Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

TRAF2 plays a central role in TNF-induced signalling to NF-kappaB and JNK/p38 MAPK. To better understand the molecular mechanisms that mediate this dual function of TRAF2, we performed a yeast two-hybrid screening for TRAF2 interacting proteins using the Sos recruitment system. This resulted in the identification of the E3 ubiquitin ligase Smurf2 as a TRAF2 binding protein. TRAF2 overexpression was shown to trigger Smurf2 ubiquitination and the formation of a TNF-R2/Smurf2 complex. Smurf2 on its turn promoted TNF-R2 ubiquitination and the relocalization of TNF-R2 as well as TRAF2 to a detergent-insoluble cell fraction. This was associated with enhanced TNF-R2-induced JNK activation, whereas TNF-R2-induced NF-kappaB activation remained unaffected. These results suggest an important role for Smurf2 binding to TRAF2 in determining specific signalling outputs of TNF-R2.
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PMID:Smurf2 is a TRAF2 binding protein that triggers TNF-R2 ubiquitination and TNF-R2-induced JNK activation. 1867 42

In response to injury, peripheral neuronal cells initiate complex signalling cascades to promote survival and regeneration. In the present study, we used a model of experimental injury in the rat pheochromocytoma cell line PC12 to investigate receptor signals that lead to neurite outgrowth. Nerve growth factor (NGF) dose-dependently induced sprouting and the expression of the NGF receptors Trk tyrosine kinase receptor (TrkA) and p75 neurotrophin receptor (p75(NTR)) as well as Fas and Fas ligand. Neurite regeneration was decreased by chemical inhibition of TrkA, but not p75(NTR), and by the Fas inhibitor protein Fas-Fc. The mitogen-activated protein kinases (MAPKs) extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinases (JNKs) were activated in response to NGF and both significantly contributed to neurite re-growth. Interestingly, otherwise apoptotic Fas ligation supported neuronal recovery exclusively via JNKs and promoted sprouting parallel to NGF. These findings suggest a novel signal integration from the NGF and Fas pathways in the JNK axis of MAPK signalling, where JNKs function as "physiological" mediators of normally apoptotic signals.
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PMID:c-Jun N-terminal kinases mediate Fas-induced neurite regeneration in PC12 cells. 1869 25

Tumor necrosis factor (TNF) is an important cytokine with multiple biological effects, including cell growth, differentiation, apoptosis, immune regulation and induction of inflammation. The effects of TNF are mediated by two receptors, TNF-R1 and TNF-R2. The major signal transduction pathways triggered by TNF include those that lead to apoptosis, activation of transcription factor NF-kappa B and protein kinase JNK. This review will discuss the molecular mechanisms of these signaling pathways.
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PMID:Molecular mechanism of signaling by tumor necrosis factor. 1876 70

NRAGE (also known as Maged1, Dlxin) is a member of the MAGE gene family that may play a role in the neuronal apoptosis that is regulated by the p75 neurotrophin receptor (p75NTR). To test this hypothesis in vivo, we generated NRAGE knockout mice and found that NRAGE deletion caused a defect in developmental apoptosis of sympathetic neurons of the superior cervical ganglia, similar to that observed in p75NTR knockout mice. Primary sympathetic neurons derived from NRAGE knockout mice were resistant to apoptosis induced by brain-derived neurotrophic factor (BDNF), a pro-apoptotic p75NTR ligand, and NRAGE-deficient sympathetic neurons show attenuated BDNF-dependent JNK activation. Hair follicle catagen is an apoptosis-like process that is dependent on p75NTR signaling; we show that NRAGE and p75NTR show regulated co-expression in the hair follicle and that identical defects in hair follicle catagen are present in NRAGE and p75NTR knockout mice. Interestingly, NRAGE knockout mice have severe defects in motoneuron apoptosis that are not observed in p75NTR knockout animals, raising the possibility that NRAGE may facilitate apoptosis induced by receptors other than p75NTR. Together, these studies demonstrate that NRAGE plays an important role in apoptotic-signaling in vivo.
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PMID:NRAGE, a p75NTR adaptor protein, is required for developmental apoptosis in vivo. 1877 98

Neural stem cells (NSC) undergo apoptotic cell death during development of nervous system and in adult. However, little is known about the biochemical regulation of neuroprotection by neurotrophin in these cells. In this report, we demonstrate that Staurosporine (STS) and Etoposide (ETS) induced apoptotic cell death of NSC by a mechanism requiring Caspase 3 activation, poly (ADP-ribose) polymerase and Lamin A/C cleavage. Although C17.2 cells revealed higher mRNA level of p75 neurotrophin receptor (p75(NTR)) compared with TrkA or TrkB receptor, neuroprotective effect of both nerve growth factor (NGF) and brain-derived growth factor (BDNF) mediated through the activation of tropomyosin receptor kinase (Trk) receptors. Moreover, both NGF and BDNF induced the activation of the phosphatidylinositide 3 kinase (PI3K)/Akt and the mitogen-activated protein kinase (MAPK) pathway. Inhibition of Trk receptor by K252a reduced PARP cleavage as well as cell viability, whereas inhibition of p75(NTR) did not affect the effect of neurotrophin on neurotoxic insults. Thus our studies indicate that the protective effect of NGF and BDNF in NSC against apoptotic stimuli is mediated by the PI3K/Akt and MAPK signaling pathway via Trk receptors.
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PMID:Neuroprotection by NGF and BDNF against neurotoxin-exerted apoptotic death in neural stem cells are mediated through Trk receptors, activating PI3-kinase and MAPK pathways. 1884 24

