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)

Phorbol-12,13-dibutyrate and 1,2-dioctanoylglycerol, activators of protein kinase C (PKC) that stimulate DNA synthesis in serum-deprived Swiss 3T3 fibroblasts, induce histone H1 kinase activity associated with anti-cdc2 immunoprecipitates after a lag period of 15h, a time point close to G1/S boundary of the cell cycle in these cells. Downregulation of PKC does not affect the basal cdc2 kinase activity, but potently inhibits both phorbol dibutyrate- and dioctanoylglycerol-induced cdc2 kinase activation. Phorbol dibutyrate induces a dramatic increase in the p34cdc2 protein level as well as the appearance of p35-p36 forms of cdc2 on Western blot. In PKC-downregulated cells, the p34 form of cdc2 remains elevated but p35-p36 forms do not appear upon phorbol dibutyrate stimulation. These results demonstrate that PKC activation leads to cdc2 kinase activation in mitogenically responsive Swiss 3T3 cells, and strongly suggest that both expression of p34cdc2 protein and its posttranslational modification(s) are involved in this process. Western blot analysis of PKC isozymes suggests that either PKC alpha, PKC delta or PKC epsilon may be involved in p34cdc2 kinase activation and mitogenesis.
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PMID:Activators of protein kinase C induce p34cdc2 histone H1 kinase stimulation in Swiss 3T3 fibroblasts. 144 45

Olomoucine (2-(2-hydroxyethylamino)-6-benzylamino-9-methylpurine) has been recently described as a competitive inhibitor (ATP-binding site) of the cell cycle regulating p34cdc2/cyclin B, p33cdk2/cyclin A and p33cdk2/cyclin E kinases, the brain p33cdk5/p35 kinase and the ERK1/MAP-kinase. The unusual specificity of this compound towards cell cycle regulating enzymes suggests that it could inhibit certain steps of the cell cycle. The cellular effects of olomoucine were investigated in a large variety of plant and animal models. This compound inhibits the G1/S transition of unicellular algae (dinoflagellate and diatom). It blocks Fucus zygote cleavage and development of Laminaria gametophytes. Stimulated Petunia mesophyl protoplasts are arrested in G1 by olomoucine. By arresting cleavage it blocks the Laminaria gametophytes. Stimulated Petunia mesophyl protoplasts are arrested in G1 by olomoucine. By arresting cleavage it blocks the development of Calanus copepod larvae. It reversibly inhibits the early cleavages of Caenorhabditis elegans embryos and those of ascidian embryos. Olomoucine inhibits the serotonin-induced prophase/metaphase transition of clam oocytes; furthermore, it triggers the the release of these oocytes from their meiotic metaphase I arrest, and induces nuclei reformation. Olomoucine slows down the prophase/metaphase transition in cleaving sea urchin embryos, but does not affect the duration of the metaphase/anaphase and anaphase/telophase transitions. It also inhibits the prophase/metaphase transition of starfish oocytes triggered by various agonists. Xenopus oocyte maturation, the in vivo and in vitro phosphorylation of elongation factor EF-1 are inhibited by olomoucine. Mouse oocyte maturation is delayed by this compound, whereas parthenogenetic release from metaphase II arrest is facilitated. Growth of a variety of human cell lines (rhabdomyosarcoma cell lines Rh1, Rh18, Rh28 and Rh30; MCF-7, KB-3-1 and their adriamycin-resistant counterparts; National Cancer Institute 60 human tumor cell lines comprising nine tumor types) is inhibited by olomoucine. Cell cycle parameter analysis of the non-small cell lung cancer cell line MR65 shows that olomoucine affects G1 and S phase transits. Olomoucine inhibits DNA synthesis in interleukin-2-stimulated T lymphocytes (CTLL-2 cells) and triggers a G1 arrest similar to interleukin-2 deprivation. Both cdc2 and cdk2 kinases (immunoprecipitated from nocodazole- and hydroxyurea-treated CTLL-2 cells, respectively) are inhibited by olomoucine. Both yeast and Drosophila embryos were insensitive to olomoucine. Taken together the results of this Noah's Ark approach show that olomoucine arrests cells both at the G1/S and the G2/M boundaries, consistent with the hypothesis of a prevalent effect on the cdk2 and cdc2 kinases, respectively.
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PMID:Cellular effects of olomoucine, an inhibitor of cyclin-dependent kinases. 754 5

