p38 mitogen-activated protein kinase inhibits calcium-dependent chloride secretion in T84 colonic epithelial cells

2003 ◽  
Vol 284 (2) ◽  
pp. C339-C348 ◽  
Author(s):  
Stephen J. Keely ◽  
Kim E. Barrett
Keyword(s):  
Protein Kinase ◽  
Epithelial Cells ◽  
Signaling Pathway ◽  
P38 Mapk ◽  
Mitogen Activated Protein Kinase ◽  
Muscarinic Agonist ◽  
Colonic Epithelial Cells ◽  
Mitogen Activated Protein ◽  
Intracellular Ca ◽  
Sb 203580

We have previously shown that Ca2+-dependent Cl−secretion across intestinal epithelial cells is limited by a signaling pathway involving transactivation of the epidermal growth factor receptor (EGFR) and activation of ERK mitogen-activated protein kinase (MAPK). Here, we have investigated a possible role for p38 MAPK in regulation of Ca2+-dependent Cl− secretion. Western blot analysis of T84 colonic epithelial cells revealed that the muscarinic agonist carbachol (CCh; 100 μM) stimulated phosphorylation and activation of p38 MAPK. The p38 inhibitor SB-203580 (10 μM) potentiated and prolonged short-circuit current ( I sc) responses to CCh across voltage-clamped T84 cells to 157.4 ± 6.9% of those in control cells ( n = 21; P < 0.001). CCh-induced p38 phosphorylation was attenuated by the EGFR inhibitor tyrphostin AG-1478 (0.1 nM–10 μM) and by the Src family kinase inhibitor PP2 (20 nM–2 μM). The effects of CCh on p38 phosphorylation were mimicked by thapsigargin (TG; 2 μM), which specifically elevates intracellular Ca2+, and were abolished by the Ca2+ chelator BAPTA-AM (20 μM), implying a role for intracellular Ca2+ in mediating p38 activation. SB-203580 (10 μM) potentiated I sc responses to TG to 172.4 ± 18.1% of those in control cells ( n= 18; P < 0.001). When cells were pretreated with SB-203580 and PD-98059 to simultaneously inhibit p38 and ERK MAPKs, respectively, I sc responses to TG and CCh were significantly greater than those observed with either inhibitor alone. We conclude that Ca2+-dependent agonists stimulate p38 MAPK in T84 cells by a mechanism involving intracellular Ca2+, Src family kinases, and the EGFR. CCh-stimulated p38 activation constitutes a similar, but distinct and complementary, antisecretory signaling pathway to that of ERK MAPK.

TGF-β1 stimulates HO-1 via the p38 mitogen-activated protein kinase in A549 pulmonary epithelial cells

2002 ◽  
Vol 283 (5) ◽  
pp. L1094-L1102 ◽  
Author(s):  
Wen Ning ◽  
Ruiping Song ◽  
Chaojun Li ◽  
Edward Park ◽  
Amir Mohsenin ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Epithelial Cells ◽  
Mrna Expression ◽  
P38 Mapk ◽  
Mapk Pathway ◽  
A549 Cells ◽  
Mitogen Activated Protein Kinase ◽  
P38 Mapk Pathway ◽  
Mitogen Activated Protein ◽  
Sb 203580

In lung injury and progressive lung diseases, the multifunctional cytokine transforming growth factor-β1 (TGF-β1) modulates inflammatory responses and wound repair. Heme oxygenase-1 (HO-1) is a stress-inducible protein that has been demonstrated to confer cytoprotection against oxidative injury and provide a vital function in maintaining tissue homeostasis. Here we report that TGF-β1 is a potent inducer of HO-1 and examined the signaling pathway by which TGF-β1 regulates HO-1 expression in human lung epithelial cells (A549). TGF-β1(1–5 ng/ml) treatment resulted in a marked time-dependent induction of HO-1 mRNA in A549 cells, followed by corresponding increases in HO-1 protein and HO enzymatic activity. Actinomycin D and cycloheximide inhibited TGF-β1-responsive HO-1 mRNA expression, indicating a requirement for transcription and de novo protein synthesis. Furthermore, TGF-β1 rapidly activated the p38 mitogen-activated protein kinase (p38 MAPK) pathway in A549 cells. A chemical inhibitor of p38 MAPK (SB-203580) abolished TGF-β1-inducible HO-1 mRNA expression. Both SB-203580 and expression of a dominant-negative mutant of p38 MAPK inhibited TGF-β1-induced ho-1 gene activation, as assayed by luciferase activity of an ho-1enhancer/luciferase fusion construct (pMHO1luc-33+SX2). These studies demonstrate the critical intermediacy of the p38 MAPK pathway in the regulation of HO-1 expression by TGF-β1.

