Epidermal growth factor upregulates serotonin transporter in human intestinal epithelial cells via transcriptional mechanisms

Serotonin transporter (SERT) regulates extracellular availability of serotonin and is a potential pharmacological target for gastrointestinal disorders. A decrease in SERT has been implicated in intestinal inflammatory and diarrheal disorders. However, little is known regarding regulation of SERT in the intestine. Epidermal growth factor (EGF) is known to influence intestinal electrolyte and nutrient transport processes and has protective effects on intestinal mucosa. Whether EGF regulates SERT in the human intestine is not known. The present studies examined the regulation of SERT by EGF, utilizing Caco-2 cells grown on Transwell inserts as an in vitro model. Treatment with EGF from the basolateral side (10 ng/ml, 24 h) significantly stimulated SERT activity (∼2-fold, P < 0.01) and mRNA levels compared with control. EGF increased the activities of the two alternate promoter constructs for human SERT gene: SERT promoter 1 (hSERTp1, upstream of exon 1a) and SERT promoter 2 (hSERTp2, upstream of exon 2). Inhibition of EGF receptor (EGFR) tyrosine kinase activity by PD168393 (1 nM) blocked the stimulatory effects of EGF on SERT promoters. Progressive deletions of the SERT promoter indicated that the putative EGF-responsive elements are present in the −672/−472 region of the hSERTp1 and regions spanning −1195/−738 and −152/+123 of hSERTp2. EGF markedly increased the binding of Caco-2 nuclear proteins to the potential AP-1 cis-elements present in EGF-responsive regions of hSERTp1 and p2. Overexpression of c-jun but not c-fos specifically transactivated hSERTp2, with no effects on hSERTp1. Our findings define novel mechanisms of transcriptional regulation of SERT by EGF via EGFR at the promoter level that may contribute to the beneficial effects of EGF in gut disorders.

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Emergence of salivary gland cell lineage diversity suggests a role for androgen-independent epidermal growth factor receptor signaling

Journal of Cell Science ◽

10.1242/jcs.108.6.2205 ◽

1995 ◽

Vol 108 (6) ◽

pp. 2205-2212

Author(s):

E.M. Durban ◽

P.G. Nagpala ◽

P.D. Barreto ◽

E. Durban

Keyword(s):

Salivary Gland ◽

Growth Factor ◽

Epidermal Growth Factor ◽

Egf Receptor ◽

Cell Lineage ◽

Mrna Levels ◽

Receptor Signaling ◽

Receptor Mrna ◽

Epidermal Growth ◽

Lineage Diversity

Diversity of cell lineages within glandular organs is generated postnatally by differentiation of committed progenitor cells. Fundamental regulatory aspects of this process are not understood. The mouse submandibular salivary gland (SSG) served as model to assess the role of epidermal growth factor (EGF) receptor signaling during emergence of cell lineage diversity. Temporal fluctuations in EGF receptor mRNA levels coincident with crucial differentiative cell lineage transitions were revealed by RNase protection analyses. Between days 2 and 5, when proacinar cells are maturing and striated duct cells emerge, EGF receptor mRNA levels were highest and all differentiating cells exhibited EGF receptor immunoreactivity. EGF receptor mRNA levels then declined sharply and immunoreactivity became confined to ductal cells. At day 11 in male mice, and days 11 and 16 in females, a second increase in EGF receptor mRNA was detected coincident with emergence of granular convoluted tubule (GCT) cells. With completion of androgen-dependent GCT cell differentiation at the onset of puberty, EGF receptor mRNA levels and intensity of immunoreactivity decreased. Androgen effects on EGF receptor mRNA or immunoreactivity could not be detected. These temporally distinct patterns of EGF receptor expression suggest that this signaling pathway is a mechanism of potential importance in emergence of cell lineage diversity in a glandular organ.

