Extracellular Signal-regulated Protein Kinase 5 Research Articles

ERK5 inhibitor BIX02189 attenuates methamphetamine-induced hyperactivity by modulating microglial activation in the striatum

Extracellular signal-regulated protein kinase 5 (ERK5) has various physiological functions. However, the physiological role of ERK5 in the treatment of mice with an illicit drug such as methamphetamine (METH) remains unknown. We revealed that mice treated with METH showed hyperactivity, and increased p-ERK5 and Iba1 (a microglia marker) levels in the striatum. Additionally, these changes were inhibited by pretreatment with the ERK5 inhibitor BIX02189. The results suggest that METH-induced hyperactivity is associated with the activation of microglia via p-ERK5 in the striatum. Thus, the ERK5 pathway components in the central nervous system are potential therapeutic targets for preventing METH addiction.

Caroli disease: an update on pathogenesis.

Caroli disease: an update on pathogenesis.

Discovery of a Gatekeeper Residue in the C-Terminal Tail of the Extracellular Signal-Regulated Protein Kinase 5 (ERK5).

The extracellular signal-regulated protein kinase 5 (ERK5) is a non-redundant mitogen-activated protein kinase (MAPK) that exhibits a unique C-terminal extension which comprises distinct structural and functional properties. Here, we sought to elucidate the significance of phosphoacceptor sites in the C-terminal transactivation domain of ERK5. We have found that Thr732 acted as a functional gatekeeper residue controlling C-terminal-mediated nuclear translocation and transcriptional enhancement. Consistently, using a non-bias quantitative mass spectrometry approach, we demonstrated that phosphorylation at Thr732 conferred selectivity for binding interactions of ERK5 with proteins related to chromatin and RNA biology, whereas a number of metabolic regulators were associated with full-length wild type ERK5. Additionally, our proteomic analysis revealed that phosphorylation of the Ser730-Glu-Thr732-Pro motif could occur independently of dual phosphorylation at Thr218-Glu-Tyr220 in the activation loop. Collectively, our results firmly establish the significance of C-terminal phosphorylation in regulating ERK5 function. The post-translational modification of ERK5 on its C-terminal tail might be of particular relevance in cancer cells where ERK5 has be found to be hyperphosphoryated.

Roles of extra-cellular signal-regulated protein kinase 5 signaling pathway in the development of spinal cord injury.

Background:In consideration of characteristics and functions, extra-cellular signal-regulated protein kinase 5 (ERK5) signaling pathway could be a new target for spinal cord injury (SCI) treatment. Our study aimed to evaluate the roles of ERK5 signaling pathway in secondary damage of SCI.Methods:We randomly divided 70 healthy Wistar rats into five groups: ten in the blank group, 15 in the sham surgery + BIX02188 (sham + B) group, 15 in the sham surgery + dimethyl sulfoxide (DMSO; sham + D) group, 15 in the SCI + BIX02188 (SCI + B) group, and 15 in the SCI + DMSO (SCI + D) group. BIX02188 is a specific inhibitor of the ERK5 signaling pathway. SCI was induced by the application of vascular clips (with the force of 30 g) to the dura on T10 level, while rats in the sham surgery group underwent only T9-T11 laminectomy. BIX02188 or DMSO was intra-thecally injected at 1, 6, and 12 h after surgery or SCI. Spinal cord samples were taken for testing at 24 h after surgery or SCI.Results:Expression of phosphorylated-ERK5 (p-ERK5) significantly increased after SCI. Application of BIX02188 indeed inhibited ERK5 signaling pathway and reduced the degree of spinal cord tissue injury, neutrophil infiltration and proinflammatory cytokine expression, nuclear factor-κB (NF-κB) activation and apoptosis (measured by TdT-mediated 2′-deoxyuridine 5′-triphosphate nick-end labeling, expression of Fas-ligand, BCL2-associated X [Bax], and B-cell lymphoma-2 [Bcl-2]). Double immunofluorescence revealed activation of ERK5 in neurons and microglia after SCI.Conclusion:ERK5 signaling pathway was activated in spinal neurons and microglia, contributing to secondary injury of SCI. Moreover, inhibition of ERK5 signaling pathway could alleviate the degree of SCI, which might be related to its regulation of infiltration of inflammatory cells and release of inflammatory cytokines, expression of NF-κB and cell apoptosis.

