Basolateral Localization and Transcytosis of Gonadotropin and Thyrotropin Receptors Expressed in Madin-Darby Canine Kidney Cells

doi:10.1074/jbc.272.8.5241

Basolateral Localization and Transcytosis of Gonadotropin and Thyrotropin Receptors Expressed in Madin-Darby Canine Kidney Cells*

From the Unité de Recherches Hormones et Reproduction, INSERM, Unité 135, Hôpital de Bicêtre, 94275 Le Kremlin Bicêtre, France

^‡ To whom correspondence should be addressed:
Hôpital de Bicêtre, 3ème niveau, 78 Rue du Général Leclerc, 94275 Le Kremlin Bicêtre, France.
Tel.: 33 (1) 45.21.33.29; Fax: 33 (1) 45.21.27.51.

Abstract

The thyrotropin (TSH) and follicle-stimulating hormone (FSH) receptors are present mainly on the basolateral cell surface in the thyroid gland and in Sertoli cells, whereas in ovarian and in testicular cells, the luteinizing hormone (LH) receptors are distributed throughout the cell surface. When expressed in Madin-Darby canine kidney (MDCK) cells, all three receptors accumulated at the basolateral cell surface showing that they carry the corresponding targeting signals. The receptors were directly delivered to the basolateral surface of the MDCK cells. A minor fraction of the gonadotropin receptors but not of TSH receptors was secondarily targeted to the apical surface through transcytosis. The mechanisms of basolateral targeting and transcytosis were analyzed using the FSH receptor as a model. Both were insensitive to brefeldin A and pertussis toxin. G_s activation by AlF₄⁻ and cholera toxin provoked a marked enhancement of FSH receptor transcytosis. The population of G_s proteins involved in this mechanism was different from that involved in signal transduction since neither FSH nor forskolin mimicked the effects of AlF₄⁻ and cholera toxin. G_s activation provoked a similar effect on LH receptor distribution in MDCK cells, whereas it did not modify the compartmentalization of the TSH receptor. Hormone-specific transcytosis was observed in MDCK cells expressing the gonadotropin (FSH and LH) receptors and was increased after cholera toxin administration.

Footnotes

↵* This work was supported in part by l'Institut National de la Santé et de la Recherche Médicale, l'Association pour la Recherche sur le Cancer, l'Unité de Formation et de Recherche Kremlin-Bicêtre, and l'Association de Recherches Scientifiques Paul Neumann. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

LH

luteinizing hormone

FSH

follicle-stimulating hormone

TSH

thyrotropin

hCG

human chorionic gonadotropin

FSHR

follicle-stimulating hormone receptor

LHR

luteinizing hormone receptor

TSHR

thyroid-stimulating hormone receptor

MDCK

Madin-Darby canine kidney

PAGE

polyacrylamide gel electrophoresis

PBS

phosphate-buffered saline

BSA

bovine serum albumin.
- Received August 5, 1996.
- Revision received October 25, 1996.