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

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

We show that promastigotes of Leishmania donovani, the causative agent of visceral leishmaniasis (kala-azar), possess heparin receptors on their surface. From a linear Scatchard plot of the binding data obtained using [3H]heparin and viable promastigotes, one derives a binding constant of 4.7 x 10(-7) M and an estimate of 860,000 receptors per parasite. The [3H]heparin bound to parasites could not be displaced by hyaluronic acid or by three other glycosaminoglycans (dermatan sulphate, chondroitin 4-sulphate and chondroitin 6-sulphate). It was demonstrated that exponential phase promastigotes growing in medium 199 supplemented with fetal bovine serum incorporate 35SO4 into a cell-associated macromolecule that has the properties of heparin proteoglycan. Heparin inhibits the activity of the cell-surface histone-protein kinase; incubation of viable promastigotes with [gamma-32P]ATP and MgCl2 (10 mM) in the absence and presence of heparin (0.01-0.5 mg/ml) for 10 min, followed by analysis by SDS/polyacrylamide-gel electrophoresis and autoradiography, revealed that the phosphorylation of 12 or 13 parasite proteins was inhibited by the glycosaminoglycan. These data suggest that heparin may play a role in the host-parasite relationship.
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PMID:Heparin binds to Leishmania donovani promastigotes and inhibits protein phosphorylation. 255 42

Ca2+ is a major regulator of exocytosis in secretory cells, however, the biochemical mechanisms underlying regulation remain to be identified. To render the secretory apparatus accessible for biochemical studies, we have developed a cell permeabilization method (cell cracking) which utilizes mechanical shear. GH3 pituitary cells subjected to cracking were permeable to macromolecules but retained a normal cytoplasmic ultrastructure including secretory granules. Incubation of the permeable cells at 30-37 degrees C with 0.1-1.0 microM Ca2+ and millimolar MgATP resulted in the release of the secretory proteins, prolactin (PRL) and a proteoglycan, but not lysosomal enzymes. Extensively washed permeable cells were incapable of releasing PRL in response to Ca2+ and MgATP addition. However, addition of cytosol was found to restore Ca2+-activated, MgATP-dependent PRL release. The cytosolic factor responsible for activity was thermolabile and protease sensitive. The protein was partially purified, and its molecular mass was estimated to be equivalent to that of a globular protein of 200-350 kDa by molecular sieve chromatography. Inhibitors of calmodulin or protein kinase C (trifluroperazine, calmidazolium, H-7) failed to inhibit Ca2+-activated PRL release, and the required cytosolic protein could not be replaced by purified calmodulin, calmodulin-dependent protein kinase II, protein kinase C, or calpactin I. Further purification and characterization of the cytosolic protein should reveal the nature of biochemical events involved in regulated secretory exocytosis.
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PMID:A new method for cell permeabilization reveals a cytosolic protein requirement for Ca2+ -activated secretion in GH3 pituitary cells. 272 69

Purified proteoglycan subunits from human articular, bovine articular and nasal cartilages, and a rat chondrosarcoma were phosphorylated in vitro by beef heart cAMP-dependent protein kinase in the presence of gamma 32P-ATP. In these experiments, a maximum of 1.7 moles of 32P were incorporated per mole of proteoglycan from human cartilage. Phosphorylation was dependent on the presence of cAMP. Analysis by autoradiography revealed that serine residues in the core protein of the proteoglycan were the sites of phosphorylation. Treatment of proteoglycan subunits with chondroitinase ABC and alkaline phosphatase prior to reaction with cAMP-dependent protein kinase increased the incorporation of 32P by 12-30% when compared with untreated proteoglycans. These data indicate that proteoglycans in cartilage can be phosphorylated by cAMP-dependent protein kinase.
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PMID:Phosphorylation of proteoglycans from human articular cartilage by a cAMP-dependent protein kinase. 647 53