The p75 neurotrophin receptor (p75(NTR)) functions as a tumor suppressor in prostate epithelial cells, where its expression declines with progression to malignant cancer. Previously, we showed that treatment with R-flurbiprofen or ibuprofen induced p75(NTR) expression in several prostate cancer cell lines leading to p75(NTR)-mediated decreased survival. Using the 2-phenyl propionic acid moiety of these profens as a pharmacophore, we screened an in silico database of 30 million compounds and identified carprofen as having an order of magnitude greater activity for induction of p75(NTR) levels and inhibition of cell survival. Prostate (PC-3 and DU-145) and bladder (T24) cancer cells were more sensitive to carprofen induction of p75(NTR)-associated loss of survival than breast (MCF-7) and fibroblast (3T3) cells. Transfection of prostate cell lines with a dominant-negative form of p75(NTR) before carprofen treatment partially rescued cell survival, showing a cause-and-effect relationship between carprofen induction of p75(NTR) levels and inhibition of survival. Carprofen induced apoptotic nuclear fragmentation in prostate but not in MCF-7 and 3T3 cells. Furthermore, small interfering RNA knockdown of the p38 mitogen-activated protein kinase (MAPK) protein prevented induction of p75(NTR) by carprofen in both prostate cell lines. Carprofen treatment induced phosphorylation of p38 MAPK as early as within 1 min. Expression of a dominant-negative form of MK2, the kinase downstream of p38 MAPK frequently associated with signaling cascades leading to apoptosis, prevented carprofen induction of the p75(NTR) protein. Collectively, we identify carprofen as a highly potent profen capable of inducing p75(NTR)-dependent apoptosis via the p38 MAPK pathway in prostate cancer cells.
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PMID:Carprofen induction of p75NTR-dependent apoptosis via the p38 mitogen-activated protein kinase pathway in prostate cancer cells. 1897 93

Neurospheres can be generated from the mouse fetal forebrain by exposing multipotent neural stem cells (NSCs) to epidermal growth factor (EGF). In the presence of EGF, NSCs can proliferate continuously while retaining the potential to differentiate into neurons, astrocytes and oligodendrocytes. We examined the expression pattern of the neurotrophin (NT) receptors tropomysin-related kinase (TRK)-A, TRK-B, TRK-C and p75 neurotrophin receptor (p75(NTR)) in NSCs and the corresponding lineage cells. Furthermore, we analyzed the action of the NT Brain-Derived Neurotrophic Factor (BDNF) on NSCs' behavior. The effects of BDNF on NSC proliferation and differentiation were examined together with the signaling pathways by which BDNF receptors transduce signaling effects. We found that all the known NT receptors, including the truncated isoforms of TRK-B (t-TRK-B) and TRK-C (t-TRK-C), were expressed by Nestin-positive cells within the neurosphere. Proliferation was enhanced in Nestin-positive and BrdU-positive cells in the presence of BDNF. In particular, we show that t-TRK-B was abundantly expressed in NSCs and the corresponding differentiated glia cells while full length TRK-B (fl-TRK-B) was expressed in fully differentiated post-mitotic neurons such as the neuronal cells of the newborn mouse cortex, suggesting that BDNF may exert its proliferative effects on NSCs through the t-TRK-B receptor. Finally, we analyzed the cell fates of NSCs differentiated with BDNF in the absence of EGF and we demonstrate that BDNF stimulated the formation of differentiated cell types in different proportions through the MAP kinase, AKT and STAT-3 signaling pathways. Thus, the in-vivo regulation of neurogenesis may be mediated by the summation of signals from the BDNF receptors, in particular the t-TRK-B receptor, regulating physiological fates as diverse as normal neural replacement, excessive neural loss, or tumor development.
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PMID:Brain-derived neurotrophic factor (BDNF) has proliferative effects on neural stem cells through the truncated TRK-B receptor, MAP kinase, AKT, and STAT-3 signaling pathways. 1935 25