Expression of collagenase-3 (MMP-13) and collagenase-1 (MMP-1) by transformed keratinocytes is dependent on the activity of p38 mitogen-activated protein kinase

2000 ◽  
Vol 113 (2) ◽  
pp. 227-235 ◽  
Author(s):  
N. Johansson ◽  
R. Ala-aho ◽  
V. Uitto ◽  
R. Grenman ◽  
N.E. Fusenig ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Epithelial Cells ◽  
Cell Line ◽  
P38 Mapk ◽  
Cell Lines ◽  
Mitogen Activated Protein Kinase ◽  
Tnf Alpha ◽  
Tgf Beta ◽  
Mitogen Activated Protein ◽  
Sb 203580

Collagenase-3 (MMP-13) is a human matrix metalloproteinase specifically expressed by transformed squamous epithelial cells, i.e. squamous cell carcinoma (SCC) cells in culture and in vivo. Here, we have elucidated the signaling pathways regulating MMP-13 expression in transformed human epidermal keratinocytes, i.e. ras-transformed HaCaT cell line A-5 and cutaneous SCC cell line (UT-SCC-7). Treatment with tumor necrosis factor-(alpha) (TNF-(alpha) resulted in activation of extracellular signal-regulated kinase (ERK)1,2, Jun N-terminal kinase and p38 mitogen-activated protein kinase (MAPK) in both cell lines. In addition, transforming growth factor-(beta) (TGF-(beta) activated p38 MAPK in both cell lines, and ERK2 in A-5 cells. Selective inhibition of p38 activity with SB 203580 abolished the enhancement of MMP-13, as well as collagenase-1 (MMP-1) and 92-kDa gelatinase (MMP-9) expression by TNF-(alpha) and TGF-(beta). Blocking the ERK1, 2 pathway by PD 98059 had no effect on the induction of MMP-13 expression by TNF-(alpha) or TGF-(beta), but potently suppressed MMP-1 and MMP-9 production. Inhibition of p38 activity by SB 203580 also suppressed collagenolytic activity produced by both cell lines and inhibited invasion of TNF-(alpha) or TGF-(beta) stimulated A-5 cells through type I collagen and reconstituted basement membrane (Matrigel). These results show that activation of p38 MAPK pathway plays a crucial role in the invasive phenotype of transformed squamous epithelial cells, suggesting p38 MAPK as a target to specifically inhibit their invasion.

scholarly journals Roles of the Ras-MEK-Mitogen-Activated Protein Kinase and Phosphatidylinositol 3-Kinase-Akt-mTOR Pathways in Jaagsiekte Sheep Retrovirus-Induced Transformation of Rodent Fibroblast and Epithelial Cell Lines

2005 ◽  
Vol 79 (7) ◽  
pp. 4440-4450 ◽  
Author(s):  
Naoyoshi Maeda ◽  
Wuxia Fu ◽  
Aurora Ortin ◽  
Marcelo de las Heras ◽  
Hung Fan
Keyword(s):  
Protein Kinase ◽  
Epithelial Cells ◽  
P38 Mapk ◽  
Cell Lines ◽  
Mitogen Activated Protein Kinase ◽  
Phosphatidylinositol 3 Kinase ◽  
Jaagsiekte Sheep Retrovirus ◽  
3T3 Fibroblasts ◽  
Mitogen Activated Protein ◽  
Nih 3T3

