Home About us Contact
|
Home About us Contact | ||
|
|
||
MKP-1 Expression (mkp-1 + expression)
Selected AbstractsCell hydration and mTOR-dependent signallingACTA PHYSIOLOGICA, Issue 1-2 2006F. Schliess Abstract Insulin- and amino acid-induced signalling by the mammalian target of rapamycin (mTOR) involves hyperphosphorylation of the p70 ribosomal S6 protein kinase (p70S6-kinase) and the eukaryotic initiation factor 4E (eIF4E) binding protein 4E-BP1 and contributes to regulation of protein metabolism. This review considers the impact of cell hydration on mTOR-dependent signalling. Although hypoosmotic hepatocyte swelling in some instances activates p70S6-kinase, the hypoosmolarity-induced proteolysis inhibition in perfused rat liver is insensitive to mTOR inhibition by rapamycin. Likewise, swelling-dependent proteolysis inhibition by insulin and swelling-independent proteolysis inhibition by leucine, a potent activator of p70S6-kinase and 4E-BP1 hyperphosphorylation, in perfused rat liver is insensitive to rapamycin, indicating that at least rapamycin-sensitive mTOR signalling is not involved. Hyperosmotic dehydration in different cell types produces inactivation of signalling components around mTOR, thereby attenuating insulin-induced glucose uptake, glycogen synthesis, and lipogenesis in adipocytes, and MAP-kinase phosphatase MKP-1 expression in hepatoma cells. Direct inactivation of mTOR, stimulation of the AMP-activated protein kinase, and the destabilization of individual proteins may impair mTOR signalling under dehydrating conditions. Further investigation of the crosstalk between the mTOR pathway(s) and hyperosmotic signalling will improve our understanding about the contribution of cell hydration changes in health and disease and will provide further rationale for fluid therapy of insulin-resistant states. [source] Reactive oxygen species control senescence-associated matrix metalloproteinase-1 through c-Jun-N-terminal kinase,JOURNAL OF CELLULAR PHYSIOLOGY, Issue 1 2010Jaya Dasgupta The lifetime exposure of organisms to oxidative stress influences many aging processes which involve the turnover of the extracellular matrix. In this study, we identify the redox-responsive molecular signals that drive senescence-associated (SA) matrix metalloproteinase-1 (MMP-1) expression. Precise biochemical monitoring revealed that senescent fibroblasts increase steady-state (H2O2) 3.5-fold (13.7,48.6,pM) relative to young cells. Restricting H2O2 production through low O2 exposure or by antioxidant treatments prevented SA increases in MMP-1 expression. The H2O2 -dependent control of SA MMP-1 is attributed to sustained JNK activation and c-jun recruitment to the MMP-1 promoter. SA JNK activation corresponds to increases and decreases in the levels of its activating kinase (MKK-4) and inhibitory phosphatase (MKP-1), respectively. Enforced MKP-1 expression negates SA increases in JNK phosphorylation and MMP-1 production. Overall, these studies define redox-sensitive signaling networks regulating SA MMP-1 expression and link the free radical theory of aging to initiation of aberrant matrix turnover. J. Cell. Physiol. 225: 52,62, 2010. © 2010 Wiley-Liss, Inc. [source] Dexamethasone suppresses monocyte chemoattractant protein-1 production via mitogen activated protein kinase phosphatase-1 dependent inhibition of Jun N-terminal kinase and p38 mitogen-activated protein kinase in activated rat microgliaJOURNAL OF NEUROCHEMISTRY, Issue 3 2007Yan Zhou Abstract Microglial cells release monocyte chemoattractant protein-1 (MCP-1) which amplifies the inflammation process by promoting recruitment of macrophages and microglia to inflammatory sites in several neurological diseases. In the present study, dexamethasone (Dex), an anti-inflammatory and immunosuppressive drug has been shown to suppress the mRNA and protein expression of MCP-1 in activated microglia resulting in inhibition of microglial migration. This has been further confirmed by the chemotaxis assay which showed that Dex or MCP-1 neutralization with its antibody inhibits the microglial recruitment towards the conditioned medium of lipopolysaccharide (LPS)-treated microglial culture. This