Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Vanadium pentoxide (V(2)O(5)) is a cause of occupational asthma and chronic bronchitis, yet the molecular mechanisms through which V(2)O(5) exerts its effects on cell function are unclear. In this study we investigated the potential of V(2)O(5) to activate the extracellular signal-regulated kinases 1 and 2 (ERK-1/2) in rat pulmonary myofibroblasts. Treatment of myofibroblasts with V(2)O(5) resulted in the activation of ERK-1/2, yet the inert metal titanium dioxide had no effect on ERK-1/2 activation. V(2)O(5)-induced ERK-1/2 activation was abolished by pretreatment with forskolin or PD98059, indicating a dependence on Raf and mitogen-activated protein (MAP) kinase kinase, respectively. Depletion of conventional protein kinase C activity with phorbol 12-myristate 13-acetate did not inhibit V(2)O(5)-induced ERK-1/2 activation. ERK-1/2 activation by V(2)O(5) was inhibited > 70% with the epidermal growth factor receptor (EGF-R) tyrosine kinase inhibitor AG1478. Phosphorylation of the 170-kD EGF-R by V(2)O(5) was detected after immunoprecipitation with an anti-EGF-R antibody followed by phosphotyrosine Western blotting. V(2)O(5) strongly tyrosine-phosphorylated a 115-kD protein (p115) and activation of p115 was inhibited 60 to 70% by AG1478, indicating that this protein was an EGF-R substrate. Phosphorylation of p115 was also observed in EGF-stimulated cells. Immunoprecipitation of V(2)O(5)- or EGF-treated cell lysates with an antibody against Src homology 2 protein tyrosine phosphatase (SH-PTP2) identified p115 as a SH-PTP2-binding protein. Pretreatment of cells with the antioxidant N-acetyl-L-cysteine blocked V(2)O(5)-induced MAP kinase activation and p115 phosphorylation > 90%. These data suggest that V(2)O(5) activation of ERK-1/2 is oxidant-dependent and mediated through tyrosine phosphorylation of EGF-R and an EGF-R substrate which we identified as a 115-kD SH-PTP2-binding protein.
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PMID:Mechanism of extracellular signal-regulated kinase (ERK)-1 and ERK-2 activation by vanadium pentoxide in rat pulmonary myofibroblasts. 1078 31

When osteoblasts are cultured on surfaces of increasing microroughness, they exhibit decreases in proliferation, increases in differentiation and local factor production, and enhanced response to 1alpha,25(OH)(2)D(3). The cells interact with surfaces through integrins, which signal by the same pathways used by 1alpha,25(OH)(2)D(3), including protein kinase C via phospholipase C and protein kinase A via phospholipase A(2). This provides opportunities for crosstalk that may contribute to the synergistic effects of surface roughness and the vitamin D metabolite. Because these pathways converge at mitogen-activated protein kinase (MAPK), we tested the hypothesis that the extracellular signal-regulated kinase (ERK1/2) subclass of MAPKs mediates the effects of surface roughness and 1alpha,25(OH)(2)D(3). MG63 osteoblast-like osteosarcoma cells were cultured on commercially pure Ti disks with various surface roughnesses: pretreatment (PT; 0.6 microm average roughness [Ra]), coarse grit-blasted and acid-etched (SLA; 4 microm RA), and titanium plasma-sprayed (TPS; 5.2-microm R(a)). At confluence, cells were treated for 24 h with control media or media containing 10(-7) M 1alpha,25(OH)(2)D(3). One-half of the cultures received 1 microm or 10 microm PD98059, a specific inhibitor of the ERK family of MAPKs. PD98059 alone did not affect proliferation, osteocalcin production, or production of transforming growth factor-beta1 or nitric oxide, regardless of the surface roughness. Alkaline phosphatase was reduced by the inhibition of the ERK family kinases on all surfaces to a comparable extent. However, when PD98059 was added to the cultures with 1alpha,25(OH)(2)D(3), the effects of the seco-steroid were blocked, including the synergistic increases seen in MG63 cells cultured on SLA or TPS. These results indicate that ERK1/2 MAPK is required for the maintenance of alkaline phosphatase at control levels and that the effects of 1alpha,25(OH)(2)D(3) are mediated by ERK1/2. However, the effects of surface roughness are not due to the ERK family of MAPKs. This suggests that alternative pathways may be used, including those mediated by other MAPK subclasses.
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PMID:Osteoblast response to titanium surface roughness and 1alpha,25-(OH)(2)D(3) is mediated through the mitogen-activated protein kinase (MAPK) pathway. 1137 60