ABSTRACT Jaagsiekte sheep retrovirus (JSRV) is the causative agent of ovine pulmonary adenocarcinoma (OPA), a transmissible lung cancer of sheep. The virus can induce tumors rapidly, and we previously found that the JSRV envelope protein (Env) functions as an oncogene, because it can transform mammalian and avian fibroblast cell lines. (N. Maeda, Proc. Natl. Acad. Sci. USA 98:4449-4454, 2001). The molecular mechanisms of JSRV Env transformation are of considerable interest. Several reports suggested that the phosphatidylinositol 3-kinase/Akt pathway is important for transformation of mammalian fibroblasts but not for chicken fibroblasts. In this study, we found that Akt/mTOR is involved in JSRV transformation of mouse NIH 3T3 fibroblasts, because treatment with the mTOR inhibitor rapamycin reduced transformation. We also found that H/N-Ras inhibitor FTI-277 and MEK1/2 inhibitors PD98059 and U0126 strongly inhibited JSRV transformation of NIH 3T3 fibroblasts, suggesting that the H/N-Ras-MEK-mitogen-activated protein kinase (MAPK) p44/42 pathway is necessary for the transformation. In RK3E epithelial cells, the MEK1/2 inhibitors also eliminated transformation, but FTI-277 only partially inhibited transformation. It was noteworthy that p38 MAPK inhibitors enhanced JSRV transformation in both fibroblasts and epithelial cells. Treatment of transformed cells with p38 inhibitors both increased levels of phospho-MEK1/2 and phospho-p44/42 and induced rapid enhancement of the transformed phenotype. Immunohistochemical staining of tumor tissues from naturally and experimentally induced OPA and naturally occurring enzootic nasal adenocarcinoma revealed strong activation of MAPK p44/42 in all cases examined. However, p38 activation was not generally observed. These results indicate that signaling through two pathways (in particular, H/N-Ras-MEK-MAPK and, to a lesser extent, Akt-mTOR) is important for JSRV-induced transformation and that p38 MAPK has a negative regulatory effect on transformation, perhaps via MEK1/2 and p44/42.

Role of p38 mitogen-activated protein kinase pathway in estrogen-mediated cardioprotection following trauma-hemorrhage

2007 ◽  
Vol 292 (6) ◽  
pp. H2982-H2987 ◽  
Author(s):  
Jun-Te Hsu ◽  
Ya-Ching Hsieh ◽  
Wen Hong Kan ◽  
Jian Guo Chen ◽  
Mashkoor A. Choudhry ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Cardiac Function ◽  
P38 Mapk ◽  
Mitogen Activated Protein Kinase ◽  
Male Rats ◽  
Mitogen Activated Protein ◽  
Salutary Effect ◽  
The Stability ◽  
Shock Proteins ◽  
Sb 203580

p38 mitogen-activated protein kinase (MAPK) activates a number of heat shock proteins (HSPs), including HSP27 and αB-crystallin, in response to stress. Activation of HSP27 or αB-crystallin is known to protect organs/cells by increasing the stability of actin microfilaments. Although our previous studies showed that 17β-estradiol (E2) improves cardiovascular function after trauma-hemorrhage, whether the salutary effects of E2 under those conditions are mediated via p38 MAPK remains unknown. Male rats (275–325 g body wt) were subjected to soft tissue trauma and hemorrhage (35–40 mmHg mean blood pressure for ∼90 min) followed by fluid resuscitation. At the onset of resuscitation, rats were injected intravenously with vehicle, E2 (1 mg/kg body wt), E2 + the p38 MAPK inhibitor SB-203580 (2 mg/kg body wt), or SB-203580 alone, and various parameters were measured 2 h thereafter. Cardiac functions that were depressed after trauma-hemorrhage were returned to normal levels by E2 administration, and phosphorylation of cardiac p38 MAPK, HSP27, and αB-crystallin was increased. The E2-mediated improvement of cardiac function and increase in p38 MAPK, HSP27, and αB-crystallin phosphorylation were abolished with coadministration of SB-203580. These results suggest that the salutary effect of E2 on cardiac function after trauma-hemorrhage is in part mediated via upregulation of p38 MAPK and subsequent phosphorylation of HSP27 and αB-crystallin.

scholarly journals Antineuroinflammatory Effects of Modified Wu-Zi-Yan-Zong Prescription in β-Amyloid-Stimulated BV2 Microglia via the NF-κB and ERK/p38 MAPK Signaling Pathways

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Qian Yu ◽  
Fang-Jiao Song ◽  
Jin-Feng Chen ◽  
Xin Dong ◽  
Yong Jiang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Signaling Pathway ◽  
P38 Mapk ◽  
Nuclear Translocation ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Nuclear Factor ◽  
Amyloid A ◽  
Mitogen Activated Protein ◽  
Bv2 Microglia

