Differential secretory rhythm of growth hormone controls the number of hepatic epidermal growth factor receptors in the rat

1989 ◽  
Vol 123 (1) ◽  
pp. 75-81 ◽  
Author(s):  
M. Kashimata ◽  
M. Hiramatsu ◽  
N. Minami
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Female Rats ◽  
Male Rats ◽  
Normal Male ◽  
Scatchard Analysis ◽  
Normal Female ◽  
Egf Receptors ◽  
Gh Secretion ◽  
Epidermal Growth

ABSTRACT The effect of human GH (hGH) on hepatic epidermal growth factor (EGF) receptors in the rat was investigated. Continuous administration of hGH through an osmotic minipump, mimicking the female pattern of GH secretion, to normal male rats reduced the binding of 125I-labelled EGF to hepatic membranes to the normal female levels. The same treatment of hGH applied to hypophysectomized males had no apparent effect on EGF binding. Intermittent s.c. administration of hGH twice a day (every 12 h), mimicking the male pattern of GH secretion, to hypophysectomized male and/or normal female rats, caused a significant increase in EGF binding to the levels of normal male rats. Scatchard analysis of the binding data clearly showed that the change in EGF binding was due to a change in the number of EGF receptors. The results on the affinity labelling and phosphorylation of EGF receptors were in good agreement with those showing differences in the number of EGF receptors among the experimental groups. These results indicate that the number of hepatic EGF receptors in the rat is regulated by the differential secretory rhythm of pituitary GH between the sexes. Journal of Endocrinology (1989) 123, 75–81

Growth hormone regulates the rodent hepatic epidermal growth factor receptor at a pretranslational level

1989 ◽  
Vol 3 (2) ◽  
pp. 113-120 ◽  
Author(s):  
S. Johansson ◽  
B. Husman ◽  
G. Norstedt ◽  
G. Andersson
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Growth Factor Receptor ◽  
Female Rats ◽  
Male Rats ◽  
Intact Male ◽  
Male And Female ◽  
Male And Female Rats ◽  
Epidermal Growth

ABSTRACT Recent studies have implicated the involvement of pituitary factor(s) in the regulation of hepatic epidermal growth factor receptor (EGF-R) levels. In the present study the possible role of GH as a regulator of EGF-R has been examined by measuring hepatic EGF-R mRNA and EGF binding in intact and GH-deficient rats and mice before and after administration of GH. Using a human EGF-R probe, 10·5 and 6·0 kb transcripts were detected in mouse and rat liver by Northern gel analysis. EGF-R mRNA was quantified by solution hybridization, and EGF binding determined by incubation of 125I-labelled EGF with a low-density membrane fraction. Levels of hepatic EGF-R mRNA and binding of EGF in female rats were about two-thirds of those in male rats. GH-deficient (lit/lit) male and female mice had approximately 10 and 25% respectively of the levels of EGF-R mRNA and EGF binding of intact male and female mice. Furthermore, hypophysectomized rats exhibited a reduced level of EGF-R mRNA and EGF binding, corresponding to about 20% of the levels detected in intact male rats. When hypophysectomized male and female rats received recombinant human GH (hGH) either as intermittent injections or by continuous infusion using osmotic minipumps, the EGF-R mRNA and EGF binding levels increased to about half those of the intact male animals. No differences between intermittent or continuous administration of hGH on the induction of EGF-R mRNA or EGF binding could be seen. The correlation between mRNA and binding levels suggests regulation at a pretranslational level. There was a reduction of EGF-R mRNA to female levels when intact male rats were given hGH. An additional reduction of EGF binding levels was seen in both intact male and female rats exposed continuously to GH. This may indicate additional translational and/or post-translational regulatory mechanisms.

Evidence for epidermal growth factor (EGF)-induced intermolecular autophosphorylation of the EGF receptors in living cells

1990 ◽  
Vol 10 (8) ◽  
pp. 4035-4044
Author(s):  
A M Honegger ◽  
A Schmidt ◽  
A Ullrich ◽  
J Schlessinger
Keyword(s):  
Signal Transduction ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Tyrosine Phosphorylation ◽  
Egf Receptor ◽  
Living Cells ◽  
Egf Receptors ◽  
Receptor Molecule ◽  
Epidermal Growth ◽  
Negative Mutant

