [5].
  • The essential mitotic function of CycA is therefore not the activation of numerous mitotic substrates by Cdk1-dependent phosphorylation [5].
  • CycA has seven exons and six introns, and its transcription unit spans 6 kb [6].
  • In roughex (rux) mutants, cells enter S phase precociously because of ectopic activation of a Cyclin A/Cdk complex in early G1 [7].

Anatomical context of CycA

  • In larvae, cyclin A is expressed predominantly in brain and imaginal disks, whereas cyclin B transcripts are abundant in testes [8].
  • Cyclin A is present at its highest concentrations throughout the cytoplasm during the interphase periods of the blastoderm cycles, although weak punctate staining can also be detected in the nucleus [9].
  • Neural cell fate in rca1 and cycA mutants: the roles of intrinsic and extrinsic factors in asymmetric division in the Drosophila central nervous system [1].
  • Cyclin A is not detectable in unfertilized eggs and is present at low levels prior to cellularization of the syncytial embryo [10].
  • In cells arrested at c-metaphase by treating with microtubule destabilizing drugs to prevent spindle formation, cyclin A has been degraded in the arrested cells, whereas cyclin B is maintained at high levels [10].

Associations of CycA with chemical compounds

  • This study suggests that, in fruit fly embryos, 1) there is a dose-dependent relationship between cell cycle length and O2 levels in fruit fly embryos, and 2) stabilized cyclin A and E2F1 are likely to be the mediators of hypoxia-induced arrest at metaphase and pre-S phase [11].

Regulatory relationships of CycA

  • Expression of rca1 transgenes in G1 or in postmitotic neurons promotes Cyclin A protein accumulation and drives cells into S phase in a Cyclin A-dependent fashion [7].
  • Surprisingly, Rux had a stimulating effect on CycA-Cdk1 activity when present in low concentrations [12].
  • Taken together, our observations support the hypothesis that cyclin B regulates cytoskeletal changes while cyclin A regulates the nuclear cycles [13].
  • These results demonstrate that CycA is directly regulated by PcG proteins, linking them to cell cycle control in vivo [14].
  • Cut promoted Cyclin A expression by negatively regulating Fizzy-related [15].

Other interactions of CycA

  • Given that Dally is known to regulate the activity of secreted growth factors our findings suggest that extracellular cues influence the degradation of Cyclin A in a manner that controls cell cycle progression and ultimately, cell division patterning [16].
  • We show that both genes encode abundant maternal mRNAs, but whereas the cyclin A mRNA is relatively uniformly distributed before cell formation, the cyclin B mRNA becomes localized to the developing pole cells [8].
  • While the loss of N leads to the specification of RP2 fates to both progeny of GMC-1 and loss of nb results in the specification of sib fates to these daughter cells, the GMC-1 in the double mutant between nb and cycA assumes a sib fate [17].
  • We have done experiments to investigate a potential functional overlap between two kinases (Dmcdc2 and Dmcdc2c) and two cyclins (cyclin A and cyclin B) [18].
  • Finally, loss of function of the Pc gene and overexpression of Pc and ph trigger up-regulation and down-regulation, respectively, of CycA expression in embryos [14].

