Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
...
PMID:Inhibition of cyclin-dependent kinases by purine analogues. 792 96

CLK is a dual-specificity protein kinase capable of phosphorylating serine, threonine, and tyrosine residues. We have investigated the action of CLK by establishing stable PC12 cell lines capable of inducibly expressing CLK. Expression of CLK in stably transfected PC12 cells mimicked a number of nerve growth factor (NGF)-dependent events, including the morphological differentiation of these cells and the elaboration of neurites. Moreover, CLK expression enhanced the rate of NGF-mediated neurite outgrowth of these cells, indicating that CLK expression and NGF treatment activate similar signal transduction pathways. CLK expression, unlike NGF, was not able to promote PC12 cell survival in serum-free media, demonstrating that CLK only partially recapitulated the actions of NGF on these cells and that the biochemical pathways necessary for morphological differentiation can be stimulated without also stimulating those necessary for survival. Induction of CLK expression also resulted in the selective activation of protein kinases that are components of growth factor-stimulated signal transduction cascades, including ERK1, ERK2, pp90RSK, and S6PKII. Induction of CLK expression, however, did not stimulate pp70S6K or Fos kinase, two NGF-sensitive protein kinases. These data indicate that CLK action mediates the morphological differentiation of these cells through its capacity to independently stimulate signal transduction pathways normally employed by NGF.
...
PMID:The dual-specificity CLK kinase induces neuronal differentiation of PC12 cells. 793 12

Mitogen-activated protein (MAP) kinase kinases (MKKs) are dual-specificity protein kinases which activate p42mapk and p44mapk by phosphorylation of regulatory tyrosine and threonine residues. cDNAs for two isotypes of MKK, MKK1 and MKK2, have been isolated from several species. Here we describe construction of recombinant baculoviruses for high-level expression of histidine-tagged rat MKK1 and MKK2, and procedures for production of nearly homogeneous MKK1 and MKK2 fusion proteins, in both inactive and active forms. Co-infection of Sf9 cells with either MKK1 or MKK2 virus together with recombinant viruses for Raf-1, pp60src (Y527F) and c-Ha-Ras resulted in activations of 250-fold and 150-fold for MKK1 and MKK2 respectively. Specific activities towards kinase-defective p42mapk were of the order of several hundred nanomoles of phosphate transferred/min per mg of MKK protein. The Michaelis constants for both enzymes were approx. 1 microM. Preparations of activated MKK were apparently free of Raf-1 as assessed by Western blotting. Raf-1 phosphorylated MKK1 on one major tryptic phosphopeptide, the phosphorylation of which increased with time. This phosphopeptide contained only phosphoserine and possessed neutral overall charge at pH 1.9 on two-dimensional peptide mapping. Phosphorylation of MKK1 by Raf-1 correlated with activation and reached a plateau of approximately 2 mol/mol.
...
PMID:Expression, purification and characterization of recombinant mitogen-activated protein kinase kinases. 794 29

The erythropoietin receptor (EpoR) belongs to the cytokine receptor family, members of which lack a tyrosine kinase domain. Recent studies, however, have shown that a cytoplasmic tyrosine kinase, JAK2, interacts with the cytoplasmic domain of the EpoR and becomes activated upon binding of Epo to the receptor. Epo has also been shown to stimulate activation of Ras and Raf-1. The present studies were undertaken to examine the possible involvement of Epo-induced tyrosine phosphorylation in activation of the Ras/mitogen-activated protein kinase (MAP kinase) pathway and to determine its significance on the growth signaling from the EpoR. In an interleukin (IL)-3-dependent cell line expressing the transfected wild-type EpoR, Epo, or IL-3 induced tyrosine phosphorylation of Shc and its association with Grb2. These cytokines also induced tyrosine phosphorylation and activation of MAP kinase isoforms ERK1 and ERK2. A mutant EpoR with a carboxyl-terminal deletion of 108 amino acids (H mutant), which is mitogenically functional but lacks tyrosine phosphorylation sites in the carboxyl-terminal region, showed markedly diminished abilities to induce tyrosine phosphorylation of Shc and to phosphorylate and activate MAP kinases. A mutant receptor (PM4 mutant) inactivated by a point mutation, Trp282 to Arg, which abrogates the interaction with JAK2, failed to induce any effect on Shc or MAP kinases. In cells expressing a mutant EpoR that is constitutively activated by a point mutation, Arg129 to Cys, in the extracellular portion of the receptor, neither tyrosine phosphorylation of Shc nor activation of MAP kinases by phosphorylation was detectable without stimulation with Epo or IL-3. These results suggest that the carboxyl-terminal region of EpoR may play a crucial role in activation of MAP kinases through the Ras signaling pathway which may be activated by tyrosine phosphorylation of Shc and its association with Grb2. The activation of MAP kinases, however, failed to correlate with the mitogenic activity of mutant EpoRs and thus may not be required for growth signaling from the EpoR.
...
PMID:Activation of the mitogen-activated protein kinase pathway by the erythropoietin receptor. 796 95

