scholarly journals Pref-1 (Preadipocyte Factor 1) Activates the MEK/Extracellular Signal-Regulated Kinase Pathway To Inhibit Adipocyte Differentiation

2006 ◽  
Vol 27 (6) ◽  
pp. 2294-2308 ◽  
Author(s):  
Kyung-Ah Kim ◽  
Jung-Hyun Kim ◽  
Yuhui Wang ◽  
Hei Sook Sul
Keyword(s):  
Adipocyte Differentiation ◽  
Transmembrane Protein ◽  
Biologically Active ◽  
Soluble Form ◽  
Null Mouse ◽  
Dependent Manner ◽  
Wild Type ◽  
Extracellular Signal Regulated Kinase ◽  
Erk Phosphorylation ◽  
Extracellular Signal

ABSTRACT Preadipocyte factor 1 (Pref-1) is found in preadipocytes but is absent in adipocytes. Pref-1 is made as a transmembrane protein but is cleaved to generate a biologically active soluble form. Although Pref-1 inhibition of adipogenesis has been well studied in vitro and in vivo, the signaling pathway for Pref-1 is not known. Here, by using purified soluble Pref-1 in Pref-1 null mouse embryo fibroblasts (MEF), we show that Pref-1 increases MEK/extracellular signal-regulated kinase (ERK) phosphorylation in a time- and dose-dependent manner. Compared to wild-type MEF, differentiation of Pref-1 null MEF into adipocytes is enhanced, as judged by lipid accumulation and adipocyte marker expression. Both wild-type and Pref-1 null MEF show a transient burst of ERK phosphorylation upon addition of adipogenic agents. Wild-type MEF show a significant, albeit lower, second increase in ERK phosphorylation peaking at day 2. This ERK phosphorylation, corresponding to Pref-1 abundance, is absent during differentiation of Pref-1 null MEF. Prevention of this second increase in ERK1/2 phosphorylation in wild-type MEF by the MEK inhibitor PD98059 or by transient depletion of ERK1/2 via small interfering RNA-enhanced adipocyte differentiation. Furthermore, treatment of Pref-1 null MEF with Pref-1 restores this ERK phosphorylation, resulting in inhibition of adipocyte differentiation primarily by preventing peroxisome proliferator-activated receptor γ2 induction. However, in the presence of PD98059 or depletion of ERK1/2, exogenous Pref-1 cannot inhibit adipocyte differentiation in Pref-1 null MEF. We conclude that Pref-1 activates MEK/ERK signaling, which is required for Pref-1 inhibition of adipogenesis.

scholarly journals Keratins Modulate c-Flip/Extracellular Signal-Regulated Kinase 1 and 2 Antiapoptotic Signaling in Simple Epithelial Cells

2004 ◽  
Vol 24 (16) ◽  
pp. 7072-7081 ◽  
Author(s):  
Stéphane Gilbert ◽  
Anne Loranger ◽  
Normand Marceau
Keyword(s):  
Tumor Necrosis Factor ◽  
Tumor Necrosis Factor Alpha ◽  
Tumor Necrosis ◽  
Null Mouse ◽  
Wild Type ◽  
Necrosis Factor Alpha ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Factor Alpha ◽  
Necrosis Factor

ABSTRACT Among the large family of intermediate filament proteins, the keratin 8 and 18 (K8/K18) pair constitutes a hallmark for all simple epithelial cells, such as hepatocytes and mammary cells. Functional studies with different cell models have suggested that K8/K18 are involved in simple epithelial cell resistance to several forms of stress that may lead to cell death. We have reported recently that K8/K18-deprived hepatocytes from K8-null mice are more sensitive to Fas-mediated apoptosis. Here we show that upon Fas, tumor necrosis factor alpha receptor, or tumor necrosis factor alpha-related apoptosis-inducing ligand receptor stimulation, an inhibition of extracellular signal-regulated kinase 1 and 2 (ERK1/2) activation sensitizes wild-type but not K8-null mouse hepatocytes to apoptosis and that a much weaker ERK1/2 activation occurs in K8-null hepatocytes. In turn, this impaired ERK1/2 activation in K8-null hepatocytes is associated with a drastic reduction in c-Flip protein, an event that also holds in a K8-null mouse mammary cell line. c-Flip, along with Raf-1, is part of a K8/K18-immunoisolated complex from wild-type hepatocytes, and Fas stimulation leads to further c-Flip and Raf-1 recruitment in the complex. This points to a new regulatory role of simple epithelium keratins in the c-Flip/ERK1/2 antiapoptotic signaling pathway.

