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Gene Review

ccna2  -  cyclin A2

Xenopus (Silurana) tropicalis

Synonyms: ccn1, ccna, ccna1
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Disease relevance of ccna1

  • Functional clam cyclin A and B proteins have been produced using a baculovirus expression system [1].

High impact information on ccna1

  • Immunoblots with an anti-cyclin A antibody reveal that cyclin A is undetectable in oocytes, appears within 15 min of fertilization, and is destroyed near the end of each meiosis and mitosis [2].
  • The clam embryo protein cyclin A induces entry into M phase and the resumption of meiosis in Xenopus oocytes [2].
  • These findings indicate that the rise in cyclin A plays a direct and natural role in driving cells into M phase [2].
  • The cloned cDNA and derived amino acid sequences of one of these, cyclin A, are presented here [2].
  • While the cyclin E/Cdk2 complex appears to have a role in the initiation of DNA replication, another Cdk kinase, possibly cyclin A/Cdk, may be involved in a later step controlling the switch from initiation to elongation [3].

Biological context of ccna1

  • High levels of cyclin A cause marked hyperactivation of cdc2 kinase and a stable arrest at the metaphase point in the cell cycle [1].
  • Binding to cyclin A and phosphorylation of this threonine are both required to activate fully the histone H1 kinase activity of p33cdk2 [4].
  • The post-MBT survival mechanism arrests cells in G(1) phase by increasing expression of the cyclin-dependent kinase inhibitor p27(Xic1). p27(Xic1) associates with cyclin D/Cdk4 and cyclin A/Cdk2 complexes to cause G(1)/S arrest, perhaps allowing more time for DNA repair [5].
  • Together, these results strongly suggest that zygote-dependent deadenylation of cyclin A1 and cyclin B2 mRNAs is responsible for the downregulation of these proteins [6].
  • This prevented histone B4 and cyclin A1 and B1 mRNA polyadenylation, indicating that the polyadenylation of these mRNAs is Mos dependent [7].

Anatomical context of ccna1

  • This centriole separation activity is dependent on cyclin/cdk2 activity; depletion of either cdk2 or of the two activating cyclins, cyclin A and cyclin E, eliminates centriole separation activity [8].
  • Cyclin A belongs to a family of proteins involved in the regulation of the eukaryotic cell cycle [9].
  • Recombinant cyclin A bound to and activated cdc2 in a cell-free system, but cyclin A and cdk2 binding was not observed [9].
  • The roles of cyclin A in the rapid activation of cyclin B-cdc2 kinase at meiosis I and II transition and in the maintenance of high maturation-promoting factor activity in mature unfertilized eggs are discussed [9].

Associations of ccna1 with chemical compounds

  • Unlike the B-type cyclins, cyclin A is barely detectable in stage VI oocytes, and only starts to be made in significant amounts after oocytes are exposed to progesterone [10].
  • In contrast, p34cdc2 is only weakly tyrosine phosphorylated when bound to cyclin A and activates rapidly [11].
  • Analysis of embryos treated with hydroxyurea or cycloheximide showed widespread cellular apoptosis coincident with cyclin A cleavage [12].
  • The increase in Mos protein and the activation of MAPK by injecting cyclin A protein into immature oocytes were both blocked also by cycloheximide treatment [13].

Analytical, diagnostic and therapeutic context of ccna1


  1. Activation of p34cdc2 kinase by cyclin A. Roy, L.M., Swenson, K.I., Walker, D.H., Gabrielli, B.G., Li, R.S., Piwnica-Worms, H., Maller, J.L. J. Cell Biol. (1991) [Pubmed]
  2. The clam embryo protein cyclin A induces entry into M phase and the resumption of meiosis in Xenopus oocytes. Swenson, K.I., Farrell, K.M., Ruderman, J.V. Cell (1986) [Pubmed]
  3. Early events in DNA replication require cyclin E and are blocked by p21CIP1. Jackson, P.K., Chevalier, S., Philippe, M., Kirschner, M.W. J. Cell Biol. (1995) [Pubmed]
  4. The cdc2-related protein p40MO15 is the catalytic subunit of a protein kinase that can activate p33cdk2 and p34cdc2. Poon, R.Y., Yamashita, K., Adamczewski, J.P., Hunt, T., Shuttleworth, J. EMBO J. (1993) [Pubmed]
  5. The midblastula transition in Xenopus embryos activates multiple pathways to prevent apoptosis in response to DNA damage. Finkielstein, C.V., Lewellyn, A.L., Maller, J.L. Proc. Natl. Acad. Sci. U.S.A. (2001) [Pubmed]
  6. Zygotic regulation of maternal cyclin A1 and B2 mRNAs. Audic, Y., Anderson, C., Bhatty, R., Hartley, R.S. Mol. Cell. Biol. (2001) [Pubmed]
  7. The Mos pathway regulates cytoplasmic polyadenylation in Xenopus oocytes. de Moor, C.H., Richter, J.D. Mol. Cell. Biol. (1997) [Pubmed]
  8. Cyclin-dependent kinase control of centrosome duplication. Lacey, K.R., Jackson, P.K., Stearns, T. Proc. Natl. Acad. Sci. U.S.A. (1999) [Pubmed]
  9. Molecular cloning and immunological analysis of goldfish cyclin A during oocyte maturation. Katsu, Y., Yamashita, M., Hirai, T., Tokumoto, T., Kajiura, H., Nagahama, Y. Dev. Biol. (1995) [Pubmed]
  10. On the synthesis and destruction of A- and B-type cyclins during oogenesis and meiotic maturation in Xenopus laevis. Kobayashi, H., Minshull, J., Ford, C., Golsteyn, R., Poon, R., Hunt, T. J. Cell Biol. (1991) [Pubmed]
  11. Cyclin A- and cyclin B-dependent protein kinases are regulated by different mechanisms in Xenopus egg extracts. Clarke, P.R., Leiss, D., Pagano, M., Karsenti, E. EMBO J. (1992) [Pubmed]
  12. Developmentally regulated activation of apoptosis early in Xenopus gastrulation results in cyclin A degradation during interphase of the cell cycle. Stack, J.H., Newport, J.W. Development (1997) [Pubmed]
  13. Initiation of Xenopus oocyte maturation by activation of the mitogen-activated protein kinase cascade. Gotoh, Y., Masuyama, N., Dell, K., Shirakabe, K., Nishida, E. J. Biol. Chem. (1995) [Pubmed]
  14. Interaction of Xenopus Cdc2 x cyclin A1 with the origin recognition complex. Romanowski, P., Marr, J., Madine, M.A., Rowles, A., Blow, J.J., Gautier, J., Laskey, R.A. J. Biol. Chem. (2000) [Pubmed]
  15. Reconstitution of p21ras-dependent and -independent mitogen-activated protein kinase activation in a cell-free system. VanRenterghem, B., Gibbs, J.B., Maller, J.L. J. Biol. Chem. (1993) [Pubmed]
  16. Caenorhabditis elegans cyclin A- and B-type genes: a cyclin A multigene family, an ancestral cyclin B3 and differential germline expression. Kreutzer, M.A., Richards, J.P., De Silva-Udawatta, M.N., Temenak, J.J., Knoblich, J.A., Lehner, C.F., Bennett, K.L. J. Cell. Sci. (1995) [Pubmed]
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