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

Brain tau protein is phosphorylated in vitro by cdc2 and MAP2 kinases, obtained through immunoaffinity purification from rat brain extracts. The phosphorylation sites are located on the tau molecule both upstream and downstream of the tubulin-binding motifs. A synthetic peptide comprising residues 194-213 of the tau sequence, which contains the epitope recognized by the monoclonal antibody tau-1, is also efficiently phosphorylated in vitro by cdc2 and MAP2 kinases. Phosphorylation of this peptide markedly reduces its interaction with the antibody tau-1, as it has been described for tau protein in Alzheimer's disease. Both cdc2 and MAP2 kinases are present in brain extracts obtained from Alzheimer's disease patients. Interestingly, the level of cdc2 kinase may be increased in patient brains as compared with non-demented controls. These results suggest a role for cdc2 and MAP2 kinases in phosphorylating tau protein at the tau-1 epitope in Alzheimer's disease.
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PMID:Implication of brain cdc2 and MAP2 kinases in the phosphorylation of tau protein in Alzheimer's disease. 132 85

During the interphase to metaphase transition, microtubules are destabilized by a cdc2 kinase-dependent phosphorylation event. This destabilization is due to a dramatic increase in the rate at which each growing microtubule starts to shrink (catastrophe rate). In principle, this could be brought about by lowering the affinity of stabilizing MAPs for the microtubule wall, by activating a factor that would actively increase the catastrophe rate or by an alteration of both parameters. Here we examine the stabilizing effect of bovine brain MAP2 on microtubules assembled in interphase Xenopus egg extracts. We show that this MAP strongly stabilizes microtubules assembled in the extracts against nocodazole-induced depolymerization. However, it does not protect them from the cdc2 kinase-induced shortening and destabilization. Moreover, the steady-state length of centrosome-nucleated microtubules in cdc2-treated extracts containing MAP2 is similar to that found in extracts lacking exogenous MAP2. We also show that although exogenous MAP2 is phosphorylated by cdc2 kinase in the extract, this is not the cause of microtubule destabilization. These results indicate that increased microtubule dynamics during mitosis is due to the activation of a factor that can function independently of the presence of active, stabilizing factors.
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PMID:cdc2 kinase-induced destabilization of MAP2-coated microtubules in Xenopus egg extracts. 156 30

Activation of the multicomponent interleukin-2 receptor (IL-2R) complex leads to a rapid increase in tyrosine phosphorylation of a number of cellular proteins including the IL-2R beta and IL-2R gamma chains of the IL-2R and the RAF-1 serine threonine kinase. In addition, phosphatidylinositol 3-kinase (PI-3K) protein and activity can be immunoprecipitated with anti-phosphotyrosine and anti-IL-2R beta antibodies from IL-2-activated but not resting T lymphocytes. We have demonstrated that the SH2 (SRC homology 2) domains of the 85 kDa subunit of PI-3K are sufficient to mediate binding of the PI-3K complex to tyrosine phosphorylated, but not non-phosphorylated IL-2R beta, suggesting that tyrosine phosphorylation is an integral component of the activation of PI-3K by the IL-2R. Since none of the members of the IL-2R complex contains an intrinsic tyrosine kinase domain, IL-2-induced tyrosine phosphorylation must be the consequence of activation of intracellular tyrosine kinases. SRC family members including lck, lyn and fyn have been demonstrated to associate with IL-2R beta through binding of the kinase domain to the acidic domain of IL-2R beta. However, we have demonstrated that the serine rich (SD) region of the cytosolic domain of IL-2R beta is also required for association of a tyrosine kinase with the IL-2R complex and that IL-2 can induce proliferation and tyrosine phosphorylation in cell lines which lack the known SRC family kinases expressed by T lymphocytes. Thus members of other kinase families besides SRC may also be involved in mediating IL-2 signal transduction. Biochemical studies and studies of cells expressing mutant IL-2 receptors indicate that IL-2-induced tyrosine kinase activation initiates a complex signaling cascade. The cascade includes SRC family kinase members such as lck, fyn, and lyn, activation of Raf-1 and PI-3K, and ras, and increased expression of the fos, fra-1, and jun protooncogenes. In addition, ligation of the IL-2R leads to rapid increases in myc expression and more delayed increases in the expression of the cdc2 and cdk2 kinases and the cyclins through a tyrosine phosphorylation independent pathway. Whether other biochemical processes initiated by IL-2R ligation, including activation of the MAP2, p70S6 and p90RSK serine threonine kinases, activation of NF-kappa B, and increased expression of Raf-1, Pim-1, bcl-2, IL-2R alpha and IL-2R beta, are consequences of the IL-2-induced tyrosine kinase cascade remains to be determined.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Transmembrane signaling by the interleukin-2 receptor: progress and conundrums. 826 Jun 51