In response to epidermal growth factor (EGF) stimulation, the intrinsic protein tyrosine kinase of EGF receptor is activated, leading to tyrosine phosphorylation of several cellular substrate proteins, including the EGF receptor molecule itself. To test the mechanism of EGF receptor autophosphorylation in living cells, we established transfected cell lines coexpressing a kinase-negative point mutant of EGF receptor (K721A) with an active EGF receptor mutant lacking 63 amino acids from its carboxy terminus. The addition of EGF to these cells caused tyrosine phosphorylation of the kinase-negative mutant by the active receptor molecule, demonstrating EGF receptor cross-phosphorylation in living cells. After internalization the kinase-negative mutant and CD63 have separate trafficking pathways. This limits their association and the extent of cross-phosphorylation of K721A by CD63. The coexpression of the kinase-negative mutant together with active EGF receptors in the same cells suppressed the mitogenic response toward EGF as compared with that in cells that express active receptors alone. The presence of the kinase-negative mutant functions as a negative dominant mutation suppressing the response of active EGF receptors, probably by interfering with EGF-induced signal transduction. It appears, therefore, that crucial events of signal transduction occur before K721A and active EGF receptors are separated by their different endocytic itineraries.

Eicosanoids enhance epidermal growth factor receptor activation and proliferation in glomerular epithelial cells

1992 ◽  
Vol 262 (4) ◽  
pp. F639-F646 ◽  
Author(s):  
A. V. Cybulsky ◽  
P. R. Goodyer ◽  
M. D. Cyr ◽  
A. J. McTavish
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Epithelial Cells ◽  
Egf Receptor ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Receptor Activation ◽  
Scatchard Analysis ◽  
Glomerular Epithelial Cells ◽  
Epidermal Growth

Proliferation of glomerular epithelial cells (GEC) and release of prostaglandins (PG) and thromboxane (Tx) A2 may occur in glomerular injury. We studied the relationship of eicosanoids to epidermal growth factor (EGF)-induced proliferation of rat GEC in culture. After 48 h of serum-deprivation, EGF stimulated [3H]thymidine incorporation ninefold above serum-deprived cells. Inhibition of cyclooxygenase with indomethacin or of Txsynthase with OKY-046 decreased the proliferative effect of EGF by 50 and 38%, respectively. The effect of indomethacin was reversed by addition of PGE2. Synthesis of PGE2, PGF2 alpha, and TxA2 by serum-deprived GEC was not enhanced by EGF. Scatchard analysis of 125I-EGF binding to GEC demonstrated two populations of EGF receptors; the high-affinity site had a dissociation constant (Kd) of 444 pM and 24,864 receptors/cell. EGF receptor autophosphorylation (reflecting receptor activation) was studied by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting of GEC membrane proteins with anti-phosphotyrosine antibody. EGF increased phosphorylation of a protein of approximately 170 kDa, which comigrated with proteins immunoprecipitated from [35S]methionine-labeled GEC with antibodies to EGF receptor. Indomethacin and OKY-046 decreased the EGF-dependent phosphorylation of the 170-kDa protein, and this decrease was overcome by addition of PGE2. Indomethacin and OKY-046 did not, however, reduce 125I-EGF binding. Thus, in GEC, the basal synthesis of eicosanoids enhanced EGF-induced proliferation. This effect appears to be due to enhancement of EGF receptor activation.

scholarly journals Expression of Insulin-Like Growth Factor 1 (IGF-1) and Epidermal Growth Factor (EGF) Receptors and the Effect of IGF-1 and EGF on Androgen and Estrogen Release in the Myometrium of Pigs—In Vitro Study

Animals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 915 ◽  
Author(s):  
Ewa Monika Waszkiewicz ◽  
Wiktoria Kozlowska ◽  
Agata Zmijewska ◽  
Anita Franczak
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
In Vitro Study ◽  
Insulin Like Growth Factor ◽  
Egf Receptors ◽  
Mrna Transcripts ◽  
Female Reproductive Status ◽  
Epidermal Growth ◽  
Estradiol 17Β

Porcine myometrium possesses steroidogenic activity but its regulation is not well understood. It was hypothesized that the regulators of myometrial steroidogenesis are insulin-like growth factor 1 (IGF-1) and epidermal growth factor (EGF), which were found to modulate the steroidogenic activity of the endometrium and embryos. Myometrial slices were collected from gravid and nongravid pigs on days 10 or 11, 12 or 13 and 15 or 16 and studied for: (1) the relative abundance of IGF-1R and EGFR mRNA transcripts and proteins, to determine myometrial readiness to response growth factors treatment and (2) the effect of IGF-1 or EGF on the myometrial release of androstenedione (A4), testosterone (T), estrone (E1) and estradiol-17β (E2). The results showed that the relative expression and abundance of IGF-1R and EGFR in the myometrium were altered regarding the female reproductive status. During the estrous cycle, EGF increased myometrial release of A4 on days 12–13 and E2 on days 15–16. In gravid pigs (days 15–16), IGF-1 and EGF increased the E1 release. In conclusion: (1) porcine myometrium possesses the potential to respond to IGF-1 and EGF treatment, (2) EGF significantly increases myometrial A4 and E2 release in cyclic pigs, while IGF-1 and EGF increase the E1 release in gravid pigs.

