Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have developed a series of immortal human-human hybrid cell lines that express phenotypic characteristics of primary oligodendrocytes, by fusing a 6-thioguanine-resistant mutant of the human rhabdomyosarcoma RD with adult human oligodendrocytes by a lectin-enhanced polyethylene glycol procedure. Hybrids were selected in an aminopterin-containing media. In contrast to the tumor parent cells, a hybrid clone M03.13 expressed surface immunoreactivity for galactosyl cerebroside and intracellular immunoreactivity for myelin basic protein (MBP), proteolipid protein (PLP), and glial fibrillary acidic protein (GFAP). Serum deprivation or chronic treatment with a protein kinase C activator 4-beta-phorbol 12-myristate 13-acetate (PMA), but not dibutyl cyclic adenosine monophosphate induced coordinate up-regulation or de novo induction of oligodendrocyte phenotypic markers with concomitant down-regulation of GFAP expression. Consistent with immunohistochemical studies, northern blot analysis demonstrated that both MBP and PLP mRNA were up-regulated in MO3.13 cells by PMA treatment. M03.13 cells provide an immortalized clonal model system suitable for study of gene expression subserving oligodendrocyte and astrocyte phenotypes.
 ...
PMID:A human glial hybrid cell line differentially expressing genes subserving oligodendrocyte and astrocyte phenotype. 770 48

Sublethal concentrations of reactive oxygen intermediates including H2O2 can alter human T cell function and inhibit proliferative responses but relatively little is known about the effects of low levels of oxidant stress on signaling pathways. In the present study, we investigated whether the exposure of Jurkat T cells to micromolar concentrations of H2O2 might influence the activity of certain serine/threonine kinases and protein phosphatases important for T cell signaling as well as initiation of nuclear events. Jurkat cells treated with 100-200 microM H2O2 exhibited rapid increases in cytosolic protein kinase C (PKC) activity without detectable translocation of PKC to the membrane/particulate compartment. The stimulation of PKC activity by H2O2 was associated with an increase in the activation of kinases phosphorylating myelin basic protein (MBP), a substrate for mitogen-activated protein (MAP) kinase and RRLSSLRA (S6 peptide; a substrate for the approximately 90-kDa ribosomal S6 kinases). Optimal activation of MAP kinase in cells treated with H2O2 was preceded by increases in protein tyrosine phosphorylations and occurred at sublethal concentrations of H2O2 which did not markedly deplete intracellular ATP. Pretreatment of cells with the PKC inhibitors sangivamycin and H7 suppressed but did not block the stimulation of MAP kinase activity in response to H2O2 or phytohemagglutinin. The activities of both protein tyrosine phosphatase (PTP) and protein phosphatase 2A (PP2A) were reduced after H2O2 treatment of intact cells. Furthermore, kinetic studies showed that H2O2 was capable of suppressing the activities of PTP and PP2A before inducing optimal increases in MAP kinase activity. These results demonstrate that the exposure of T cells to sublethal levels of oxidant stress acutely stimulates the MAP kinase cascade and suggest that this activation may involve PKC-dependent and -independent pathways as well as inhibition of certain protein phosphatases.
 ...
PMID:Sublethal levels of oxidant stress stimulate multiple serine/threonine kinases and suppress protein phosphatases in Jurkat T cells. 777 89

The extension of cellular processes from the oligodendrocyte soma is an early and critical event in myelin formation. Previous reports from this laboratory have implicated a role for protein kinase C (PKC) as an important intracellular mediator of this critical step in myelinogenesis. In the current study, the regrowth of fibers by adult human oligodendrocytes was examined and was found to be significantly enhanced by the PKC stimulator, 4 beta-phorbol-12,13-didecanoate (PDB); this was accompanied by a 400-500% increase in oligodendroglial PKC activity. In contrast to other cell types, the increased PKC activity in oligodendrocytes was not followed by subsequent down-regulation of the enzyme. The role of PKC in oligodendroglial process formation was further demonstrated by the ability of inhibitors of PKC to block the basal- or PDB-enhanced fiber outgrowth. As well, studies employing isoform-specific agonists implicated PKC alpha as the major determinant of fiber outgrowth by oligodendrocytes. The potential significance of PKC in myelin formation was further underscored by the observation that the synthesis of myelin basic protein, a prerequisite component for myelinogenesis, was increased by 2-fold in PDB-treated oligodendrocytes. Collectively, these observations suggest that PKC, in particular the alpha isoform, constitutes an important mediator in the initiation of myelin formation.
 ...
PMID:Protein kinase C in cultured adult human oligodendrocytes: a potential role for isoform alpha as a mediator of process outgrowth. 780 94