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Asbestos-induced phosphorylation of epidermal growth factor receptor is linked to c-fos and apoptosis

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1999.277.4.l684 ◽

1999 ◽

Vol 277 (4) ◽

pp. L684-L693 ◽

Cited By ~ 29

Author(s):

Christine L. Zanella ◽

Cynthia R. Timblin ◽

Andrew Cummins ◽

Michael Jung ◽

Jonathan Goldberg ◽

...

Keyword(s):

Growth Factor ◽

Epidermal Growth Factor ◽

Egf Receptor ◽

Growth Factor Receptor ◽

Direct Interaction ◽

Mrna Levels ◽

Binding Studies ◽

Therapeutic Implications ◽

Asbestos Fibers ◽

Epidermal Growth

We examined the mechanisms of interaction of crocidolite asbestos fibers with the epidermal growth factor (EGF) receptor (EGFR) and the role of the EGFR-extracellular signal-regulated kinase (ERK) signaling pathway in early-response protooncogene (c- fos/c- jun) expression and apoptosis induced by asbestos in rat pleural mesothelial (RPM) cells. Asbestos fibers, but not the nonfibrous analog riebeckite, abolished binding of EGF to the EGFR. This was not due to a direct interaction of fibers with ligand, inasmuch as binding studies using fibers and EGF in the absence of membranes showed that EGF did not adsorb to the surface of asbestos fibers. Exposure of RPM cells to asbestos caused a greater than twofold increase in steady-state message and protein levels of EGFR ( P < 0.05). The tyrphostin AG-1478, which inhibits the tyrosine kinase activity of the EGFR, but not the tyrphostin A-10, which does not affect EGFR activity, significantly ameliorated asbestos-induced increases in mRNA levels of c- fos but not of c- jun. Pretreatment of RPM cells with AG-1478 significantly reduced apoptosis in cells exposed to asbestos. Our findings suggest that asbestos-induced binding to EGFR initiates signaling pathways responsible for increased expression of the protooncogene c- fos and the development of apoptosis. The ability to block asbestos-induced elevations in c- fos mRNA levels and apoptosis by small-molecule inhibitors of EGFR phosphorylation may have therapeutic implications in asbestos-related diseases.

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Prolactin inhibits epidermal growth factor (EGF)-stimulated signaling events in mouse mammary epithelial cells by altering EGF receptor function.

Molecular Biology of the Cell ◽

10.1091/mbc.4.8.773 ◽

1993 ◽

Vol 4 (8) ◽

pp. 773-780 ◽

Cited By ~ 16

Author(s):

S E Fenton ◽

L G Sheffield

Keyword(s):

Growth Factor ◽

Epidermal Growth Factor ◽

Epithelial Cells ◽

Egf Receptor ◽

Mammary Epithelial Cells ◽

Mammary Epithelial ◽

Mammary Tissue ◽

Mrna Levels ◽

Signaling Events ◽

Epidermal Growth

We have previously shown that lactogenic hormones stimulate epidermal growth factor (EGF) mRNA accumulation in mouse mammary glands in vivo and in mouse mammary epithelial cells (NMuMG line). However, our in vitro studies indicate that the lactogenic hormone prolactin (PRL) completely inhibits EGF-stimulated DNA synthesis. PRL does not alter cholera toxin or insulin-like growth factor-1-stimulated cell growth, thus the inhibition appears to be specific for EGF. Our current studies are designed to evaluate the effects of PRL on EGF-stimulated signaling events in the NMuMG cell line. Cells treated with PRL for 30 min demonstrated a loss of high affinity EGF-binding ability. After long-term PRL treatment (18 h) there was a decrease in EGF receptor (R) number, as determined by [125I]EGF binding. PRL treatment (8 h) also decreased EGF-R mRNA levels. An EGF-stimulated increase in EGF-R mRNA observed 2-4 h after treatment was decreased when PRL was added to the cultures. Furthermore, levels of EGF-stimulated tyrosine phosphorylation of the EGF-R (170 kDa) and phospholipase C gamma (145 kDa) are dramatically decreased in cells treated with PRL. Also of great interest was a decrease in EGF-stimulated c-myc mRNA in PRL-treated cells. We conclude that PRL is acting to down-regulate the EGF-R, thus limiting EGF-stimulated cell signaling in mammary tissue.

