A role for PKCε and MAP kinase in bradykinin-induced arachidonic acid release in rabbit CCD cells

1998 ◽  
Vol 274 (4) ◽  
pp. F728-F735 ◽  
Author(s):  
Mark A. Lal ◽  
Pierre R. Proulx ◽  
Richard L. Hébert

Arachidonic acid (AA) release is the rate-limiting step in the production of prostaglandins, an important class of autocrine/paracrine factors that modulate collecting duct function. Previous results from this laboratory have established cytosolic phospholipase A2(cPLA2) as the enzyme responsible for bradykinin (BK)-stimulated AA mobilization in rabbit cortical collecting duct (RCCD) cells, and the present study pursues the intracellular signaling mechanisms responsible for its activation. Pretreatment of cells with Ro-31-8220, an inhibitor of protein kinase C (PKC), or PD-98059, an inhibitor of the mitogen-activated protein kinase (MAPK) cascade, resulted in a 50–60% reduction in BK-stimulated AA release. Incubation of RCCD cells with a combination of both Ro-31-8220 and PD-98059 did not achieve a greater inhibition of either BK-stimulated AA release or cPLA2 activity, possibly indicating that MAPK activation was dependent upon prior activation of PKC. This was supported by the observation that BK-induced MAPK activation could be reversed by either inhibitor. Additional experiments dealing with immunoblots for PKC isozymes revealed that RCCD cells express PKC species α, γ, ε, and ζ. Following BK stimulation, only PKCε translocated to the particulate fraction. Based on these results, it appears that PKC is activated and involved in the sequential activation of MAPK and cPLA2 following BK treatment. The results also suggest that PKCε may be the isozyme implicated in the process.

2004 ◽  
Vol 72 (10) ◽  
pp. 5662-5667 ◽  
Author(s):  
Nicola J. Mason ◽  
Jim Fiore ◽  
Takashi Kobayashi ◽  
Katherine S. Masek ◽  
Yongwon Choi ◽  
...  

ABSTRACT The production of interleukin-12 (IL-12) is critical to the development of innate and adaptive immune responses required for the control of intracellular pathogens. Many microbial products signal through Toll-like receptors (TLR) and activate NF-κB family members that are required for the production of IL-12. Recent studies suggest that components of the TLR pathway are required for the production of IL-12 in response to the parasite Toxoplasma gondii; however, the production of IL-12 in response to this parasite is independent of NF-κB activation. The adaptor molecule TRAF6 is involved in TLR signaling pathways and associates with serine/threonine kinases involved in the activation of both NF-κB and mitogen-activated protein kinase (MAPK). To elucidate the intracellular signaling pathways involved in the production of IL-12 in response to soluble toxoplasma antigen (STAg), wild-type and TRAF6−/− mice were inoculated with STAg, and the production of IL-12(p40) was determined. TRAF6−/− mice failed to produce IL-12(p40) in response to STAg, and TRAF6−/− macrophages stimulated with STAg also failed to produce IL-12(p40). Studies using Western blot analysis of wild-type and TRAF6−/− macrophages revealed that stimulation with STAg resulted in the rapid TRAF6-dependent phosphorylation of p38 and extracellular signal-related kinase, which differentially regulated the production of IL-12(p40). The studies presented here demonstrate for the first time that the production of IL-12(p40) in response to toxoplasma is dependent upon TRAF6 and p38 MAPK.


2009 ◽  
Vol 20 (3) ◽  
pp. 1020-1029 ◽  
Author(s):  
Wei Zuo ◽  
Ye-Guang Chen

Transforming growth factor (TGF)-β regulates a spectrum of cellular events, including cell proliferation, differentiation, and migration. In addition to the canonical Smad pathway, TGF-β can also activate mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K)/Akt, and small GTPases in a cell-specific manner. Here, we report that cholesterol depletion interfered with TGF-β–induced epithelial-mesenchymal transition (EMT) and cell migration. This interference is due to impaired activation of MAPK mediated by cholesterol-rich lipid rafts. Cholesterol-depleting agents specifically inhibited TGF-β–induced activation of extracellular signal-regulated kinase (ERK) and p38, but not Smad2/3 or Akt. Activation of ERK or p38 is required for both TGF-β–induced EMT and cell migration, whereas PI3K/Akt is necessary only for TGF-β–promoted cell migration but not for EMT. Although receptor heterocomplexes could be formed in both lipid raft and nonraft membrane compartments in response to TGF-β, receptor localization in lipid rafts, but not in clathrin-coated pits, is important for TGF-β–induced MAPK activation. Requirement of lipid rafts for MAPK activation was further confirmed by specific targeting of the intracellular domain of TGF-β type I receptor to different membrane locations. Together, our findings establish a novel link between cholesterol and EMT and cell migration, that is, cholesterol-rich lipid rafts are required for TGF-β–mediated MAPK activation, an event necessary for TGF-β–directed epithelial plasticity.