Cultured cerebellar granule neurons died in an apoptotic manner when the K+ concentration in culture medium was lowered to the normal level (5 mM) after maturation of cells with a high concentration of K+ (26 mM). The changes in expression of 14 cell cycle-related genes in this CNS apoptosis model were analyzed by quantitative RT-PCR. Most of the genes analyzed were stable during apoptosis. The expression of cyclin A mRNA, however, transiently decreased 1 h after the induction of apoptosis, and recovered within 3 h to above the basal level. In this system, the level of cyclin D1, which has been reported to be up-regulated in apoptosis of NGF-deprived cultured sympathetic neurons, did not change. These results suggest that the molecular mechanisms in these two apoptosis models are different. To determine cyclin A protein level, we used an immunostaining method. The number of cyclin A-positive neurons decreased during apoptosis. Moreover, the numbers of MAP2- and cdk2-positive neurons also decreased in a similar manner. Taken together, these results suggest that there is a relationship between apoptosis and cell cycle, and that morphological changes during apoptosis result from cytoskeletal structure degradation.
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PMID:Expression of cyclin A decreases during neuronal apoptosis in cultured rat cerebellar granule neurons. 894 58

Microtubules are one of the major filament of the cytoskelton and play a role in various biological functions such as mitosis, cell motility and intracellular transport. Therefore, microtubules are considered one of the most important molecular targets for cancer chemotherapy. Tubulin is one of the major microtubular components, and its polymerization and depolymerization regulate microtubular dynamics. Other microtubular components such as microtubule-associated protein (MAPs), actin, and intermediate and microfilaments have also been demonstrated to be involved in microtubular dynamics. Recent studies provide evidence that the functions of MAPs and filaments in microtubule assembly are regulated by phosphorylation, which is catalyzed by mitogenactivated protein kinase (MAP kinase) and cdc2 kinase. Antimitotic agents that disrupt microtubules can be classified in two categories according to the mechanism of action, vinca alkaloids and taxanes. Vinca alkoloids, estramustine, rhizoxin, and E7010 inhibit microtubule polymerization. In contrast, taxanes such as paclitaxel and docetaxel promote polymerization of microtubules and enhance microtubule stability. We have demonstrated that paclitaxel inhibits the catalytic activity of MAP kinase and cdc2 kinase in lung cancer cell lines. This biological effect may be responsible for the increased affinity between MAP2 and tubulins, resulting in promotion of microtubule assembly. Factors that contribute to the resistance to antimitotic agents include intracellular accumulation of the drugs, genetic or functional alternations in tubulin, and alternations in MAP kinase cascade. Antimitotic agents showed a broad spectrum of preclinical antitumor activity. Clinical trials of taxanes revealed that they were effective for several cancers which were advanced or resistant against other anticancer drugs, especially for breast cancers, ovarian cancers and non-small cell lung cancers.
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PMID:[Antimitotic agents]. 930 50

In Alzheimer disease brain the microtubule associated protein (MAP) tau is abnormally hyperphosphorylated. The role of protein phosphatases (PP) in the regulation of phosphorylation of tau was studied in undifferentiated SY5Y cells. In cells treated with 10 nM okadaic acid (OA), a PP-2A/PP-1 inhibitor, the PP-1 and -2A activities decreased by 60% and 100% respectively and the activities of MAPKs, cdc2 kinase and cdk5, but not of GSK-3, increased. OA increased the phosphorylation of tau at Thr-231/Ser-235 and Ser-3961404, but not at Ser-262/356 or Ser-199/202. An increase in tyrosinated/detyrosinated tubulin ratio, a decrease in the microtubule binding activities of tau, MAP1b and MAP2, and cell death were observed. Treatment with 1 microm taxol partially inhibited the cell death. These data suggest (1) that OA induced hyperphosphorylation of tau is probably the result of activated MAPK and cdks in addition to decreased PP-2A and PP-1 activities and (2) that in SY5Y cells the OA induced cell death is associated with a decrease in stable microtubules.
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PMID:The regulation of phosphorylation of tau in SY5Y neuroblastoma cells: the role of protein phosphatases. 959 18