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Ontogeny of epidermal growth factor (EGF), EGF receptor (EGFR) and basic fibroblast growth factor (bFGF) mRNA levels in pancreas, liver, kidney, and skeletal muscle of pig

Domestic Animal Endocrinology ◽

10.1016/s0739-7240(97)00025-8 ◽

1997 ◽

Vol 14 (5) ◽

pp. 286-294 ◽

Cited By ~ 17

Author(s):

M. Peng ◽

M.-F. Palin ◽

S. Véronneau ◽

D. LeBel ◽

G. Pelletier

Keyword(s):

Skeletal Muscle ◽

Growth Factor ◽

Epidermal Growth Factor ◽

Fibroblast Growth Factor ◽

Basic Fibroblast Growth Factor ◽

Egf Receptor ◽

Mrna Levels ◽

Fibroblast Growth ◽

Epidermal Growth

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

Reproduction Fertility and Development ◽

10.1071/rdv20n1ab115 ◽

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.

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Amphiregulin Is Coordinately Expressed with Heparin-Binding Epidermal Growth Factor-Like Growth Factor in the Interstitial Smooth Muscle of the Human Prostate1

Endocrinology ◽

10.1210/endo.140.12.7221 ◽

1999 ◽

Vol 140 (12) ◽

pp. 5866-5875 ◽

Cited By ~ 21

Author(s):

Rosalyn M. Adam ◽

Joseph G. Borer ◽

B. Jill Williams ◽

James A. Eastham ◽

Kevin R. Loughlin ◽

...

Keyword(s):

Smooth Muscle ◽

Growth Factor ◽

Epithelial Cell ◽

Epidermal Growth Factor ◽

Epithelial Cells ◽

Egf Receptor ◽

Human Prostate ◽

Enzyme Analysis ◽

Mrna Levels ◽

Epidermal Growth

Abstract Peptide growth factors have been proposed as mediators of smooth muscle-epithelial cell interactions in the human prostate; however, the identity of these molecules has not been established. In this study, we compared expression levels of messenger RNAs (mRNAs) encoding the epidermal growth factor (EGF) receptor-related receptor tyrosine kinases (ErbB1 through 4), the six EGF receptor ligands, EGF, transforming growth factor (TGF)-α, amphiregulin (ARG), HB-EGF, betacellulin, and epiregulin, and the related molecule heregulin-α, in a series of 10 prostate tissue specimens. Only EGF showed a disease-specific association, with increased mRNA levels in four of five PCa specimens in comparison to matched normal tissue from the same subject. In contrast, ARG and HB-EGF mRNAs showed a coordinate pattern of expression in 7/10 specimens that was distinct from all other growth factor or receptor genes examined and from mRNAs for prostate specific antigen, the androgen receptor and GAPDH, a housekeeping enzyme. Analysis of an additional series of benign prostatic hyperplasia and prostate cancer specimens from 60 individuals confirmed that ARG and HB-EGF mRNA levels varied in a highly coordinate manner (r = 0.93; P < 0.0001) but showed no association with disease. ARG was immunolocalized largely to interstitial smooth muscle cells (SMC), previously identified as the site of synthesis of HB-EGF in the prostate, while the cognate ARG and HB-EGF receptor, ErbB1, was localized exclusively to ductal epithelial cells and carcinoma cells. Although ARG was a relatively poor mitogen for Balb/c3T3 cells in comparison to HB-EGF, it was similar in potency to HB-EGF in stimulating human prostate epithelial cell growth, suggesting that prostate epithelia may be a physiologic target for ARG in vivo. Expression of both ARG and HB-EGF mRNAs was induced in cultured prostate SMC by fibroblast growth factor-2, a human prostate SMC mitogen linked to prostate disease. These findings indicate that ARG and HB-EGF are likely to be key mediators of directional signaling between SMC and epithelial cells in the human prostate and appear to be coordinately regulated.

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