1994 ◽  
Vol 267 (4) ◽  
pp. C1130-C1135 ◽  
Author(s):  
Y. Wang ◽  
P. M. Rose ◽  
M. L. Webb ◽  
M. J. Dunn

Endothelin (ET) has been shown to activate mitogen-activated protein kinase (MAPK). However, it has been unclear which of the ET receptors is coupled to MAPK activation. In the present study, we conducted experiments to determine which ET receptor is linked to MAPK activation. We found that both human ETA and ETB were coupled to the MAPK cascade in ETA or ETB cDNA-transfected Chinese hamster ovary cells. ET-1 was more potent than ET-3 in the activation of p42 MAPK, induction of MAPK kinase (MAPKK) gel retardation and uptake of [3H]thymidine in ETA-transfected cells, whereas sarafotoxin (S6c) showed no stimulatory effect on the kinases and [3H]thymidine uptake. ET-1, ET-3, and S6c had approximately the same potency to activate p42 MAPK, MAPKK gel retardation, and [3H]thymidine uptake in ETB-transfected cells. These data suggest that 1) ET isopeptides, through either ETA or ETB receptors, induce the MAPK cascade as well as cell proliferation; and 2) the different potencies of ET isopeptides for activation of the MAPK cascade and induction of cell growth are mainly due to their different affinities toward ETA and ETB.


2011 ◽  
Vol 300 (1) ◽  
pp. E103-E110 ◽  
Author(s):  
Xiaoban Xin ◽  
Lijun Zhou ◽  
Caleb M. Reyes ◽  
Feng Liu ◽  
Lily Q. Dong

The adaptor protein APPL1 mediates the stimulatory effect of adiponectin on p38 mitogen-activated protein kinase (MAPK) signaling, yet the underlying mechanism remains unclear. Here we show that, in C2C12 cells, overexpression or suppression of APPL1 enhanced or suppressed, respectively, adiponectin-stimulated p38 MAPK upstream kinase cascade, consisting of transforming growth factor-β-activated kinase 1 (TAK1) and mitogen-activated protein kinase kinase 3 (MKK3). In vitro affinity binding and coimmunoprecipitation experiments revealed that TAK1 and MKK3 bind to different regions of APPL1, suggesting that APPL1 functions as a scaffolding protein to facilitate adiponectin-stimulated p38 MAPK activation. Interestingly, suppressing APPL1 had no effect on TNFα-stimulated p38 MAPK phosphorylation in C2C12 myotubes, indicating that the stimulatory effect of APPL1 on p38 MAPK activation is selective. Taken together, our study demonstrated that the TAK1-MKK3 cascade mediates adiponectin signaling and uncovers a scaffolding role of APPL1 in regulating the TAK1-MKK3-p38 MAPK pathway, specifically in response to adiponectin stimulation.


Endocrinology ◽  
2001 ◽  
Vol 142 (6) ◽  
pp. 2336-2342 ◽  
Author(s):  
Christian B. Wade ◽  
Siobhan Robinson ◽  
Robert A. Shapiro ◽  
Daniel M. Dorsa

