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)

Gene expression changes in neuropsychiatric and neurodegenerative disorders, and gene responses to therapeutic drugs, provide new ways to identify central nervous system (CNS) targets for drug discovery. This review summarizes gene and pathway targets replicated in expression profiling of human postmortem brain, animal models, and cell culture studies. Analysis of isolated human neurons implicates targets for Alzheimer's disease and the cognitive decline associated with normal aging and mild cognitive impairment. In addition to tau, amyloid-beta precursor protein, and amyloid-beta peptides (Abeta), these targets include all three high-affinity neurotrophin receptors and the fibroblast growth factor (FGF) system, synapse markers, glutamate receptors (GluRs) and transporters, and dopamine (DA) receptors, particularly the D2 subtype. Gene-based candidates for Parkinson's disease (PD) include the ubiquitin-proteosome system, scavengers of reactive oxygen species, brain-derived neurotrophic factor (BDNF), its receptor, TrkB, and downstream target early growth response 1, Nurr-1, and signaling through protein kinase C and RAS pathways. Increasing variability and decreases in brain mRNA production from middle age to old age suggest that cognitive impairments during normal aging may be addressed by drugs that restore antioxidant, DNA repair, and synaptic functions including those of DA to levels of younger adults. Studies in schizophrenia identify robust decreases in genes for GABA function, including glutamic acid decarboxylase, HINT1, glutamate transport and GluRs, BDNF and TrkB, numerous 14-3-3 protein family members, and decreases in genes for CNS synaptic and metabolic functions, particularly glycolysis and ATP generation. Many of these metabolic genes are increased by insulin and muscarinic agonism, both of which are therapeutic in psychosis. Differential genomic signals are relatively sparse in bipolar disorder, but include deficiencies in the expression of 14-3-3 protein members, implicating these chaperone proteins and the neurotransmitter pathways they support as possible drug targets. Brains from persons with major depressive disorder reveal decreased expression for genes in glutamate transport and metabolism, neurotrophic signaling (eg, FGF, BDNF and VGF), and MAP kinase pathways. Increases in these pathways in the brains of animals exposed to electroconvulsive shock and antidepressant treatments identify neurotrophic and angiogenic growth factors and second messenger stimulation as therapeutic approaches for the treatment of depression.
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PMID:Target identification for CNS diseases by transcriptional profiling. 1892 5

Abnormalities of striatal function have been implicated in several major neurological and psychiatric disorders, including Parkinson's disease, schizophrenia and depression. Adenosine, via activation of A(2A) receptors, antagonizes dopamine signaling at D2 receptors and A(2A) receptor antagonists have been tested as therapeutic agents for Parkinson's disease. We found a direct physical interaction between the G protein-coupled A(2A) receptor (A(2A)R) and the receptor tyrosine kinase fibroblast growth factor receptor (FGFR). Concomitant activation of these two classes of receptors, but not individual activation of either one alone, caused a robust activation of the MAPK/ERK pathway, differentiation and neurite extension of PC12 cells, spine morphogenesis in primary neuronal cultures, and cortico-striatal plasticity that was induced by a previously unknown A(2A)R/FGFR-dependent mechanism. The discovery of a direct physical interaction between the A(2A) and FGF receptors and the robust physiological consequences of this association shed light on the mechanism underlying FGF functions as a co-transmitter and open new avenues for therapeutic interventions.
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PMID:FGF acts as a co-transmitter through adenosine A(2A) receptor to regulate synaptic plasticity. 1895 46

