Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.12.2 (MEK)
 18,161 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To clarify the molecular mechanism of substance P (SP) release from dorsal root ganglion (DRG) neurons, we investigated the involvement of several intracellular effectors in the regulation of SP release evoked by capsaicin, potassium or/and bradykinin. Bradykinin-evoked SP release from cultured adult rat DRG neurons was attenuated by either the mitogen-activated protein kinase kinase (MEK) inhibitor (U0126) or cycloheximide. As the long-term exposure of DRG neurons to bradykinin (3 h) resulted in extracellular signal-regulated kinase (ERK) phosphorylation at an early stage and thereafter induced cyclooxygenase-2 (COX-2) protein expression, which both contribute to the SP release triggered by bradykinin B2 receptor. The long-term exposure of DRG neurons to bradykinin enhanced the SP release by capsaicin, but attenuated that by potassium. Interestingly, the inositol 1,4,5-triphosphate (IP3)-induced calcium release blocker [2-aminoethyl diphenylborinate (2-APB)] not only inhibited the potassium-evoked SP release, but also completely abolished the enhancement of capsaicin-induced SP release by bradykinin from cultured DRG neurons. Together, these findings suggest that the molecular mechanisms of SP release by bradykinin involve the activation of MEK, and also require the de novo protein synthesis of COX-2 in DRG neurons. The IP3-dependent calcium release could be involved in the processes of the regulation by bradykinin of capsaicin-triggered SP release.
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PMID:Substance P release evoked by capsaicin or potassium from rat cultured dorsal root ganglion neurons is conversely modulated with bradykinin. 1669 51

Using a highly sensitive substance P (SP) radioimmunoassay, we attempted to elucidate the molecular mechanism of SP release from cultured adult rat dorsal root ganglion (DRG) neurons triggered by capsaicin. As a result, we found that capsaicin can induce SP release in the absence of extracellular Ca2+ by activating transient receptor potential vanilloid receptor subtype 1 (TRPV1). Therefore, we compared the pharmacological profile of SP release involved in several intracellular effectors (phosphoinositide 3-kinase (PI3K), Ca2+ release from intracellular stores, and mitogen-activated protein (MAP) kinases) in the presence/absence of extracellular Ca2+ by stimulating DRG neurons with various concentrations (10 to 1,000 nM) of capsaicin. In the presence of extracellular Ca2+, a capsaicin-induced maximal release of SP obtained at 100 nM capsaicin was attenuated by either the phosphoinositide 3-kinase (PI3K) inhibitors (wortmannin and LY294002), the inositol 1,4,5-triphosphate (IP3)-induced Ca2+ release blocker (2-aminoethyl diphenylborinate, 2-APB) or a specific antagonist of TRPV1 (capsazepine). In contrast, in the absence of extracellular Ca2+, only a high concentration (1 microM) of capsaicin induced a significant increase in the SP release, which was then completely abolished by either a mitogen-activated protein kinase kinase (MEK) inhibitor U0126 or capsazepine, and significantly inhibited by either thapsigargin (a Ca2+-ATPase inhibitor) or BAPTA-AM (a rapid Ca2+ chelator). In summary, the activation of TRPV1 by capsaicin modulates the SP release from DRG neurons via two different mechanisms, one requiring extracellular Ca2+, the activation of PI3K and the IP3-dependent intracellular Ca2+ release, and the other which is independent of extracellular Ca2+ but involves the activation of MEK. These data suggest that a distinct SP release mechanism exists on DRG through the activation of TRPV1 without extracellular Ca2+ by capsaicin to facilitate neuropeptide release.
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PMID:The activation of transient receptor potential vanilloid receptor subtype 1 by capsaicin without extracellular Ca2+ is involved in the mechanism of distinct substance P release in cultured rat dorsal root ganglion neurons. 1803 35

The hypothesis is that the ghrelin signal pathway consists of new participants including a local second mediator in human mesenteric arteries. The contractile force of isometric artery preparations was measured using a wire-myograph. Whole-cell patch clamp experiments were performed on freshly isolated single smooth muscle cells from the same tissue. After the addition of ghrelin (100 nmol) the outward potassium currents conducted through iberiotoxin-sensitive calcium-activated potassium channels with a large conductance were almost entirely abolished. The effect of ghrelin on potassium currents was insensitive to selective inhibitors of cAMP-dependent protein kinase and soluble guanylate cyclase, but was eliminated in the presence of des-octanoyl ghrelin and O-(octahydro-4,7-methano-1H-inden-5-yl) carbonopotassium dithioate (D-609). Ghrelin dose-dependently increased the force of contraction of native, endothelium-denuded and mostly of endothelium-denuded and treated with tetrodotoxin human mesenteric arteries preconstricted with 1 nmol endothelin-1. This effect of ghrelin was blocked when the bath solution contained 1,4-diamino-2,3-dicyano-1,4-bis(2-aminophenylthio)butadiene (U0126), 4-amino-5-(4-methylphenyl)-7-(t-butyl) pyrazolo[3,4-d] pyrimidine (PP2), D-609, 2-[1-(3-dimethylaminopropyl)indol-3-yl]-3-(indol-3-yl) maleimide (GF109203x), pertussis toxin, 2-aminoethyl diphenylborinate (2-APB), indomethacin, (5Z,13E)-(9S,11S,15R)-9,15,Dihydroxy-11-fluoro-15-(2-indanyl)-16,17,18,19,20,pentanor-5,13-prostadienoic acid (AL-8810) - a non-selective prostanoid receptor antagonist, 5-(4-Chlorophenyl)-1-(4-methoxyphenyl)-3-trifluoromethyl pyrazolo (SC-560) - a selective cyclooxygenase 1 inhibitor, ozagrel - a selective thromboxane A(2) synthase inhibitor or T prostanoid receptor antagonist GR32191B. It is concluded that ghrelin increases the force of contraction of human mesenteric arteries by a novel mechanism that involves Src kinase, mitogen-activated protein kinase kinase (MEK), cyclooxygenase 1 and T prostanoid receptor agonist, most probably thromboxane A(2).
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PMID:Ghrelin signaling in human mesenteric arteries. 2081 65