Involvement of the extracellular signal-regulated kinase 1/2 signaling pathway in amylin's eating inhibitory effect

2012 ◽  
Vol 302 (3) ◽  
pp. R340-R351 ◽  
Author(s):  
Catarina Soares Potes ◽  
Christina Neuner Boyle ◽  
Peter John Wookey ◽  
Thomas Riediger ◽  
Thomas Alexander Lutz
Keyword(s):  
Area Postrema ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Neuronal Responses ◽  
Extracellular Signal Regulated Kinase ◽  
Erk Phosphorylation ◽  
Extracellular Signal ◽  
Anorectic Effect ◽  
Feeding Trials ◽  
Dose Dependent

Peripheral amylin inhibits eating via the area postrema (AP). Because amylin activates the extracellular-signal regulated kinase 1/2 (ERK) pathway in some tissues, and because ERK1/2 phosphorylation (pERK) leads to acute neuronal responses, we postulated that it may be involved in amylin's eating inhibitory effect. Amylin-induced ERK phosphorylation (pERK) was investigated by immunohistochemistry in brain sections containing the AP. pERK-positive AP neurons were double-stained for the calcitonin 1a/b receptor, which is part of the functional amylin-receptor. AP sections were also phenotyped using dopamine-β-hydroxylase (DBH) as a marker of noradrenergic neurons. The effect of fourth ventricular administration of the ERK cascade blocker U0126 on amylin's eating inhibitory action was tested in feeding trials. The number of pERK-positive neurons in the AP was highest ∼10–15 min after amylin treatment; the effect appeared to be dose-dependent (5–20 μg/kg amylin). A portion of pERK-positive neurons in the AP carried the amylin-receptor and 22% of the pERK-positive neurons were noradrenergic. Pretreatment of rats with U0126 decreased the number of pERK-positive neurons in the AP after amylin injection. U0126 also attenuated the ability of amylin to reduce eating, at least when the animals had been fasted 24 h prior to the feeding trial. Overall, our results suggest that amylin directly stimulates pERK in AP neurons in a time- and dose-dependent manner. Part of the AP neurons displaying pERK were noradrenergic. At least under fasting conditions, pERK was shown to be a necessary part in the signaling cascade mediating amylin's anorectic effect.

scholarly journals Pref-1 Interacts with Fibronectin To Inhibit Adipocyte Differentiation

2010 ◽  
Vol 30 (14) ◽  
pp. 3480-3492 ◽  
Author(s):  
Yuhui Wang ◽  
Ling Zhao ◽  
Cynthia Smas ◽  
Hei Sook Sul
Keyword(s):  
Adipocyte Differentiation ◽  
Transmembrane Protein ◽  
Dominant Negative ◽  
Biologically Active ◽  
Mitogen Activated Protein Kinase ◽  
Soluble Form ◽  
Necrosis Factor Alpha ◽  
Rgd Peptides ◽  
Downstream Signaling ◽  
Erk Mapk