A number of reports have provided genetic evidence for an association between the DTNBP1 gene (coding dysbindin) and schizophrenia. In addition, sandy mice, which harbor a deletion in the DTNBP1 gene and lack dysbindin, display behavioral abnormalities suggestive of an association with schizophrenia. However, the mechanism by which the loss of dysbindin induces schizophrenia-like behaviors remains unclear. Here, we report that small interfering RNA-mediated knockdown of dysbindin resulted in the aberrant organization of actin cytoskeleton in SH-SY5Y cells. Furthermore, we show that morphological abnormalities of the actin cytoskeleton were similarly observed in growth cones of cultured hippocampal neurons derived from sandy mice. Moreover, we report a significant correlation between dysbindin expression level and the phosphorylation level of c-Jun N-terminal kinase (JNK), which is implicated in the regulation of cytoskeletal organization. These findings suggest that dysbindin plays a key role in coordinating JNK signaling and actin cytoskeleton required for neural development.
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PMID:Dysbindin engages in c-Jun N-terminal kinase activity and cytoskeletal organization. 1909 65

We examined the regulation of mGlu2 and mGlu3 metabotropic glutamate receptor signaling prompted by the emerging role of these receptor subtypes as therapeutic targets for psychiatric disorders, such as anxiety and schizophrenia. In transfected human embryonic kidney 293 cells, G-protein-coupled receptor kinase (GRK) 2 and GRK3 fully desensitized the agonist-dependent inhibition of cAMP formation mediated by mGlu3 receptors. In contrast, GRK2 or other GRKs did not desensitize the cAMP response to mGlu2 receptor activation. Desensitization of mGlu3 receptors by GRK2 required an intact kinase activity, as shown by the use of the kinase-dead mutant GRK2-K220R or the recombinant GRK2 C-terminal domain. Overexpression of beta-arrestin1 also desensitized mGlu3 receptors and did not affect the cAMP signaling mediated by mGlu2 receptors. The difference in the regulation of mGlu2 and mGlu3 receptors was signal-dependent because GRK2 desensitized the activation of the mitogen-activated protein kinase pathway mediated by both mGlu2 and mGlu3 receptors. In vivo studies confirmed the resistance of mGlu2 receptor-mediated cAMP signaling to homologous desensitization. Wild-type, mGlu2(-/-), or mGlu3(-/-) mice were treated intraperitoneally with saline or the mixed mGlu2/3 receptor agonist (-)-2-oxa-4-aminobicyclo[3.1.0]-exhane-4,6-dicarboxylic acid (LY379268; 1 mg/kg) once daily for 7 days. Inhibition of forskolin-stimulated cAMP formation by LY379268 was measured in cortical slices prepared 24 h after the last injection. Agonist pretreatment fully desensitized the cAMP response in wild-type and mGlu2(-/-) mice but had no effect in mGlu3(-/-) mice, in which LY379268 could only activate the mGlu2 receptor. We predict the lack of tolerance when mixed mGlu2/3 receptor agonists or selective mGlu2 enhancers are used continually in patients.
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PMID:Regulation of group II metabotropic glutamate receptors by G protein-coupled receptor kinases: mGlu2 receptors are resistant to homologous desensitization. 1916 43

The atypical antipsychotic drug clozapine is effective in treatment-refractory schizophrenia. The intracellular signaling pathways that mediate clozapine action remain unknown. A potential candidate is the mitogen-activated protein kinase extracellular signal-regulated kinase (MAPK-ERK) cascade that links G-protein-coupled receptor and ErbB growth factor signaling systems, thereby regulating synaptic plasticity and connectivity, processes impaired in schizophrenia. Here, we examined how clozapine differentially modulated phosphorylation of the MAPK isoforms, ERK1/ERK2 in primary murine prefrontal cortical neurons compared to the typical antipsychotic drug haloperidol. While clozapine and haloperidol acutely decreased cortical pERK1 activation, only clozapine but not haloperidol stimulated pERK1 and pERK2 with continued drug exposure. This delayed ERK increase however, did not occur via the canonical dopamine D(2)-Gi/o-PKA or serotonin 5HT(2A)-Gq-phospholipase-C-linked signaling pathways. Rather, epidermal growth factor (EGF) receptor signaling mediated clozapine-induced ERK activation, given dose-dependent reduction of pERK1 and pERK2 stimulation with the EGF receptor inhibitor, AG1478. Immunocytochemical studies indicated that clozapine treatment increased EGF receptor (Tyr1068) phosphorylation. In vivo mouse treatment studies supported the in vitro findings with initial blockade, subsequent activation, and normalization of the cortical ERK response over 24 h. Furthermore, in vivo clozapine-induced ERK activation was significantly reduced by AG1478. This is the first report that clozapine action on prefrontal cortical neurons involves the EGF signaling system. Since EGF receptor signaling has not been previously linked to antipsychotic drug action, our findings may implicate the EGF system as a molecular substrate in treatment-resistant schizophrenia.
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PMID:Clozapine-induced ERK1 and ERK2 signaling in prefrontal cortex is mediated by the EGF receptor. 1927 91

