Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.22 (cdc2)
 8,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Three major cyclin-dependent kinases, p34cdc2, p33cdk2, and p34cdk4 were examined in normal human T cells stimulated to enter the cell cycle in vitro. None of the three genes was expressed in resting T cells. Transcripts form the cdk4 and cdk2 genes were detectable as early as 3 and 8 hr after stimulation, respectively, whereas cdc2 gene transcripts were not detectable until about 24 hr, shortly before S phase entry. Immunoblot analysis showed that resting T cells contained little p34cdk4, no p34cdc2, and a low level of p33cdk2 protein. Increased amounts of p34cdk4, p33cdk2, and p34cdc2 proteins were seen at about 7, 10, and 30 hr after stimulation, respectively. Immunoprecipitates of each of the kinases were assessed for histone H1 kinase activity. Activity due to p33cdk2 first became detectable in mid-G1 phase and increased dramatically after entry into S phase. Active p34cdc2 kinase was not detected until about 40 hr after stimulation, about 10 hr after the first appearance of the protein. Immunoprecipitates of p34cdk4 possessed almost no H1 histone kinase activity; however, activity was detected as early as 10 hr after cell activation when a protein (p60Rb) derived from the retinoblastoma susceptibility gene product was used as substrate. Cells were synchronized about the G1/S and G2/M borders by aphidicolin and nocodazole. Cells arrested prior to S-phase contained high levels of active p33cdk2 and essentially no active p34cdc2, despite the fact that large amounts of both proteins were present. Cells arrested by nocodazole had high levels of active p34cdc2 and greatly reduced levels of p33cdk2 kinase activity. The results suggest that the major role for the p34cdc2 kinase is at mitosis, whereas that for p33cdk2 is in late G1 and/or S phase. The p34cdk4 protein, present in aphidicolin-blocked cells, was nearly absent from cells arrested at the G2/M border; however, kinase activity was low in cells blocked at both points, suggesting that the major role for p34cdk4 may be in G1 phase.
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PMID:Differential regulation of the synthesis and activity of the major cyclin-dependent kinases, p34cdc2, p33cdk2, and p34cdk4, during cell cycle entry and progression in normal human T lymphocytes. 759 19

Iron removal by the chelating-agent deferoxamine (DFO) arrests cell cycle progression of activated human T cells in late G1 phase, before the G1/S border. The effects of the drug on molecules that regulate progression through the cell cycle were defined. DFO (10 mumol/L) inhibited induction of transcription of the cdc2 gene, but had no effect on accumulation of cdk2, cdk4, or interleukin (IL)-2-transcripts. No detectable p34cdc2 protein accumulated, but synthesis of the p33cdk2 protein was begun. It accumulated to normal levels during the first 20 to 30 hours of incubation in the presence of DFO. Furthermore, p33cdk2 was activated as an H1 histone kinase. As active p33cdk2 primarily represents complexes of the p33 protein with cyclin E or cyclin A, the effects of DFO on these cyclins were examined. Although the induction of synthesis and early accumulation of cyclin E and cyclin E-associated kinase activity appeared normal, the appearance of cyclin A and cyclin A-associated kinase activity were inhibited by DFO. However, the production of cyclin A mRNA appeared to be normal in the presence of DFO. A major effect of DFO in blocking cell cycle progression may be mediated through inhibition of the appearance of cyclin A protein and, therefore, a major component of p33cdk2 activity. The results also indicate that the p33cdk2/cyclin E activity produced in the presence of DFO was not sufficient for completion of the G1 phase of the cell cycle.
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PMID:Effects of iron-depletion on cell cycle progression in normal human T lymphocytes: selective inhibition of the appearance of the cyclin A-associated component of the p33cdk2 kinase. 766 74