ABSTRACT Pref-1/Dlk1 is made as an epidermal growth factor (EGF) repeat-containing transmembrane protein but is cleaved by tumor necrosis factor alpha converting enzyme (TACE) to generate a biologically active soluble form. Soluble Pref-1 inhibits adipocyte differentiation through the activation of extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) and the subsequent upregulation of Sox9 expression. However, others have implicated Notch in Pref-1 signaling and function. Here, we show that Pref-1 does not interact with, or require, Notch for its function. Instead, we show a direct interaction of Pref-1 and fibronectin via the Pref-1 juxtamembrane domain and fibronectin C-terminal domain. We also show that fibronectin is required for the Pref-1-mediated inhibition of adipocyte differentiation, the activation of ERK/MAPK, and the upregulation of Sox9. Furthermore, disrupting fibronectin binding to integrin by the addition of RGD peptides or by the knockdown of α5 integrin prevents the Pref-1 inhibition of adipocyte differentiation. Pref-1 activates the integrin downstream signaling molecules, FAK and Rac, and ERK activation by Pref-1 is blunted by the knockdown of Rac or by the forced expression of dominant-negative Rac. We conclude that, by interacting with fibronectin, Pref-1 activates integrin downstream signaling to activate MEK/ERK and to inhibit adipocyte differentiation.

scholarly journals OspF and OspC1 Are Shigella flexneri Type III Secretion System Effectors That Are Required for Postinvasion Aspects of Virulence

2006 ◽  
Vol 74 (10) ◽  
pp. 5964-5976 ◽  
Author(s):  
Daniel V. Zurawski ◽  
Chieko Mitsuhata ◽  
Karen L. Mumy ◽  
Beth A. McCormick ◽  
Anthony T. Maurelli
Keyword(s):  
Type Iii Secretion ◽  
Shigella Flexneri ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Host Cells ◽  
Dependent Manner ◽  
Wild Type ◽  
Extracellular Signal Regulated Kinase ◽  
Type Iii ◽  
Extracellular Signal

ABSTRACT Shigella flexneri is the causative agent of dysentery, and its pathogenesis is mediated by a type III secretion system (T3SS). S. flexneri secretes effector proteins into the eukaryotic cell via the T3SS, and these proteins usurp host cellular functions to the benefit of the bacteria. OspF and OspC1 are known to be secreted by S. flexneri, but their functions are unknown. We transformed S. flexneri with a plasmid that expresses a two-hemagglutinin tag (2HA) in frame with OspF or OspC1 and verified that these proteins are secreted in a T3SS-dependent manner. Immunofluorescence of HeLa cells infected with S. flexneri expressing OspF-2HA or OspC1-2HA revealed that both proteins localize in the nucleus and cytoplasm of host cells. To elucidate the function of these T3SS effectors, we constructed ΔospF and ΔospC1 deletion mutants by allelic exchange. We found that ΔospF and ΔospC1 mutants invade host cells and form plaques in confluent monolayers similar to wild-type S. flexneri. However, in the polymorphonuclear (PMN) cell migration assay, a decrease in neutrophil migration was observed for both mutants in comparison to the migration of wild-type bacteria. Moreover, infection of polarized T84 intestinal cells infected with ΔospF and ΔospC1 mutants resulted in decreased phosphorylation of extracellular signal-regulated kinase 1/2 in comparison to that of T84 cells infected with wild-type S. flexneri. To date, these are the first examples of T3SS effectors implicated in mitogen-activated protein kinase kinase/extracellular signal-regulated kinase pathway activation. Ultimately, OspF and OspC1 are essential for PMN transepithelial migration, a phenotype associated with increased inflammation and bacterial access to the submucosa, which are fundamental aspects of S. flexneri pathogenesis.

scholarly journals Oxidized alkyl phospholipids stimulate sodium transport in proximal tubules via PPAR-dependent pathway

2021 ◽  
Author(s):  
Tomohito Mizuno ◽  
Nobuhiko Satoh ◽  
Shoko Horita ◽  
Hiroyuki Tsukada ◽  
Yusuke Sato ◽  
...  
Keyword(s):  
Volume Expansion ◽  
Bicarbonate Transport ◽  
Kidney Cortex ◽  
Peroxisome Proliferator ◽  
Dependent Manner ◽  
Peroxisome Proliferator Activated Receptor ◽  
Ppar Agonist ◽  
Extracellular Signal Regulated Kinase ◽  
Erk Phosphorylation ◽  
Extracellular Signal

