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)

The activation of cyclin-dependent kinase 5 (Cdk5) depends on the binding of its neuronal specific activator Nck5a. The minimal activation domain of Nck5a is located in the region of amino acid residues 150 to 291 (Tang, D., Chun, A. C. S., Zhang, M., and Wang, J. H. (1997) J. Biol. Chem. 272, 12318-12327). In this work we show that a 29-residue peptide, denoted as the alphaN peptide, encompassing amino acid residues Gln145 to Asp173 of Nck5a is capable of binding Cdk5 to result in kinase inhibition. This peptide also inhibits an active phospho-Cdk2-cyclin A complex, with a similar potency. Direct competition experiments have shown that this inhibitory peptide does not compete with Nck5a or cyclin A for Cdk5 or Cdk2, respectively. Steady state kinetic analysis has indicated that the alphaN peptide acts as a non-competitive inhibitor of Cdk5. Nck5a complex with respect to the peptide substrate. To understand the molecular basis of kinase inhibition by the peptide, we determined the structure of the peptide in solution by circular dichroism and two-dimensional 1H NMR spectroscopy. The peptide adopts an amphipathic alpha-helical structure from residues Ser149 to Arg162 which can be further stabilized by the helix-stabilizing solvent trifluoroethanol. The hydrophobic face of the helix is likely to be the kinase binding surface.
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PMID:Identification and structure characterization of a Cdk inhibitory peptide derived from neuronal-specific Cdk5 activator. 1006 70

Alterations in the status of microtubules contribute to the cytoskeletal rearrangements that occur during apoptosis. The microtubule-associated protein tau regulates microtubule dynamics and thus is likely to play an important role in the cytoskeletal changes that occur in apoptotic cells. Previously, we demonstrated that the phosphorylation of tau at the Tau-1 epitope was increased during neuronal PC12 cell apoptosis, and further that the microtubule binding of tau from apoptotic cells was significantly impaired because of altered phosphorylation. The fact that the microtubule-binding capacity of tau from apoptotic cells was reduced to approximately 30% of control values indicated that sites in addition to those within the Tau-1 epitope were hyperphosphorylated during apoptosis. In this study using a combination of immunological and biochemical approaches, numerous sites were found to be hyperphosphorylated on tau isolated from apoptotic cells. Further, during apoptosis, the activities of cell division control protein kinase (cdc2) and cyclin-dependent kinase 5 (cdk5) were selectively and significantly increased. The association of these two protein kinases with tau was also increased during apoptosis. These findings are intriguing because many of the sites found to be hyperphosphorylated on tau during apoptosis are also hyperphosphorylated on tau from Alzheimer's disease brain. Likewise, there are data indicating that in Alzheimer's disease the activities of cdc2 and cdk5 are also increased.
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PMID:Tau protein is hyperphosphorylated in a site-specific manner in apoptotic neuronal PC12 cells. 1108 Jan 86

The adult mammalian cerebral cortex arises from a complex series of neuronal migrations. The primitive layer known as the preplate is split into an outer marginal zone and an inner subplate by invading cortical plate neurons in an "inside-out" pattern of layering with respect to time of neuronal origin. In cyclin-dependent kinase 5 (Cdk5)-deficient mice (cdk5(-/-)), the earliest born cortical neurons split the preplate, but later born neurons arrest below the subplate, resulting in an ectopic "outside-in" layer of neurons normally destined for layers II-V. We have pursued this analysis in cdk5(-/-) <--> wild-type chimeric mice coupled with experiments in cell culture. In vitro migration assays show no difference in migrational ability between embryonic cdk5(-/-) and wild-type neurons. In cdk5(-/-) chimeras, layers I and VI are made up of both mutant and wild-type genotype neurons, whereas layers II-V contain predominantly wild-type cells. In addition, a thin layer of neurons is found below layer VI, made up of cdk5(-/-) cells; bromodeoxyuridine labeling suggests that these neurons were destined for layers II-V. Scattered cdk5(-/-) cells are found throughout layers II-V, but these neurons are always found to be GABAergic. The findings suggest that Cdk5 is not required for migration of either the deepest cortical plate neurons or the GABAergic neurons from the ganglionic eminences. The migration of layer II-V pyramidal neurons, however, is intrinsically blocked by Cdk5 deficiency, thus suggesting that different neuronal cell types use distinct mechanisms of migration.
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PMID:Neocortical cell migration: GABAergic neurons and cells in layers I and VI move in a cyclin-dependent kinase 5-independent manner. 1173 78