In order to investigate regulatory mechanisms and to identify potential substrates of a novel member of the protein kinase C (PKC) family, PKC mu, specific antibodies have been raised against unique amino- and carboxy-terminal regions. PKC mu kinase activity was studied upon immunoprecipitation from stably transfected cell lines as well as from the A549 carcinoma cell line expressing the endogenous PKC mu gene. Cell fractionation revealed that PKC mu is predominantly found in the particulate fraction, suggesting an association with the membrane or membrane-bound structures. In vitro kinase assays with immunoprecipitated PKC mu demonstrated a Ca2+ independent enhancement of constitutive autophosphorylation activity by phosphatidylserine. Despite a limited in vitro phorbol ester response, an apparent phorbol ester activation of PKC mu was observed when cell cultures, instead of immunoprecipitated enzyme, were treated with either phorbol 12-myristate 13-acetate or 1,2 dioleoyl-sn-glycerol. Both in vitro autophosphorylation and substrate phosphorylation of myelin basic protein and histone III were enhanced under these conditions. However, long-term treatment with the phorbol ester did not result in downregulation of PKC mu protein levels and kinase activity. Studies with several protein kinase inhibitors revealed a novel sensitivity profile of PKC mu, with no inhibition by calphostin C, reduced sensitivity to staurosporine but, compared to other PKCs, an approximately 60-fold higher sensitivity to the selective PKA inhibitor H89. Together, the data presented here show that localization of PKC mu and regulation of its kinase activity differ from that of other PKCs suggesting a novel function of PKC mu in intracellular signal pathways.
 ...
PMID:Characterization of activators and inhibitors of protein kinase C mu. 785

The unique structures of process-bearing cells in the central nervous system (CNS) present an ideal model with which to study the differential distribution of mRNA. We conducted a side-by-side examination of the intracellular distribution of nine neural mRNAs by in situ hybridization histochemistry in mammalian brain and observed four general types of mRNA distributions. (1) Some mRNA species were confined to cell somas and included those encoding the glial proteins, myelin proteolipid protein and 2'3'-cyclic nucleotide-3'-phosphodiesterase and the neuronal enzymes, neuron-specific enolase and glutamate decarboxylase-67. (2) Some mRNAs were found abundantly within the cell soma and were also located throughout cellular processes. These included myelin basic protein (MBP) mRNA, which was localized to the cell soma and myelin sheaths of oligodendrocytes, and glial fibrillary acidic protein (GFAP) mRNA, which was localized to the cell soma and processes of reactive and some non-reactive astrocytes in the adult brain and radial glia in embryonic brain. (3) Some mRNAs were found primarily in perinuclear cytoplasm but in some cells were also observed in cell processes. These included mRNAs encoding the protein kinase C/calmodulin-binding substrates, RC3 (neurogranin) and GAP-43, which were identified in the somas as well as within the proximal dendritic branches of specific forebrain neurons. (4) Some mRNAs were localized primarily within cell processes. These included MAP2 mRNA, which was identified by deep staining within dendritic fields but by only light staining within neuronal cell bodies. The data also indicated that the stage of cellular development and the regional location of a cell within the CNS had a profound influence on translocation events. MAP2 mRNA was found in the dendritic processes of most neurons but was confined to the soma of neurons in specific brainstem nuclei. MBP mRNA was confined to the perinuclear cytoplasm of immature oligodendrocytes and was then transported into the myelin sheath at a developmental stage corresponding to myelination. The distribution patterns of these mRNAs are likely to reflect the mechanism by which the protein products of these molecules are targeted within neurons and glia. In addition, mRNA movement may be influenced by cellular and regional factors not encoded solely within the structure of the translocated mRNA.
 ...
PMID:Cellular influences on RNA sorting in neurons and glia: an in situ hybridization histochemical study. 787 39