We have identified and purified from bovine brain a novel protein kinase which catalyzes in vitro phosphorylation of neurofilament proteins NF-H and NF-M and tau proteins at sites implicating the enzyme in the regulation of neurocytoskeleton dynamics and in Alzheimer pathology. The protein kinase displays a phosphorylation site specificity similar or identical to the cell cycle regulatory kinase, cdc2 kinase. The purified kinase is a heterodimer of a cdc2-like catalytic subunit, called cdk5, and a 25 kDa regulatory subunit. The regulatory subunit is essential for kinase activity, and it is derived from a 35 kDa protein, p35 by proteolysis. Northern blot analysis of tissue distribution indicates that cdk5 is widely distributed but especially rich in brain, whereas p35 expression is only found in brain. The protein kinase is therefore termed neuronal cdc2-like kinase. The neuron-specificity of the enzyme appears to be conferred by the regulatory subunit. During cell division, cdc2 kinase is regulated by complex phosphorylation mechanisms involving a network of specific protein kinases. Some of these kinases or their homologs have been found in mammalian brains and they may be involved in the regulation of neuronal cdc2-like kinase.
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PMID:Structure, function, and regulation of neuronal Cdc2-like protein kinase. 756 36

p21Cip1 is a cyclin-dependent kinase (Cdk) inhibitor that is transcriptionally activated by p53 in response to DNA damage. We have explored the interaction of p21 with the currently known Cdks. p21 effectively inhibits Cdk2, Cdk3, Cdk4, and Cdk6 kinases (Ki 0.5-15 nM) but is much less effective toward Cdc2/cyclin B (Ki approximately 400 nM) and Cdk5/p35 (Ki > 2 microM), and does not associate with Cdk7/cyclin H. Overexpression of P21 arrests cells in G1. Thus, p21 is not a universal inhibitor of Cdks but displays selectivity for G1/S Cdk/cyclin complexes. Association of p21 with Cdks is greatly enhanced by cyclin binding. This property is shared by the structurally related inhibitor p27, suggesting a common biochemical mechanism for inhibition. With respect to Cdk2 and Cdk4 complexes, p27 shares the inhibitory potency of p21 but has slightly different kinase specificities. In normal diploid fibroblasts, the vast majority of active Cdk2 is associated with p21, but this active kinase can be fully inhibited by addition of exogenous p21. Reconstruction experiments using purified components indicate that multiple molecules of p21 can associate with Cdk/cyclin complexes and inactive complexes contain more than one molecule of p21. Together, these data suggest a model whereby p21 functions as an inhibitory buffer whose levels determine the threshold kinase activity required for cell cycle progression.
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PMID:Inhibition of cyclin-dependent kinases by p21. 762 5

Expression of cyclin dependent kinase cdk5 and its regulator p35 has been shown in the cytoplasm of adult neurons. Here we demonstrate that another potential regulator of cdk5, cyclin E, is expressed in the nervous system and forms complexes with cdk5. Western blot analyses identifies expression of two forms of cyclin E in the mouse nervous system with the 56 kDa form mainly expressed in neurons and 51 kDa form expressed in astrocytes and oligodendrocytes.
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PMID:Cyclin E is expressed in neurons and forms complexes with cdk5. 766 93

