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)

1. Endothelial cells can be stimulated by the pro-inflammatory cytokines interleukin (IL)-1 alpha and tumour necrosis factor (TNF) alpha to express the leukocyte adhesion molecules E-selectin, vascular cell adhesion molecule (VCAM)-1 and intercellular adhesion molecule (ICAM)-1 but the intracellular signalling mechanisms leading to this expression are incompletely understood. We have investigated the role of protein tyrosine kinases (PTK) in adhesion molecule expression by cytokine-activated human umbilical vein endothelial cells (HUVEC) using the PTK inhibitors genistein and herbimycin A, and the protein tyrosine phosphatase (PTP) inhibitor sodium orthovanadate. 2. Maximal E-selectin expression induced by incubation of HUVEC for 4 h with IL-1 alpha (100 u ml-1) and TNF alpha (100 u ml-1) was dose-dependently inhibited by genistein and herbimycin A. Although similar effects were seen on phorbol 12-myristate, 13-acetate (PMA)-induced expression, this was not due to inhibition of protein kinase C (PKC) activity as the selective inhibitors of PKC, bisindolylmaleimide (BIM), Ro31-7549 or Ro31-8220 did not affect IL-1 alpha- or TNF alpha-induced E-selectin expression at concentrations which maximally inhibited PMA-induced expression. 3. Genistein inhibited VCAM-1 expression induced by incubation of HUVEC for 24 h with TNF alpha or IL-1 alpha whereas it did not affect ICAM-1 expression induced by 24 h incubation with either of these cytokines. Herbimycin A inhibited both VCAM-1 and ICAM-1 expression induced by TNF alpha. 4. Basal expression of E-selectin, VCAM-1 and ICAM-1 was dose-dependently enhanced by sodium orthovanadate. In contrast, vanadate differentially affected TNF alpha-induced expression of these molecules with maximal E-selectin and ICAM-1 expression being slightly enhanced and VCAM-1 expression dose-dependently reduced. 5. We also studied the effects of PTK and PTP inhibitors on adhesion of the human pre-myeloid cell line U937 to TNF alpha-stimulated HUVEC. Adhesion of U937 cells to HUVEC pretreated for 4 or 24 h with TNF alpha was dose-dependently inhibited by genistein and herbimycin A but unaffected by daidzein. Adhesion of U937 cells after 4 h was partially inhibited by blocking antibodies against both E-selectin and VCAM-1 but after 24 h was only inhibited by anti-VCAM-1. 6. Sodium orthovanadate had no effect on TNF alpha-induced U937 adhesion but dose-dependently enhanced adhesion to unstimulated HUVEC. Vanadate-induced adhesion was inhibited by an antibody against VCAM-1. 7. These results demonstrate that PTK-mediated phosphorylation events are important for the regulation of adhesion molecule expression by human endothelial cells, and additionally show that PTK inhibitors differentially affect upregulation of different adhesion molecules, implicating divergent regulatory pathways for cytokine-induced adhesion molecule expression.
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PMID:Effects of protein tyrosine kinase inhibitors on cytokine-induced adhesion molecule expression by human umbilical vein endothelial cells. 884 42

Lymphocyte-endothelium interactions are pivotal steps in mediating inflammatory responses. The authors have analysed the influence of ultraviolet B (UVB) irradiation on intercellular adhesion molecule (ICAM)-1 expression on cells of the human microvascular endothelial cell line (HMEC)-1 and the intracellular signalling pathways involved. Flow cytometry revealed dose-dependent ICAM-1 up-regulation with maximum induced expression 24h after sublethal UVB irradiation of 10 mJ/cm2. While anti-tumour necrosis factor (TNF)-alpha antibodies or recombinant human interleukin (IL)-10 did not influence this response, anti-interferon (IFN)-gamma antibodies blocked the UVB-induced ICAM-1 up-regulation. Significant induction of intracellular/membrane-bound IFN-gamma was measured as early as 6 h post-UVB. Since previous work has shown a differential role of protein kinase C (PKC) in cytokine induced ICAM-1 expression, the effect of a selective bisindolylmaleimide-derived PKC-inhibitor (GF109203X) was studied. Ultraviolet B-induced ICAM-1 up-regulation was effectively blocked by the PKC-inhibitor, whereas a PKA-inhibitor was ineffective. Moreover, immunofluorescence analysis showed a radiation-induced membrane translocation of PKC-alpha, indicative of enzyme activation, in HMEC-1 cells already 30 min post-UVB. The functional relevance of the UVB-induced ICAM-1 expression and involvement of PKC in this process was demonstrated in an adhesion assay with peripheral blood mononuclear cells. In conclusion, UVB-induced ICAM-1 expression on human endothelial cells involves PKC-dependent pathways and can be prevented by a PKC-inhibitor. The use of PKC-inhibitors as additive modulators in immune reactions may bear clinical potential. The mechanisms of IFN-gamma induction in endothelial cells by UVB deserve further investigation.
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PMID:Protein kinase C activation is involved in ultraviolet B irradiation-induced endothelial cell ICAM-1 up-regulation and lymphocyte-endothelium interaction in vitro. 884 28