The existence and activation of mitogen-activated protein (MAP) kinase in isolated pancreatic acini have been demonstrated. Immunoblotting and immunoprecipitation revealed two forms of MAP kinase in pancreatic acini, with relative molecular masses of approximately 42 and 44 kDa. Both forms of MAP kinase were activated by cholecystokinin (CCK). The threshold concentration of CCK was approximately 3 pM, and the maximal effect occurred at 1 nM, which enhanced MAP kinase activity by 2.5-fold, as determined in polyacrylamide gel copolymerized with substrate myelin basic protein. Activation of MAP kinase by CCK was rapid, reaching a maximum within 5-10 min that subsequently declined. Bombesin and carbachol but not secretin or vasoactive intestinal peptide also activated MAP kinase. CCK-induced activation of MAP kinase may be mediated by protein kinase C, since 12-O-tetradecanoylphorbol 13-acetate (TPA) mimicked the effect of CCK and staurosporine concentration dependently inhibited the action of CCK. Treatment of acini with thapsigargin, ionomycin, or ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid did not influence MAP kinase, indicating that mobilization of intracellular calcium by CCK is not important in activation of acinar MAP kinase. CCK and TPA increased tyrosine phosphorylation of both 42- and 44-kDa forms. Genistein and tyrphostin 23, the inhibitors of tyrosine kinase, suppressed the activation of MAP kinase by CCK. In conclusion, MAP kinase in pancreatic acini is activated by agonists related to hydrolysis of phosphoinositide, via a mechanism involving protein kinase C and tyrosine kinase.
 ...
PMID:Cholecystokinin rapidly activates mitogen-activated protein kinase in rat pancreatic acini. 794 37

To identify consensus sequence motif for a new family of protein kinase termed autophosphorylation-dependent protein serine/threonine kinase (auto-kinase), we have tested several synthetic peptides. The well established protein serine/threonine kinases such as cAMP-dependent protein kinase, Ca2+/calmodulin-dependent protein kinase (CaM-kinase), and protein kinase C were found to be inactive toward phosphorylation of syntide-3 (RPRPASVPPSPSLSRHA), which turned out to be an excellent substrate only for auto-kinase, indicating that syntide-3 is a specific substrate for auto-kinase. Modification of syntide-3 to become RPRPASVPPS/T did not affect the activity of auto-kinase. By contrast, autokinase became rather or almost inactive when the peptide was modified to become RPRPASVPPA/G/F/K/R/D/E/Y, indicating that amino acid number 10 in syntide-3 is crucial to the sequence motif recognized by auto-kinase. Phosphorylation of myelin basic protein (MBP) by autokinase revealed that auto-kinase predominantly phosphorylates MBP on one particular site with RT-T(p)HYGS as the phosphorylation site sequence, which could not be phosphorylated by any other reported MBP kinases including cAMP-dependent protein kinase, CaM-kinase, protein kinase C, mitogen-activated protein kinase, and kinase FA/GSK-3. Taken together, the results provide initial evidence that -Arg-X-(X)-Ser/Thr-X3-Ser/Thr- may represent a unique consensus sequence motif specifically recognized by autophosphorylation-dependent protein kinase, a new family of multi-substrate/multifunctional protein serine/threonine kinase.
 ...
PMID:Identification of -R-X-(X)-S/T-X3-S/T- as consensus sequence motif for autophosphorylation-dependent protein kinase. 785 32

UCN-01 (7-hydroxystaurosporine) has been demonstrated to be a potent inhibitor of tumor cell growth both in cell culture and with in vivo xenograft models. The ability of UCN-01 to inhibit the kinase activity of recombinant protein kinase C (PKC) isozymes alpha, beta, gamma, delta, epsilon, and zeta was characterized using an in vitro kinase assay. Two distinct groups of isozymes could be defined on the basis of relative potency of kinase inhibition. UCN-01 was 15-20-fold more potent for inhibition of the Ca(2+)-dependent isozymes, compared with the Ca(2+)-independent isozymes. In contrast, UCN-02 (the diastereomer of UCN-01) and staurosporine exhibited less ability to discriminate between Ca(2+)-dependent and -independent isozymes. PKC-zeta was not inhibited by UCN-01, UCN-02, or staurosporine. IC50 values for UCN-01 inhibition of the Ca(2+)-dependent PKC-alpha, -beta, and -gamma were 29, 34, and 30 nM, respectively, and for the Ca(2+)-independent PKC-delta and -epsilon were 530 and 590 nM, respectively. IC50 values for staurosporine inhibition of the isozymes alpha, beta, and gamma were 58, 65, and 49 nM, respectively, and for the isozymes delta and epsilon were 325 and 160 nM, respectively. UCN-02 was significantly less potent for the inhibition of PKC-alpha, -beta, -gamma, -delta, and -epsilon (IC50 values of 530, 700, 385, 2800, and 1200 nM, respectively). An analysis of the inhibition by UCN-01 and staurosporine of the kinase activity of PKC-alpha and -delta indicated mixed inhibition kinetics. Increasing the ATP concentration resulted in decreased potency, as shown by increased IC50 values. In contrast, increasing the peptide substrate concentration resulted in increased potency, as shown by decreased IC50 values. Increasing concentrations of myelin basic protein as a PKC-alpha or -delta substrate also caused increased potency of inhibition by UCN-01. Because of the competitive nature of inhibition with respect to ATP and the uncompetitive nature with respect to substrate, the concentrations of these substrates can have dramatically different effects on the degree of inhibition observed. These data also suggest that UCN-01 may be an important tool for the dissection of PKC isozyme contributions to signal transduction pathways.
 ...
PMID:Differential inhibition of protein kinase C isozymes by UCN-01, a staurosporine analogue. 802 14

