scholarly journals Biphasic regulation of ENaC by TGF-α and EGF in renal epithelial cells

2009 ◽  
Vol 296 (6) ◽  
pp. F1417-F1427 ◽  
Author(s):  
Lian Liu ◽  
Billie Jeanne Duke ◽  
Bela Malik ◽  
Qiang Yue ◽  
Douglas C. Eaton
Keyword(s):  
Growth Factor ◽  
Acute Treatment ◽  
Egf Receptor ◽  
Transforming Growth Factor ◽  
Kinase Inhibitor ◽  
Single Channel ◽  
Sodium Current ◽  
Mrna Levels ◽  
Channel Measurements ◽  
Open Probability

The epithelial sodium channel (ENaC) is regulated by epidermal growth factor (EGF). We investigate whether ENaC is regulated by another EGF receptor (EGFR) ligand, transforming growth factor-α (TGF-α). We show that chronic (24 h) treatment with TGF-α inhibits ENaC in Xenopus laevis kidney cells 20 times more strongly than EGF. By using single-channel measurements, we show that TGF-α significantly reduces the number of ENaC per patch. The open probability ( Po) is unchanged by 24-h treatment with TGF-α. α-, β-, and γ-ENaC mRNA levels are significantly reduced by TGF-α or EGF. TGF-α or EGF reduces α- and γ-ENaC proteins in the membrane; however, β-ENaC is unchanged. TGF-α or EGF inhibits ENaC by activating EGFR since the EGFR inhibitor AG1478 blocks the effects of both. The MAPK 1/2 inhibitor U0126 also blocks the effect of TGF-α or EGF on ENaC, indicating that the MAPK1/2 pathway is involved in the TGF-α- or EGF-induced inhibition of ENaC. Interestingly, acute treatment (<1 h) with TGF-α or EGF does not inhibit ENaC current; it enhances ENaC activity by increasing Po. Pretreatment of the cells with U0126 potentiates the acute TGF-α- or EGF-induced stimulation of ENaC. This TGF-α- or EGF-induced increase in sodium current is abolished by a phosphatidylinositol 3-kinase (PI-3 kinase) inhibitor, LY294002, suggesting that PI-3 kinase is involved in the activation of sodium transport. In conclusion, chronic treatment with TGF-α or EGF inhibits ENaC by decreasing the number of channels in the membrane transcriptionally through MAPK1/2 pathways, but acute treatment with TGF-α or EGF activates ENaC by increasing Po via PI-3 kinase.

213. Regulation of TGFβ superfamily-related genes in the newborn mouse testis by activin

2005 ◽  
Vol 17 (9) ◽  
pp. 82
Author(s):  
S. H. S. Mendis ◽  
C. Brown ◽  
K. L. Loveland
Keyword(s):  
Growth Factor ◽  
Transforming Growth Factor ◽  
Kinase Inhibitor ◽  
Rna Extraction ◽  
Tissue Inhibitor Of Metalloproteinase ◽  
Pcr Analysis ◽  
Newborn Mouse ◽  
Mrna Levels ◽  
The Impact ◽  
Tgfβ Superfamily

Several members of the transforming growth factor-β (TGFβ) superfamily of ligands are known to influence development of male germ cells. In our ongoing investigations of genetically modified mice with different bioactive levels of activin, we noted that testicular germ cell numbers at birth are increased in the absence of activin.1 In this study we compared expression levels of TGFβ-related genes in mice with 0, 1 or 2 copies of the activin βA subunit gene. Candidate genes were identified through hybridisation of total testis RNA from newborn (Day 0) wild type (WT; 2 copies) and activin βA null mice (KO; 0 copies) to a TGFβ SuperArray Simplicity™ membrane. Densitometric analysis of resulting signals revealed several genes that appeared to differ between genotypes. To validate these findings, pooled testes from newborn WT (2 independent groups), heterozygous (het; 2 groups) and activin βA KO (3 groups) mice were collected for RNA extraction. Quantitative real-time PCR analysis was performed using the Roche Light Cycler, with β-actin mRNA level used as the housekeeping reference. The mRNAs selected for analysis were: inhibin α, p15INK4b, Smad5, insulin-like growth factor 1 (IGF-1), ALK6 (BMPRI-B), and tissue inhibitor of metalloproteinase 1 (Timp1). The inhibin α transcript level was significantly decreased in the activin βA KO animal compared with WT, while the het sample showed an intermediate effect. Both Smad5 and IGF-1 transcripts appeared to increase in the KO animals compared with WT; however, the cyclin-dependent kinase inhibitor, p15INK4b, did not change significantly across the genotypes. Similarly, ALK-6 and Timp1 mRNA levels were also unaffected by genotype. These findings illustrate the impact of graded levels of activin A on specific genes in the fetal testis. (1)Mendis et al. (2004). Reprod. Fertil. Dev. 16(Suppl.), 103.