Modified Wu-Zi-Yan-Zong prescription (MWP), a traditional Chinese medicinal decoction, has possessed the neuroprotective and anti-inflammatory properties. The mechanisms associated with these properties, however, are not completely understood. We designed the experiments to elucidate the antineuroinflammatory property of MWP in BV2 microglia activated by β-amyloid (Aβ), which is a characteristic feature of Alzheimer’s disease (AD). The composition of MWP was studied using HPLC. BV2 microglia cells were then treated with Aβ in the presence or absence of MWP. The effects of MWP treatment on Aβ-activated neuroinflammation were determined using PCR, western blotting, and immunofluorescence staining. MWP significantly inhibited the mRNA expression of inflammatory mediators such as IL-1β, IL-6, TNF-α, and MCP-1, as well as the expression of inducible nitric oxide synthase (iNOS) in Aβ-activated BV2 microglia. MWP also inhibited the nuclear translocation and signaling pathway of nuclear factor kappa B (NF-κB) by suppressing inhibitor of nuclear factor-κB (IκB) degradation and downregulating IκB kinase β (IKKβ) phosphorylation. Moreover, MWP decreased extracellular regulated protein kinase (ERK)/p38 mitogen-activated protein kinase (MAPK) phosphorylation, which is an important signaling pathway for proinflammatory gene expression. We concluded that MWP could suppress neuroinflammatory responses in Aβ-activated BV2 microglia via the NF-κB and ERK/p38 MAPK signaling cascades and could prove an effective therapeutic agent for the prevention and treatment of neuroinflammatory diseases such as AD.

scholarly journals Involvement of the Mannose Receptor and p38 Mitogen-Activated Protein Kinase Signaling Pathway of the Microdomain of the Integral Membrane Protein after Enteropathogenic Escherichia coli Infection

2012 ◽  
Vol 80 (4) ◽  
pp. 1343-1350 ◽  
Author(s):  
Zhihua Liu ◽  
Yanlei Ma ◽  
Mary Pat Moyer ◽  
Peng Zhang ◽  
Chenzhang Shi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Protein Kinase ◽  
Signaling Pathway ◽  
P38 Mapk ◽  
Mannose Receptor ◽  
Integral Membrane Protein ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Content Type ◽  
Mitogen Activated Protein

ABSTRACTThe microdomain of the integral membrane protein (MIMP) has been shown to adhere to mucin and to antagonize the adhesion of enteropathogenicEscherichia coli(EPEC) to epithelial cells; however, the mechanism has not been fully elucidated. In this study, we further identified the receptor of MIMP on NCM460 cells and investigated the mechanism (the p38 mitogen-activated protein kinase [MAPK] pathway) following the interaction of MIMP and its corresponding receptor, mannose receptor. We first identified the target receptor of MIMP on the surfaces of NCM460 cells using immunoprecipitation-mass spectrometry technology. We also verified the mannose receptor and examined the degradation and activation of the p38 MAPK signaling pathway. The results indicated that MIMP adhered to NCM460 cells by binding to the mannose receptor and inhibited the phosphorylation of p38 MAPK stimulated after EPEC infection via inhibition of the Toll-like receptor 5 pathway. These findings indicated that MIMPs relieve the injury of NCM460 cells after enteropathogenicE. coliinfection through the mannose receptor and inhibition of the p38 MAPK signaling pathway, both of which may therefore be potential therapeutic targets for intestinal diseases, such as inflammatory bowel disease.

The p38 mitogen-activated protein kinase pathway plays a critical role in thrombin-induced endothelial chemokine production and leukocyte recruitment

Blood ◽  
2001 ◽  
Vol 98 (3) ◽  
pp. 667-673 ◽  
Author(s):  
Valérie Marin ◽  
Catherine Farnarier ◽  
Sandra Grès ◽  
Solange Kaplanski ◽  
Michael S.-S. Su ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Signaling Pathway ◽  
P38 Mapk ◽  
Mapk Pathway ◽  
Endothelial Activation ◽  
Mapk Signaling ◽  
Mapk Signaling Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Chemokine Production ◽  
Mitogen Activated Protein