Within the past several years research on the interaction of cytokines and adhesion molecules with airway epithelium in diseases has allowed us to develop a better understanding of the disease process. The cytokine, TNF alpha and the adhesion molecule ICAM-1 are important mediators in the pathogenesis of airway diseases such as asthma, chronic bronchitis, and adult respiratory distress syndrome. Effects of TNF alpha on ICAM-1 surface expression was investigated in both primary cultures of normal human bronchial epithelial (NHBE) cells and immortalized human bronchial epithelial cell line BEAS-2B. TNF alpha (0.015-150 ng/mL) significantly enhanced ICAM-1 surface expression (measured by flow cytometry) in a dose and time-dependent manner, with peak expression seen at 24 hours. This response was negated by heat inactivation of the TNF alpha prior to incubation. TNF alpha-induced ICAM-1 expression also was inhibited by pre- and coincubation of TNF alpha with 3 micrograms/mL soluble TNF-R1 or by the PKC inhibitor, Calphostin C (0.1 and 0.5 microM). The ROI scavengers, dimethylthiourea (4 mM), and dimethyl sulfoxide (0.001%), enhanced TNF alpha-induced ICAM-1 expression. Collectively, these results indicate that TNF alpha-induced ICAM-1 surface expression is a specific receptor-mediated response (TNF-R1), which is mediated by mechanisms dependent on PKC and intracellular reactive oxygen species.
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PMID:Tumor necrosis factor alpha (TNF alpha)-induced ICAM-1 surface expression in airway epithelial cells in vitro: possible signal transduction mechanisms. 890 9

Cigarette smoking is clearly linked with increased incidence of atherosclerosis and cardiovascular disease. The adherence of blood monocytes to the endothelium, followed by their migration beneath the endothelium, are initiating events in the formation of foam cells, promoting atherogenesis. We show that cigarette smoke condensate (CSC)-induced surface expression of a subset of cell adhesion molecules (CAM) [intercellular adhesion molecule 1 (ICAM-1), endothelial leukocyte adhesion molecule 1 (ELAM-1), and vascular cell adhesion molecule 1 (VCAM-1)] in human umbilical vein endothelial cells (HUVEC) is associated with an increase in the binding activity of nuclear transcription factor NF-kappa B to the consensus motif common to the CAM genes. Furthermore, CSC (25 microgram/ml) both increases the rate of transendothelial migration of vitamin D3-differentiated monocyte-like cells across the HUVEC monolayer by 200% and causes an approximately 10-fold increases in the phosphorylation of platelet endothelial CAM (PECAM-1), an adhesion molecule located at intercellular junctions and involved in endothelial cell-cell adhesion. Our results show that CSC-induced activation of protein kinase C in endothelial cells initiates a signaling pathways, leading to heightened binding of NF-kappa B to specific DNA sequences, which in turn increases surface expression of the subset of CAMs. Furthermore, our studies demonstrate a link between the phosphorylation of PECAM-1 and the migration of blood monocytes across vascular endothelium.
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PMID:Cigarette smoke condensate-induced adhesion molecule expression and transendothelial migration of monocytes. 892 67

Polymorphonuclear neutrophils (PMN) adhere to the vascular endothelium under hypoxic conditions, causing microvascular injury. The molecular mechanism of hypoxia-induced adhesion of PMN to and diapedesis through the vascular endothelium is poorly understood. We examined the effects of hypoxia on the transendothelial migration of monocytes. Exposure of human umbilical vein endothelial cells (HUVEC) cultured in Transwell chambers under low oxygen tension (3% O2 compared with 21% O2) resulted in an increased rate of migration of both monocyte-like HL-60 cells and human peripheral blood monocytes. Migration was inhibited by addition of an antibody to platelet endothelial cell adhesion molecule-1 (PECAM-1), a protein kinase C (PKC) inhibitor, or a platelet-activating factor (PAF)-receptor antagonist. In HUVEC, hypoxic conditions (1, 3, 5, and 14% O2) increased the phosphorylation of PECAM-1. The extent of phosphorylation of PECAM-1 was inversely related to the concentration of oxygen to which HUVEC were exposed. Hypoxia-induced phosphorylation of PECAM-1 was inhibited by either a PKC inhibitor or a PAF-receptor antagonist, indicating the involvement of hypoxia-induced release of PAF in both PKC activation and the concomitant phosphorylation of PECAM-1. These results were substantiated by the findings that treatment of HUVEC with 100 nM PAF under normoxic conditions augmented 11.8-fold the phosphorylation of PECAM-1 and twofold increase in the transendothelial migration of monocyte-like HL-60 cells. We conclude that PAF, produced by cultured endothelial cells in response to hypoxia, acts in an autocrine fashion to activate PKC, causing PECAM-1 phosphorylation and thus the transendothelial migration of monocytes.
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PMID:Hypoxia induces PECAM-1 phosphorylation and transendothelial migration of monocytes. 894 22

