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)

Kinins are proinflammatory peptides that mediate numerous vascular and pain responses to tissue injury. Two pharmacologically distinct kinin receptor subtypes have been identified and characterized for these peptides, which are named B1 and B2 and belong to the rhodopsin family of G protein-coupled receptors. The B2 receptor mediates the action of bradykinin (BK) and lysyl-bradykinin (Lys-BK), the first set of bioactive kinins formed in response to injury from kininogen precursors through the actions of plasma and tissue kallikreins, whereas the B(1) receptor mediates the action of des-Arg9-BK and Lys-des-Arg9-BK, the second set of bioactive kinins formed through the actions of carboxypeptidases on BK and Lys-BK, respectively. The B2 receptor is ubiquitous and constitutively expressed, whereas the B1 receptor is expressed at a very low level in healthy tissues but induced following injury by various proinflammatory cytokines such as interleukin-1beta. Both receptors act through G alpha(q) to stimulate phospholipase C beta followed by phosphoinositide hydrolysis and intracellular free Ca2+ mobilization and through G alpha(i) to inhibit adenylate cyclase and stimulate the mitogen-activated protein kinase pathways. The use of mice lacking each receptor gene and various specific peptidic and nonpeptidic antagonists have implicated both B1 and B2 receptors as potential therapeutic targets in several pathophysiological events related to inflammation such as pain, sepsis, allergic asthma, rhinitis, and edema, as well as diabetes and cancer. This review is a comprehensive presentation of our current understanding of these receptors in terms of molecular and cell biology, physiology, pharmacology, and involvement in human disease and drug development.
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PMID:International union of pharmacology. XLV. Classification of the kinin receptor family: from molecular mechanisms to pathophysiological consequences. 1573 27

Nociceptin activation of ORL1 (opioid receptor-like 1 receptor) has been shown to antagonize mu receptor-mediated analgesia at the supraspinal level. ORL1 and mu-opioid receptor (muR) are co-expressed in several subpopulations of CNS neurons involved in regulating pain transmission. The amino acid sequence of ORL1 also shares a high degree of homology with that of mu receptor. Thus, it is hypothesized that ORL1 and muR interact to form the heterodimer and that ORL1/muR heterodimerization may be one molecular basis for ORL1-mediated antiopioid effects in the brain. To test this hypothesis, myc-tagged ORL1 and HA-tagged muR are co-expressed in human embryonic kidney (HEK) 293 cells. Co-immunoprecipitation experiments demonstrate that ORL1 dimerizes with muR and that intracellular C-terminal tails of ORL1 and muR are required for the formation of ORL1/muR heterodimer. Second messenger assays further indicate that formation of ORL1/muR heterodimer selectively induces cross-desensitization of muR and impairs the potency by which [D-Ala(2),N-methyl-Phe(4),Gly-ol(5)]enkephalin (DAMGO) inhibits adenylate cyclase and stimulates p42/p44 mitogen-activated protein kinase (MAPK) phosphorylation. These results provide the evidence that ORL1/muR heterodimerization and the resulting impairment of mu receptor-activated signaling pathways may contribute to ORL1-mediated antiopioid effects in the brain.
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PMID:Heterodimerization of opioid receptor-like 1 and mu-opioid receptors impairs the potency of micro receptor agonist. 1574 48