Roles of epidermal growth factor and Na+/H+ exchanger-1 in esophageal epithelial defense against acid-induced injury

2006 ◽  
Vol 290 (4) ◽  
pp. G665-G673 ◽  
Author(s):  
Yasuhiro Fujiwara ◽  
Kazuhide Higuchi ◽  
Takashi Takashima ◽  
Masaki Hamaguchi ◽  
Tsuyoshi Hayakawa ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Epithelial Cells ◽  
Acid Reflux ◽  
Dependent Manner ◽  
Egf Receptors ◽  
Epithelial Proliferation ◽  
Epidermal Growth ◽  
Esophageal Epithelial Cells ◽  
Chronic Esophagitis

Epidermal growth factor (EGF) is predominantly secreted by salivary glands and activates Na+/H+ exchanger-1 (NHE-1), which regulates intracellular pH (pHi). We investigated the roles of EGF and NHE-1 in esophageal epithelial defense against acid using human esophageal epithelial cell lines and a rat chronic esophagitis model. Esophageal epithelial cells were incubated with acidified medium in the absence or presence of EGF. Cell viability and changes in pHi were measured. Chronic acid reflux esophagitis was induced in rats with and without sialoadenectomy. Esophageal lesion index, epithelial proliferation, and expression of EGF receptors and NHE-1 were examined. EGF protected esophageal epithelial cells against acid in a dose-dependent manner, and the cytoprotective effect of EGF was completely blocked by treatment with NHE-1 inhibitors. Tyrosine kinase, calmodulin, and PKC inhibitors significantly inhibited cytoprotection by EGF, whereas MEK, phosphatidylinositol 3-kinase, and PKA inhibitors had no effect. EGF significantly increased pHi recovery after NH4Cl pulse acidification, and this increase in pHi recovery was significantly blocked by inhibitors of calmodulin and PKC. Sialoadenectomy led to an increase in the severity of chronic esophagitis but affected neither epithelial proliferation nor expression of EGF receptors. Expression of NHE-1 mRNA was increased in esophagitis and upregulated in rats with sialoadenectomy. The increasing severity of esophagitis in rats with sialoadenectomy was prevented by exogenous administration of EGF. In conclusion, EGF protects esophageal epithelial cells against acid through NHE activation via Ca2+/calmodulin and the PKC pathway. Deficiency in endogenous EGF is associated with increased severity of esophagitis. EGF and NHE-1 play crucial roles in esophageal epithelial defense against acid.

Characterization and autoradiographic localization of the epidermal growth factor receptor in the jejunum of neonatal and weaned pigs

1992 ◽  
Vol 4 (2) ◽  
pp. 183 ◽  
Author(s):  
D Kelly ◽  
M McFadyen ◽  
TP King ◽  
PJ Morgan
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Binding Sites ◽  
Growth Factor Receptor ◽  
Saturation Curve ◽  
Egf Receptors ◽  
Weaned Pigs ◽  
Single Class ◽  
Epidermal Growth

Receptors for epidermal growth factor (EGF) were characterized on the intestinal membranes of newborn, sucking and weaned pigs. 125I-labelled EGF (125I-EGF) binding to membrane homogenates was time-dependent, saturable, linearly correlated to membrane protein and reversible. Analysis of saturation curve data revealed a single class of 125I-EGF binding sites in both newborn and weaned pigs. Receptor levels tended to be higher in weaned than in newborn pigs; the converse was true for the receptor affinity. In contrast, virtually no binding sites were found on the intestinal membranes of sucking pigs. Autoradiography in vitro of jejunal sections of newborn and weaned pigs demonstrated 125I-EGF receptors on both microvillar and basolateral surfaces of enterocytes, suggesting that luminal EGF could influence developmental processes in the intestine either directly or indirectly following transcytosis of the ligand.

Segmental distribution of epidermal growth factor binding sites in rabbit nephron

1990 ◽  
Vol 259 (4) ◽  
pp. F553-F558 ◽  
Author(s):  
M. D. Breyer ◽  
R. Redha ◽  
J. A. Breyer
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Transforming Growth Factor ◽  
Specific Binding ◽  
Rabbit Kidney ◽  
Egf Receptors ◽  
Collecting Ducts ◽  
Epidermal Growth ◽  
Sites Of Action ◽  
Convoluted Tubules