We have investigated the possibility of a protein kinase participating in the signal transduction mechanisms of the interleukin-1 (IL-1) type I receptor (IL-1RI). Our data show that a protein kinase was co-precipitated with the IL-1RI from the two murine T helper cell lines D10N and EL-4. The kinase activity was detected in an in vitro kinase assay performed with the immuno beads in the presence of exogenous substrates. IL-1 treatment of the cells resulted in a rapid activation of this protein kinase in a concentration-dependent manner. Both forms of IL-1, IL-1 alpha and IL-1 beta, induced this kinase activity, whereas the IL-1 receptor antagonist (IL-1ra) was inactive. In excess IL-1ra competitively antagonized IL-1 stimulation. In the in vitro kinase assay the exogenous substrates myelin basic protein and histone H1 were phosphorylated, whereas casein or heat-shock protein HSP27 were not accepted, reflecting a certain selectivity of this protein kinase. The IL-1RI co-precipitable protein kinase showed a serine/threonine specificity and was inhibited by staurosporine, but not by inhibitors specific for protein tyrosine kinase or protein kinase C. These results show that a serine/threonine protein kinase directly interacts with the IL-1RI at the plasma membrane level of T helper cells forming a novel type of IL-1 inducible signaling complex. This protein kinase may resemble the link coupling the plasma membrane IL-1 receptor to cytosolic downstream elements in the IL-1 signaling pathway.
 ...
PMID:Interleukin-1-induced activation of a protein kinase co-precipitating with the type I interleukin-1 receptor in T cells. 802 18

Intracellular signaling pathways regulating vascular smooth muscle (VSM) cell growth and hypertrophy can be initiated by activation of receptor tyrosine kinases and/or protein kinase C (PKC). Mitogen-activated protein kinases (MAP kinases) are cytosolic serine/threonine kinases, proposed to act as a point of convergence for diverse growth factors utilizing these signaling pathways. The goals of this study were (1) to determine whether MAP kinase is expressed in cultured rat aortic VSM, (2) to assess the activation of MAP kinase by known proliferative and hypertrophic stimuli, and (3) to determine if stimulation of a PKC-dependent signaling pathway in these cells results in MAP kinase activation. MAP kinase activity was measured in cytosolic extracts of aortic VSM by quantifying myelin basic protein phosphorylation. Three peaks of activity were resolved chromatographically and identified as MAP kinase isoforms (MW 42, 44, and 46 kDa) by immunoblotting with antipeptide antibodies specific for MAP kinase. MAP kinase activity in quiescent growth-arrested cells (157 +/- 19 pmole 32P/min/mg) was markedly stimulated within 15 min by known mitogens (10% serum, 731 +/- 40 pmole 32P/min/mg; 40 ng/ml PDGF, 670 +/- 105 pmole 32P/min/mg; P < 0.01) and partially sustained for at least 90 min (serum, 606 +/- 34 pmole 32P/min/mg; PDGF, 323 +/- 59 pmole 32P/min/mg P < 0.05). Angiotensin II (AII, 0.1 microM) and a pharmacological PKC activator, phorbol 12,13-dibutyrate (PDB, 0.1 microM), are reported to be nonmitogenic hypertrophic stimuli in these cells. These stimuli transiently increased MAP kinase activity with a peak at 5 min (AII, 328 +/- 15 pmole 32P/min/mg; PDB, 592 +/- 41 pmole 32P/min/mg; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Regulation of MAP kinase activity by growth stimuli in vascular smooth muscle. 804 Nov 41


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