The pleiotropic effects of oxidized phospholipids (oxPLs) have been identified. 1-O-hexadecyl-2-azelaoyl-sn-glycero-3-phosphocholine (azPC), an oxPL formed from alkyl phosphatidylcholines, is a potent peroxisome proliferator-activated receptor (PPAR) agonist. Although it has been reported that thiazolidinediones can induce volume expansion by enhancing renal sodium and water retention, the role of azPC, an endogenous PPAR agonist, in renal transport functions is unknown. In the present study, we investigated the effect of azPC on renal proximal tubule (PT) transport using isolated PTs and kidney cortex tissues. We showed that azPC rapidly stimulated Na+/HCO3- cotransporter 1 activity and luminal Na+/H+ exchanger (NHE) activities in a dose-dependent manner, at submicromolar concentrations, in isolated PTs from rats and humans. Additionally, the stimulatory effects were completely blocked by a specific PPAR antagonist, 2-chloro-5-nitro-N-phenylbenzamide (GW9662), and a mitogen-activated protein/extracellular signal-regulated kinase (MEK) inhibitor, PD98059. Treatment with an siRNA against PPAR significantly suppressed the expression of PPAR mRNA, and it completely blocked the stimulation of both Na+/HCO3- cotransporter 1 and NHE activities by azPC. Moreover, azPC induced extracellular signal-regulated kinase (ERK) phosphorylation in rat and human kidney cortex tissues, and the induced ERK phosphorylation by azPC was completely suppressed by GW9662 and PD98059. These results suggest that azPC stimulates renal PT sodium-coupled bicarbonate transport via the PPAR/MEK/ERK pathway. The stimulatory effects of azPC on PT transport may be partially involved in the development of volume expansion.

Mepivacaine-induced contraction involves phosphorylation of extracellular signal-regulated kinase through activation of the lipoxygenase pathway in isolated rat aortic smooth muscle

2013 ◽  
Vol 91 (4) ◽  
pp. 285-294 ◽  
Author(s):  
Hyo Min Lee ◽  
Seong-Ho Ok ◽  
Hui-Jin Sung ◽  
So Young Eun ◽  
Hye Jung Kim ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Nordihydroguaiaretic Acid ◽  
Rat Aorta ◽  
Dependent Manner ◽  
Aortic Smooth Muscle ◽  
Extracellular Signal Regulated Kinase ◽  
Erk Phosphorylation ◽  
Extracellular Signal ◽  
Cox 2 ◽  
Isolated Rat

Mepivacaine is an aminoamide local anesthetic with an intermediate duration that intrinsically produces vasoconstriction both in vivo and in vitro. This study investigated the arachidonic acid metabolic pathways involved in mepivacaine-induced contraction, and elucidated the associated cellular mechanism with a particular focus on extracellular signal-regulated kinase (ERK) in endothelium-denuded rat aorta. Isolated rat thoracic aortic rings were suspended for isometric tension recording. Cumulative mepivacaine concentration–response curves were generated in the presence or absence of the following inhibitors: quinacrine dihydrochloride, nordihydroguaiaretic acid, phenidone, AA-861, indomethacin, NS-398, SC-560, fluconazole, PD 98059, and verapamil. Mepivacaine-induced ERK phosphorylation, 5-lipoxygenase (5-LOX) expression, and cyclooxygenase (COX)-2 expression in rat aortic smooth muscle cells were detected by Western blot analysis in the presence or absence of inhibitors. Mepivacaine produced tonic contraction in isolated endothelium-denuded rat aorta. Quinacrine dihydrochloride, nordihydroguaiaretic acid, phenidone, AA-861, NS-398, PD 98059, and verapamil attenuated mepivacaine-induced contraction in a concentration-dependent manner. However, fluconazole had no effect on mepivacaine-induced contraction. PD 98059, quinacrine dihydrochloride, nordihydroguaiaretic acid, AA-861, phenidone, and indomethacin attenuated mepivacaine-induced ERK phosphorylation. Mepivacaine upregulated 5-LOX and COX-2 expression. These results suggest that mepivacaine-induced contraction involves ERK activation, which is primarily mediated by the 5-LOX pathway and in part by the COX-2 pathway.