Up to now, most of the studies addressing the critical roles played by protrusive and contractile cell-matrix contacts in cell adhesion, guidance, migration, matrix assembly, and activation of signaling molecules have been performed on two-dimensional surfaces. Here, we analysed the organization of chondrosarcoma cell contacts in a new three-dimensional environment made of titanium beads. Surface charges were modified by deposition of polyelectrolyte multilayer films built up by alternated polycations poly-(L-lysine) or poly(allylamine hydrochloride) and polyanions poly-(L-glutamic acid) or poly(sodium 4-styrenesulfonate). Negatively charged 3-D titanium surfaces amplified the occurrence and length of cell protrusions. These protrusions had pseudopod characteristics extended to 200 microm in length, growing off the substratum to distant beads. Pseudopod formation is inhibited by the exocytosis inhibitor concanamycin A and is triggered by a secreted factor. Chondrosarcoma cells adhering on uncoated or on negatively charged surfaces contained discrete focal spots of vinculin and actin cables. In cells plated onto these surfaces, phosphorylation of p44/42 MAPK/ERK was twofold increased. In contrast, no cytoskeletal vinculin and actin organization was observed when the surface was positively charged. These data suggest that chondrosarcoma cells adapt a more stable adhesion on uncoated or negatively charged surfaces. This point may be critical in tissue engineering strategies designed for cartilage repair.
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PMID:3-D surface charges modulate protrusive and contractile contacts of chondrosarcoma cells. 1456 95

Chemokines, or chemotactic cytokines, are major regulators of the inflammatory response and have been identified as pathogenic factors in the periprosthetic soft tissue. Particulate wear debris induced NF-kappaB activation, the major transcriptional regulator of IL-8 and MCP-1 pro-inflammatory genes and, indeed, both IL-8 and MCP-1 chemokine gene expressions were upregulated in titanium particulate-stimulated human osteoblasts. Here, we demonstrate that phagocytosed particles activate the IL-8 gene promoter via a NF-kappaB-mediated mechanism. Transfection of a dominant negative mutant IkappaBalpha protein that cannot be serine phosphorylated led to suppression of IL-8 promoter activity. The p65/RelA NF-kappaB subunit activity was affected in both a time- and titanium particle concentration-dependent fashion. Titanium particles led to increased ERK, JNK, and p38 activation in MG-63 osteoblast cells, and IL-8 protein release was suppressed by specific inhibitors of the ERK and p38 MAPK pathways. Together, our results suggest that wear debris particles induce chemokine expression in osteoblasts via NF-kappaB-mediated transcriptional activation, which is controlled by the MAPK signal transduction pathway.
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PMID:Chemokine IL-8 induction by particulate wear debris in osteoblasts is mediated by NF-kappaB. 1595 Apr 27

Bone formation around an implant surface is indispensable for osseointegration of dental implants. Transcriptional factor Runx2 is essential for osteoblast differentiation and bone formation. However, little is known about the involvement of Runx2 in osseointegration. The purpose of this study was to investigate molecular interactions between Runx2 and implant titanium materials at the transcriptional level. Primary osteoblasts isolated from mouse calvaria and C3H10T1/2 cells were cultured on titanium plates or in the presence of titanium particles. Transcriptional activity of Runx2 was measured by reporter assay using osteocalcin gene promoter. We found significant increase (p < 0.05) in Runx2 transcriptional activity in cells cultured on titanium plates compared to plastic plates. Titanium particles also upregulated Runx2 transcriptional activity for over 2-folds compared to control and this effect was abolished by the specific inhibitor for ERK1/2, PD98059. Moreover, treatment with PD98059 clearly suppressed osteoblast mineralization cultured on titanium plates. These data suggest that osteoblast attachment to titanium enhanced Runx2 transcriptional activity and bone formation via MAPK pathway during the osseointegration of dental implants.
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PMID:Osteoblast response to titanium regulates transcriptional activity of Runx2 through MAPK pathway. 1711 76

