+ Site Statistics
References:
54,258,434
Abstracts:
29,560,870
PMIDs:
28,072,757
+ Search Articles
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ PDF Full Text
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Translate
+ Recently Requested

Regulation of expression of epidermal growth factor receptors in gonadotropes by epidermal growth factor and estradiol: studies in cycling female rats



Regulation of expression of epidermal growth factor receptors in gonadotropes by epidermal growth factor and estradiol: studies in cycling female rats



Endocrinology 138(12): 5434-5441



Changes in expression of epidermal growth factor (EGF) receptors by gonadotropes parallel those of GnRH receptors. Gonadotropes increase their expression of EGF receptors (EGFR) during diestrus to reach a peak on the morning of proestrus. This is followed by a decline in expression to reach a nadir by estrus. We hypothesized that regulatory factors that stimulate changes in GnRH receptors might mediate the same changes in EGFR. To test this hypothesis, pituitary cells were collected from cycling rats and grown overnight in media with or without serum, 100 pm estradiol, or 60 ng/ml activin. On the next day, some of the cultures were further stimulated with 1 nM GnRH (4 h). The cells were then dual-labeled for EGFR and LHbeta or FSHbeta antigens and analyzed for their content of EGFR and gonadotropins. Neither activin nor estradiol increased percentages of cells with gonadotropin antigens and EGFR. Estradiol decreased percentages of cells with EGFR and LH in proestrous rats and those with EGFR and FSH in diestrous rats. The estradiol-mediated decline in EGFR expression during proestrus is similar to that seen when GnRH receptors are studied. Serum containing media alone increased percentages of LH and FSH cells with EGFR in populations from estrous or metestrous rats. Therefore, further experiments were conducted to learn if serum factors or EGF might be a regulator. Removal of serum from the growth media did not prevent the increase in percentages of LH cells with EGFR over the 18-h growth period. However, removal of serum did prevent the increased percentages of FSH cells with EGFR. Similarly, adding 1:100 anti-EGF to the serum containing media did not affect expression of EGFR by LH cells. However, it did cause a 27% decrease in percentages of FSH cells with EGFR. Finally, when 10 ng/ml EGF was added to metestrous populations in serum free media there was a 1.4-1.5-fold increase in percentages of LH or FSH cells with EGFR. Collectively, these studies show that EGF receptors are not stimulated in gonadotropes by the same hormones that up-regulate GnRH receptors. Furthermore, EGF itself may be among the factors that up regulate EGFR in gonadotropes. EGF receptors may be down-regulated by estradiol during proestrus, but the effect is limited to LH cells. Finally, EGF's differential effects on LH and FSH cells suggests that it may selectively act on monohormonal gonadotropes. EGF receptors may be a marker for a unique subset of developing gonadotropes.

(PDF emailed within 0-6 h: $19.90)

Accession: 009321523

Download citation: RISBibTeXText

PMID: 9389529

DOI: 10.1210/endo.138.12.5620


Related references

Mda 648 a human breast cancer cell line with a high number of epidermal growth factor receptors has an amplified epidermal growth factor receptor gene and is growth inhibited by epidermal growth factor. Biochemical & Biophysical Research Communications 128(2): 898-905, 1985

Down regulation and its effect of epidermal growth factor receptors on the pharmacokinetics of human epidermal growth factor after i.v. administration in rats. International Journal of Pharmaceutics 54(3): 259-268, 1989

Down-regulation and its effect of epidermal growth factor receptors on the pharmacokinetics of human epidermal growth factor after i.v. administration in rats. International Journal of Pharmaceutics 54(3): 259-267, 1989

Cholera toxin potentiates down regulation of epidermal growth factor receptors by platelet derived growth factor and abrogates the requirement for epidermal growth factor in mitogenesis. Clinical Research 30(2): 488A, 1982

Effective inhibition of the epidermal growth factor/epidermal growth factor receptor binding by anti-epidermal growth factor antibodies is related to better survival in advanced non-small-cell lung cancer patients treated with the epidermal growth factor cancer vaccine. Clinical Cancer Research 14(3): 840-846, 2008

Quantitation of the mRNA expression of the epidermal growth factor system: selective induction of heparin-binding epidermal growth factor-like growth factor and amphiregulin expression by growth factor stimulation of prostate stromal cells. Journal of Laboratory and Clinical Medicine 136(3): 209-217, 2000

Tumor necrosis factor (TNF) up-regulates the expression of p75 but not p55 TNF receptors, and both receptors mediate, independently of each other, up-regulation of transforming growth factor alpha and epidermal growth factor receptor mRNA. Journal of Biological Chemistry 268(4): 2762-2766, 1993

Tumor necrosis factor (TNF) up-regulates the expression of p75 but not p55 TNF receptors, and both receptors mediate, independently of each other, up-regulation of transforming growth factor a and epidermal growth factor receptor mRNA. The Journal of Biological Chemistry 268: 62-6, 1993

Regulation of epidermal growth factor and insulin-like growth factor I receptors by estradiol and progesterone in normal and neoplastic endometrial cell cultures. Gynecologic Oncology 38(3): 396-406, 1990

Comparative studies of epidermal growth factor, epidermal growth factor, epidermal growth factor receptor, K-ras, and p53 in gallbladder carcinomas with and without an anomalous junction of pancreaticobiliary duct. Gastroenterology 108(4 SUPPL ): A417, 1995

Mitogenic response to epidermal growth factor relationship to number affinity and down regulation of epidermal growth factor receptors in 3 murine embryo cell lines. Journal of Supramolecular Structure 9(1): 41-46, 1978

Baculovirus-mediated expression of the epidermal growth factor-like modules of human factor IX fused to the factor XIIIa transamidation site in fibronectin. Evidence for a direct interaction between the NH2-terminal epidermal growth factor-like module of factor IXab and factor X. The Journal of Biological Chemistry 269: 90-7, 1994

Baculovirus-mediated expression of the epidermal growth factor-like modules of human factor IX fused to the factor XIIIa transamidation site in fibronectin. Evidence for a direct interaction between the NH2-terminal epidermal growth factor-like module of factor IXa beta and factor X. Journal of Biological Chemistry 269(5): 3690-3697, 1994

Ha-ras induction of the invasive phenotype results in up-regulation of epidermal growth factor receptors and altered responsiveness to epidermal growth factor in human papillary transitional cell carcinoma cells. Cancer Research 51(16): 4486-4491, 1991

Immunohistochemical study of estradiol, epidermal growth factor, transforming growth factor alpha and epidermal growth factor receptor in endometrial neoplasia. Japanese Journal of Clinical Oncology 26(6): 411-416, 1996