scholarly journals MIF Signal Transduction Initiated by Binding to CD74

2003 ◽  
Vol 197 (11) ◽  
pp. 1467-1476 ◽  
Author(s):  
Lin Leng ◽  
Christine N. Metz ◽  
Yan Fang ◽  
Jing Xu ◽  
Seamas Donnelly ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Cell Activation ◽  
Immune Cell ◽  
Transmembrane Protein ◽  
Soluble Form ◽  
Expression Cloning ◽  
Target Cells ◽  
Extracellular Signal Regulated Kinase ◽  
Natural Ligand ◽  
Extracellular Signal

Macrophage migration inhibitory factor (MIF) accounts for one of the first cytokine activities to have been described, and it has emerged recently to be an important regulator of innate and adaptive immunity. MIF is an upstream activator of monocytes/macrophages, and it is centrally involved in the pathogenesis of septic shock, arthritis, and other inflammatory conditions. The protein is encoded by a unique but highly conserved gene, and X-ray crystallography studies have shown MIF to define a new protein fold and structural superfamily. Although recent work has begun to illuminate the signal transduction pathways activated by MIF, the nature of its membrane receptor has not been known. Using expression cloning and functional analysis, we report herein that CD74, a Type II transmembrane protein, is a high-affinity binding protein for MIF. MIF binds to the extracellular domain of CD74, and CD74 is required for MIF-induced activation of the extracellular signal–regulated kinase–1/2 MAP kinase cascade, cell proliferation, and PGE2 production. A recombinant, soluble form of CD74 binds MIF with a dissociation constant of ∼9 × 10−9 Kd, as defined by surface plasmon resonance (BIAcore analysis), and soluble CD74 inhibits MIF-mediated extracellular signal–regulated kinase activation in defined cell systems. These data provide a molecular basis for MIF's interaction with target cells and identify it as a natural ligand for CD74, which has been implicated previously in signaling and accessory functions for immune cell activation.

scholarly journals Involvement of phospholipases D1 and D2 in sphingosine 1-phosphate-induced ERK (extracellular-signal-regulated kinase) activation and interleukin-8 secretion in human bronchial epithelial cells

2002 ◽  
Vol 367 (3) ◽  
pp. 751-760 ◽  
Author(s):  
Lixin WANG ◽  
Rhett CUMMINGS ◽  
Peter USATYUK ◽  
Andrew MORRIS ◽  
Kaikobad IRANI ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Bronchial Epithelial Cells ◽  
Interleukin 8 ◽  
Wild Type ◽  
Bronchial Epithelial ◽  
Extracellular Signal Regulated Kinase ◽  
Erk Phosphorylation ◽  
Extracellular Signal ◽  
Sphingosine 1 Phosphate ◽  
Dose Dependent