We have developed surfaces for the selective presentation of biotinylated peptides and proteins in a background that resists nonspecific protein adsorption; controlled amounts of biotinylated poly(ethylene glycol) (MW 3400 Da; PEG3400) anchored to titanium-dioxide-coated surfaces via an adhesive tri-peptide sequence of L-3,4-dihydroxyphenylalanine (DOPA3-PEG3400-biotin; DPB) were incorporated within a DOPA3-PEG2000 background. Using optical waveguide lightmode spectroscopy, we found that the amounts of sequentially adsorbed NeutrAvidin and singly biotinylated molecules increased proportionally with the amount of DPB in the surface. Biotinylated peptides (MW approximately 2000 Da) were able to fill all three of the remaining avidin-binding sites, while only one molecule of biotinylated PEG5000 or stem cell factor bound to each avidin. The resulting biotin-avidin-biotin linkages were stable for prolonged periods under continuous perfusion, even in the presence of excess free biotin. Hematopoietic M07e cells bound to immobilized peptide ligands for alpha5beta1 (cyclic RGD) and alpha4beta1 (cylic LDV) integrins in a DPB-dose-dependent manner, with near-maximal binding to cylic LDV for surfaces containing 1% DPB. Multiple ligands were adsorbed in a controlled manner by incubating NeutrAvidin with the respective ligands in the desired molar ratio and then adding the resulting complexes to DPB-containing surfaces. Cell adhesion to surfaces containing both cylic LDV and cyclic RGD increased in an additive manner compared to that for the individual ligands. The bioactivity of adsorbed biotinylated stem cell factor was retained, as demonstrated by DPB-dose-dependent M07e cell adhesion and ERK1/2 activation.
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PMID:Surface presentation of bioactive ligands in a nonadhesive background using DOPA-tethered biotinylated poly(ethylene glycol). 1780 26

Periprosthetic osteolysis poses a significant clinical problem for patients who have undergone total joint arthroplastic surgeries. It has been widely recognized that there is a strong correlation between wear particles from orthopedic implants and osteolysis. However, the molecular mechanism underlying osteolysis still remains unclear. Although wear particles interact with a mixed cellular environment, namely macrophages and immune cells, osteoblasts compose the majority of the cell population surrounding orthopedic implants. Osteoblasts are also one of the major sources of receptor activator of nuclear factor-kappa beta (NF-kappaB) ligand (RANKL), a factor necessary for osteoclastogenesis. However, macrophage colony-stimulating factor (M-CSF), another cytokine responsible for preosteoclast proliferation, must also be present with RANKL for osteoclastogenesis to occur. The purpose of our study is to determine the signal transduction pathway by which titanium (Ti) particles, a metallic component of many orthopedic implants, induce M-CSF expression in MC3T3.E1 murine calvarial preosteoblastic cells. Using reverse transcriptase-polymerase chain reaction (RT-PCR) and enzyme- linked immunosorbent assay (ELISA), our study demonstrated that submicron-sized Ti particles induce M-CSF expression via the extracellular signal-regulated kinase (ERK) pathway in a dose-dependent manner. Moreover, inhibition studies showed that a specific ERK inhibitor, PD98059, significantly downregulated M-CSF production. Our results support the hypothesis that submicron-sized Ti particles can induce M-CSF expression in osteoblasts and thus may have a significant role in contributing to the onset of periprosthetic osteolysis.
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PMID:ERK signaling regulates macrophage colony-stimulating factor expression induced by titanium particles in MC3T3.E1 murine calvarial preosteoblastic cells. 1805 41