Known high and low molecular weight (LMW) MAP2 protein isoforms result from alternative splicing of the MAP2 gene. Contrary to previous reports that MAP2 is neural-specific, we recently identified MAP2 mRNA and protein in somatic and germ cells of rat testis, and showed the predominant testicular isoform is LMW. Although cytoplasmic in neural tissue, MAP2 appeared predominantly nuclear in germ cells using immunohistochemistry. We sought to determine whether this unexpected localization was due to the inclusion of exon 10 within novel LMW MAP2 isoforms. Normally excluded from the LMW MAP2c, exon 10 harbors a putative CcN motif, comprising a nuclear localization sequence (NLS) flanked by regulatory phosphorylation sites for protein kinase CK2 and cdc2 kinase. Characterization of MAP2 mRNA in adult and immature brain and testis, by reverse transcriptase-polymerase chain reaction/Southern analysis and Northern blot, identified novel LMW forms containing exons 10 and 11, previously detected only in high molecular weight MAP2a and 2b. The MAP2 NLS targeted a large heterologous protein to the nucleus, as demonstrated using bacterially expressed MAP2-CcN-beta-galactosidase fusion protein and an in vitro nuclear import assay. Antibodies raised against the fusion protein produced a testicular immunohistochemical staining pattern correlating with MAP2 protein distribution in the nucleus of most germ cells, and precipitated both approximately 70-kDa and >220-kDa proteins recognized by the commercial MAP2-specific HM2 monoclonal antibody, supporting our hypothesis of a novel LMW MAP2 isoform. These results demonstrate the presence of a functional NLS in MAP2 and indicate that novel LMW MAP2 isoforms may be targeted to the nucleus in both neural and non-neuronal tissues.
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PMID:Novel low molecular weight microtubule-associated protein-2 isoforms contain a functional nuclear localization sequence. 1038 34

Regulation of expression and function of microtubule-associated proteins (MAPs) is critical for neurons to maintain normal cytoskeletal architecture and functions. We have shown previously that in differentiated human neuroblastoma SY5Y cells, the expression of tau, a major neuronal MAP, is dramatically increased, and tau phosphorylation is differentially regulated. In the present study, we investigated the expression, the subcellular distribution and the microtubule-binding activities of several MAPs in SY5Y cells upon differentiation. We also studied the activities of protein kinases and phosphatases that are involved in regulation of tau phosphorylation during cell differentiation. We found that the expression of MAP1b in addition to tau was upregulated upon differentiation. Tau, MAP1a, MAP1b and MAP2 had distinct immunocytochemical staining patterns in differentiated SY5Y cells, suggesting differential biological functions. The microtubule-binding activity of tau increased after cell differentiation, whereas the activities of MAP1a and MAP2 decreased. Upon differentiation, the phosphorylation of tau at Ser198/Ser199/Ser202 and Ser396/Ser404 was increased, but that at Ser262/Ser356 was decreased. These changes in tau phosphorylation were accompanied by an upregulation of activities of several protein kinases (cdk5, MAPK, PKC and CK-1) as well as protein phosphatases PP-1 and PP-2A. These results suggest that the expression, post-translational modifications and biological activities of various MAPs are differentially regulated to meet the biological needs during cell differentiation.
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PMID:Regulation of microtubule-associated proteins, protein kinases and protein phosphatases during differentiation of SY5Y cells. 1546 92

SH-SY5Y neuroblastoma cells, a model for studying neuronal differentiation, are able to differentiate into either cholinergic or dopaminergic/adrenergic phenotypes depending on media conditions. Using this system, we asked whether guanosine (Guo) or guanosine-5'-triphosphate (GTP) are able to drive differentiation towards one particular phenotype. Differentiation was determined by evaluating the frequency of cells bearing neurites and assessing neurite length after exposure to different concentrations of Guo or GTP for different durations. After 6 days, 0.3 mM Guo or GTP induced a significant increase in the number of cells bearing neurites and increased neurite length. Western blot analyses confirmed that purines induced differentiation; cells exposed to purines showed increases in the levels of GAP43, MAP2, and tyrosine hydroxylase. Proliferation assays and cytofluorimetric analyses indicated a significant anti-proliferative effect of purines, and a concentration-dependent accumulation of cells in S-phase, starting after 24 h of purine exposure and extending for up to 6 days. A transcriptional profile analysis using gene arrays showed that an up-regulation of cyclin E2/cdk2 evident after 24 h was responsible for S-phase entry, and a concurrent down-regulation of cell-cycle progression-promoting cyclin B1/B2 prevented S-phase exit. In addition, patch-clamp recordings revealed that 0.3 mM Guo or GTP, after 6 day incubation, significantly decreased Na(+) currents. In conclusion, we showed Guo- and GTP-induced cell-cycle arrest in neuroblastoma cells and suggest that this makes these cells more responsive to differentiation processes that favor the dopaminergic/adrenergic phenotype.
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PMID:Extracellular guanosine and GTP promote expression of differentiation markers and induce S-phase cell-cycle arrest in human SH-SY5Y neuroblastoma cells. 1911 4