Abstract Thrombin, the terminal serine protease in the coagulation cascade, is a proinflammatory molecule in vivo and induces endothelial activation in vitro. The cellular signaling mechanisms involved in this function are unknown. The role of the p38 mitogen-activated protein kinase (MAPK) signaling pathway in thrombin-induced chemokine production was studied. Phosphorylation of both p38 MAPK and its substrate, ATF-2, was observed in human umbilical vein endothelial cells (HUVECs) stimulated with thrombin, with a maximum after 5 minutes of stimulation. Using the selective p38 MAPK inhibitor SB203580, there was a significant decrease in thrombin-induced interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1) protein production and messenger RNA steady-state levels. In addition, SB203580 decreased IL-8 and MCP-1 production induced by the thrombin receptor-1 agonist peptide (TRAP), suggesting functional links between the thrombin G protein–coupled receptor and the p38 MAPK pathway. Furthermore, endothelial activation in the presence of SB203580 decreased the chemotactic activity of thrombin-stimulated HUVEC supernatant on neutrophils and monocytic cells. In contrast, the p42/p44 MAPK pathway did not appear to be involved in thrombin- or TRAP-induced endothelial chemokine production, because there was no reduction in the presence of the p42/p44-specific inhibitor PD98059. These results demonstrate that the p38 rather than p42/44 MAPK signaling pathway plays an important role in thrombin-induced endothelial proinflammatory activation and suggest that inhibition of p38 MAPK may be an interesting target for anti-inflammatory strategies in vascular diseases combining thrombosis and inflammation.

scholarly journals Down-regulation of Cytokine-induced Interleukin-8 Requires Inhibition of p38 Mitogen-activated Protein Kinase (MAPK) via MAPK Phosphatase 1-dependent and -independent Mechanisms

2011 ◽  
Vol 286 (18) ◽  
pp. 15998-16007 ◽  
Author(s):  
Nurlan Dauletbaev ◽  
Daniel Eklove ◽  
Nadir Mawji ◽  
Michele Iskandar ◽  
Sergio Di Marco ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Epithelial Cells ◽  
P38 Mapk ◽  
Mrna Stability ◽  
Airway Epithelial Cells ◽  
Mitogen Activated Protein Kinase ◽  
Airway Epithelial ◽  
Down Regulation ◽  
Mitogen Activated Protein ◽  
Mapk Phosphatase

Down-regulation of overabundant interleukin (IL)-8 present in cystic fibrosis (CF) airways could ease excessive neutrophil burden and its deleterious consequences for the lung. IL-8 production in airway epithelial cells, stimulated with e.g. inflammatory cytokines IL-1β and tumor necrosis factor (TNF)-α, is regulated by several signaling pathways including nuclear factor (NF)-κB and p38 mitogen-activated protein kinase (MAPK). We previously demonstrated that the anti-inflammatory drugs dexamethasone and ibuprofen suppress NF-κB; however, only dexamethasone down-regulates cytokine-induced IL-8, highlighting the importance of non-NF-κB mechanisms. Here, we tested the hypothesis that down-regulation of cytokine-induced IL-8 requires modulation of the MAPK phosphatase (MKP)-1/p38 MAPK/mRNA stability pathway. The effects of dexamethasone (5 nm) and ibuprofen (480 μm) on this pathway and IL-8 were studied in CF (CFTE29o−, CFBE41o−) and non-CF (1HAEo−) airway epithelial cells. We observed that dexamethasone, but not ibuprofen, destabilizes IL-8 mRNA and up-regulates MKP-1 mRNA. Further, siRNA silencing of MKP-1, via p38 MAPK, leads to IL-8 overproduction and diminishes the anti-IL-8 potential of dexamethasone. However, MKP-1 overexpression does not significantly alter IL-8 production. By contrast, direct inhibition of p38 MAPK (inhibitor SB203580) efficiently suppresses IL-8 with potency comparable with dexamethasone. Similar to dexamethasone, SB203580 decreases IL-8 mRNA stability. Dexamethasone does not affect p38 MAPK activation, which excludes its effects upstream of p38 MAPK. In conclusion, normal levels of MKP-1 are necessary for a full anti-IL-8 potential of pharmacological agents; however, efficient pharmacological down-regulation of cytokine-induced IL-8 also requires direct effects on p38 MAPK and mRNA stability independently of MKP-1.