Sphingosine 1-phosphate (S1P), a metabolite of sphingomyelin degradation, stimulates interleukin-8 (IL-8) secretion in human bronchial epithelial (Beas-2B) cells. The molecular mechanisms regulating S1P-mediated IL-8 secretion are yet to be completely defined. Here we provide evidence that activation of phospholipases D1 and D2 (PLD1 and PLD2) by S1P regulates the phosphorylation of extracellular-signal-regulated kinase (ERK) and IL-8 secretion in Beas-2B cells. S1P, in a time- and dose-dependent manner, enhanced the threonine/tyrosine phosphorylation of ERK. The inhibition of S1P-induced ERK phosphorylation by pertussis toxin and PD 98059 indicated coupling of S1P receptors to Gi and the ERK signalling cascade respectively. Treatment of Beas-2B cells with butan-1-ol, but not butan-3-ol, abrogated the S1P-induced phosphorylation of Raf-1 and ERK, suggesting that PLD is involved in this activation. The roles of PLD1 and PLD2 in ERK activation and IL-8 secretion activated by S1P were investigated by infecting cells with adenoviral constructs of wild-type and catalytically inactive mutants of PLD1 and PLD2. Infection of Beas-2B cells with the wild-type constructs resulted in the activation of PLD1 and PLD2 by S1P and PMA. Also, the enhanced production of [32P]phosphatidic acid and [32P]phosphatidylbutanol in the presence of butan-1-ol and the increased phosphorylation of ERK by S1P were blocked by the catalytically inactive mutants hPLD1-K898R and mPLD2-K758R. Transient transfection of Beas-2B cells with human PLD1 and mouse PLD2 cDNAs potentiated S1P-mediated IL-8 secretion compared with vector controls. In addition, PD 98059 attenuated IL-8 secretion induced by S1P in a dose-dependent fashion. These results demonstrate that both PLD1 and PLD2 participate in S1P stimulation of ERK phosphorylation and IL-8 secretion in bronchial epithelial cells.

scholarly journals Preventive Effects of a Kampo Medicine, Kakkonto, on Inflammatory Responses via the Suppression of Extracellular Signal-Regulated Kinase Phosphorylation in Lipopolysaccharide-Treated Human Gingival Fibroblasts

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Hiroyuki Kitamura ◽  
Hiroko Urano ◽  
Toshiaki Ara
Keyword(s):  
Periodontal Disease ◽  
Inflammatory Responses ◽  
Human Gingival Fibroblasts ◽  
Kampo Medicine ◽  
Prostaglandin E ◽  
Gingival Fibroblasts ◽  
Extracellular Signal Regulated Kinase ◽  
Erk Phosphorylation ◽  
Extracellular Signal ◽  
Cox 2

Periodontal disease is accompanied by inflammation of the gingiva and destruction of periodontal tissues, leading to alveolar bone loss in severe clinical cases. The chemical mediator prostaglandin E2 (PGE2) and cytokines such as interleukin- (IL-)6 and IL-8 have been known to play important roles in inflammatory responses and tissue degradation. In the present study, we investigated the effects of a kampo medicine, kakkonto (TJ-1), on the production of prostaglandin E2 (PGE2), IL-6, and IL-8 by human gingival fibroblasts (HGFs) treated with lipopolysaccharide (LPS) from Porphyromonas gingivalis. Kakkonto concentration dependently suppressed LPS-induced PGE2 production but did not alter basal PGE2 levels. In contrast, kakkonto significantly increased LPS-induced IL-6 and IL-8 production. Kakkonto decreased cyclooxygenase- (COX-)1 activity to approximately 70% at 1 mg/mL but did not affect COX-2 activity. Kakkonto did not affect cytoplasmic phospholipase A2 (cPLA2), annexin1, or LPS-induced COX-2 expression. Kakkonto suppressed LPS-induced extracellular signal-regulated kinase (ERK) phosphorylation, which is known to lead to ERK activation and cPLA2 phosphorylation. These results suggest that kakkonto decreased PGE2 production by inhibition of ERK phosphorylation which leads to inhibition of cPLA2 phosphorylation and its activation. Therefore, kakkonto may be useful to improve gingival inflammation in periodontal disease.

scholarly journals Tangeretin inhibits extracellular-signal-regulated kinase (ERK) phosphorylation

FEBS Letters ◽  
2005 ◽  
Vol 579 (7) ◽  
pp. 1665-1669 ◽  
Author(s):  
Séverine Van Slambrouck ◽  
Virinder S. Parmar ◽  
Sunil K. Sharma ◽  
Bart De Bondt ◽  
Fleur Foré ◽  
...  
Keyword(s):  
Extracellular Signal Regulated Kinase ◽  
Erk Phosphorylation ◽  
Extracellular Signal
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