Disease relevance of CDC2

• Due to the functional and structural similarity with the beta-subunit of Escherichia coli DNA polymerase III, it has been proposed that PCNA would act as a molecular clamp during DNA synthesis [1].
• The major structural proteins capsid and nucleocapsid (NC) of the Saccharomyces cerevisiae retroviruslike element Ty3 are produced as domains within the Gag3 and Gag3-Pol3 precursor polyproteins [2].
• PITALRE, a nuclear CDC2-related protein kinase that phosphorylates the retinoblastoma protein in vitro [3].
• Heterologous fusion proteins linking the transcriptional activation domain of herpes simplex virus VP16 protein to the sliding clamp protein beta of the Escherichia coli DNA polymerase III holoenzyme are shown to function as topologically DNA-linked activators of yeast and Drosophila RNA polymerase II [4].
• Like most retroviruses and retrotransposons, the retrotransposon Ty3 expresses its pol gene analog (POL3) as a translational fusion to the upstream gag analog (GAG3) [5].

High impact information on CDC2

• In the absence of p97-Ufd1-Npl4 function, microtubules in Xenopus egg extracts remain as monopolar spindles attached to condensed chromosomes after Cdc2 kinase activity has returned to the interphase level [6].
• The nim1-catalyzed phosphorylation of the wee1 protein occurs in its C-terminal region and leads to a substantial drop in its activity as a cdc2-specific tyrosine kinase [7].
• SGV1 encodes a CDC28/cdc2-related kinase required for a G alpha subunit-mediated adaptive response to pheromone in S. cerevisiae [8].
• Since the S. cerevisiae CDC2 gene has recently been shown to have DNA sequence similarity to the active site regions of other known DNA polymerases, but to nevertheless be different from DNA polymerase I, we examined cdc2 mutants for the presence of DNA polymerases II and III [9].
• These findings suggest that ORC functions are conserved among eukaryotes and provide evidence that Cdc2 controls DNA replication initiation by acting directly at chromosomal origins [10].

Biological context of CDC2

• These results suggest that in human cells, two different CDC2-like kinases may regulate the cell cycle at distinct stages [11].
• In this paper we determine partial amino acid sequences of the 125 and 55 kDa polypeptides and find that they match parts of the amino acid sequences predicted from the nucleotide sequence of the CDC2 and HYS2 genes respectively [12].
• The temperature-sensitive growth phenotype of hys2-1 and hys2-2 mutations could be suppressed by the CDC2 gene on a multicopy plasmid [12].
• The nucleotide sequence of a 5 kb EcoRI-NcoI fragment of chromosome IV, contiguous to gene POL3 (CDC2), has been determined [13].
• Thermal inactivation of DNA polymerase delta in pol3 nuclear extracts enhanced DNA repair synthesis approximately 2-fold, an effect which could be specifically reversed by the addition of purified yeast DNA polymerase delta to the extract [14].

Anatomical context of CDC2

• CDK2 mRNA appeared late in G1 or in early S phase, slightly before CDC2 mRNA, after growth stimulation in normal human fibroblast cells [11].
• One deduced amino acid sequence shares 72% identity with rabbit skeletal muscle phosphorylase kinase gamma-subunit, while another is closely related to the yeast protein-serine kinases CDC2 in Schizosaccharomyces pombe and CDC28 in Saccharomyces cerevisiae [15].
• Investigators have used the budding yeast Saccharomyces cerevisiae as a model system in which to study the beta-adrenergic receptor, the T-cell receptor pathway, initiation of mammalian DNA replication, initiation of mammalian transcription, secretion, the CDC2 kinase system, cell cycle control, and aging, as well as the function of oncogenes [16].
• The mouse FT210 cell line is a temperature-sensitive cdc2 mutant [17].
• The cdc2 protein kinase plays a central role in control of the eukaryotic cell cycle of animals and yeasts [18].

Associations of CDC2 with chemical compounds

• Results obtained with mutants (cdc2, 6, 8, 9, and 21) defective in DNA replication and with an inhibitor of DNA replication (hydroxyurea) suggest that some DNA replication required for execution of the MBC-sensitive step but that the completion of replication is not [19].
• The POL3 encoded catalytic subunit of DNA polymerase delta possesses a highly conserved C-terminal cysteine-rich domain in Saccharomyces cerevisiae [20].
• We report here that the CDC28 gene product (the S. cerevisiae homologue of cdc2) is phosphorylated on the equivalent tyrosine (Y19) during S phase but that mutations that prevent tyrosine phosphorylation do not lead to premature mitosis and do not abolish feedback controls [21].
• In eukaryotes, mitosis requires the activation of cdc2 kinase via association with cyclin B and dephosphorylation of the threonine 14 and tyrosine 15 residues [22].
• DNA isolated from terminally arrested cells was of normal size as measured on neutral and alkaline sucrose gradients, suggesting that partially replicated DNA molecules do not accumulate and that DNA strands are ligated properly in cdc2 mutants [23].

Physical interactions of CDC2

• We also show by Western blotting that Hys2 protein co-purifies with DNA polymerase III activity as well as Cdc2 polypeptide [12].
• In particular, the G2/M transition is initiated by the activity of a complex formed by a CDK of the Cdc2/Cdc28 family and B-type cyclins of the Cdc13/C1b family in the yeasts, Schizosaccharomyces pombe (Sp) and Saccharomyces cerevisiae (Sc) [24].
• The Cdc6 protein interacts in vivo with Cdc2 kinase complexes [25].

Regulatory relationships of CDC2

• However, the pol3-stimulated Tn5 excision was reduced in rad52 and rad50 mutants [26].
• On a molar basis yPCNA and calf thymus PCNA/cyclin are equally active in stimulating DNA synthesis by DNA polymerase III [27].
• The subunits of histone H1 kinase have now been shown to be cyclins and the p34CDC2 kinase product of the cell cycle control gene CDC2 [28].

Other interactions of CDC2

• Cloning of a human cDNA encoding a CDC2-related kinase by complementation of a budding yeast cdc28 mutation [11].
• Such an involvement was previously suggested by in vivo analysis for CDC2 but was less clear for CDC16 [29].
• The second subunit of DNA polymerase III (delta) is encoded by the HYS2 gene in Saccharomyces cerevisiae [12].
• New alleles of the CDC2 and CDC17 genes were recovered among these mutants [30].
• The mutator effects of mutations in the DNA polymerase delta (POL3) gene and the recombinational repair RAD52 gene were studied in combination with mismatch repair defects [31].

Analytical, diagnostic and therapeutic context of CDC2

• DNA polymerase III (delta) of Saccharomyces cerevisiae is purified as a complex of at least two polypeptides with molecular masses of 125 and 55 kDa as judged by SDS-PAGE [12].
• Through the use of gel-filtration chromatography, we have studied the interaction of the model template-primer system poly(dA).(dT)16 (40:1) with yeast DNA polymerase III and with PCNAs [32].
• Southern blot analysis, as well as isolation of another cDNA clone, cdc2ZmB, which is 96% identical to cdc2ZmA, indicates that maize has multiple cdc2 genes [33].
• Studies of expression of the maize cdc2 gene(s) by Northern blot analysis indicated a correlation between the abundance of cdc2 mRNA and the proliferative state of the tissue [33].
• Five putative cleavage sites of this protease in Ty3 GAG3 and GAG3-POL3 polyproteins were defined by amino-terminal sequence analysis [34].

References