The expression of many genes is altered upon the activation of macrophages by bacterial LPS. These genes play a crucial role in the orchestration of various responses to protect the host against infection. A novel 2.3 kilobase (kb) cDNA, designated IRG1, was obtained from a cDNA library prepared with RNA isolated from RAW 264.7 following lipopolysaccharide stimulation. Sequence analysis of the clone revealed no identity to any known genes but showed the presence of many potential phosphorylation sites suggesting that IRG1 protein product may be regulated at this level. Furthermore, IRG1 contains the motif for glycosaminoglycan attachment site, implying that IRG1 may be a proteoglycan. By interspecific back-cross analysis, Irg1 was mapped to mouse chromosome 14 linked to Tyrp2 and Rap2a. The IRG1 message appears 1.5 h following LPS exposure and its induction was not dependent on new protein synthesis. In fact, cycloheximide induced the expression of IRG1, suggesting that a protein repressor prevents the expression of IRG1 when uninduced. The role of the protein kinase A pathway in regulating the induction of IRG1 by LPS is questionable, because although forskolin inhibited its induction, neither dibutyrl-cAMP nor 8-(4-chlorophenylthio)-cAMP had much effect on its expression. In contrast, activation of protein kinase C potentiated the LPS response. Chelation of extracellular calcium inhibited IRG1 4 h after LPS induction, while increasing intracellular calcium had little effect on the levels of the IRG1 transcript. Inhibiting tyrosine phosphorylation abrogated the induction of IRG1 by LPS. Hence, the induction of IRG1 by LPS is mediated by tyrosine kinase and protein kinase C pathway.
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PMID:Cloning and analysis of gene regulation of a novel LPS-inducible cDNA. 772 48

The secreted proteoglycan decorin has been implicated in the negative control of cell proliferation primarily by virtue of its ability to block transforming growth factor-beta. Moreover, decorin expression is markedly up-regulated during quiescence but suppressed upon viral transformation, whereas de novo decorin expression in colon carcinoma cells abrogates the malignant phenotype by arresting the cells in the G1 phase of the cell cycle. Here we show that this decorin-induced growth arrest is associated with up-regulation of p21 mRNA and protein in a transforming growth factor-beta- and p53-independent pathway. The augmented p21 protein is present as a multimeric complex with various cyclins and cyclin-dependent kinases in the nuclei of decorin-expressing cells, thereby leading to suppression of cyclin-dependent kinase activity and block of cell division. Through the usage of decorin-specific antisense oligodeoxynucleotide treatment, we demonstrate that the expression of decorin is closely linked to that of p21 and that abrogation of decorin leads to suppression of p21 and restoration of cell division. Collectively, our results provide a plausible mechanism by which decorin may contribute to retard and suppress the growth of tumor cells in vivo.
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PMID:Decorin-induced growth suppression is associated with up-regulation of p21, an inhibitor of cyclin-dependent kinases. 870 60

The role of p38 mitogen-activated protein kinase (MAPK) in responses of human fibroblasts and vascular endothelial cells to IL-1 was investigated by use of a pyridinyl imidazole compound (SB 203580), which specifically inhibits the enzyme. SB 203580 inhibited (50% inhibitory concentration approximately 0.5 microM) IL-1-induced phosphorylation of heat shock protein 27 (an indicator of p38 MAPK activity) in fibroblasts without affecting the other known IL-1-activated protein kinase pathways (p42/p44 MAPK, p54 MAPK/c-Jun N-terminal kinase and beta-casein kinase). SB 203580 significantly inhibited IL-1-stimulated IL-6, (30 to 50% at 1 microM) but not IL-8 production from human fibroblasts (gingival and dermal) and umbilical vein endothelial cells. IL-1 induction of steady state level of IL-6 mRNA was not significantly inhibited, which is consistent with p38 MAPK regulating IL-6 production at the translational level. SB 203580 strongly inhibited IL-1-stimulated PG production by fibroblasts and human umbilical vein endothelial cells. This was associated with the inhibition of the induction of PGH synthase-2 protein and mRNA. SB 203580 also inhibited the stimulation of collagenase-1 and stromelysin-1 production by IL-1 without affecting synthesis of the tissue inhibitor of metalloproteinases (TIMP)-1. SB 203580 prevented the increase in collagenase-1 and stromelysin-1 mRNA stimulated by IL-1. In a model of cartilage breakdown, short-term IL-1-stimulated proteoglycan resorption and inhibition of proteoglycan synthesis were unaffected by SB 203580, while longer term collagen breakdown was prevented. It is concluded that 1) p38 MAPK plays an important role in the regulation of some, but not all, responses to IL-1, and 2) it is involved in the regulation of mRNA levels of some IL-1-responsive genes.
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PMID:Actions of IL-1 are selectively controlled by p38 mitogen-activated protein kinase: regulation of prostaglandin H synthase-2, metalloproteinases, and IL-6 at different levels. 912 Feb 70