Analysis of Nkx3.1:Cre-driven Erk5 deletion reveals a profound spinal deformity which is linked to increased osteoclast activity

Extracellular signal-regulated protein kinase 5 (ERK5) has been implicated during development and carcinogenesis. Nkx3.1-mediated Cre expression is a useful strategy to genetically manipulate the mouse prostate. While grossly normal at birth, we observed an unexpected phenotype of spinal protrusion in Nkx3.1:Cre;Erk5fl/fl (Erk5fl/fl) mice by ~6–8 weeks of age. X-ray, histological and micro CT (µCT) analyses showed that 100% of male and female Erk5fl/fl mice had a severely deformed curved thoracic spine, with an associated loss of trabecular bone volume. Although sex-specific differences were observed, histomorphometry measurements revealed that both bone resorption and bone formation parameters were increased in male Erk5fl/fl mice compared to wild type (WT) littermates. Osteopenia occurs where the rate of bone resorption exceeds that of bone formation, so we investigated the role of the osteoclast compartment. We found that treatment of RANKL-stimulated primary bone marrow-derived macrophage (BMDM) cultures with small molecule ERK5 pathway inhibitors increased osteoclast numbers. Furthermore, osteoclast numbers and expression of osteoclast marker genes were increased in parallel with reduced Erk5 expression in cultures generated from Erk5fl/fl mice compared to WT mice. Collectively, these results reveal a novel role for Erk5 during bone maturation and homeostasis in vivo.

Research progress of the role and mechanism of extracellular signal-regulated protein kinase 5 (ERK5) pathway in pathological pain.

Extracellular signal-regulated protein kinase 5 (ERK5), also known as big mitogen-activated protein kinase 1 (MAPK1), is an important member of ERK family, which is a subfamily of the large MAPK family. ERK5 is expressed in many tissues, including the dorsal root ganglion (DRG) neurons and the spinal cord. In this review, we focus on elaborating ERK5-associated pathway in pathological pain, in which the ERK5/CREB (cyclic adenosine monophosphate (cAMP)-response element-binding protein) pathway plays a crucial role in the transduction of pain signal and contributes to pain hypersensitivity. ERK5 activation in the spinal dorsal horn occurs mainly in microglia. The activation of ERK5 can be mediated by N-methyl-D-aspartate (NMDA) receptors. We also elaborate the relationship between ERK5 activation and nerve growth factor-tyrosine kinase A (NGF-TrkA), and the connection between ERK5 activation and brain-derived neurotrophic factor (BDNF) in pathological pain in detail.

Extracellular Signal-Regulated Kinase 5 in the Cerebrospinal Fluid-Contacting Nucleus Contributes to Neuropathic Pain in Rats