We recently reported that hyperalgesia induced by the inflammatory mediator prostaglandin E(2) (PGE(2)) requires intact alpha1, alpha3 and beta1 integrin subunit function, whereas epinephrine-induced hyperalgesia depends on alpha5 and beta1. PGE(2)-induced hyperalgesia is mediated by protein kinase A (PKA), while epinephrine-induced hyperalgesia is mediated by a combination of PKA, protein kinase Cepsilon (PKCepsilon) and mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK). We hypothesized that inflammatory mediator-induced hyperalgesia involves specific interactions between different subsets of integrin subunits and particular second messenger species. In the present study, function-blocking anti-integrin antibodies and antisense oligodeoxynucleotides were used to elucidate these interactions in rat. Hyperalgesia produced by an activator of adenylate cyclase (forskolin) depended on alpha1, alpha3 and beta1 integrins. However, hyperalgesia induced by activation of the cascade at a point farther downstream (by cAMP analog or PKA catalytic subunit) was independent of any integrins tested. In contrast, hyperalgesia induced by a specific PKCepsilon agonist depended only on alpha5 and beta1 integrins. Hyperalgesia induced by agonism of MAPK/ERK depended on all four integrin subunits tested (alpha1, alpha3, alpha5 and beta1). Finally, disruption of lipid rafts antagonized hyperalgesia induced by PGE(2) and by forskolin, but not that induced by epinephrine. Furthermore, alpha1 integrin, but not alpha5, was present in detergent-resistant membrane fractions (which retain lipid raft components). These observations suggest that integrins play a critical role in inflammatory pain by interacting with components of second messenger cascades that mediate inflammatory hyperalgesia, and that such interaction with the PGE(2)-activated pathway may be organized by lipid rafts.
Pain 2005 May
PMID:Primary afferent second messenger cascades interact with specific integrin subunits in producing inflammatory hyperalgesia. 1583 82

Hepatocyte growth factor is a mesenchyme-derived pleiotropic factor that regulates the growth, motility and morphogenesis of various types of cells, and is also a member of the angiogenic growth factors. Hepatocyte growth factor is secreted by vascular endothelial cells and smooth muscle cells, and the hepatocyte growth factor receptor, c-met, was also observed in these vascular cells. Treatment of human aortic endothelial cells with recombinant hepatocyte growth factor resulted in a significant increase in cell proliferation, accompanied by mitogen-activated protein kinase and Akt/protein kinase B phosphorylation. Recently, a novel therapeutic strategy for ischemic diseases using angiogenic growth factors to augment collateral artery development has been proposed. As preclinical study of gene therapy using hepatocyte growth factor to treat peripheral arterial disease, naked hepatocyte growth factor plasmid was intramuscularly injected into the ischemic hind limb of rabbits in order to evaluate its angiogenic activity. Intramuscular injection of hepatocyte growth factor plasmid once on day 10 following surgery, produced significant augmentation of collateral vessel development in the ischemic limb on day 30. In the clinical setting, the authors further investigated the safety and efficacy of hepatocyte growth factor plasmid DNA in patients with critical limb ischemia, in a prospective open-labeled trial. Intramuscular injection of naked plasmid DNA was performed in the ischemic limbs of six patients with critical limb ischemia with arteriosclerosis obliterans (n = 3) or Buerger disease (n = 3) graded as Fontaine III or IV. In the efficacy evaluation, a reduction of pain scale of more than 1 cm on a visual analog pain scale was observed in five out of six patients. An increase in ankle pressure index of more than 0.1 was observed in five out of five patients. The long diameter of eight out of 11 ischemic ulcers in four patients was reduced by more than 25%. Intramuscular injection of naked hepatocyte growth factor plasmid is safe, feasible and can achieve successful improvement of ischemic limbs. Although the present data were obtained to demonstrate safety in a Phase I/early Phase II trial, the initial clinical outcome with hepatocyte growth factor gene transfer seems to indicate its usefulness as sole therapy for critical limb ischemia. Randomized placebo-controlled clinical trials of alternative dosing regimens of gene therapy will be required to define the efficiency of this therapy.
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PMID:Hepatocyte growth factor as potential cardiovascular therapy. 1588 78