Repeated administration of NMDA antagonists can induce behavioral alterations that mimic symptoms of psychosis, as seen in schizophrenia. JNK, one of the MAPKs, and c-Jun, its downstream target molecule, play important roles in regulating apoptosis in neural cells, and have been suggested as being associated with the pathophysiology of psychosis and the mechanism of action of some antipsychotics. We investigated changes in the JNK-c-Jun pathway and other Jun family proteins in the rat frontal cortex after single and repeated administration of MK-801 to examine acute and chronic responses. Neither the protein level nor the phosphorylation of JNK changed after single or repeated doses of MK-801. However, after repeated treatments, but not a single treatment, with MK-801, a down-regulation occurred in the protein level and of Ser73 phosphorylation of c-Jun in the rat frontal cortex. Other members of the Jun family, JunB and JunD, were unchanged. Repeated exposure to MK-801 down-regulated the phosphorylation and protein level of c-Jun in the rat frontal cortex, which may be related to the long-term effects of chronic treatment with MK-801.
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PMID:Reduction in the protein level of c-Jun and phosphorylation of Ser73-c-Jun in rat frontal cortex after repeated MK-801 treatment. 1934 5

Heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) are the largest group of structurally related proteins encoded by the human genome. As signal effectors and allosteric regulators, GPCRs dynamically recruit not only specific heterotrimeric G proteins but also the cytosolic scaffold proteins, beta-arrestin 1 and 2, which were originally thought only to serve as negative regulators of GPCR signaling. Although about half of currently available therapeutics target GPCR function, usually at the ligand-binding, orthosteric site, evidence suggests that beta-arrestins may be therapeutic targets themselves. Indeed, a hitherto undiscovered action of various antipsychotics is to inhibit the ability of the dopamine D2 receptor to engage beta-arrestin 2 and activate glycogen synthase kinase 3, which may be a target for developing therapeutics for schizophrenia. Also, certain beta-antagonists (blockers) used to treat heart failure, such as carvedilol, have the added effect of promoting activation of extracellular signal-regulated kinase through beta-arrestin. It seems likely that the structure of beta-arrestins allows them to detect different types and conformational states of GPCRs and to respond in functionally distinct fashions by using separate cohorts of signaling proteins, thus generating additional possibilities for therapeutic intervention.
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PMID:Arrestin times for developing antipsychotics and beta-blockers. 1936 91

Neuregulin 1 (NRG1) has been implicated in the pathophysiology of psychotic disorders. NRG1 exerts its effects via the Ras-MAPK and phosphatidylinositol-3 kinase-protein kinase B (PI3K-PKB/AKT) intracellular signaling pathways through ErbB receptors. The aim of this study was to investigate the relationship between NRG1-stimulated AKT phosphorylation and neurocognitive functions in patients with schizophrenia and in patients with other psychotic disorders. B lymphoblasts of patients (n=40) and controls (n=20) were stimulated with NRG1a (65 amino-acid residue recombinant protein from the epidermal growth factor [EGF] domain) for 30-min. The protein isolated from the cells was analyzed by Western blotting. The dependent measure was the ratio of phosphorylated AKT (pAKT) and total AKT at baseline (without NRG1 stimulation) and after NRG1 stimulation (pAKT/AKT). The neurocognitive functions (attention, immediate and long-term memory, language, visual-spatial skills) were evaluated by the repeatable brief assessment of neuropsychological status (RBANS) battery. The results revealed a significantly reduced pAKT/AKT ratio in patients with schizophrenia as compared with healthy controls and with patients with other psychotic disorders. The patients with other psychotic disorders did not differ from the healthy controls. Despite the fact that neurocognitive functions were significantly impaired in the patients, these functions did not reveal significant correlations with the pAKT/AKT ratio. In conclusion, NRG1-induced AKT phosphorylation is decreased in schizophrenia but not in other psychotic disorders. This peripheral marker is not related to neurocognitive functions.
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PMID:Neuregulin 1-stimulated phosphorylation of AKT in psychotic disorders and its relationship with neurocognitive functions. 1952 2