Doublecortin (DCX) is a 40 kDa microtubule-associated protein required for normal neural migration and cortical layering during development. Mutations in the human DCX gene cause a disruption of cortical neuronal migration. Defects in cdk5 (cyclin-dependent kinase 5) also cause defects in neural migration and cortical layering. DCX is a substrate for cdk5 in vitro and in vivo and the major site of in vitro phosphorylation is Ser-297. We used a highly developed MS strategy to identify the cdk5 phosphorylation sites and determine the major and minor sites. Several phosphopeptides were identified from a tryptic digest of 32P-labelled, cdk5-phosphorylated DCX using a combination of off-line HPLC and matrix-assisted laser-desorption ionization-MS with alkaline phosphatase treatment. Tandem MS/MS enabled the identification of seven phosphorylation sites for cdk5. Monitoring of 32P label indicated that there was one major site, Ser-28, at the N-terminus, and a major site, Ser-339, in the serine/proline-rich domain at the C-terminus. Five other sites, Ser-287, Thr-289, Ser-297, Thr-326 and Ser-332, were also found in the tail. Site-directed mutagenesis largely supported these findings. Single mutation of Ser-28 reduced but did not abolish phosphorylation. Double, rather than single, mutation for Ser-332 and Ser-339 was required to reduce overall phosphorylation, suggesting an interaction between these sites. Truncations of the tail produced a significant reduction in cdk5 phosphorylation of DCX. These results do not support Ser-297 as the major cdk5 phosphorylation site in DCX, but indicate that DCX is subject to complex multisite phosphorylation. This illustrates the importance of a well-developed MS strategy to identify phosphorylation sites.
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PMID:Multisite phosphorylation of doublecortin by cyclin-dependent kinase 5. 1509 91

Axonal damage is a major morphological correlate and cause of permanent neurological deficits in patients with multiple sclerosis (MS), a multifocal, inflammatory and demyelinating disease of the central nervous system. Hyperphosphorylation and pathological aggregation of microtubule-associated protein tau is a common feature of many neurodegenerative diseases with axonal degeneration including Alzheimer's disease. We have therefore analyzed tau phosphorylation, solubility and distribution in the brainstem of rats with experimental autoimmune encephalomyelitis (EAE), an animal model of MS. Tau was hyperphosphorylated at several sites also phosphorylated in Alzheimer's disease and became partially detergent-insoluble in EAE brains. Morphological examination demonstrated accumulation of amorphous deposits of abnormally phosphorylated tau in the cell body and axons of neurons within demyelinating plaques. Hyperphosphorylation of tau was accompanied by up-regulation of p25, an activator of cyclin-dependent kinase 5. Phosphorylation of tau, activation of cdk5, and axonal pathology were significantly reduced when diseased rats were treated with prednisolone, a standard therapy of acute relapses in MS. Hyperphosphorylation of tau was not observed in a genetic or nutritional model of axonal degeneration or demyelination, suggesting that inflammation as detected in the brains of rats with EAE is the specific trigger of tau pathology. In summary, our data provide evidence that axonal damage in EAE and possibly MS is linked to tau pathology.
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PMID:Hyperphosphorylation and aggregation of tau in experimental autoimmune encephalomyelitis. 1549 5