Background: The activation of mitogen-activated protein kinases (MAPKs) have been observed in synaptic plasticity processes of learning and memory in neuropathic pain. Cerebrospinal fluidcontacting nucleus (CSF-CN) has been identified with the onset and persistence of neuropathic pain. However, whether extracellular signal-regulated protein kinase 5 (ERK5), a member of MAPKs, in CSF-CN participates in neuropathic pain has not been studied yet. Objective: The aim of the present study was to identify the role of ERK5 in CSF-CN on the formation and development of neuropathic pain, and to investigate its possible mechanism. Study Design: Controlled animal study. Setting: University laboratory. Methods: After a chronic constriction injury (CCI) model was produced, BIX02188 was dissolved in 1% DMSO and injected into the lateral ventricles LV in a volume of 3 μl with different doses (0.1 μg, 1 μg, 10 μg). Mechanical allodynia and thermal hypersensitivity behavioral test, immunofluorescence, and western blot technique were used in this research. Result: Following CCI, mechanical allodynia and thermal hypersensitivity were developed within a day, peaked at 14 days, and persisted for 21 days. ERK5 was remarkably activated by CCI in CSFCN. Moreover, selective inhibiting of p-ERK5 expression in CSF-CN by BIX02188 could significantly relieve CCI-induced mechanical allodynia and thermal hypersensitivity, accompanying with the decreased phosphorylation of cAMP response-element binding protein (CREB) in CSF-CN. Limitations: More underlying mechanism(s) of the role of ERK5 in CSF-CN on the formation and development of neuropathic pain will be needed to explore in future research. Conclusion: These findings suggest activation of ERK5 in CSF-CN might contribute to the onset and development of neuropathic pain and its role might be partly accomplished by p-CREB. Key words: Neuropathic pain, extracellular signal-regulated kinase 5, distal cerebrospinal fluidcontacting neurons, cerebrospinal fluid-contacting nucleus, chronic constriction injury, cAMP response-element binding protein

Alteration of the ERK5 pathway by hydroxysafflor yellow A blocks expression of MEF2C in activated hepatic stellate cells in vitro: Potential treatment for hepatic fibrogenesis

Context: Hepatic fibrosis ultimately leads to cirrhosis if not treated effectively. Hepatic stellate cells (HSC) are a main mediator of hepatic fibrosis through the accumulation of extracellular matrix proteins. Suppression activation of passaged HSC has been proposed as therapeutic strategies for the treatment and prevention of hepatic fibrosis.Objective: To evaluate the effect of hydroxysafflor yellow A (HSYA), an active chemical compound derived from the flowers of Carthamus tinctorius L. (Compositae), on HSC inhibition, and to begin elucidating underlying mechanisms.Materials and methods: Primary HSCs were isolated from rats by in situ pronase/collagenase perfusion. Culture-activated HSCs were treated with or without HSYA at 30 μM in the presence or absence of PD98059 for 48 h, and then cell proliferation was measured by MTS assays. Messenger RNA (mRNA) expression was quantified by polymerase chain reaction, and protein was quantified by Western blots or enzyme-linked immunosorbent assays.Results: HSYA significantly inhibits culture-activated HSC proliferation in a dose-dependent and time-dependent manner with an IC50 value of 112.79 μM. HSYA (30 μM) induce the suppression of HSC activation, as indicated by decreases in contents of type I alpha collagen in HSC-cultured media and expression of α-smooth muscle actin protein in culture-activated HSC by 55 and 71%, respectively. HSYA (30 μM) also caused significant decreases in mRNA expression of type III alpha collagen in HSC by 28%. HSYA (30 μM) suppresses myocyte enhancer factor 2 C (MEF2C) expression both at its mRNA and protein levels by 60 and 61%, respectively. Further study demonstrated that HSYA (30 μM) caused significant decreases in p-ERK5 by 49%. Blocking extracellular signal-regulated protein kinase 5 (ERK5) activity by XMD 8--92, an ERK5 inhibitor, markedly abrogated the inhibitive effects of HSYA on HSC activation, and blocked the HSYA-mediated MEF2C down-regulation.Conclusions: HSYA suppress HSC activation by ERK5-mediated MEF2C down-regulation and makes it a potential candidate for prevention and treatment of hepatic fibrogenesis.

