Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.11.18 (MAP)
 7,412 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies suggest that endotoxin (LPS) stimulation of CD14 receptors may be coupled to heterotrimeric G proteins. However, characterization of the G protein-coupled signaling pathways is incomplete. Also, specific changes in the transduction pathways occur in a phenomenon known as LPS tolerance or desensitization induced by prior exposure to LPS. In the present study, we examined potential CD14-dependent G protein-coupled signaling events in response to LPS, and changes in signaling in these pathways during LPS desensitization in Chinese Hamster Ovary (CHO) cells. LPS stimulated inhibitory kappa B alpha (IkappaB alpha) degradation and p38 phosphorylation in CHO cells transfected with human CD14 receptor (CHO-CD14), but not in CHO cells transfected with vector only. However, activation of these signaling events diverged early in the signal transduction pathways. Pretreatment with pertussis toxin, which inactivates inhibitor G protein (G alpha i) function, significantly inhibited LPS-induced p38 phosphorylation, but not LPS-induced IkappaB alpha degradation. Mastoparan, a putative G alpha i agonist, synergized with LPS to induce p38 phosphorylation. Thus, LPS stimulation of p38 phosphorylation is, in part, G alpha i coupled, whereas IkappaB alpha degradation is not. In subsequent studies, CHO-CD14 cells were desensitized by prior LPS exposure. LPS-desensitized cells exhibited augmented IkappaB alpha content and were refractory to LPS-induced IkappaB alpha degradation and p38 phosphorylation. Pretreatment with cycloheximide, a protein synthesis inhibitor, prevented the effect of LPS desensitization on augmenting cellular IkappaB alpha content and its refractoriness to LPS-induced degradation. However, cycloheximide pretreatment did not prevent impaired p38 phosphorylation in desensitized cells. IkappaB alpha upregulation in LPS tolerance may occur through increased synthesis and/or induction of protein that suppress IkappaB alpha degradation. The latter protein synthesis-dependent mechanisms may be distinct from mechanismis inhibiting p38 phosphorylation in tolerance. These findings suggest that LPS tolerance induces CD14-dependent signaling alterations in G alpha i-coupled pathways leading to mitogen-activated (MAP) kinase activation as well as G alpha i-independent pathways inducing IkappaB alpha degradation.
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PMID:Signal transduction events in Chinese hamster ovary cells expressing human CD14; effect of endotoxin desensitization. 1130 28

Cordyceps militaris, a caterpillar-grown traditional medicinal mushroom, produces an important bioactive compound, cordycepin (3'-deoxyadenosine). Cordycepin is reported to possess many pharmacological activities including immunological stimulating, anti-cancer, anti-virus and anti-infection activities. The molecular mechanisms of cordycepin on pharmacological and biochemical actions of macrophages in inflammation have not been clearly elucidated yet. In the present study, we tested the role of cordycepin on the anti-inflammation cascades in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. In LPS-activated macrophage, nitric oxide (NO) production was inhibited by butanol fraction of C. militaris and the major component of C. militaris butanol faction was identified as cordycepin by high performance liquid chromatography. To investigate the mechanism by which cordycepin inhibits NO production and inducible nitric oxide synthase (iNOS) expression, we examined the activation of Akt and MAP kinases in LPS-activated macrophage. Cordycepin markedly inhibited the phosphorylation of Akt and p38 in dose-dependent manners in LPS-activated macrophage. Moreover, cordycepin suppressed tumor necrosis factor (TNF-alpha) expression, IkappaB alpha phosphorylation, and translocation of nuclear factor-kappaB (NF-kappaB). The expressions of cycloxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) were significantly decreased in RAW 264.7 cell by cordycepin. Taken together, these results suggest that cordycepin inhibits the production of NO production by down-regulation of iNOS and COX-2 gene expression via the suppression of NF-kappaB activation, Akt and p38 phosphorylation. Thus, cordycepin may provide a potential therapeutic approach for inflammation-associated disorders.
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PMID:Cordycepin inhibits lipopolysaccharide-induced inflammation by the suppression of NF-kappaB through Akt and p38 inhibition in RAW 264.7 macrophage cells. 1689 39