Schizophrenia is a debilitating chronic mental disorder characterized by significant lifetime risk and high social costs. Although its etiology remains unknown, many of its symptoms may be mitigated by treatment with antipsychotic drugs (APDs). These compounds, generally classified as first- or second-generation antipsychotics, have complex receptor profiles that may account for short-term clinical response and normalization of acute manifestation of the disease. However, APDs have additional therapeutic properties that may not be directly related to receptor mechanisms, but rather involve neuroadaptive changes in selected brain regions. Indeed the neurodevelopmental origin of schizophrenia suggests that the disease is characterized by neuroanatomical and pathophysiological impairments that, at molecular level, may reflect compromised neuroplasticity; the process by which the brain adapts to changes in a specific environment. Accordingly, it is possible that the long-term clinical efficacy of APDs might result from their ability in modulating systems crucially involved in neuroplasticity and cellular resilience. We have reviewed and discussed the results of several studies investigating the post-receptor mechanisms in the action of APDs. We specifically focused on intracellular signaling cascades (PKA, DARPP-32, MAPK, Akt/GSK-3, beta arrestin-2), neurotrophic factors and the glutamatergic system as important mediators for antipsychotic drug induced-neuroplasticity. Altogether, these data highlight the possibility that post-receptor mechanisms will eventually be promising targets for the development of novel drugs that, through their impact on neuroplasticity, may contribute to the improved treatment of patients diagnosed with schizophrenia.
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PMID:Antipsychotic drug actions on gene modulation and signaling mechanisms. 1954 Aug 75

The recent discovery of allosteric potentiators and agonists of the muscarinic M(1) receptor represents a significant advance in the muscarinic receptor pharmacology. In the current study we describe the receptor pharmacology and pro-cognitive action of the allosteric agonist AC-260584. Using in vitro cell-based assays with cell proliferation, phosphatidylinositol hydrolysis or calcium mobilization as endpoints, AC-260584 was found to be a potent (pEC(50) 7.6-7.7) and efficacious (90-98% of carbachol) muscarinic M(1) receptor agonist. Furthermore, as compared to orthosteric binding agonists, AC-260584 showed functional selectivity for the M(1) receptor over the M(2), M(3), M(4) and M(5) muscarinic receptor subtypes. Using GTPgammaS binding assays, its selectivity was found to be similar in native tissues expressing mAChRs to its profile in recombinant systems. In rodents, AC-260584 activated extracellular signal-regulated kinase 1 and 2 (ERK1/2) phosphorylation in the hippocampus, prefrontal cortex and perirhinal cortex. The ERK1/2 activation was dependent upon muscarinic M(1) receptor activation since it was not observed in M(1) knockout mice. AC-260584 also improved the cognitive performance of mice in the novel object recognition assay and its action is blocked by the muscarinic receptor antagonist pirenzepine. Taken together these results indicate for the first time that a M(1) receptor agonist selective over the other mAChR subtypes can have a symptomatically pro-cognitive action. In addition, AC-260584 was found to be orally bioavailable in rodents. Therefore, AC-260584 may serve as a lead compound in the development of M(1) selective drugs for the treatment of cognitive impairment associated with schizophrenia and Alzheimer's disease.
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PMID:AC-260584, an orally bioavailable M(1) muscarinic receptor allosteric agonist, improves cognitive performance in an animal model. 1983 92


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