cDNA of cyclin-dependent kinase 5 (Cdk5) was cloned based on its primary sequence homology to Cdc2 and Cdk2. Cdk5 requires the neuronal Cdk5 activators such as p35 or p39(nck5ai) (p39) for its activity. In this study, we examined post-natal changes in the p39 expression pattern during the development of the rat cerebellum. p39 began to express in somata and dendrites of Purkinje cells at post-natal day 3 (PD3). In particular, at PD12, parasagittal bands (stripes) with p39 immunoreactivity were weakly observed. At PD21, p39-immunoreactive stripes were developed when compared with the PD12 group. At this age stage, p39 immunoreactivity became weak in somata of Purkinje cells, not forming stripes. At PD28, a series of parasagittal bands were more distinct than those of the PD21 group, and p39 immunoreactivity disappeared in Purkinje cells, not forming p39 immunoreactive stripes. In the adults, p39 immunoreactivity in Purkinje cells was similar to that found in the PD28 group which showed that parasagittal bands were very narrow, and became progressively more slender. Therefore, we suggest that the post-natal changes of p39 expression in Purkinje cells in the cerebellum is an autonomous characteristic of Purkinje cells with a role of Cdk5 activators.
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PMID:Post-natal changes of cyclin-dependent kinase 5 activator expression in the developing rat cerebellum. 1564 22

Collapsin response mediating protein-2 (CRMP2) has been identified as an intracellular protein mediating Semaphorin3A (Sema3A), a repulsive guidance molecule. In this study, we demonstrate that cyclin-dependent kinase 5 (Cdk5) and glycogen synthase kinase 3beta (GSK3beta) plays a critical role in Sema3A signalling. In In vitro kinase assay, Cdk5 phosphorylated CRMP2 at Ser522, while GSK3beta did not induce any phosphorylation of CRMP2. Phosphorylation by GSK3beta was exclusively observed in Cdk5-phosphorylated CRMP2, but barely in CRMP2T509A. These results indicate that Cdk5 primarily phosphorylates CRMP2 at Ser522 and GSK3beta secondarily phosphorylates at Thr509. The dual-phosphorylated CRMP2, but not non-phosphorylated or single-phosphorylated CRMP2, is recognized with the antibody 3F4, which is highly reactive with the neurofibrillary tangles of Alzheimer's disease. 3F4 recognized the CRMP2 in the wild-type but not cdk5-/- mouse embryonic brain lysates. The phosphorylation of CRMP2 at Ser522 caused reduction of its affinity to tubulin. In dorsal root ganglion neurones, Sema3A stimulation enhanced the levels of the phosphorylated form of CRMP2 detected by 3F4. Over-expression of CRMP2 mutant substituting either Ser522 or Thr509 to Ala attenuates Sema3A-induced growth cone collapse response. These results suggest that the sequential phosphorylation of CRMP is an important process of Sema3A signalling and the same mechanism may have some relevance to the pathological aggregation of the microtubule-associated proteins.
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PMID:Semaphorin3A signalling is mediated via sequential Cdk5 and GSK3beta phosphorylation of CRMP2: implication of common phosphorylating mechanism underlying axon guidance and Alzheimer's disease. 1567 27