Breast cancer in humans, as in mice and rats, is thought to be the result of sequential changes in the epithelial cells of the mammalian glands. This study examines the altered expression or activation of cell cycle related proteins in an in situ system composed of hyperplasia, preneoplasia and neoplasia of mouse mammary glands. The results showed a high level of cdc2/cdk2 kinase activities in tumors compared to hyperplasias which was independent of cdc2/cdk2 protein levels. Some of the cdk-associated proteins which are thought to regulate cdk kinase activity were examined in these tissues. Cyclin A was overexpressed in all hyperplasias irrespective of their tumorigenic potentials. However, a number of alterations in cyclin E protein were associated with cdk2 and its associated kinase activity during mammary tumorigenesis. First, the level of normal cyclin E (p50) expression was positively correlated with the tumorigenic potentials of different hyperplasia lines. Second, several cyclin E isoforms (p48, p43, p35, p34, p32) were detected only in tumor tissues. Third, a 2.3- and 8.3-fold increase in cyclin E-associated cdk2 kinase activity was present in highly tumorigenic hyperplasias and neoplasias respectively compared to the low tumorigenic hyperplasias. Polymorphic cell nuclear antigen (PCNA) protein bound to cdk2 was a better indicator for cell proliferation and cdk2 kinase activity than the PCNA labeling index. These results suggest a sequential pattern of multiple derangements in factors regulating cdk2 protein function during mammary tumorigenesis. High levels of cdk2 kinase activity are observed only in tumors and appear to be closely related to alterations in cyclin E protein expression.
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PMID:Cell cyclins and cyclin-dependent kinase activities in mouse mammary tumor development. 772 62

While testing purines related to the non-specific protein kinase inhibitors N6-dimethylaminopurine and N6-(delta 2-isopentenyl)adenine as potential inhibitors of the p34cdc2/cyclin B kinase, we discovered a compound with high specificity, 2-(2-hydroxyethylamino)-6- benzylamino-9-methylpurine (olomoucine). Kinetic analysis of kinase inhibition reveals that olomoucine behaves as a competitive inhibitor for ATP and as a non-competitive inhibitor for histone H1 (linear inhibition for both substrates). The kinase specificity of this inhibition was investigated for 35 highly purified kinases (including p34cdk4/cyclin D1, p40cdk6/cyclin D3, cAMP-dependent and cGMP-dependent kinases, eight protein kinase C isoforms, calmodulin-dependent kinase II, myosin light-chain kinase, mitogen-activated S6 kinase, casein kinase 2, double-stranded RNA-activated protein kinase, AMP-stimulated kinase, eight tyrosine kinases). Most kinases are not significantly inhibited. Only the cell-cycle regulating p34cdc2/cyclin B, p33cdk2/cyclin A and p33cdk2/cyclin E kinases, the brain p33cdk5/p35 kinase and the ERK1/MAP-kinase (and its starfish homologue p44mpk) are substantially inhibited by olomoucine (IC50 values are 7, 7, 7, 3 and 25 microM, respectively). The cdk4/cyclin D1 and cdk6/cyclin D3 kinases are not significantly sensitive to olomoucine (IC50 values greater than 1 mM and 150 microM, respectively). N6-(delta 2-Isopentenyl)adenine is confirmed as a general kinase inhibitor with IC50 values of 50-100 microM for many kinases. The purine specificity of cyclin-dependent kinase inhibition was investigated: among 81 purine derivatives tested, only C2, N6 and N9-substituted purines exert a strong inhibitory effect on the p34cdc2/cyclin B kinase. An essentially similar sensitivity to this olomoucine family of compounds was observed for the brain-specific cdk5/p35 kinase. Structure/activity relationship studies allow speculation on the interactions of olomoucine and its analogues with the kinase catalytic subunit. Olomoucine inhibits in vitro M-phase-promoting factor activity in metaphase-arrested Xenopus egg extracts, inhibits in vitro DNA synthesis in Xenopus interphase egg extracts and inhibits the licensing factor, an essential replication factor ensuring that DNA is replicated only once in each cell cycle. Olomoucine inhibits the starfish oocyte G2/M transition in vivo. Through its unique selectivity olomoucine provides an anti-mitotic reagent that may preferentially inhibit certain steps of the cell cycle.
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PMID:Inhibition of cyclin-dependent kinases by purine analogues. 792 96