The activities of nuclear histone-H1 kinase and C-kinase as well as the amount of phosphate bound to histone-H1 following partial hepatectomy were studied in rat. It was found that the nuclear histone-H1 kinase activity increased twice within 80 h, first 20 to 30 h, and second at 50 to 70 h after partial hepatectomy. The timing of increase of the enzyme activity correlated with increased amount of bound phosphate. On the other hand, the increase of the C-kinase activities occurred between 5 and 15 h after partial hepatectomy. Antibodies raised against human cdk2, human cyclin-A and mouse cdc2 kinase showed no detectable effect on the nuclear histone H1 kinase activity. These results suggest that phosphorylation of histone-H1 in liver regeneration may be catalysed by a putative kinase(s).
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PMID:Role of nuclear histone-H1 kinase in regeneration of rat liver. 770 10

Proliferating cells characteristically undergo programmed (i.e. apoptotic) death if their progression through the cell cycle is sufficiently perturbed. To determine whether androgen ablation-induced programmed death of prostatic glandular cells involves apoptosis triggered by recruitment of nonproliferating cells into a perturbed cell cycle, rat ventral prostates were assessed temporally after castration for several stereotypical molecular stigmata of entry into the proliferative cell cycle. Northern blot analysis was used to assess levels of transcripts from genes characteristically activated 1) during the transition from quiescence (G(0)) into G1 of the proliferative cell cycle (cyclin-D1 and cyclin-C), 2) during the transition from G1 to S (cyclin-E, cdk2, thymidine kinase, and H4-histone), and 3) during progression through S (cyclin-A). Although levels of each of these transcripts increased as expected in prostatic glandular epithelial cells stimulated to proliferate by the administration of exogenous androgen to previously castrated rats, levels of the same transcripts decreased in prostatic glandular cells induced to undergo apoptosis after androgen withdrawal. Northern and Western blot analyses also demonstrated that there was no increase in prostatic p53 messenger RNA or protein content per cell after androgen ablation. Likewise, after castration, there was no enhanced prostatic expression of the WAF1/CIP1 gene, a gene whose expression is known to be induced in both a p53-dependent and -independent manner during recruitment from G0 into G1. In addition, androgen ablation-induced apoptosis of prostatic glandular cells was not accompanied by retinoblastoma protein phosphorylation, which is characteristic of progression into late G1. Nuclear run-on assays demonstrated that there was no increase in the prostatic rate of transcription of the c-myc and c-fos genes after castration. These results demonstrate that prostatic glandular cells undergo programmed death in G(0) without recruitment into the G1 phase of a defective cell cycle, and that an increase in p53 protein or its function is not involved in this death process.
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PMID:Androgen ablation-induced programmed death of prostatic glandular cells does not involve recruitment into a defective cell cycle or p53 induction. 772 Jun 36

Neurofilament (NF) protein [high molecular mass (NF-H)] is extensively phosphorylated in vivo. The phosphorylation occurs mainly in its characteristic KSP (Lys-Ser-Pro) repeat motifs. There are two major types of KSP motifs in the NF-H tail domain: KSPXKX and KSPXXX. Recent studies by two different laboratories have demonstrated the presence of a cdc2-like kinase [cyclin-dependent kinase-5 (cdk5)] in nervous tissue that selectively phosphorylates KSPXKX and XS/TXK motifs in NF-H and lysine-rich histone (H1). This article describes the identification of phosphatases dephosphorylating three different substrates: histone (H1), NF-H in a NF preparation, and a bacterially expressed C-terminal tail domain of NF-H, each containing KSPXKX repeats phosphorylated in vitro by cdk5. Among various phosphatases identified, protein phosphatase (PP) 2A from rabbit skeletal muscle appeared to be the most effective phosphatase in in vitro assays. Three phosphatase activity peaks--P1, P2, and P3--were partially purified from frozen rat spinal cord by ion exchange and size exclusion column chromatography and then characterized on the basis of biochemical, pharmacological, and immunochemical studies. One of the three peaks was identified as PP2A, whereas the others were mixtures of both PP2A and PP1. These three peaks could dephosphorylate cdk5-phosphorylated 32P-histone (H1), 32P-NF-H in the NF preparation, and 32P-NF-H tail fusion protein. These studies suggest the involvement of PP2A or a PP2A-like activity in the regulation of the phosphorylation state of KSPXKX motifs in NF-H.
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PMID:Neuronal cyclin-dependent kinase-5 phosphorylation sites in neurofilament protein (NF-H) are dephosphorylated by protein phosphatase 2A. 776 48