The role of the ERK1/2 signal transduction pathway and related transcription factors in the regulation of gene expression and pain behavior following excitotoxic spinal cord injury (SCI) was examined. Specifically, phosphorylation of ERK1/2, activation of transcription factors NF-kB, ELK-1, and CREB, and gene expression of the neurokinin-1 receptor and NMDA receptor subunits NR1 and NR-2A were investigated. Excitotoxic injury was produced by intraspinal injection of quisqualic acid (QUIS) in male Sprague-Dawley rats. Western blots were used to evaluate phosphorylation and activation of ERK1/2 and transcription factors using phospho-specific or total antibodies. Real-time PCR was used to evaluate gene expression of NK-1R, NR-1, and NR-2A. Assessment of excessive grooming behavior was used to evaluate the presence of spontaneous pain behavior. Excitotoxic spinal injury resulted in: (1) increased phosphorylation of ERK1/2; (2) increased activation of NF-kB and phosphorylation of ELK-1; and (3) increased gene expression for the NK-1 receptor and NR1 and NR-2A subunits of the NMDA receptor. Blockade of the ERK cascade with the MEK inhibitor PD98059 inhibited phosphorylation of ELK-1, activation of NF-kB and gene expression of NR1, NR-2A and NK-1R, and prevented the development of excessive grooming behavior. The results have shown that excitotoxic spinal injury leads to the injury-induced activation of the ERK-->ELK-1 and NF-kB signaling cascades and transcriptional regulation of receptors important in the development of chronic pain. Blockade of this intracellular kinase cascade prevented the onset of injury-induced pain behavior.
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PMID:Activation of the ERK1/2 signaling cascade by excitotoxic spinal cord injury. 1592 85

IL-6 contributes to pain and hyperalgesia in inflamed tissue. We have investigated short- and long-term effects of IL-6 on dorsal root ganglion (DRG) neurones. Glycoprotein 130-like immunoreactivity (the signal transduction receptor subunit) was found in almost all neurones in DRG sections and in cultured DRG neurones from adult rat. In calcium-imaging studies bath application of IL-6 caused an increase of intracellular calcium in about one-third of the DRG neurones suggesting functional IL-6 receptors in a proportion of neurones. Long-term but not short-term exposure of DRG neurones to IL-6 in vitro significantly enhanced the proportion of DRG neurones expressing neurokinin 1 receptor-like immunoreactivity from 10% to up to 40%. This up-regulation was dependent on the activation of mitogen-activated protein kinase kinase (MEK) in the neurones, suggesting that the mitogen-activated protein kinase (MAPK) pathway is important for this effects of IL-6. Calcium-imaging studies demonstrated that previous exposure of DRG neurones to IL-6 enhanced the proportion of neurones that exhibit a substance P-induced rise in intracellular calcium. These data show that IL-6 has short- and long-term effects on a proportion of DRG neurones. These effects are likely to contribute to pro-nociceptive effects of IL-6.
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PMID:Acute and long-term effects of IL-6 on cultured dorsal root ganglion neurones from adult rat. 1595 66

Brain-derived neurotrophic factor (BDNF) is a neurotrophin implicated in the phenomena of synaptic plasticity in the adult. It is found in terminals of nociceptive primary afferents. Following a pain-related stimulus, it is released in the spinal cord, where it activates its high-affinity receptor TrkB, leading to the phosphorylation of the mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase (ERK). A large body of evidence suggests that BDNF has a positive neuromodulatory effect on glutamate transmission in the spinal cord. However, none of these studies examined anatomically whether projection neurons known to be involved in transmission of nociceptive inputs express BDNF's receptor. Because the spinothalamic tract (STT) is a well-characterized pathway for its role in the transfer and integration of sensory and nociceptive informations, this study in rats aimed to 1) determine whether neurons of the STT pathway express the TrkB receptor, 2) establish the rostrocaudal and laminar distribution of STT-TrkB neurons in the whole spinal cord, and 3) test the potential functionality of TrkB expression in these cells by investigating the ability of BDNF to activate the MAP kinase ERK. Using tract tracing coupled to immunofluorescent labeling for TrkB, we observed that in all levels of the spinal cord most STT neurons were immunoreactive for TrkB. Furthermore, microinjections of BDNF into the spinal cord or release of endogenous BDNF by intraplantar injection of capsaicin activated ERK phosphorylation in TrkB-containing STT neurons. These data suggest an important role for BDNF in nociception as an activator of spinothalamic projection neurons.
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PMID:TrkB expression and phospho-ERK activation by brain-derived neurotrophic factor in rat spinothalamic tract neurons. 1597 64