A functional polymorphism in the promoter of ERK5 gene interacts with tobacco smoking to increase the risk of lung cancer in Chinese populations

Mitogen/extracellular signal-regulated kinase-5 (MEK5)/extracellular signal-regulated protein kinase-5 (ERK5) pathway plays a pro-oncogenic role in tumourigenesis by anticell apoptosis, promoting cell proliferation and differentiation in response to extracellular stimuli. As overexpressed MEK5/ERK5 is involved in the development of lung cancer, we hypothesised that the single nucleotide polymorphisms (SNPs) in MEK5 and ERK5 genes may influence gene expression and thus be associated with lung cancer risk. Five putative functional polymorphisms (rs3743353T>C, rs7172582C>T and rs2278076A>G of MEK5 and rs3866958G>T and rs2233083C>T of ERK5) were genotyped in two independent case-control studies with a total of 1559 lung cancer patients and 1679 controls in southern and eastern Chinese population. We found the rs3866958G>T of ERK5 was significantly associated with lung cancer risk, while other SNPs were not. Compared with the rs3866958TG/TT genotypes, the GG genotype conferred an increased risk of lung cancer (odds ratio = 1.30, 95% confidence interval = 1.12-1.51, P = 5.0×10(-4)), and this effect was more pronounced in smokers, accompanying with a significant interaction with smoking (P interaction = 0.013). The GG genotype also had significant higher mRNA levels of ERK5 in lung cancer tissues than TG/TT genotypes (P = 1.0×10(-4)); the luciferase reporter with the G allele showed significant higher transcription activities than the T allele, especially after the treatment with tobacco extract in vitro. Our data indicated that the functional polymorphism rs3866958G>T in ERK5 was associated with an increased lung cancer risk in smokers by virtue of the positive interaction with smoking on promoting the ERK5 expression, which might be a valuable indicator for predicting lung cancer risk in smokers.

Changes in activity of extracellular signal-regulated protein kinase 5 in spinal cord in a rat model of bone cancer pain

Objective To evaluate the changes in the activity of extracellular signal-regulated protein kinase 5 (ERK5) in the spinal cord in a rat model of bone cancer pain (BCP).Methods One hundred and eight female Sprague-Dawley rats,weighing 160-180 g,were randomly divided into 3 groups (n =36 each):control group (group C):sham operation (group S) and group BCP.In group BCP Walker 256 mammary gland cancer cell suspension (1 × 105 cells/ml) 5 μl was injected into the left tibia,while in group S normal saline 5μl was injected into the left tibia instead of cancer cell suspension.Group C underwent no treatment.Mechanical paw withdrawal threshold to von Frey filament stimulation (MWT) was measured at 1 day before inoculation and 3,5,7,14 and 21 days after inoculation.Six rats were sacrificed after the last measurement of MWT in groups C and S or after measurement of MWT at 3,5,7,14 and 21 days after inoculation in group BCP and the spinal cord was removed for determination of the expression of phosphorylated ERK5 (p-ERK5),ERK5 and Fos protein in the spinal dorsal horn by Western blot analysis.Results There was no significant difference in the MWT and expression of p-ERK5,ERK5 and Fos protein at each time point between groups C and S (P ＞ 0.05).Compared with groups C and S,MWT was significantly decreased at 7-21 days after inoculation,the expression of p-ERK5 and Fos protein was significantly up-regulated at 5-21 days after inoculation (P ＜ 0.05),and no significant change was found in the expression of ERK5 in group BCP (P ＞ 0.05).Conclusion Intra-tibial inoculation of Walker-256 breast cancer cells can increase the activity of ERK5 in the spinal cord in rats,leading to the increased release of Fos protein,thus inducing BCP. Key words: Bone neoplasms; Pain; Extracellular signal-regulated MAP kinases; Spinal cord

CX3CL1/CX3CR1 regulates nerve injury‐induced pain hypersensitivity through the ERK5 signaling pathway

Peripheral nerve injury induces the cleavage of CX3CL1 from the membrane of neurons, where the soluble CX3CL1 subsequently plays an important role in the transmission of nociceptive signals between neurons and microglia. Here we investigated whether CX3CL1 regulates microglia activation through the phosphorylation of extracellular signal-regulated protein kinase 5 (ERK5) in the spinal cord of rats with spinal nerve ligation (SNL). ERK5 and microglia were activated in the spinal cord after SNL. The knockdown of ERK5 by intrathecal injection of antisense oligonucleotides suppressed the hyperalgesia and nuclear impact of nuclear factor-κB induced by SNL. The blockage of CX3CR1, the receptor of CX3CL1, significantly reduced the level of ERK5 activation following SNL. In addition, the antisense knockdown of ERK5 reversed the CX3CL1-induced hyperalgesia and spinal microglia activation. Our study suggests that CX3CL1/CX3CR1 regulates nerve injury-induced pain hypersensitivity through the ERK5 signaling pathway.