Analytical, diagnostic and therapeutic context of CycA


  1. Neural cell fate in rca1 and cycA mutants: the roles of intrinsic and extrinsic factors in asymmetric division in the Drosophila central nervous system. Lear, B.C., Skeath, J.B., Patel, N.H. Mech. Dev. (1999) [Pubmed]
  2. roughex is a dose-dependent regulator of the second meiotic division during Drosophila spermatogenesis. Gönczy, P., Thomas, B.J., DiNardo, S. Cell (1994) [Pubmed]
  3. The roles of Drosophila cyclins A and B in mitotic control. Lehner, C.F., O'Farrell, P.H. Cell (1990) [Pubmed]
  4. Expression and function of Drosophila cyclin A during embryonic cell cycle progression. Lehner, C.F., O'Farrell, P.H. Cell (1989) [Pubmed]
  5. Requirements of cyclin a for mitosis are independent of its subcellular localization. Dienemann, A., Sprenger, F. Curr. Biol. (2004) [Pubmed]
  6. Structure of the Drosophila melanogaster gene encoding cyclin A. Takahisa, M., Togashi, S., Ueda, R., Mikuni, M., Tsurumura, S., Kondo, K., Miyake, T. Gene (1992) [Pubmed]
  7. Control of G1 in the developing Drosophila eye: rca1 regulates Cyclin A. Dong, X., Zavitz, K.H., Thomas, B.J., Lin, M., Campbell, S., Zipursky, S.L. Genes Dev. (1997) [Pubmed]
  8. Transcripts of one of two Drosophila cyclin genes become localized in pole cells during embryogenesis. Whitfield, W.G., González, C., Sánchez-Herrero, E., Glover, D.M. Nature (1989) [Pubmed]
  9. Cyclins A and B associate with chromatin and the polar regions of spindles, respectively, and do not undergo complete degradation at anaphase in syncytial Drosophila embryos. Maldonado-Codina, G., Glover, D.M. J. Cell Biol. (1992) [Pubmed]
  10. The A- and B-type cyclins of Drosophila are accumulated and destroyed in temporally distinct events that define separable phases of the G2-M transition. Whitfield, W.G., Gonzalez, C., Maldonado-Codina, G., Glover, D.M. EMBO J. (1990) [Pubmed]
  11. Hypoxia induces major effects on cell cycle kinetics and protein expression in Drosophila melanogaster embryos. Douglas, R.M., Farahani, R., Morcillo, P., Kanaan, A., Xu, T., Haddad, G.G. Am. J. Physiol. Regul. Integr. Comp. Physiol. (2005) [Pubmed]
  12. Rux is a cyclin-dependent kinase inhibitor (CKI) specific for mitotic cyclin-Cdk complexes. Foley, E., O'Farrell, P.H., Sprenger, F. Curr. Biol. (1999) [Pubmed]
  13. Cyclin A and B functions in the early Drosophila embryo. Stiffler, L.A., Ji, J.Y., Trautmann, S., Trusty, C., Schubiger, G. Development (1999) [Pubmed]
  14. Polycomb group-dependent Cyclin A repression in Drosophila. Martinez, A.M., Colomb, S., Déjardin, J., Bantignies, F., Cavalli, G. Genes Dev. (2006) [Pubmed]
  15. Notch-dependent downregulation of the homeodomain gene cut is required for the mitotic cycle/endocycle switch and cell differentiation in Drosophila follicle cells. Sun, J., Deng, W.M. Development (2005) [Pubmed]
  16. dally, a Drosophila member of the glypican family of integral membrane proteoglycans, affects cell cycle progression and morphogenesis via a Cyclin A-mediated process. Nakato, H., Fox, B., Selleck, S.B. J. Cell. Sci. (2002) [Pubmed]
  17. Cell division genes promote asymmetric interaction between Numb and Notch in the Drosophila CNS. Wai, P., Truong, B., Bhat, K.M. Development (1999) [Pubmed]
  18. Cyclins and cdc2 kinases in Drosophila: genetic analyses in a higher eukaryote. Lehner, C.F., Ried, G., Stern, B., Knoblich, J.A. Ciba Found. Symp. (1992) [Pubmed]
  19. Sensory mother cell division is specifically affected in a Cyclin-A mutant of Drosophila melanogaster. Ueda, R., Togashi, S., Takahisa, M., Tsurumura, S., Mikuni, M., Kondo, K., Miyake, T. EMBO J. (1992) [Pubmed]
  20. Ecdysone-induced accumulation of mosquito cells in the G1 phase of the cell cycle. Gerenday, A., Fallon, A.M. J. Insect Physiol. (2004) [Pubmed]
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