The epsilon isoform of protein kinase C (PKCepsilon) has emerged as a critical second messenger in sensitization toward mechanical stimulation in models of neuropathic (diabetes, alcoholism, and cancer therapy) as well as acute and chronic inflammatory pain. Signaling pathways leading to activation of PKCepsilon remain unknown. Recent results indicate signaling from cAMP to PKC. A mechanism connecting cAMP and PKC, two ubiquitous, commonly considered separate pathways, remains elusive. We found that, in cultured DRG neurons, signaling from cAMP to PKCepsilon is not mediated by PKA but by the recently identified cAMP-activated guanine exchange factor Epac. Epac, in turn, was upstream of phospholipase C (PLC) and PLD, both of which were necessary for translocation and activation of PKCepsilon. This signaling pathway was specific to isolectin B4-positive [IB4(+)] nociceptors. Also, in a behavioral model, cAMP produced mechanical hyperalgesia (tenderness) through Epac, PLC/PLD, and PKCepsilon. By delineating this signaling pathway, we provide a mechanism for cAMP-to-PKC signaling, give proof of principle that the mitogen-activated protein kinase pathway-activating protein Epac also stimulates PKC, describe the first physiological function unique for the IB4(+) subpopulation of sensory neurons, and find proof of principle that G-protein-coupled receptors can activate PKC not only through the G-proteins alpha(q) and betagamma but also through alpha(s).
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PMID:Epac mediates a cAMP-to-PKC signaling in inflammatory pain: an isolectin B4(+) neuron-specific mechanism. 1614 18

Necdin is a multifunctional signaling protein that stabilizes terminal differentiation of postmitotic neurons. The human necdin gene in chromosome 15q11-q12 is maternally imprinted, paternally transcribed, and not expressed in Prader-Willi syndrome, a human genomic imprinting-associated neurodevelopmental disorder. Although necdin-deficient mice display several abnormal phenotypes reminiscent of this syndrome, little is known about molecular mechanisms that lead to the neurodevelopmental defects. Here, we demonstrate that paternally expressed necdin is required for physiological development of nerve growth factor (NGF)-dependent sensory neurons. Mouse embryos defective in the paternal necdin allele displayed absent necdin expression in the dorsal root ganglia, in which the tropomyosin-related kinase A (TrkA) receptor tyrosine kinase and the p75 neurotrophin receptor were expressed in a normal manner. Necdin interacted with both TrkA and p75 to facilitate the association between these receptors. NGF-induced phosphorylation of TrkA and mitogen-activated protein kinase was significantly diminished in the necdin-null sensory ganglia. Furthermore, the mice lacking the paternal necdin allele displayed augmented apoptosis in the sensory ganglia in vivo and had a reduced population of substance P-containing neurons. These mutant mice showed significantly high tolerance to thermal pain, which is often seen in individuals with Prader-Willi syndrome. These results suggest that paternally expressed necdin facilitates TrkA signaling to promote the survival of NGF-dependent nociceptive neurons.
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PMID:Disruption of the paternal necdin gene diminishes TrkA signaling for sensory neuron survival. 1604 86

Inflammatory pain, characterized by a decrease in the nociceptive threshold, arises through the actions of inflammatory mediators. Mitogen-activated protein kinase cascades participate in peripheral nociceptive sensitization. We examined the involvement of c-Jun N-terminal kinase (JNK) in the dorsal root ganglion (DRG) in the early phase of inflammation-induced hyperalgesia. An intra-plantar (i.pl.) injection of complete Freund's adjuvant induced the activation of JNK in DRG neurons within 30 min. Pre-treatment as well as post-treatment of rats with a JNK inhibitor, SP600125, significantly attenuated thermal hyperalgesia, as assessed by paw-withdrawal latency, and the upregulation of c-fos immunoreactivity in dorsal horn neurons. An i.pl. injection of nerve growth factor (NGF) also induced the phosphorylation of JNK as well as thermal hyperalgesia, and SP600125 improved hyperalgesia. Inhibitor experiments suggest that JNK and extracellular signal-regulated protein kinase act on primary nociceptive neurons synergistically. These findings demonstrate that JNK is a therapeutic target for treating inflammation-induced pain hypersensitivity.
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PMID:c-Jun N-terminal kinase activation in dorsal root ganglion contributes to pain hypersensitivity. 1605 88


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