High Concentration of Insulin Induces MUC5AC Expression via Phosphoinositide 3 Kinase/AKT and Mitogen-activated Protein Kinase Signaling Pathways in Human Airway Epithelial Cells

2018 ◽  
Vol 32 (5) ◽  
pp. 350-358 ◽  
Author(s):  
Hyung Gyun Na ◽  
Yong-Dae Kim ◽  
Chang Hoon Bae ◽  
Yoon Seok Choi ◽  
Hyun Jung Jin ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Epithelial Cells ◽  
Signaling Pathway ◽  
Airway Epithelial Cells ◽  
Mitogen Activated Protein Kinase ◽  
Airway Epithelial ◽  
High Concentration ◽  
Human Airway ◽  
Mitogen Activated Protein ◽  
Phosphoinositide 3 Kinase

Background Insulin is involved in a glucose homeostatic regulation and a cellular metabolism via phosphorylation of phosphoinositide 3 kinase (PI3K) pathway and mitogen-activated protein kinase (MAPK) pathway. Hyperinsulinemia reduces insulin sensitivity and is an obvious potential factor affecting airway inflammation in chronic airway diseases. MUC5AC is a major secreted mucin, which plays a critical role in inflammatory response in the respiratory tract. However, the relationship between insulin and MUC5AC expression has not been studied. Objective This study investigated the effect and the brief signaling pathway of high concentration of insulin (HI) on MUC5AC expression in human airway epithelial cell. Methods In NCI-H292 cells and primary cultures of normal nasal epithelial cells, the effect and signaling pathway of HI on MUC5AC expression were investigated using reverse transcriptase-polymerase chain reaction (RT-PCR), real-time PCR, enzyme immunoassay, and immunoblot analysis with several specific inhibitors and small interfering RNA (siRNA). Results HI significantly increased MUC5AC expression and activated PI3K/AKT, extracellular signal-related kinase 1/2 (ERK1/2) and p38 MAPKs. The specific PI3K and AKT inhibitor as well as knockdown of AKT1 and AKT2 by the respective siRNAs significantly blocked HI-mediated expression of MUC5AC. Meanwhile, the specific ERK1/2 MAPK and p38 MAPK inhibitor as well as knockdown of ERK1, ERK2, and p38 MAPK by the respective siRNAs also attenuated HI-induced expression of MUC5AC. Conclusion The results of this study suggest that HI induces MUC5AC expression via PI3K/AKT and MAPK signaling pathways in human airway epithelial cells.

scholarly journals JNK mitogen-activated protein kinase limits calcium-dependent chloride secretion across colonic epithelial cells

2010 ◽  
Vol 298 (1) ◽  
pp. G37-G44 ◽  
Author(s):  
Fergal Donnellan ◽  
Niamh Keating ◽  
Paul Geoghegan ◽  
Frank E. Murray ◽  
Brian J. P. Harvey ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Growth Factor Receptor ◽  
Intestinal Transport ◽  
Chloride Secretion ◽  
Mitogen Activated Protein Kinase ◽  
Colonic Epithelial Cells ◽  
Egfr Transactivation ◽  
Calcium Dependent ◽  
Mitogen Activated Protein ◽  
Intracellular Ca

Neuroimmune agonists induce epithelial Cl− secretion through elevations in intracellular Ca2+ or cAMP. Previously, we demonstrated that epidermal growth factor receptor (EGFR) transactivation and subsequent ERK MAPK activation limits secretory responses to Ca2+-dependent, but not cAMP-dependent, agonists. Although JNK MAPKs are also expressed in epithelial cells, their role in regulating transport function is unknown. Here, we investigated the potential role for JNK in regulating Cl− secretion in T84 colonic epithelial cells. Western blot analysis revealed that a prototypical Ca2+-dependent secretagogue, carbachol (CCh; 100 μM), induced phosphorylation of both the 46-kDa and 54-kDa isoforms of JNK. This effect was mimicked by thapsigargin (TG), which specifically elevates intracellular Ca2+, but not by forskolin (FSK; 10 μM), which elevates cAMP. CCh-induced JNK phosphorylation was attenuated by the EGFR inhibitor, tyrphostin-AG1478 (1 μM). Pretreatment of voltage-clamped T84 cells with SP600125 (2 μM), a specific JNK inhibitor, potentiated secretory responses to both CCh and TG but not to FSK. The effects of SP600125 on CCh-induced secretion were not additive with those of the ERK inhibitor, PD98059. Finally, in apically permeabilized T84 cell monolayers, SP600125 potentiated CCh-induced K+ conductances but not Na+/K+ATPase activity. These data demonstrate a novel role for JNK MAPK in regulating Ca2+ but not cAMP-dependent epithelial Cl− secretion. JNK activation is mediated by EGFR transactivation and exerts its antisecretory effects through inhibition of basolateral K+ channels. These data further our understanding of mechanisms regulating epithelial secretion and underscore the potential for exploitation of MAPK-dependent signaling in treatment of intestinal transport disorders.

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