Environmental Health Perspectives 103, Supplement 7, October 1995

[Citation in PubMed]

The Other Estrogen Receptor in the Plasma Membrane: Implications for the Actions of Environmental Estrogens

Cheryl S. Watson,¹ Todd C. Pappas,¹ and Bahiru Gametchu²

¹Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston, Texas;
²Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin

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Abstract
Environmental or nutritional estrogenic toxicants are thought to mediate developmental and carcinogenic pathologies. Estrogen receptor (ER) measurements are currently used to predict hormonal responsiveness; therefore all ER subpopulations should be considered. We have been involved in the immunoidentification and characterization of membrane steroid receptors in several systems and have recently shown that binding of estradiol (E₂) to a subpopulation of ERs (mER) residing in the plasma membrane of GH₃ pituitary tumor cells mediates the rapid release of prolactin (PRL). Here we review these findings and present other important characterizations of these receptors such as trypsin and serum susceptibility, movement in the membrane, confocal localization to the membrane, binding to and function of impeded ligands, and immunoseparation of cells bearing mER. We plan to use this system as a model for both the physiological and pathological nongenomic effects of estrogens and estrogenic xenobiotics. Specifically, it should be useful as an in vitro assay system for the ability of estrogenic xenobiotics to cause rapid PRL release as an example of nongenomic estrogen effects. -- Environ Health Perspect 103(Suppl 7):41-50 (1995)

Key words: estrogen, plasma membrane, steroid receptor, xenobiotics, pituitary, nongenomic, prolactin

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This paper was presented at the Symposium on Estrogens in the Environment, III: Global Health Implications held 9-11 January 1994 in Washington, DC. Manuscripts received: March 15,1995; manuscripts accepted: April 4,1995.

We would like to acknowledge David Konkel for his thoughtful critique of this paper, Peter Moller for his assistance with fluorescence microscopy, Judy Yaniariello-Brown for immunocytochemistry advice, and Thomas J. Collins for RIA advice. Access to the confocal microscopy facilities and advice of M. Correia, N. Wills, S. Lewis, and their staff were greatly appreciated. This research was supported by the John Sealy Memorial Endowment Fund (awarded to C. S. W.).

Address correspondence to Dr. Cheryl S. Watson, Route F-45, Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston, TX 77555. Telephone (409) 772-2382. Fax (409) 772-2382. E-mail cswatson@beach.utmb.edu

Abbreviations used: ER, estrogen receptor; E₂, estradiol; mER, membrane ER; PRL, prolactin; Ab, antibody; mGR, membrane glucocorticoid receptor; SSM, serum supplemented medium; DM1, defined medium; PBS, phosphate buffered saline; RIA, radioimmunoassay; BSA, bovine serum albumin; PBSA, phosphate buffered saline with 1% bovine serum albumin.

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