The activation of cyclin-dependent protein kinases (Cdks) is dependent upon site-specific phosphorylation and dephosphorylation reactions, as well as positive and negative regulatory subunits. The human Cdk-activating protein kinase (Cak1) is itself a Cdc2-related cyclin-dependent protein kinase that associates with cyclin H. The present study utilized specific anti-Cak1 antibodies and immunoaffinity chromatography to identify additional Cak1-associated proteins and potential target substrates. Immunoprecipitation of metabolically labeled human osteosarcoma cells revealed a number of Cak1-associated proteins, including p95, p37 (cyclin H), and a 35-kDa protein that was further characterized herein. Microsequence analysis obtained after limited proteolysis revealed peptide fragments that are similar, but not identical to, human and yeast cyclins, thus identifying p35 as a cyclin-like regulatory subunit. The greatest sequence similarity of human p35 is with Mcs2, a yeast cyclin that is essential for cell cycle progression. Immunoaffinity chromatography performed under nondenaturing conditions afforded the isolation of enzymatically active Cak1 from cell lysates, enabling studies of kinase autophosphorylation and comparative substrate utilization. Immunoaffinity-purified Cak1 phosphorylated monomeric Cdc2 and Cdk2, but not Cdk4; the phosphorylation of both Cdc2 and Cdk2 were increased in the presence of recombinant cyclin A. These studies indicate that the Cak1 catalytic subunit, like Cdc2 and Cdk2, associates with multiple regulatory partners and suggests that subunit composition may be an important determinant of this multifunctional enzyme.
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PMID:Biochemical characterization of the human cyclin-dependent protein kinase activating kinase. Identification of p35 as a novel regulatory subunit. 855 Jun 4

Neuronal cdc2-like kinase, nclk, is a heterodimer of cyclin dependent protein kinase 5, cdk5, and a 25 kDa subunit derived from a novel, neuron-specific, 35 kDa protein: p35. The characterization and regulation of nclk will be summarized in this minireview. The activity of nclk appears to be governed by highly complex regulatory mechanisms including protein-protein interaction, protein phosphorylation and isoforms. The histone H1 kinase activity of nclk is absolutely dependent of the interaction between the 25 kDa subunit and the catalytic subunit, cdk5. In addition, nclk interacts with other cellular proteins to form macromolecular complexes. The kinase activity of nclk is inhibited in vitro by the phosphorylation reactions of a weel-like protein tyrosine kinase and a protein serine/threonine kinase from bovine thymus. Northern blot analysis has revealed the existence of two populations of p35 mRNA of 2 and 4 kb. A novel cDNA encoding a p35 homologous protein has been obtained from a human hippocampus library.
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PMID:Regulatory properties of neuronal cdc2-like kinase. 856 47

Cell cycle withdrawal in postmitotic cells involves cyclin-dependent kinase (Cdk) inhibitors that repress cell cycle Cdk activity. During mouse neurogenesis, cortical postmitotic neurons are shown here to accumulate high levels of the p27 Cdk inhibitor compared with their progenitor neuroblasts. Elevated p27 levels in staged embryo brain extracts correlate with p27 binding to Cdk2, and Cdk inactivation. Yet, Cdk5, which is associated with the noncyclin activator p35 in neurons, remains active in the presence of high p27 levels. Both in vitro and in vivo, p27 and related inhibitors can recognize a cyclin D-Cdk5 complex but not a p35-Cdk5 complex. The results indicate that the choice of activator determines the susceptibility of Cdk5 to p27 and related Cdk inhibitors, and thus its ability to act in postmitotic cells.
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PMID:The brain-specific activator p35 allows Cdk5 to escape inhibition by p27Kip1 in neurons. 862 24


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