TGF-β1-induced EMT can occur independently of its proapoptotic effects and is aided by EGF receptor activation

2006 ◽  
Vol 290 (5) ◽  
pp. F1202-F1212 ◽  
Author(s):  
Neil G. Docherty ◽  
Orfhlaith E. O'Sullivan ◽  
Declan A. Healy ◽  
Madeline Murphy ◽  
Amanda J. O'Neill ◽  
...  
Keyword(s):  
Growth Factor ◽  
Western Blotting ◽  
Egf Receptor ◽  
Transforming Growth Factor ◽  
Kinase Inhibitor ◽  
Receptor Activation ◽  
Concomitant Treatment ◽  
Dependent Manner ◽  
Akt Phosphorylation

Apoptosis and epithelial-mesenchymal transdifferentiation (EMT) occur in stressed tubular epithelial cells and contribute to renal fibrosis. Transforming growth factor (TGF)-β1 promotes these responses and we examined whether the processes were interdependent in vitro. Direct (caspase inhibition) and indirect [epidermal growth factor (EGF) receptor stimulation] strategies were used to block apoptosis during TGF-β1 stimulation, and the subsequent effect on EMT was assessed. HK-2 cells were exposed to TGF-β1 with or without preincubation with ZVAD-FMK (pan-caspase inhibitor) or concomitant treatment with EGF plus or minus preincubation with LY-294002 (PI3-kinase inhibitor). Cells were then assessed for apoptosis and proliferation by flow cytometry, crystal violet assay, and Western blotting. Markers of EMT were assessed by microscopy, immunofluorescence, real-time RT-PCR, Western blotting, PAI-1 reporter assay, and collagen gel contraction assay. TGF-β1 caused apoptosis and priming for staurosporine-induced apoptosis. This was blocked by ZVAD-FMK. However, ZVAD-FMK did not prevent EMT following TGF-β1 treatment. EGF inhibited apoptosis and facilitated TGF-β1 induction of EMT by increasing proliferation and accentuating E-cadherin loss. Additionally, EGF significantly enhanced TGF-β1-induced collagen I gel contraction. EGF increased Akt phosphorylation during EMT, and the prosurvival effect of this was confirmed using LY-294002, which reduced EGF-induced Akt phosphorylation and reversed its antiapoptotic and proproliferatory effects. TGF-β1 induces EMT independently of its proapoptotic effects. TGF-β1 and EGF together lead to EMT. EGF increases proliferation and resistance to apoptosis during EMT in a PI3-K Akt-dependent manner. In vivo, EGF receptor activation may assist in the selective survival of a transdifferentiated, profibrotic cell type.

EGF receptor ligands are a large fraction of in vitro branching morphogens secreted by embryonic kidney

1997 ◽  
Vol 273 (3) ◽  
pp. F463-F472 ◽  
Author(s):  
H. Sakurai ◽  
T. Tsukamoto ◽  
C. A. Kjelsberg ◽  
L. G. Cantley ◽  
S. K. Nigam
Keyword(s):  
Growth Factor ◽  
Egf Receptor ◽  
Transforming Growth Factor ◽  
Kinase Inhibitor ◽  
Collecting Duct ◽  
Branching Morphogenesis ◽  
Epithelial Cell Line ◽  
Egfr Ligands ◽  
Process Formation