Mir143 expression inversely correlates with nuclear ERK5 immunoreactivity in clinical prostate cancer

Background:Aberrant mitogen/extracellular signal-regulated kinase 5 (MEK5)–extracellular signal-regulated protein kinase 5 (ERK5)-mediated signalling has been implicated in a number of tumour types including prostate cancer (CaP). The mechanism for ERK5 activation in CaP remains to be fully elucidated. Studies have recently implicated the role of microRNA (miRNA) mir143 expression in the regulation of ERK5 expression.Methods:We utilised a tissue microarray (TMA) of 530 CaP cores from 168 individual patients and stained for both mir143 and ERK5. These TMAs were scored by a combination of observer and automated methods.Results:We observed a strong inverse relation between ERK5 and mir143, which manifested itself most strongly in the subgroup of 417 cores with non-zero mir143 and ERK5 immunoreactivity, or with only one of mir143 or ERK5 being zero (cc=0.2558 and P<0.0001). Mir143 neither correlate with Gleason scores or prostate-specific antigen levels, nor was it a predictor of disease-specific survival on univariate analysis.Conclusion:Although the mechanism for ERK5 activation in CaP remains to be fully elucidated, we have further validated the potential role of mir143 in regulating ERK5 levels in the clinical context. In addition, we demonstrate that the automated counting method for nuclear ERK5 is a clinically useful alterative to observer counting method in patient stratification in the context of ERK5 targeting therapy.

Activation of the spinal extracellular signal-regulated kinase 5 signaling pathway contributes to morphine physical dependence in rats

The activation of mitogen-activated protein kinases (MAPKs) has been observed in synaptic plasticity processes of learning and memory in morphine dependence. However, the role of extracellular signal-regulated protein kinase 5 (ERK5), a member of MAPKs, has not been studied yet in morphine dependence. To identify the function of ERK5 in the formation and development of morphine physical dependence, morphine withdrawal-like behavioral test and western blot technique were used in this research. Morphine was subcutaneously injected by an intermittent and escalating procedure to induce physical dependence, which was measured by withdrawal symptoms. In this study, spinal ERK5 signaling pathway was remarkably activated by chronic morphine injection and naloxone-precipitated withdrawal. Intrathecal injection of BIX02188, a novel specific inhibitor of mitogen-activated protein kinases kinase 5 (MEK5), produced a dose- and time-dependent inhibition of the activation of spinal ERK5, without affecting activation of other MAPKs. Moreover, selective attenuation of spinal p-ERK5 expression by BIX02188 could significantly relieve morphine withdrawal symptom, accompanying with the decreased phosphorylation of cAMP response-element binding protein (CREB) in the spinal cord. These findings suggested that activation of the ERK5 signaling pathway might contribute to morphine physical dependence and its specific pharmacological inhibitor BIX02188 could be a potential therapeutic choice for alleviation of morphine withdrawal symptoms in the future.