The kidney possesses epidermal growth factor (EGF) receptors and is a major site of synthesis for the EGF precursor, prepro-EGF. To examine the segmental localization of EGF receptors in the rabbit kidney, we characterized 125I-labeled EGF binding to micro-dissected rabbit nephron segments. Specific binding constituted 70-80% of total binding and was saturable with an apparent Kd of 8 nM. Kinetic studies (0 degrees C) revealed an association t1/2 of 20.7 min and a dissociation t1/2 of 27 min. Competition studies revealed that 125I-EGF binding was inhibited by unlabeled EGF or its homologue transforming growth factor-alpha, but not by parathyroid hormone or insulin. Mapping studies showed specific 125I-EGF binding (attomoles per centimeter) was highest in proximal straight tubules, followed by proximal convoluted tubules, cortical collecting ducts, inner medullary collecting ducts, outer medullary collecting ducts, and distal convoluted tubules. Specific binding to glomeruli was also observed. Interestingly, no specific binding of 125I-EGF to thick ascending limbs, a site of EGF precursor synthesis, was observed. These studies suggest potential sites of action for EGF in the rabbit kidney.

Specific receptors for epidermal growth factor in rat intestinal microvillus membranes

1988 ◽  
Vol 254 (3) ◽  
pp. G429-G435 ◽  
Author(s):  
J. F. Thompson
Keyword(s):  
Small Intestine ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Sodium Dodecyl ◽  
Intestinal Lumen ◽  
Scatchard Analysis ◽  
Rat Small Intestine ◽  
Binding Studies ◽  
Epidermal Growth ◽  
Specific Receptors

Epidermal growth factor (EGF) is present in high concentrations in milk, salivary, and pancreaticobiliary secretions. EGF, delivered to the intestinal lumen by these fluids, appears to influence intestinal proliferation. Because EGF exerts its mitogenic effect through binding to specific membrane-bound receptors, binding studies of 125I-labeled EGF to purified microvillus membrane (MVM) preparations from fetal, newborn, and adult rat small intestine were performed. Using the membrane filter technique, binding of 125I-EGF to adult MVM was specific, saturable, and reversible. Adult and fetal MVM binding was rapid and reached a plateau after 30 min at both 20 and 37 degrees C. No binding was detected at 4 degrees C. Specific binding increased linearly from 0 to 75 micrograms MVM protein. Scatchard analysis revealed a single class of receptors in fetal and adult MVM with an association constant of 1.0 +/- 0.35 X 10(9) and 2.3 +/- 1.6 X 10(9) M-1, respectively. Binding capacity was 435.0 +/- 89 and 97.7 +/- 41.3 fmol 125I-EGF bound/mg MVM protein for fetal and adult MVM, respectively. Newborn MVM binding was negligible. After binding, cross-linking utilizing disuccinimidyl suberate, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, autoradiography revealed a 170-kDa receptor. These data demonstrate specific receptors for EGF on MVM of rat small intestine and, thus, suggest a mechanism for the intraluminal regulation of enterocyte proliferation by EGF.

scholarly journals Loss of epidermal growth factor receptors and release of transforming growth factors do not correlate with sarcoma virus-transformation in clonally-related NIH/3T3-derived cell lines

1985 ◽  
Vol 229 (1) ◽  
pp. 119-125 ◽  
Author(s):  
K D Brown ◽  
D M Blakeley ◽  
P Roberts ◽  
R J Avery
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Cell Line ◽  
Conditioned Medium ◽  
Cell Lines ◽  
Egf Receptors ◽  
3T3 Cells ◽  
Sarcoma Virus ◽  
Epidermal Growth ◽  
Nih 3T3

Transformation of NIH/3T3 cells by Kirsten murine sarcoma virus (MSV) caused a dramatic reduction in the number of cell-surface receptors for epidermal growth factor (EGF). However, the number of EGF receptors remained at a very low level in a non-tumourigenic revertant cell line isolated from the virus-transformed cells, indicating that an increase in EGF receptors is not a requirement for the phenotypic reversion of Kirsten MSV-transformed 3T3 cells. Serum-free conditioned medium from normal and virus-transformed cell lines contained similar amounts of cell growth-promoting activity as assayed by the ability to stimulate DNA synthesis in quiescent Swiss 3T3 cell cultures. However, the concentrated conditioned medium from these cell lines showed no evidence of beta-transforming growth factor (TGF) activity as assayed by promotion of anchorage-independent growth of untransformed normal rat kidney (NRK) fibroblasts in agarose. The cellular release of alpha-TGF activity was assayed by measuring the ability of concentrated conditioned medium to inhibit the binding of 125I-EGF to Swiss 3T3 cells. Conditioned medium protein from the virus-transformed cell line inhibited 125I-EGF binding but only to the same extent as conditioned medium protein prepared from the untransformed cell line. The alpha-TGF secretion by these cell lines was estimated to be 30-45-fold lower than the level of alpha-TGF released by a well-characterized alpha-TGF-producing cell line (3B11). These results suggest that the induction of TGF release is not a necessary event in the transformation of NIH/3T3 cells by Kirsten MSV.

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