Neurotrophin-3 (NT-3) can negatively modulate trkA and associated phenotype in intact sensory neurons, while positively regulating trkC and associated phenotype. How NT-3 effects this response is not clear. Whether NT-3 exerts a differential influence on levels of activated ERK1/2 signaling in trkA- versus trkC-mRNA-positive subpopulations of neurons and the role that the common neurotrophin receptor, p75NTR, plays in this response was assessed by examining alterations in the levels of phospho-ERK1/2 immunofluorescence signal over nuclei of sensory neurons expressing trkA alone, trkC alone, or both trkA and trkC mRNA. NT-3 intrathecal infusion differentially modulated nuclear phospho-ERK1/2 levels detected over neurons expressing trkA alone or trkC alone. Levels were significantly decreased over nuclei of neurons expressing trkA alone and significantly increased over the nuclei of neurons expressing trkC alone. Neurons expressing both trkA and trkC or neurons expressing neither trkA nor trkC had no significant alteration in phospho-ERK1/2. Antisense oligonucleotides directed against p75NTR were infused intrathecally with or without NT-3 infusion to examine the impact of suppressing p75NTR expression on the ability of NT-3 to diminish phospho-ERK1/2 signaling in neurons expressing only trkA. NT-3 did not significantly attenuate levels of phospho-ERK1/2 when p75NTR expression was suppressed by antisense infusion, despite being able to do so when NT-3 was infused alone. In conclusion, NT-3's ability to negatively modulate ERK1/2 signaling in a p75-dependent manner in sensory neurons that express trkA to the exclusion of trkC provides a feasible mechanism by which it negatively modulates other aspects of nociceptive phenotype in these neurons.
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PMID:p75 neurotrophin receptor is implicated in the ability of neurotrophin-3 to negatively modulate activated ERK1/2 signaling in TrkA-expressing adult sensory neurons. 1956 63

A 24-h treatment with the cytokine tumor necrosis factor-alpha (TNF-alpha) suppresses transcription of E-box-driven clock genes (D-site albumin promoter binding protein, Dbp; Tyrotroph embryonic factor, Tef ; Hepatic leukemia factor, Hlf; Period homolog to Drosophila 1/2/3, Per1, Per2, and Per3) by yet unknown molecular mechanisms. The attenuation of clock genes has been suggested as a putative cause for the development of sickness behavior syndrome in infectious and autoimmune diseases. Here, the authors studied the effect of TNF-alpha at early time points (<3 h) on intracellular signaling events and clock gene expression in fibroblasts. Interaction of TNF-alpha with TNFR1 (Tnfrsf1a , CD120a, p55), but not TNFR2 (Tnfrsf1b, CD120b , p75), leads to fast downregulation of gene expression of Dbp and upregulation of negative regulators of the molecular clock, Per1 and Per2, Cryptochrome-1 (Cry1), and Differentiated embryo chondrocytes-1 (Dec1). Since the decrease of Dbp is also observed in cells deficient for Per1/Per2, Cry1/Cry2 , or Dec1, these genes are unlikely to be responsible for inhibition of Dbp. The early effect of TNF-alpha on the clock gene Per1 is dependent on p38, mitogen-activated protein kinase (MAPK), and/or calcium signaling, whereas the effect on Dbp is independent of p38 MAPK, but also involves calcium signaling. Both genes remain unaffected by the NF-kappaB and AP-1 pathway. Taken collectively these data show p38 MAPK- and calcium-dependent TNFR1-mediated transient increase of the negative regulator Per1 and an independent decrease of Dbp.
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PMID:Clock gene modulation by TNF-alpha depends on calcium and p38 MAP kinase signaling. 1962 30

Afflicted neurons in Alzheimer disease have been shown to display an imbalance in the expression of TrkA and p75(NTR) at the cell surface, and administration of nerve growth factor (NGF) has been considered and attempted for treatment. However, wild-type NGF causes extensive elaboration of neurites while providing survival support. This study was aimed at developing recombinant NGF muteins that did not support neuritogenesis while maintaining the survival response. Critical residues were identified at the ligand-receptor interface by point mutagenesis that played a greater importance in neuritogenesis versus survival. By combining point mutations, two survival-selective recombinant NGF muteins, i.e./7-84-103 and KKE/7-84-103, were generated. Both muteins reduced neuritogenesis in PC12 (TrkA(+)/p75(NTR+)) cells by >90%, while concurrently retaining near wild-type survival activity in MG139 (TrkA(+) only) and PCNA fibroblast (p75(NTR+)-only) cells. Additionally, survival in both naive and terminally differentiated PC12 cells was shown to be intermediate between NGF and negative controls. Dose-response curves with 7-84-103 showed that the differentiation curve was shifted by about 100-fold, whereas the EC(50) for survival was only increased by 3.3-fold. Surface plasmon resonance analysis revealed a 200-fold decrease in binding of 7-84-103 to TrkA. The retention of cell survival was attributed to maintenance of signaling through the Akt survival pathway with reduced MAPK signaling for differentiation. The effect of key mutations along the NGF receptor interface are transmitted inside the cell to enable the generation of survival-selective recombinant NGF muteins that may represent novel pharmacologic lead agents for the amelioration of Alzheimer disease.
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PMID:Identification of critical residues within the conserved and specificity patches of nerve growth factor leading to survival or differentiation. 1976 68


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