Nuclear accumulation of epidermal growth factor in cultured rat pituitary cells

Nature ◽  
1980 ◽  
Vol 287 (5780) ◽  
pp. 340-343 ◽  
Author(s):  
L. K. Johnson ◽  
I. Vlodavsky ◽  
J. D. Baxter ◽  
D. Gospodarowicz
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Nuclear Accumulation ◽  
Pituitary Cells ◽  
Rat Pituitary ◽  
Epidermal Growth ◽  
Rat Pituitary Cells

Epidermal growth factor stimulates luteinizing hormone and arachidonic acid release in rat pituitary cells

1988 ◽  
Vol 57 (1-2) ◽  
pp. 157-162 ◽  
Author(s):  
Andrzej Przylipiak ◽  
Ludwig Kiesel ◽  
Thomas Rabe ◽  
Klaus Helm ◽  
Maria Przylipiak ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Growth Factor ◽  
Luteinizing Hormone ◽  
Epidermal Growth Factor ◽  
Pituitary Cells ◽  
Arachidonic Acid Release ◽  
Rat Pituitary ◽  
Epidermal Growth ◽  
Acid Release ◽  
Rat Pituitary Cells

Transcriptional down-regulation by epidermal growth factor of TRH receptor mRNA in rat pituitary cells

1995 ◽  
Vol 15 (1) ◽  
pp. 73-79 ◽  
Author(s):  
T Monden ◽  
M Yamada ◽  
S Konaka ◽  
T Satoh ◽  
H Ezawa ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Mrna Level ◽  
Pituitary Cells ◽  
Mrna Levels ◽  
Dependent Manner ◽  
R Gene ◽  
Binding Studies ◽  
Epidermal Growth ◽  
Rat Pituitary Cells

ABSTRACT To gain insight into the mechanism underlying the epidermal growth factor (EGF)-induced changes in responsiveness to TRH and in the numbers of TRH receptors (TRH-Rs) in the pituitary, we investigated the transcriptional regulation by EGF of the TRH-R gene in GH4C1 cells. Northern blot analyses and binding studies revealed that EGF reduced both TRH binding and TRH-R mRNA levels in a dose- and time-dependent manner, while no significant changes were observed in β-actin mRNA levels. Addition of actinomycin D caused an acute increase in the basal TRH-R mRNA level, and the rate of decrease of the TRH-R mRNA was identical in control and EGF-treated groups, suggesting that the stability of the TRH-R mRNA was not significantly affected in EGF-treated cells. Incubation with cycloheximide also induced an increase in the basal TRH-R mRNA level and completely reversed the EGF-induced reduction of TRH-R mRNA levels. Furthermore, a nuclear run-on assay demonstrated that the rate of transcription of the TRH-R gene was significantly inhibited in cells treated with EGF. We conclude that (1) EGF decreases the expression of the TRH-R mRNA largely by reducing its rate of transcription, and this action requires the synthesis of new proteins, and (2) inhibitors of protein and RNA synthesis cause a significant increase in the basal TRH-R mRNA level, suggesting that there may be a short-lived protein suppressing the TRH-R mRNA level in the pituitary.

scholarly journals Receptor-bound somatostatin and epidermal growth factor are processed differently in GH4C1 rat pituitary cells.

1986 ◽  
Vol 102 (3) ◽  
pp. 878-888 ◽  
Author(s):  
D H Presky ◽  
A Schonbrunn
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Cell Surface ◽  
Acid Treatment ◽  
Biological Effects ◽  
Membrane Receptors ◽  
Pituitary Cells ◽  
Rat Pituitary ◽  
Epidermal Growth ◽  
Initial Binding

GH4C1 cells, a clonal strain of rat pituitary tumor cells, have high-affinity, functional receptors for the inhibitory hypothalamic peptide somatostatin (SRIF) and for epidermal growth factor (EGF). In this study we have examined the events that follow the initial binding of SRIF to its specific plasma membrane receptors in GH4C1 cells and have compared the processing of receptor-bound SRIF with that of EGF. When cells were incubated with [125I-Tyr1]SRIF at temperatures ranging from 4 to 37 degrees C, greater than 80% of the specifically bound peptide was removed by extraction with 0.2 M acetic acid, 0.5 M NaCl, pH 2.5. In contrast, the subcellular distribution of receptor-bound 125I-EGF was temperature dependent. Whereas greater than 95% of specifically bound 125I-EGF was removed by acid treatment after a 4 degrees C binding incubation, less than 10% was removed when the binding reaction was performed at 22 or 37 degrees C. In pulse-chase experiments, receptor-bound 125I-EGF was transferred from an acid-sensitive to an acid-resistant compartment with a half-time of 2 min at 37 degrees C. In contrast, the small amount of [125I-Tyr1]SRIF that was resistant to acid treatment did not increase during a 2-h chase incubation at 37 degrees C. Chromatographic analysis of the radioactivity released from cells during dissociation incubations at 37 degrees C showed that greater than 90% of prebound 125I-EGF was released as 125I-tyrosine, whereas prebound [125I-Tyr1]SRIF was released as a mixture of intact peptide (55%) and 125I-tyrosine (45%). Neither chloroquine (0.1 mM), ammonium chloride (20 mM), nor leupeptin (0.1 mg/ml) increased the amount of [125I-Tyr1]SRIF bound to cells at 37 degrees C. Furthermore, chloroquine and leupeptin did not alter the rate of dissociation or degradation of prebound [125I-Tyr1]SRIF. In contrast, these inhibitors increased the amount of cell-associated 125I-EGF during 37 degrees C binding incubations and decreased the subsequent rate of release of 125I-tyrosine. The results presented indicate that, as in other cell types, EGF underwent rapid receptor-mediated endocytosis in GH4C1 cells and was subsequently degraded in lysosomes. In contrast, SRIF remained at the cell surface for several hours although it elicits its biological effects within minutes. Furthermore, a constant fraction of the receptor-bound [125I-Tyr1]SRIF was degraded at the cell surface before dissociation. Therefore, after initial binding of [125I-Tyr1]SRIF and 125I-EGF to their specific membrane receptors, these peptides are processed very differently in GH4C1 cells.

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