In response to various external stimuli, MAP kinases are activated by phosphorylation on tyrosine and threonine by MAP kinase kinase (MAPKK), a dual specificity kinase. This kinase is in turn activated via Raf-1 and MAPKK kinase (MAPKKK). To determine regulatory phosphorylation sites of MAPKK, we isolated a Chinese hamster cDNA, that we epitope-tagged and expressed in fibroblasts. This hamster MAPKK (MEK1 isoform) can reactivate recombinant p44mapk when immunoprecipitated from growth factor-stimulated cells or when incubated with an active form of MAPKKK. Mutations at either of two residues that are conserved among kinases, D208N or S222A, abolished MAPKK activity. However, only S222A/MAPKK showed a reduction in phosphorylation in response to active MAPKKK and exerted a dominant negative effect on the serum-stimulated endogenous MAPKK. Finally, replacing Ser222 with Asp, a negatively charged residue, restored MAPKK activity independently of the upstream kinase. These results strongly suggest that Ser222 represents one key MAPKKK-dependent phosphorylation site switching on and off the activity of MAPKK, an event crucial for growth control.
...
PMID:Constitutive mutant and putative regulatory serine phosphorylation site of mammalian MAP kinase kinase (MEK1). 803 96

The transcriptional response to growth factors and other mitogenic signals is mediated by the serum response elements (SREs) located in the promoters of many immediate early genes, including the c-fos and beta-actin genes. We investigated SRE-regulated transcription in cell cycle-synchronized nuclei and found that a SRE-regulated reporter gene was transcribed actively during G1 and, surprisingly, during G2-M as well. One possible mechanism involved in the latter event is microtubule reorganization. Microtubule disassembly is mimicked by microtubule-disrupting drugs, and we found that these drugs, including colchicine, nocodazole, and vinblastine, could activate SRE-dependent reporter genes, as well as the c-fos protooncogene, in asynchronously growing cells. Taken together, our results suggested a possible relationship between cytoplasmic microtubule dynamics and cell cycle gene expression. Although the detailed molecular mechanisms of drug action are not known, protein phosphorylations may be involved, since drug-induced stimulation could be abrogated by several protein kinase inhibitors. Furthermore, the overexpression of mitogen-activated protein kinase ERK1 could superinduce the stimulation of SRE-dependent reporter gene expression by colchicine and suggests that the microtubule disassembly signal may be transduced by microtubule-associated kinases.
...
PMID:Serum response element-regulated transcription in the cell cycle: possible correlation with microtubule reorganization. 804 19

Ras proteins exert their mitogenic and oncogenic effects through activation of downstream protein kinases. An important question is how Ras-generated signals reach the nucleus to activate downstream target genes. AP-1, a heterodimeric complex of Jun and Fos proteins, which activates mitogen-inducible genes, is a major nuclear target of Ras. Ras can stimulate AP-1 activity by inducing c-fos transcription, a process which is probably mediated by the ERK1 and -2 mitogen-activated protein (MAP) kinases, which phosphorylate the transcription factor Elk-1/TCF. Besides inducing transcription from fos and jun genes, mitogens and Ras proteins enhance AP-1 activity through phosphorylation of c-Jun. Phosphorylation of the c-Jun activation domain leads to c-jun induction through an autoregulatory loop. Ras- and ultra-violet-responsive protein kinases that phosphorylate c-Jun on serine residues at positions 63 and 73 and stimulate its transcriptional activity have been identified. These proline-directed kinases, termed JNKs, are novel MAP kinases. It is not clear, however, whether c-Jun is the only recipient and JNK the only transducer of the Ras signal to AP-1 proteins. A short sequence surrounding the major JNK phosphorylation site of c-Jun is conserved in c-Fos and is part of its activation domain, suggesting that c-Fos may be similarly regulated. Here we show that Ras does indeed augment the transcriptional activity of c-Fos through phosphorylation at Thr 232, the homologue of Ser 73 of c-Jun. However, this is mediated by a novel Ras- and mitogen-responsive proline-directed protein kinase that is different from JNKs and ERKs. Therefore, at least three types of proline-directed kinases transmit Ras- and mitogen-generated signals to the transcriptional machinery.
...
PMID:c-Fos transcriptional activity stimulated by H-Ras-activated protein kinase distinct from JNK and ERK. 807 47