ERK5 signalling in prostate cancer promotes an invasive phenotype

Background:Aberrant mitogen/extracellular signal-regulated kinase 5 (MEK5)–extracellular signal-regulated protein kinase 5 (ERK5)-mediated signalling has been implicated in a number of tumour types including prostate cancer (PCa). The molecular basis of ERK5-driven carcinogenesis and its clinical relevance remain to be fully characterised.Methods:Modulation of ERK5 expression or function in human PCa PC3 and PC3–ERK5 (stably transfected with ERK5) cells was performed using siRNA-mediated knockdown or the MEK inhibitor PD18435 respectively. In vitro significance of ERK5 signalling was assessed by assays for proliferation, motility, invasion and invadopodia. Expression of matrix metalloproteinases/tissue inhibitors of metalloproteases was determined by Q-RT–PCR. Extracellular signal-regulated protein kinase 5 expression in primary and metastatic PCa was examined using immunohistochemistry.Results:Reduction of ERK5 expression or signalling significantly inhibited the motility and invasive capability of PC3 cells. Extracellular signal-regulated protein kinase 5-mediated signalling significantly promoted formation of in vivo metastasis in an orthotopic PCa model (P<0.05). Invadopodia formation was also enhanced by forced ERK5 expression in PC3 cells. Furthermore, in metastatic PCa, nuclear ERK5 immunoreactivity was significantly upregulated when compared with benign prostatic hyperplasia and primary PCa (P=0.013 and P<0.0001, respectively).Conclusion:Our in vitro, in vivo and clinical data support an important role for the MEK5–ERK5 signalling pathway in invasive PCa, which represents a potential target for therapy in primary and metastatic PCa.

381 ABERRANT EXTRACELLULAR SIGNAL-REGULATED PROTEIN KINASE 5 (ERK5) SIGNALLING PROMOTES CELLULAR MOTILITY AND INVASION IN PROSTATE CARCINOGENESIS

You have accessJournal of UrologyProstate Cancer: Basic Research III1 Apr 2010381 ABERRANT EXTRACELLULAR SIGNAL-REGULATED PROTEIN KINASE 5 (ERK5) SIGNALLING PROMOTES CELLULAR MOTILITY AND INVASION IN PROSTATE CARCINOGENESIS Alison Ramsay, Stuart McCracken, Rosie Morland, Janis Fleming, Laura Machesky, Xinzi Yu, Dylan Edwards, Robert Nuttall, Morag Seywright, Evan Keller, and Hing Leung Alison RamsayAlison Ramsay Glasgow, United Kingdom More articles by this author , Stuart McCrackenStuart McCracken Newcastle Upon Tyne, United Kingdom More articles by this author , Rosie MorlandRosie Morland Glasgow, United Kingdom More articles by this author , Janis FlemingJanis Fleming Glasgow, United Kingdom More articles by this author , Laura MacheskyLaura Machesky Glasgow, United Kingdom More articles by this author , Xinzi YuXinzi Yu Glasgow, United Kingdom More articles by this author , Dylan EdwardsDylan Edwards Norwich, United Kingdom More articles by this author , Robert NuttallRobert Nuttall Norwich, United Kingdom More articles by this author , Morag SeywrightMorag Seywright Glasgow, United Kingdom More articles by this author , Evan KellerEvan Keller Ann Arbor, MI More articles by this author , and Hing LeungHing Leung Glasgow, United Kingdom More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2010.02.449AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The MEK5/ERK5 pathway is implicated in a number of tumour types including prostate cancer. Its molecular mechanism for carcinogenesis remains to be fully characterised. We have further investigated the functional role of ERK5 in prostate cancer and tested its relationship ERK1/2. METHODS Functional assays were performed in prostate cancer cells (PC3 and PC3M cells) following transfection with ERK1, ERK2 and ERK5 siRNA or treatment with the mitogen-activated protein kinase kinase (MEK) inhibitor (PD184352): proliferation by cell count, motility by culture chamber, migration/invasion by time-lapse microscropy. Matrix metalloproteinase (MMP) expression was studied by promoter luciferase reporter assay and real time PCR. Invadopodia assays were performed as described previously (J Cell Sci 2008, 121: 369), and data were analysed using Image J software. Immunohistochemistry for ERK5 expression was also performed on metastatic prostate tissue (Oncogene 2008, 27: 2978). RESULTS Using siRNA and PD184352 to target ERK5 expression and function respectively, both motility and invasion of PC3 cells were significantly impaired (P<0.005 for all parameters). Q-PCR and promoter activity analysis revealed activation of MMP-2, -9, -12 and TIMP2 expression, and suppression of MMP-16 by ERK5. Following ERK5 transfection, PC3 cells formed significantly more invadopodia (P=0.0048). Immunohistochemistry further confirmed upregulated ERK5 expression in both primary and metastatic prostate tumours. Among the informative metastatic lesions (n=11), strong ERK5 immunoreactivity, cytoplasmic (55%) and nuclear (73%), was observed. Potential ‘cross-talk' between ERK5 and ERK1/2 was explored. ERK1 knockdown resulted in prolonged and enhanced activation of both ERK5 and ERK2. This was associated with a small but reproducible mitogenic effect following ERK1 specific knockdown, supporting published data that ERK1 acts as a negative regulator and ERK2 as a positive regulator of cell proliferation. CONCLUSIONS Our results validate the importance of the ERK5 signalling pathway as a potential target for therapy and highlight a novel functional and biochemical relationship between ERK1 and ERK5 signalling. © 2010 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 183Issue 4SApril 2010Page: e151 Advertisement Copyright & Permissions© 2010 by American Urological Association Education and Research, Inc.MetricsAuthor Information Alison Ramsay Glasgow, United Kingdom More articles by this author Stuart McCracken Newcastle Upon Tyne, United Kingdom More articles by this author Rosie Morland Glasgow, United Kingdom More articles by this author Janis Fleming Glasgow, United Kingdom More articles by this author Laura Machesky Glasgow, United Kingdom More articles by this author Xinzi Yu Glasgow, United Kingdom More articles by this author Dylan Edwards Norwich, United Kingdom More articles by this author Robert Nuttall Norwich, United Kingdom More articles by this author Morag Seywright Glasgow, United Kingdom More articles by this author Evan Keller Ann Arbor, MI More articles by this author Hing Leung Glasgow, United Kingdom More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Role of microRNA-143 in Fas-mediated apoptosis in human T-cell leukemia Jurkat cells