Dynamin I (dynI) is phosphorylated in synaptosomes at Ser(774) and Ser(778) by cyclin-dependent kinase 5 to regulate recruitment of syndapin I for synaptic vesicle endocytosis, and in PC12 cells on Ser(857). Hierarchical phosphorylation of Ser(774) precedes phosphorylation of Ser(778). In contrast, Thr(780) phosphorylation by cdk5 has been reported as the sole site (Tomizawa, K., Sunada, S., Lu, Y. F., Oda, Y., Kinuta, M., Ohshima, T., Saito, T., Wei, F. Y., Matsushita, M., Li, S. T., Tsutsui, K., Hisanaga, S. I., Mikoshiba, K., Takei, K., and Matsui, H. (2003) J. Cell Biol. 163, 813-824). To resolve the discrepancy and to better understand the biological roles of dynI phosphorylation, we undertook a systematic identification of all phosphorylation sites in rat brain nerve terminal dynI. Using phosphoamino acid analysis, exclusively phospho-serine residues were found. Thr(780) phosphorylation was not detectable. Mutation of Ser(774), Ser(778), and Thr(780) confirmed that Thr(780) phosphorylation is restricted to in vitro conditions. Mass spectrometry of (32)P-labeled phosphopeptides separated by two-dimensional mapping revealed seven in vivo phosphorylation sites: Ser(774), Ser(778), Ser(822), Ser(851), Ser(857), Ser(512), and Ser(347). Quantification of (32)P radiation in each phosphopeptide showed that Ser(774) and Ser(778) were the major sites (up to 69% of the total), followed by Ser(851) and Ser(857) (12%), and Ser(853) (2%). Phosphorylation of Ser(851) and Ser(857) was restricted to the long tail splice variant dynIxa and was not hierarchical. Co-purified, (32)P-labeled dynIII was phosphorylated at Ser(759), Ser(763), and Ser(853). Ser(853) is homologous to Ser(851) in dynIxa. The results identify all major and several minor phosphorylation sites in dynI and provide the first measure of their relative abundance and relative responses to depolarization. The multiple phospho-sites suggest subtle regulation of synaptic vesicle endocytosis by new protein kinases and new protein-protein interactions. The homologous dynI and dynIII phosphorylation indicates a high mechanistic similarity. The results suggest a unique role for the long splice variants of dynI and dynIII in nerve terminals.
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PMID:The in vivo phosphorylation sites of rat brain dynamin I. 1737 71

This study is to explore the effect of ginsenoside Rb1 on the process of beta-amyloid peptide(25-35) (Abeta(25-35)) -induced hyperphosphorylation of tau protein, and on the level of cyclin-dependent kinase 5 activator, p25/p35. Western blotting and/or immunocytochemical staining were used to detect the levels of phosphorylation of tau protein at the sites of Thr205, Ser396, Ser404 in hippocampal neurons, cdk5 and p25/p35. After exposure to Abeta(25-35) (20 micromol x L(-1)) for 12 h, the levels of tau protein phosphorylation at the sites of Thr205, Ser396, Ser404 were enhanced, the level of p25 was increased, but the level of protein cdk5 was not changed markedly. Pretreatment with ginsenoside Rb1 reduced Abeta(25-35) -induced hyperphosphorylation of tau protein and decreased the lever of p25, but had no effect on cdk5. Ginsenoside Rb1 can attenuate Abeta(25-35) -induced hyperphosphorylation of tau protein through CDK5 signal pathway.
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PMID:[Ginsenoside Rb1 attenuates beta-amyloid peptide(25-35) -induced hyperphosphorylation of tau protein through CDK5 signal pathway]. 1794 29

Hyperammonemia in neonates and infants causes irreversible damages in the developing CNS due to brain cell loss. Elucidating the mechanisms triggering ammonia-induced cell death in CNS is necessary for the development of neuroprotective strategies. We used reaggregated developing brain cell cultures derived from fetal rat telencephalon exposed to ammonia as an experimental model. Ammonia induced neuronal and oligodendroglial death, triggered apoptosis and activated caspases and calpain. Probably due to calpain activation, ammonia caused the cleavage of the cyclin-dependent kinase 5 activator, p35, to p25, the cdk5/p25 complex being known to lead to neurodegeneration. Roscovitine, a cdk5 inhibitor, protected neurons from ammonia-induced cell death. However, roscovitine also impaired axonal growth, probably through inhibition of the remaining cdk5/p35 activity, which is involved in neurite outgrowth. Thus, cdk5 appears as a promising therapeutic target for treating hyperammonemic newborns and infants, especially if one develops specific cdk5/p25 inhibitors.
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PMID:Role of caspases, calpain and cdk5 in ammonia-induced cell death in developing brain cells. 1872 28


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