The protein kinase cascade Raf-MAPKK/MEK-MAPK/ERK connects protein tyrosine kinase receptors in the membrane with control of transcription factor activity in the nucleus. We have examined whether Raf is obligatory for activation of this cascade and whether this signaling pathway is relevant to transformation. By use of transient assays with epitope-tagged ERK-1 cDNA and a dominant inhibitory mutant of Raf-1 we found that serum and 12-O-tetradecanoylphorbol-13-acetate as well as representatives of three classes of oncogenes (protein tyrosine kinases abl/src, Ras, and protein serine/threonine kinases mos/cot) were all Raf-dependent for stimulation of MAPK. All of the MAPK stimulating oncogenes were also activators of Raf kinase as judged by shift induction. It thus appears that there is little or no redundancy in pathways used by growth regulators for activation of MAPK/ERK. Furthermore, the ability to stimulate MAPK/ERK appears to be critical for transformation by oncogenic Raf-1 and ERK-1 and -2 synergized with v-raf in a focus induction assay on NIH3T3 cells and kinase dead mutants of ERK-2 were inhibitory. Raf/ERK synergism was also observed in transcriptional transactivation of the oncogene-response element in the polyoma enhancer. We conclude that this Raf signaling pathway, which connects to many upstream activators and downstream effectors, is essential for transformation by most oncogenes.
...
PMID:Mitogen-activated protein kinase/extracellular signal-regulated protein kinase activation by oncogenes, serum, and 12-O-tetradecanoylphorbol-13-acetate requires Raf and is necessary for transformation. 812 67

The vasoactive peptides endothelin-1 (ET-1) and angiotensin-II (AII) have been implicated in chronic hypertension and may play important roles in related vascular diseases such as restenosis and atherosclerosis. Using a rat aortic smooth muscle (RASM) cell model, both ET-1 and AII induced concentration-dependent delayed increases in DNA synthesis relative to that in the serum-deprived controls. Stimulation of DNA synthesis was maximal at 100 nM for each peptide. All treatment of RASM cells resulted in a greater mitogenic effect (4- to 7-fold) than that observed for ET-1 (3-fold). When added in the presence of AII, ET-1 had a supplemental effect on DNA synthesis (5- to 10-fold above control). Although RASM cells expressed both ETA and AT1 receptors, radioligand binding experiments indicated that approximately 10-fold as many AT1 receptors as ETA receptors were present. In signal transduction studies, ET-1 and AII each elicited concentration-dependent increases in the intracellular Ca2+ concentration. ET-1 and AII also stimulated phosphoinositide metabolism and phosphorylation of a specific substrate for protein kinase-C. The release of total inositol phosphates in response to ET-1 and AII was concentration dependent and inhibited by the ETA receptor-selective antagonist BQ-123 and the AT1 receptor-selective antagonist losartan, respectively. In addition, tyrosine phosphorylation of 120- and 75-kilodalton proteins as well as the mitogen-activated protein kinases p44mapk and p42mapk was observed within 5 min of the addition of either ET-1 or AII. Taken together, these data indicate that ET-1 and AII may promote smooth muscle cell growth through common intracellular signaling mechanisms.
...
PMID:Endothelin-1 and angiotensin-II stimulate delayed mitogenesis in cultured rat aortic smooth muscle cells: evidence for common signaling mechanisms. 817 Apr 71

RCR cells are NRK clones in which Raf-1 production is blocked by the expression of an antisense RNA, and consequently they are refractory to transformation by various oncogenes. In RCR cells, MAP kinases (ERK1 and ERK2) were activated to an extent and in a time course similar to those of the original NRK cells, irrespective of whether the stimulus was oncogenic or non-oncogenic. Moreover, there was no significant elevation of ERK activities in oncogene-transformed NRK cells. These results indicate that Raf-1 kinase is not the major upstream activator of ERK's in NRK cells and that neither ERK1 nor ERK2 are likely to mediate oncogenic signals from Raf-1 kinase.
...
PMID:Raf-1 is not a major upstream regulator of MAP kinases in rat fibroblasts. 826 40


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---