Much attention has recently focused upon hepatocyte growth factor (HGF) as a potential regulator of epithelial branching morphogenesis. However, since neither the HGF nor c-met "knockout" mice show abnormal kidney branching morphogenesis, we sought to analyze the relative importance of HGF in in vitro branching morphogenesis compared with other factors secreted by the embryonic kidney. Exploiting an assay that employs kidney epithelial cells (murine inner medullary collecting duct, mIMCD3) seeded in collagen cocultured with the embryonic kidney, we found that a tyrosine kinase inhibitor that is highly specific for the epidermal growth factor (EGF) receptor (EGFR), tyrphostin AG1478, inhibited mIMCD3 cell process formation (an early step in branching tubulogenesis) by 40%, whereas high concentrations of neutralizing anti-HGF antibodies had a lesser effect (20% inhibition), suggesting that EGFR ligands account for a larger fraction of branching morphogens secreted by the embryonic kidney than HGF. In addition, when an embryonic epithelial cell line derived from c-met (-/-) mice was cocultured with the embryonic kidney, these c-met (-/-) cells underwent process formation. EGFR ligands but not HGF were able to induce branching tubulogenesis in these cells. All EGFR ligands tested, including EGF, transforming growth factor-alpha, heparin-binding EGF, betacellulin, and amphiregulin, induced mIMCD3 cell tubulogenesis. EGFR ligands caused upregulation of urokinase, urokinase receptor, and matrix metalloprotease-1, and tubulogenesis could be inhibited by the metalloprotease inhibitor 1,10-phenanthroline. Our results support the notion that multiple parallel and potentially redundant growth factor-dependent pathways regulate branching tubulogenesis.

115 RAT EPIDERMAL GROWTH FACTOR GENE EXPRESSION CONTROLLED BY PROGESTERONE DURING PREGNANCY

2008 ◽  
Vol 20 (1) ◽  
pp. 138
Author(s):  
H.-S. Byun ◽  
S.-H. Ko ◽  
G.-S. Lee ◽  
S.-H. Hyun ◽  
E.-B. Jeung
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Egf Receptor ◽  
Transforming Growth Factor ◽  
Expression Patterns ◽  
Uterine Wall ◽  
Mrna Levels ◽  
Heparin Binding ◽  
Pregnant Rats ◽  
Epidermal Growth

The implantation of the developing blastocyst into the uterine wall is regulated by a precisely timed interplay of the ovarian hormones estrogen and progesterone, which control a set of regulatory factors that make the uterus receptive to implantation. These factors include EGF receptor (Egfr) and members of the epidermal growth factor (Egf) family, namely, EGF, heparin-binding EGF (Hbegf), transforming growth factor-alpha (Tgfa), and amphiregulin (Areg). However, the exact role(s) these factors play in pregnancy remain unclear. To address this, a group of three rats was euthanized every day from gestation day (GD) 0 through to GD21. The uterus, attached uterus (these tissues are mostly composed of stromal cells), and placenta were rapidly excised and used directly for total RNA. We used real-time PCR with the TaqMan system (Applied Biosystems, Foster City, CA, ISA) to examine the uterine expression patterns of these factors in rats during the entire pregnancy. Data were analyzed by nonparametric one-way analysis of variance using the Kruskal-Wallis test, followed by Dunnett's test for multiple comparisons. Egf and Egfr mRNA levels increased significantly at implantation, especially on GD3 and GD6, after which their expression gradually decreased. Hbegf and Tgfa showed a modest spike of transcription around the implantation period (GD4 and GD3, respectively) but were much more strongly expressed at mid-pregnancy, which is when progesterone is secreted at high levels. Areg expression peaked strongly around implantation (GD4) and at mid-pregnancy (GD12). Treatment of pregnant rats on GD5 or GD8 with the progesterone receptor antagonist RU486 (2.5 mg per rat) blocked the expression of all of the genes on the days of treatment. Moreover, injection of immature rats with progesterone induced the uterine expression of all of the genes except Hbegf, while injection with estrogen or estrogen plus progesterone had no effect. Taken together, all genes tested may be assumed to regulate the implantation process. Moreover, Hbegf, Tgfa, and Areg may participate during mid-pregnancy. In addition, all of these activities are likely to be controlled by progesterone in the uterus of rats during pregnancy.

scholarly journals EGF antagonizes TGF-β-induced tropoelastin expression in lung fibroblasts via stabilization of Smad corepressor TGIF