study also revealed that the down-regulation of the MCP-1 mRNA expression by Dex in activated microglial cells was mediated via mitogen-activated protein kinase (MAPK) pathways. It has been demonstrated that Dex inhibited the phosphorylation of Jun N-terminal kinase (JNK) and p38 MAP kinases as well as c-jun, the JNK substrate in microglia treated with LPS. The involvement of JNK and p38 MAPK pathways in induction of MCP-1 production in activated microglial cells was confirmed as there was an attenuation of MCP-1 protein release when microglial cells were treated with inhibitors of JNK and p38. In addition, Dex induced the expression of MAP kinase phosphatase-1 (MKP-1), the negative regulator of JNK and p38 MAP kinases in microglial cells exposed to LPS. Blockade of MKP-1 expression by triptolide enhanced the phosphorylation of JNK and p38 MAPK pathways and the mRNA expression of MCP-1 in activated microglial cells treated with Dex. In summary, Dex inhibits the MCP-1 production and subsequent microglial cells migration to the inflammatory site by regulating MKP-1 expression and the p38 and JNK MAPK pathways. This study reveals that the MKP-1 and MCP-1 as novel mediators of biological effects of Dex may help developing better therapeutic strategies for the treatment of patients with neuroinflammatory diseases. [source] Aurothiomalate inhibits cyclooxygenase 2, matrix metalloproteinase 3, and interleukin-6 expression in chondrocytes by increasing MAPK phosphatase 1 expression and decreasing p38 phosphorylation: MAPK phosphatase 1 as a novel target for antirheumatic drugsARTHRITIS & RHEUMATISM, Issue 6 2010Riina Nieminen Objective Aurothiomalate is a disease-modifying antirheumatic drug that suppresses inflammation and retards cartilage degradation and bone erosion in arthritis. The molecular mechanisms of action of aurothiomalate are not known in detail. MAPK pathways are major signaling pathways in inflammation that regulate the production of many inflammatory and destructive factors in arthritis. The purpose of the present study was to investigate the effects of aurothiomalate on the activity of p38 MAPK and on the expression of MAPK phosphatase 1 (MKP-1), cyclooxygenase 2 (COX-2), matrix metalloproteinase 3 (MMP-3), and interleukin-6 (IL-6) in immortalized murine H4 chondrocytes and in intact human and murine cartilage. Methods Protein expression was examined by Western blotting or by enzyme-linked immunosorbent assay, and messenger RNA (mRNA) expression was examined by real-time reverse transcription,polymerase chain reaction analysis. The mediator role of MKP-1 was investigated by using small interfering RNA (siRNA) methods to down-regulated MKP-1 expression in chondrocytes in culture and by comparing the responses in intact cartilage from MKP-1,deficient and wild-type mice. The effects of aurothiomalate were also confirmed in human rheumatoid cartilage by using tissue samples obtained at the time of total knee replacement surgery. Results Aurothiomalate inhibited IL-1,,induced COX-2 expression and prostaglandin E2 production by destabilizing COX-2 mRNA, as did the p38 MAPK inhibitor SB203580. Interestingly, aurothiomalate also increased the expression of MKP-1 and reduced the IL-1,,induced phosphorylation of p38 MAPK. Knockdown of MKP-1 by siRNA significantly impaired the ability of aurothiomalate to inhibit the phosphorylation of p38 MAPK and the expression of COX-2, MMP-3, and IL-6. Likewise, aurothiomalate reduced COX-2, MMP-3, and IL-6 expression in articular cartilage from patients with rheumatoid arthritis, as well as in articular cartilage from wild-type mice but not from MKP-1,/, mice. Conclusion Our findings indicate a novel mechanism for the antiinflammatory and antierosive actions of aurothiomalate, through increased expression of MKP-1, which leads to reduced activation of p38 MAPK and suppressed expression of COX-2, MMP-3, and IL-6. The results suggest that manipulation of MKP-1 levels is a promising new mechanism to be directed in the search and development of novel antiinflammatory and antierosive compounds that have the good efficacy of gold compounds but not their toxicity. [source] | ||||||||||