Treatment of Jurkat T cells with Fas-activating antibody (CH-11) facilitated rapid cell death that was shown to be caspase-dependent apoptosis. The expression of miR-143 was up-regulated during the apoptosis with time. The increased expression of miR-143 emerged from 1 to 2h after the treatment, at which time the caspases-8 and -3 were also activated; and this increase was almost canceled by the pretreatment with an inhibitor of caspase-3 or -8. Furthermore, the transfection of Jurkat cells with mature miR-143 induced a significant growth suppression and enhancement of CH-11-induced apoptosis. On the contrary, an extracellular signal-regulated protein kinase 5 (ERK5), which was determined to be a target of miR-143 in colon cancer DLD-1 cells, was time-dependently down-regulated at the translational level after the treatment. During the apoptosis, the expression level of FasL was maintained and the level of nuclear-Foxo3a was increased in the early phase. These data suggest that the up-regulation of miR-143 could be related to the apoptosis in part by targeting ERK5, which leads to promotion of Foxo3a/FasL positive feedback loop.

Regulation of neuronal survival by the extracellular signal-regulated protein kinase 5

The extracellular signal-regulated protein kinase 5 (ERK5) is a mitogen-activated protein kinase (MAPK) that phosphorylates and regulates various transcription factors in response to growth factors and extra-cellular stresses. To address its biological function during the development of the peripheral nervous system (PNS), we have engineered a novel model of sympathetic neurons in which the erk5 gene can be deleted in vitro. Our data provide for the first time genetic evidence that ERK5 is required to mediate the survival response of neurons to nerve growth factor (NGF). Increased cell death associated with the loss of ERK5 is caused by elevated expression of the BH3-only members of the Bcl-2 family, Bad and Bim. Further investigation indicated that ERK5 suppresses the transcription of the bad and the bim genes via Ca++/cAMP response element binding protein (CREB) and Forkhead box 03a (Foxo3a), respectively. Consistently, we found that the phosphorylation of both p90 ribosomal S6 kinase (RSK) and protein kinase B (PKB) is impaired in neurons lacking ERK5. Together these findings reveal a novel signaling mechanism that promotes neuronal survival during the development of the PNS.