Oxidised low-density lipoprotein (LDL) contributes to atherogenesis by a number of mechanisms, and antioxidants may act as anti-atherogens. LDL oxidation is inhibited by LDL-associated antioxidants, particularly alpha-tocopherol (vitamin E), and water-soluble antioxidants present in LDL's biologic milieu, especially ascorbate (vitamin C). In addition to protecting LDL against oxidation, antioxidants may act at the level of the vascular cell by limiting cellular production of reactive oxygen species, and, thus, cell-mediated LDL oxidation. Cellular antioxidants can also protect against vascular cell dysfunction that would otherwise promote atherogenesis, such as increased adhesion molecule expression and monocyte recruitment, impaired production or release of nitric oxide, or both, and the proliferation of smooth muscle cells. Some of these processes are regulated by nuclear factor-kappa B or related transcription factors, which are redox-sensitive and inhibited by antioxidants. Furthermore, cellular antioxidants can limit cytotoxic effects of oxidised LDL and other oxidant insults, inhibiting vascular cell necrosis and lesion progression. Finally, some antioxidants, in particular alpha-tocopherol, may affect atherogenesis by inhibiting platelet function and mural thrombosis, although this effect appears to be explained by the inhibition of protein kinase C independent of alpha-tocopherol's antioxidant activity.
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PMID:Basic research in antioxidant inhibition of steps in atherogenesis. 894 64

The adhesion molecule L-selectin (CD62L) is rapidly shed from the plasma membrane during leukocyte activation as a result of proteolytic cleavage between Lys321 and Ser322 within the extracellular domain. L-selectin is also down-modulated from the surface in response to cross-linking, possibly through a similar mechanism. To further characterize the mechanism of down-modulation, several L-selectin mutants were generated and transfected into COS cells. Wild-type L-selectin as well as mutants with one or two amino acid substitutions at the cleavage site were nearly quantitatively shed into the culture supernatant. However, mutants in which a nine-amino acid stretch that included the protease-sensitive site was either deleted or replaced with a polyglycine spacer or a comparable region of E-selectin were retained on the cell surface and not detected in the supernatant. These results are consistent with other reports describing protease resistant L-selectin mutants. We also demonstrate that when expressed in L1-2 pre-B cells, the L-selectin nine-amino acid deletion mutant (321del.9), but not wild-type L-selectin, is resistant to down-regulation induced by PMA. However, both wild-type and mutant 321del.9 are completely lost from the cell surface in response to cross-linking with an L-selectin Ab. PMA-induced- but not L-selectin cross-linking-induced down-modulation was inhibited by staurosporine. These data are consistent with the idea that the L-selectin protease(s) can tolerate minor structural alterations at the cleavage site, and that L-selectin down-modulation can be induced by more than one mechanism, at least one of which (cross-linking) is protein kinase C independent.
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PMID:Protease-resistant L-selectin mutants. Down-modulation by cross-linking but not cellular activation. 895 18