2008 ◽  
Vol 295 (1) ◽  
pp. L143-L151 ◽  
Author(s):  
Shenghong Yang ◽  
Matthew A. Nugent ◽  
Mikhail P. Panchenko
Keyword(s):  
Growth Factor ◽  
Egf Receptor ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Lung Fibroblasts ◽  
Nuclear Accumulation ◽  
Mrna Levels ◽  
Erk Pathway ◽  
Transcriptional Corepressor ◽  
Egfr Ligands

We previously reported that neutrophil elastase (NE) downregulates transforming growth factor-β (TGF-β)-maintained tropoelastin mRNA levels in lung fibroblasts through transactivation of the epidermal growth factor (EGF) receptor (EGFR)/Mek/Erk pathway, which is dependent on the NE-initiated release of soluble EGFR ligands. In the present study, we investigated the mechanism by which EGF downregulates tropoelastin expression. We found that EGF downregulates tropoelastin expression through inhibition of TGF-β signaling. We show that EGF does not prevent the TGF-β-induced nuclear accumulation of Smad2/3; rather, EGF stabilizes the short-lived Smad transcriptional corepressor TG-interacting factor (TGIF) via EGFR/Mek/Erk-mediated phosphorylation of TGIF. Elevation of TGIF levels, either by TGIF overexpression or prevention of TGIF degradation, is sufficient to inhibit TGF-β-induced tropoelastin expression. Moreover, TGIF is essential for EGF-mediated downregulation of tropoelastin expression, inasmuch as small interfering RNA knockdown of TGIF blocked EGF-induced downregulation of tropoelastin. Finally, we demonstrated that NE treatment, which releases EGF-like growth factors, causes stabilization of TGIF through the EGFR/Mek/Erk pathway. These results suggest that EGFR/Mek/Erk signaling specifically antagonizes the proelastogenic action of TGF-β in lung fibroblasts by stabilizing the Smad transcriptional corepressor TGIF.

947: Chemopreventive Effects of COX-2 Inhibitor and Epidermal Growth Factor (EGF)-Receptor Kinase Inhibitor on Rat Urinary Bladder Tumorigenesis

2004 ◽  
Vol 171 (4S) ◽  
pp. 251-251
Author(s):  
Kazunori Hattori ◽  
Katsuyuki Iida ◽  
Akira Johraku ◽  
Sadamu Tsukamoto ◽  
Taeko Asano ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Urinary Bladder ◽  
Egf Receptor ◽  
Kinase Inhibitor ◽  
Receptor Kinase ◽  
Rat Urinary Bladder ◽  
Epidermal Growth ◽  
Cox 2

Met -/- kidneys express epithelial cells that chemotax and form tubules in response to EGF receptor ligands

1997 ◽  
Vol 272 (2) ◽  
pp. F222-F228
Author(s):  
C. Kjelsberg ◽  
H. Sakurai ◽  
K. Spokes ◽  
C. Birchmeier ◽  
I. Drummond ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epithelial Cell ◽  
Egf Receptor ◽  
Transforming Growth Factor ◽  
Growth Factor Receptor ◽  
Receptor Ligands ◽  
Tubule Formation ◽  
Human Papillomavirus 16 ◽  
Immortalized Cells

The growth factor/receptor combination of hepatocyte growth factor (HGF)/c-met has been postulated to be critical for mesenchymal-to-epithelial conversion and tubule formation in the developing kidney. We therefore isolated and immortalized cells from embryonic kidneys of met -/- transgenic mice to determine whether these cells were epithelial and able to chemotax and form tubules in vitro. The cells were immortalized with retrovirus expressing human papillomavirus 16 (HPV 16) E6/E7 genes. Two rapidly dividing clones were isolated and found to express the epithelial cell markers cytokeratin, zonula occludens-1, and E-cadherin but not to express the fibroblast marker vimentin. The met -/- cells were able to chemotax in response to epidermal growth factor and transforming growth factor-alpha (TGF-alpha) and form tubules in vitro in response to TGF-alpha but not HGF. These experiments suggest that the HGF/c-met axis is not essential for epithelial cell development in the embryonic kidney and demonstrate that other growth factors are capable of supporting early tubulogenesis.

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