Insulin-like growth factor-1, IGF-1, is believed to be an important anabolic modulator of cartilage metabolism whose action is mediated by high affinity cell surface receptors and bioactivity and bioavailability regulated, in part, by IGF-1 binding proteins (IGFBPs). Prostaglandin E2 (PGE2) stimulates collagen and proteoglycan synthesis in cartilage via an autocrine feedback loop involving IGF-1. We determined whether the eicosanoid could regulate IGFBP-4, a major form expressed by chondrocytes and, as such, act as a modifier of IGF-1 action at another level. Using human articular chondrocytes in high-density primary culture, Western and Western ligand blotting to measure secreted IGFBP-4 protein, and Northern analysis to monitor IGFBP-4 mRNA levels, we demonstrated that PGE2 provoked a 2.7 +/- 0.3- and 3.8 +/- 0.5- (n = 3) fold increase in IGFBP-4 mRNA and protein, respectively. This effect was reversed by the Ca(++) channel blocker, verapamil, and the Ca(++)/calmodulin inhibitor, W-7. The Ca(++)ionophore, ionomycin, mimicked the effects of PGE2. The phorbol ester, PMA, which activated phospholipid-dependent protein kinase C (PKC) in chondrocytes, had no effect on IGFBP-4 production. Cyclic AMP mimetics and PKA activators, IBMX, and Sp-cAMP, inhibited the expression of the binding protein as did the PGE2 secretagogue, interleukin-1 beta (IL-beta). The inhibitory effect of the latter cytokine was mediated by a erbstatin/genistein (tyrosine) sensitive kinase. Dexamethasone, an inhibitor of cyclooxygenase (COX-2) expression and PGE2 synthesis, down-regulated control, constitutive levels of IGFBP-4 mRNA and protein, eliminating the previously demonstrated possibility of cross-talk between glucocorticoid receptor (GR) and PGE2-receptor signalling pathways. The results suggest that extracellular signals control IGFBP-4 production by a number of different transducing networks with changes in Ca(++) and calmodulin activity exerting a strong positive influence, possibly maintaining the constitutivity of IGFBP-4 synthesis under basal conditions. PGE2 activation of the IGF-1/IGFBP axis may play a pivotal role in the metabolism of cartilage and possibly connective tissues in general. Eicosanoid biosynthesis may be a rate-limiting step in cartilage repair processes.
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PMID:Prostaglandin E2 stimulates insulin-like growth factor binding protein-4 expression and synthesis in cultured human articular chondrocytes: possible mediation by Ca(++)-calmodulin regulated processes. 913 96

The pericellular proteoglycan biglycan is among the major secretory products of osteoblasts and articular chondrocytes but the regulatory agents and signal transduction pathways that ultimately lead to alterations in biglycan gene expression are poorly defined. We report here on the transcriptional up-regulation of biglycan in MG-63 osteosarcoma cells by agents that increase intracellular cAMP levels. Transfection of these cells with biglycan promoter luciferase reporter fusion genes and subsequent treatment with forskolin or the cAMP analog 8-Bromo-cAMP resulted in an up to 3.8-fold stimulation of biglycan promoter activity. This effect could be prevented with the compound KT5720, a specific inhibitor of the cAMP-dependent protein kinase. Up-regulation of transcription is also reflected at the level of mRNA expression, since biglycan mRNA steady state levels in MG-63 cells increased approximately 2-fold after 24 hours of forskolin treatment. These data suggest that elevated levels of intracellular cAMP increase transcription from the biglycan promoter in bone cells and implicate for the first time the cAMP/protein kinase A signal transduction pathway in the regulation of biglycan gene expression.
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PMID:Biglycan gene promoter activity in osteosarcoma cells is regulated by cyclic AMP. 919 8