Localized adhesion of peripheral blood leukocytes to the endothelial lining is essential for their exit from the blood under both physiological and pathological conditions. The establishment, development, and resolution of the inflammatory response is regulated by an array of mediators, many of which remain to be categorized. These include arachidonic acid (20:4n-6) and its hydroperoxy (HPETE) and hydroxy (HETE) derivatives, which are released during inflammation. The data show that human umbilical vein endothelial cells, pretreated with these fatty acids, have a reduced ability to be stimulated by tumor necrosis factor-alpha (TNF-alpha) for enhanced neutrophil and monocyte adhesion; the order of inhibitory activity being 15-HPETE > 15-HETE > 20:4 (n-6). This fatty acid-induced inhibitory activity was reflected in the ability of the mediators to decrease the TNF-alpha-induced expression of the following endothelial adhesion molecules: intercellular adhesion molecule-1 (ICAM-1), E-selectin, and vascular cell adhesion molecule-1 (VCAM-1), measured by both enzyme-linked immunosorbent assay and flow cytometric analysis. TNF-alpha-induced increased expression of ICAM-1, E-selectin, and VCAM-1 mRNA was significantly depressed by 15-HPETE. Constitutively expressed ICAM-1 and ICAM-1 mRNAs were unchanged by the fatty acids. The saturated fatty acid 20:0 and the methyl ester of 20:4(n-6) had no inhibitory activity. The binding of TNF-alpha to its receptors was not altered by these fatty acids. The fatty acids also inhibited the expression of ICAM-1 and E-selectin induced by phorbol 12-myristate 13-acetate, showing that inhibition occurred at a post-TNF-alpha receptor binding level. The 15-HPETE was found to inhibit the TNF-alpha-induced increase in adhesion molecule expression in the early stage of the incubation, but expression returned to normal after 18 hours. An effect of 15-HPETE on the early cell signaling system was demonstrated by the ability of this fatty acid to inhibit agonist-induced protein kinase C translocation.
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PMID:Inhibition of stimulus-induced endothelial cell intercellular adhesion molecule-1, E-selectin, and vascular cellular adhesion molecule-1 expression by arachidonic acid and its hydroxy and hydroperoxy derivatives. 901 37

One of the earliest events after aggregation of the high affinity receptor for IgE (FcepsilonRI) on mast cells is the activation of protein tyrosine kinases resulting in tyrosine phosphorylation of numerous proteins. Using a monoclonal antibody raised against the rat basophilic leukemia RBL-2H3 cells, we identified that platelet/endothelial cell adhesion molecule 1 (PECAM-1 or CD31) was tyrosine phosphorylated in these cells. Aggregation of PECAM-1 did not induce a detectable increase in its tyrosine phosphorylation, nor did it result in degranulation. However, the minimal tyrosine phosphorylation of PECAM-1 in nonstimulated cells was dramatically increased after FcepsilonRI aggregation. This receptor-induced tyrosine phosphorylation of PECAM-1 was an early event, independent of Ca2+ influx or of the activation of protein kinase C and of cell adhesion. PECAM-1 is an adhesion molecule that is required for the transmigration of leukocytes across the endothelium into sites of inflammation. Therefore tyrosine phosphorylation of PECAM-1 may modulate its interaction with other molecules, thereby regulating the migration of basophils into inflammatory sites.
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PMID:Aggregation of the high affinity IgE receptor results in the tyrosine phosphorylation of the surface adhesion protein PECAM-1 (CD31). 914 65

The L-selectin adhesion molecule mediates lymphocyte extravasation in peripheral lymph nodes, and has also been implicated in directing leukocyte recruitment to inflammatory tissues and metastasis of lymphoid malignancies. In this study, we demonstrate a novel level of regulation of L-selectin expression that involves the 16-kDa Leu-13 signal transduction molecule. Leu-13 is a member of a multimeric cell surface complex in lymphocytes that includes TAPA-1 (target of antiproliferative Ab-1, CD81) as well as lineage-specific proteins. In the present study, mAb-induced ligation of Leu-13 was shown to rapidly down-regulate L-selectin surface density on normal and malignant human lymphocytes, and to markedly inhibit L-selectin-mediated adhesion of lymphocytes to soluble carbohydrate ligands (i.e., PPME, phosphomonoester core polysaccharide) and to lymph node high endothelial venules. Through the use of genistein and staurosporine, potent inhibitors of tyrosine kinases (TK) and protein kinase C (PKC), respectively, Leu-13-induced L-selectin down-modulation was demonstrated to involve a TK-dependent, PKC-independent pathway, and was attributed to increased L-selectin shedding from surface membranes. Notably, direct L-selectin ligation, modeling cross-linking interactions with endothelial cell ligands, similarly down-regulates L-selectin surface expression through a TK-dependent, PKC-independent mechanism. In sharp contrast, PMA and anti-CD3 mAb down-regulate L-selectin via a staurosporine-sensitive, genistein-resistant pathway that is closely linked to lymphocyte proliferation. Taken together, these results demonstrate a novel role for Leu-13- and L-selectin-induced TK activity in control of L-selectin expression, thus providing insight into the complex molecular mechanisms that potentially regulate L-selectin-dependent lymphocyte homing in vivo.
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PMID:Tyrosine kinase-dependent regulation of L-selectin expression through the Leu-13 signal transduction molecule: evidence for a protein kinase C-independent mechanism of L-selectin shedding. 916 64


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