Ultrafine or fine titanium dioxide (TiO(2)) particles are widely used in the production of white pigments, for sunscreens, and in cleanup techniques. However, currently knowledge is deficient concerning cellular responses to these particles. The study evaluated and compared the biological activity of ultrafine and fine TiO(2) particles in RAW 264.7 macrophages according to an oxidative stress paradigm. In vitro exposure of macrophages to ultrafine or fine TiO(2) in the range of 0.5-200 microg/ml did not significantly alter cell viability. However, ultrafine TiO(2) enhanced intracellular generation of reactive oxygen species (ROS) to a greater extent than fine TiO(2) at each exposure concentration. Ultrafine TiO(2) induced ERK1/2 activation in a concentration-dependent manner, while the fine TiO(2)-induced changes were minimal. Phosphorylation of ERK1/2 occurred following 10 min exposure to higher concentrations of ultrafine TiO(2) (> or = 25 microg/ml). Similarly, ultrafine TiO(2) exposure significantly enhanced tumor necrosis factor (TNF)-alpha and macrophage inflammatory protein (MIP)-2 secretion in a concentration-dependent manner, and its potency was higher than fine TiO(2). These findings suggest that when exposure concentration is based upon equivalent mass, ultrafine TiO(2) exerts greater biological activity as measured by ROS generation, ERK 1/2 activation, and proinflammatory mediator secretion in RAW 264.7 macrophages than fine TiO(2).
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PMID:Comparison of the biological activity between ultrafine and fine titanium dioxide particles in RAW 264.7 cells associated with oxidative stress. 1833 82

As the applications of industrial nanoparticles are being developed, the concerns on the environmental health are increasing. Cytotoxicities of titanium dioxide nanoparticles of different concentrations (5, 10, 20 and 40 microg/ml) were evaluated in this study using a cultured human bronchial epithelial cell line, BEAS-2B. Exposure of the cultured cells to nanoparticles led to cell death, reactive oxygen species (ROS) increase, reduced glutathione (GSH) decrease, and the induction of oxidative stress-related genes such as heme oxygenase-1, thioredoxin reductase, glutathione-S-transferase, catalase, and a hypoxia inducible gene. The ROS increase by titanium dioxide nanoparticles triggered the activation of cytosolic caspase-3 and chromatin condensation, which means that titanium dioxide nanoparticles exert cytotoxicity by an apoptotic process. Furthermore, the expressions of inflammation-related genes such as interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-8 (IL-8), TNF-a, and C-X-C motif ligand 2 (CXCL2) were also elevated. The induction of IL-8 by titanium dioxide nanoparticles was inhibited by the pre-treatment with SB203580 and PD98059, which means that the IL-8 was induced through p38 mitogen-activated protein kinase (MAPK) pathway and/or extracellular signal (ERK) pathway. Uptake of the nanoparticles into the cultured cells was observed and titanium dioxide nanoparticles seemed to penetrate into the cytoplasm and locate in the peri-region of the nucleus as aggregated particles, which may induce direct interactions between the particles and cellular molecules, to cause adverse biological responses.
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PMID:Oxidative stress and apoptosis induced by titanium dioxide nanoparticles in cultured BEAS-2B cells. 1866 54

The application of titanium (Ti) alloy in joint prostheses is a good choice in orthopedic reconstruction. An elevated serum concentration of Ti has been shown in the patients with loosened knee prostheses. The precise actions of elevated Ti on the circulation remain unclear. In this study the maximal contractile responses elicited by phenylephrine in the aortas of rats 4 weeks after Ti alloy implantation and in cultured rat aortas treated with a soluble form of Ti for a period of 18h were significantly decreased as compared with controls. Aortas isolated from rats with Ti alloy implants or aortas treated with a soluble form of Ti had enhanced protein expression of endothelial nitric oxide synthase (eNOS) and protein kinase C (PKC)-alpha and enhanced phosphorylation of extracellular signal-regulated kinase (ERK) 1/2. Treatment of human umbilical vein endothelial cells (HUVECs) with a soluble form of Ti for 24h dose-dependently increased eNOS protein expression. Short-term treatment of HUVECs with Ti for 1h effectively enhanced the phosphorylation of eNOS, PKC (pan) and ERK1/2. PKC inhibitors RO320432 and chelerythrine effectively inhibited Ti-enhanced phosphorylation of eNOS and PKC (pan). These results indicate that Ti in the circulation may alter endothelial function and reduce vasoconstriction.
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PMID:Titanium implants alter endothelial function and vasoconstriction via a protein kinase C-regulated pathway. 1944 49


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