There is good evidence that gallbladder epithelium is permeable to a diverse range of molecules which move into the epithelial cell from the lumen or the basement membrane. Morphological investigations have shown both secretory mucous droplets, components of the endocytosis pathway together with evidence of a system allowing passage of molecules across the basement membrane. This indicates that the gallbladder epithelium may be influenced by molecules presented via the apical and basal membranes, complicating our understanding of gallbladder function, particularly in disease. Gallbladder disease increases the proteoglycan content of the basement membrane, but the implication of this in terms of permeability remains to be defined. Indeed, it remains unknown whether this precedes disease or is a manifestation of the disease process. The removal of water from hepatic bile by gallbladder involves two counter ion transport systems. Autoradiography shows that ion transport occurs into the lateral intracellular spaces but it remains unclear whether this leads to a hypertonic solution in these spaces causing an osmotically driven water absorption or if the process involves an osmotically linked isotonic secretion. These ion pumps are reversible, for water is absorbed during the interdigestive phase but fluid is secreted into the lumen during digestion or in the presence of disease. Appropriate neural stimulation can increase or decrease fluid absorption from the lumen while vasoactive intestinal peptide or secretin promote fluid secretion, probably mediated by prostaglandins leading to raised cyclic AMP acting at the cellular level. Immediate control may depend on intracellular Ca2+ which activates a calmodulin-protein kinase, phosphorylating the counter ion transporters to downregulate their activity. Failure of this regulatory process may explain the initial increase in bile concentrating potential seen in the development of gallstones although the mechanism of such failure remains unknown. More concentrated bile increases movement of biliary compounds into gallbladder epithelial cells which alter gallbladder function in a complex manner. Secondary bile acids are raised in gallstone disease and increase permeability of the gallbladder epithelium to molecules including cholesterol. This cholesterol absorbed from the lumen may have paramount importance to gallbladder function. Raised biliary cholesterol reduces gallbladder motility, possibly by increasing the amount of cholesterol in gallbladder muscle membranes and reducing contraction in response to cholecystokinin. However, increased secondary bile acids are also associated with an alteration in phospholipid acyl groups which may alter ion transport activity and/or cholesterol solubility within the micelle/vesicle. As the acyl groups show increased arachidonate levels the production of prostaglandins could be raised, although currently it is not known if this phospholipid arachidonate enters the epithelial cells. In addition, gallbladder inflammation is associated with raised phospholipase A2 activity, leading to formation of fatty acids and lysophospholipid which causes membrane damage. The fatty acids are likely to displace cholesterol from the micelle but may also act directly on the epithelium, possibly increasing prostaglandin production and thus stimulating mucin secretion. Increased mucin secretion is seen early in gallstone disease but the evidence presently available cannot determine if this is a causative factor.
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PMID:Biochemical and morphological correlations in human gallbladder with reference to membrane permeability. 933 Mar 51

In this study we demonstrate that the gene encoding the small leucine-rich proteoglycan biglycan is expressed in human myometrial tissue and in the human leiomyosarcoma cell line SK-UT-1. Treatment of SK-UT-1 cells with forskolin or 8-bromo-cAMP strongly increased biglycan mRNA and this effect was transcriptional as shown by transient transfection experiments with biglycan promoter-luciferase reporter fusion genes. The cAMP-mediated induction of the transfected biglycan promoter in SK-UT-1 cells was abolished by coexpression of a specific protein kinase A inhibitor, and was mimicked by overexpression of the catalytic subunit (Cbeta) of protein kinase A. By 5' deletion analysis, part of the cAMP response was localized to the segment from residues -78 to -46 of the biglycan promoter. This region conferred strong cAMP responsiveness to a heterologous promoter. Electrophoretic mobility shift and antibody supershift assays identified two specific complexes that contained nuclear proteins antigenically related to the ubiquitous transcription factors Sp1 and Sp3, respectively. The binding site of these proteins was mapped to a CT-rich sequence extending from -59 to -49 in the biglycan promoter. Mutating this sequence eliminated complex formation and markedly reduced basal and cAMP-dependent promoter activity of transfected reporter genes. In vitro binding studies using recombinant Sp1 revealed that the nuclear factor binding to the CT element was not Sp1 but a Sp1-like protein(s). Western blot analysis of SK-UT-1 nuclear proteins confirmed expression of Sp3, Sp1 and nuclear proteins that crossreacted with Sp1 antibody but according to their molecular weight were not Sp1. These results indicate that all cAMP-dependent as well as some basal biglycan transcription in SK-UT-1 cells is mediated through activated protein kinase A and that both functions are conferred at the promoter level through the interaction of Sp1-like/Sp3 factors with the CT element at -59 in the biglycan promoter.
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PMID:Biglycan gene expression in the human leiomyosarcoma cell line SK-UT-1. Basal and protein kinase A-induced transcription involves binding of Sp1-like/Sp3 proteins in the proximal promoter region. 978 35


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