Transcription factor E2F-1 has a putative consensus sequence for phosphorylation by cyclin dependent kinase (Ser-Pro-X-Lys/Arg). Therefore, we studied the phosphorylation of E2F-1 in vivo and in vitro and its biological functions. E2F-1 was prepared by immunoprecipitation with anti-E2F-1 antibody from IMR32 lysates and was effectively phosphorylated by human cyclin A-cdk2 which was expressed in insect cells using baculovirus system. GST-E2F-1 was phosphorylated by cyclin A-cdk2 more efficiently than by cyclin E-cdk2. Cyclin D1-cdk4 phosphorylated pRB but scarcely phosphorylated GST-E2F-1 or H1 histone. The 60 kd protein precipitated with anti-E2F-1 antibody was phosphorylated in vivo. Phospho-peptide mapping indicated that its cleavage profile was identical with that of E2F-1 phosphorylated by cyclin A-cdk2 in vitro. This 60 kd protein, which is likely to be E2F-1, was not phosphorylated during the G0 and early G1 phase. Phosphorylation of E2F-1 began from the S phase while phosphorylation of pRB started nearly at G1/S. The in vivo phosphorylation of E2F-1 was inhibited by butyrolactone I, a cyclin-dependent kinase inhibitor (Kitagawa et al., 1993, Oncogene, 8, 2425-2432). The binding of E2F-1 to E2 promoter was found to be reduced by phosphorylation of E2F-1 by cyclin A-cdk2, suggesting that phosphorylation of E2F-1 may induce shut off of gene expression at the transcriptional level. These results suggest that E2F-1 is phosphorylated by cyclin A-cdk2 in the S phase in vivo as well as in vitro and that its phosphorylation by cyclin A-cdk2 may modulate its activity.
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PMID:Phosphorylation of E2F-1 by cyclin A-cdk2. 783 23

The histone-encoding genes in Schizosaccharomyces pombe were physically mapped by hybridisation to filters containing cosmid and P1 genomic libraries. The H2A.2 gene and the H2A.1-H2B.1 gene pair mapped between the ade6 and rikI genes on chromosome III. The three H4-H3 gene pairs were mapped to three different regions by a H4.1 probe. Southern analysis of clones from each region revealed the positions of the three H4-H3 gene pairs. H4.1-H3.1 was localised to chromosome I between the mei2 and rad1 genes; H4.2-H3.2 mapped between rad3 and cdc2 on chromosome II; H4.3-H3.3 was localised to a region between the nuc1 and puc1 genes on chromosome II.
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PMID:Physical mapping of the Schizosaccharomyces pombe histone genes. 787 52