ERK5/MAPK is activated by TGFβ in hepatocytes and required for the GSK-3β-mediated Snail protein stabilization

Extracellular signal-regulated protein kinase 5 (ERK5) is a mitogen-activated protein kinase, specifically activated by MEK5, and involved in the regulation of many cellular functions including proliferation, survival, differentiation and apoptosis. MEK5/ERK5 module is an important element of different signal transduction pathways. The aim of this study was to investigate whether ERK5 participates to the signalling of the multifunctional cytokine TGFβ, known to play an important role in the regulation of hepatic growth. Here, we reported that ERK5 is phosphorylated and activated by TGFβ in hepatocytes, with a rapid and sustained kinetic, through a Src-dependent pathway. Moreover, we demonstrated that ERK5 participates to the TGFβ-induced Snail protein regulation being required for its stabilization. We also found that the functional inactivation of ERK5 impedes the TGFβ-mediated glycogen synthase kinase-3β inactivation suggesting this as mechanism responsible for ERK5-mediated Snail stabilization. Thus, results presented in this study uncovered for the first time a role for ERK5 in the TGFβ-induced cellular responses.

The activation of extracellular signal-regulated protein kinase 5 in spinal cord and dorsal root ganglia contributes to inflammatory pain

Activation of mitogen-activated protein kinases (MAPKs) in dorsal root ganglia (DRG) and the spinal dorsal horn contributes to inflammatory pain by transcription-dependent and -independent means. In this study, we investigated extracellular signal-regulated protein kinase 5 (ERK5) activation by peripheral inflammation in the spinal cord and DRG of rats and whether this activation contributes to a heat and mechanical hyperalgesia response. Injection of complete Freund's adjuvant (CFA) into a hindpaw produced persistent inflammation and sustained ERK5 activation in DRG and the spinal dorsal horn. Knockdown of the ERK5 by antisense oligonucleotides suppressed the heat and mechanical hyperalgesia. In addition, the antisense knockdown of ERK5 reduced CFA-induced phosphorylation of cAMP response-element binding protein (CREB), a downstream substrate of the ERK5 pathway, and expression of Fos, a marker for neuronal activation in the central nervous system. Our study suggests that activation of the ERK5 signaling pathway contributes to persistent hyperalgesia induced by peripheral inflammation.

Activation of extracellular signal‐regulated protein kinases 5 in primary afferent neurons contributes to heat and cold hyperalgesia after inflammation

Heat and cold hyperalgesia is a common feature of inflammatory pain. To investigate whether activation of extracellular signal-regulated protein kinase 5 (ERK5), also known as big mitogen-activated protein kinase 1, in primary sensory neurons participates in inflammatory pain, we examined the phosphorylation of ERK5 in the dorsal root ganglion (DRG) after peripheral inflammation. Inflammation induced by complete Freund's adjuvant produced heat and cold hyperalgesia on the ipsilateral hind paw and induced an increase in the phosphorylation of ERK5, mainly in tyrosine kinase A-expressing small- and medium-size neurons. In contrast, there was no change in ERK5 phosphorylation in the spinal dorsal horn. ERK5 antisense, but not mismatch, oligodeoxynucleotide decreased the activation of ERK5 and suppressed inflammation-induced heat and cold hyperalgesia. Furthermore, the inhibition of ERK5 blocked the induction of transient receptor potential channel TRPV1 and TRPA1 expression in DRG neurons after peripheral inflammation. Our results show that ERK5 activated in DRG neurons contribute to the development of inflammatory pain. Thus, blocking ERK5 signaling in sensory neurons that has the potential for preventing pain after inflammation.