Abstract The rapid, nongenomic effects of estrogen are increasingly recognized as playing an important role in several aspects of estrogen action. Rapid activation of the mitogen-activated protein kinase (MAPK) signaling pathway by estrogen is among the more recently identified of these effects. To explore the role of estrogen receptors (ERs) in mediating these effects, we have transfected ER-negative Rat-2 fibroblasts with complementary DNA clones encoding either human ERα or rat ERβ and examined their ability to couple to activation of MAPK in response to 17β-estradiol (17β-E2) and other ligands. For both receptors, addition of E2 resulted in a rapid phosphorylation of MAPK. Activation of MAPK in ERα-transfected cells was partially and completely blocked by the antiestrogens tamoxifen and ICI 182,780, respectively. In ERβ-transfected cells, MAPK activation was less sensitive to inhibition by tamoxifen and ICI 182,780. We have also observed that, in this model system, a membrane-impermeable estrogen (BSA-E2) and 17α-E2 were both able to activate MAPK in a manner similar to E2 alone. Here also, ICI 182,780 blocked the ability of BSA-E2 to activate MAPK through ERα, but failed to block ERβ-mediated effects. BSA-E2 treatment, however, failed to activate nuclear estrogen-response-element-mediated gene transcription. These data show that these nuclear ERs are necessary for estrogen’s effects at the membrane. This model system will be useful in identifying molecular interactions involved in the rapid effects mediated by the ERs.


1993 ◽  
Vol 265 (3) ◽  
pp. F399-F405 ◽  
Author(s):  
T. Satoh ◽  
H. T. Cohen ◽  
A. I. Katz

We recently reported a novel intracellular mechanism of Na-K-adenosinetriphosphatase (Na-K-ATPase) regulation in the cortical collecting duct (CCD) by agents that increase cell adenosine 3',5'-cyclic monophosphate (cAMP), which involves stimulation of protein kinase A (PKA) and phospholipase A2 (PLA2). We now determined whether this mechanism also operates in other nephron segments. In the medullary thick ascending limb (MTAL) dopamine, the DA1 agonist fenoldopam, forskolin, or dibutyryl-cAMP inhibited Na-K-ATPase activity, similar to results in CCD. In both segments this effect was blocked by 20-residue inhibitory peptide (IP20), a peptide inhibitor of PKA, but not by staurosporine, a protein kinase C (PKC) inhibitor. PKC activators phorbol 12-myristate 13-acetate, phorbol 12,13-dibutyrate, and 1,2-myristate 13-acetate, phorbol 12,13-dibutyrate, and 1,2-dioctanoylglycerol had no effect on Na-K pump activity in either CCD or MTAL. In contrast, all three PKC activators inhibited pump activity in the proximal convoluted tubule (PCT), an effect reproduced only by dopamine or by parathyroid hormone [PTH-(1-34)]. In PCT the pump inhibition by dopamine or PTH-(1-34) was abolished by staurosporine but not by IP20. The PLA2 inhibitor mepacrine prevented the effect of all agents, and arachidonic acid produced a dose-dependent pump inhibition in each of the three segments studied. We conclude that intracellular mechanisms of Na-K-ATPase regulation differ along the nephron, as they involve activation of PKA in CCD and MTAL and of PKC in PCT. These two pathways probably share a common mechanism in stimulating PLA2, arachidonic acid release, and production of eicosanoids in both the proximal and distal nephron.


2013 ◽  
Vol 81 (11) ◽  
pp. 4299-4310 ◽  
Author(s):  
Pierre-Joseph Royer ◽  
Andrew J. Rogers ◽  
Karl G. Wooldridge ◽  
Patrick Tighe ◽  
Jafar Mahdavi ◽  
...  

ABSTRACTWe have investigated the response of primary human meningothelial cells toNeisseria meningitidis. Through a transcriptome analysis, we provide a comprehensive examination of the response of meningothelial cells to bacterial infection. A wide range of chemokines are elicited which act to attract and activate the main players of innate and adaptive immunity. We showed that meningothelial cells expressed a high level of Toll-like receptor 4 (TLR4), and, using a gene silencing strategy, we demonstrated the contribution of this pathogen recognition receptor in meningothelial cell activation. Secretion of interleukin-6 (IL-6), CXCL10, and CCL5 was almost exclusively TLR4 dependent and relied on MyD88 and TRIF adaptor cooperation. In contrast, IL-8 induction was independent of the presence of TLR4, MyD88, and TRIF. Transcription factors NF-κB p65, p38 mitogen-activated protein kinase (MAPK), Jun N-terminal protein kinase (JNK1), IRF3, and IRF7 were activated after contact with bacteria. Interestingly, the protein kinase IRAK4 was found to play a minor role in the meningothelial cell response toNeisseriainfection. Our work highlights the role of meningothelial cells in the development of an immune response and inflammation in the central nervous system (CNS) in response to meningococcal infection. It also sheds light on the complexity of intracellular signaling after TLR triggering.


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