Chromosome condensation at mitosis correlates with the activation of p34cdc2 kinase, the hyperphosphorylation of histone H1 and the phosphorylation of histone H3. Chromosome condensation can also be induced by treating interphase cells with the protein phosphatase 1 and 2A inhibitors okadaic acid and fostriecin. Mouse mammary tumour FT210 cells grow normally at 32 degrees C, but at 39 degrees C they lose p34cdc2 kinase activity and arrest in G2 because of a temperature-sensitive lesion in the cdc2 gene. The treatment of these G2-arrested FT210 cells with fostriecin or okadaic acid resulted in full chromosome condensation in the absence of p34cdc2 kinase activity or histone H1 hyperphosphorylation. However, phosphorylation of histones H2A and H3 was strongly stimulated, partly through inhibition of histone H2A and H3 phosphatases, and cyclins A and B were degraded. The cells were unable to complete mitosis and divide. In the presence of the protein kinase inhibitor starosporine, the addition of fostriecin did not induce histone phosphorylation and chromosome condensation. The results show that chromosome condensation can take place without either the histone H1 hyperphosphorylation or the p34cdc2 kinase activity normally associated with mitosis, although it requires a staurosporine-sensitive protein kinase activity. The results further suggest that protein phosphatases 1 and 2A may be important in regulating chromosome condensation by restricting the level of histone phosphorylation during interphase, thereby preventing premature chromosome condensation.
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PMID:Chromosome condensation induced by fostriecin does not require p34cdc2 kinase activity and histone H1 hyperphosphorylation, but is associated with enhanced histone H2A and H3 phosphorylation. 788 43

H1 histone kinase activity has been followed in selection-synchronised cultures of fission yeast wild-type and wee1 mutant cells, and in induction-synchronised cells of the mutant cdc2-33. The main conclusions are: (1) in all three cases, the peak of activity is near mitosis. (2) The rise in activity is relatively slow starting in wild type at 0.4 of the cycle before mitosis. It is proposed that the beginning of the rise is the first identified event in the mitotic control. (3) The rise is twice as fast in wee and starts nearer to mitosis. (4) In all cases the beginning of the rise is in G2. (5) The fall in activity is also slow, lasting for 0.25 of the cycle, in wild type. Exit from mitosis happens well before activity has fallen to baseline. (6) In a range of size mutants, activity is roughly proportional to cell size. It is suggested that the kinase may have a cytoplasmic function. (7) Estimates have been made of the timing of mitosis in the mutants. In wee, mitosis is 0.14 of the cycle earlier than in wild type because the cells have a longer septated period at the end of the cycle. (8) A novel method has been developed for eliminating the effects of the partial asynchrony in synchronous cultures, without which the kinetic analysis would have been inaccurate.
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PMID:The kinetics of H1 histone kinase activation during the cell cycle of wild-type and wee mutants of the fission yeast Schizosaccharomyces pombe. 792 29

The proliferating cell nuclear antigen (PCNA) is an auxiliary protein of DNA polymerase delta and appears to be needed for both DNA synthesis and DNA repair. It is present in low amount in resting normal human T lymphocytes and, upon mitogenic stimulation with phorbol dibutyrate and ionomycin, begins to increase in mid-G1 phase, approximately 12 to 15 hours before entry into S phase. PCNA continues to increase in amount throughout the cell cycle and remains high in proliferating cultures. PCNA was extracted from activated normal T cells and from the transformed T-lymphoblastoid cell line Jurkat by a method that recovered approximately 98% of total cellular PCNA but yet retained its associations with other proteins. PCNA immunoprecipitates possessed H1 histone kinase activity, which increased in parallel with increasing cellular content of PCNA. Both the cdc2 and cdk2 kinases were found associated with PCNA in normal T cells, in amounts consistent with detected kinase activity. The results indicate that PCNA is not an inhibitory molecule of cdk/cyclin activity. Both normal and transformed T cells contained PCNA in association with cdk2, cdk4, cdk5, and cdk6, with the amount of PCNA associated with these molecules increasing in the order listed. Relatively high amounts of PCNA were also found associated with cyclins D2 and D3, the major cyclin partners of cdk6 in T cells. Though detected in normal cells, PCNA/cdc2 complexes were present in exceedingly low amount, if at all, in Jurkat cells. This cell line appeared to contain more of nearly all of the cdk and cyclin molecules analyzed, but there seemed to be little difference in the patterns of association of these molecules with PCNA in the cell line as compared with normal human T cells.
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PMID:Association of proliferating cell nuclear antigen with cyclin-dependent kinases and cyclins in normal and transformed human T lymphocytes. 794 95


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