HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Dai, X. Articles by Galligan, J. J. Search for Related Content PubMed PubMed Citation Articles by Dai, X. Articles by Galligan, J. J.

---

BASIC BIOLOGY

Differential Trafficking and Desensitization of Human ET_A and ET_B Receptors Expressed in HEK 293 Cells

Department of Pharmacology and Toxicology and the Neuroscience Program, Michigan State University, East Lansing, MI 48824

To whom requests for reprints should be addressed at ¹ Department of Pharmacology and Toxicology, Life Science Building Room B308, Michigan State University, East Lansing, MI 48824. E-mail: daixiaol{at}msu.edu

Abstract

Endothelin-1 (ET-1) is a vasoconstrictor peptide that acts on ET_A and ET_B receptors on smooth muscle cells (SMCs). Because vascular SMCs can express both receptors, it is difficult to study the localization and properties of each subtype. Therefore, we investigated the localization and function of ET_A and ET_B receptors transfected into HEK 293 cells. Immunocytochemistry was used to examine colocalization of ET receptors with the plasma membrane marker, pan cadherin. In cells transfected with ET_A receptors, 83 ± 2% of these receptors colocalized with pan cadherin. In ET_B receptor–transfected cells, 54 ± 2% of the receptor colocalized with pan cadherin. When ET_A and ET_B receptors were cotransfected, 97 ± 1% of ET_B receptors colocalized with ET_A receptors and 84 ± 2% of ET_B receptors colocalized with pan cadherin. ET-1 and sarafotoxin 6c (S6c, ET_B receptor agonist) increased [Ca²⁺]_i in cells transfected with ET_A or ET_B receptors; 100 nM of ET-1 and S6c caused maximal responses. When stimulated with ET-1, ET_B receptors desensitized faster (t_1/2 = 21 ± 1 sec) than ET_A receptors (t_1/2 = 48 ± 1 sec). S6c-induced increases in [Ca²⁺]_i desensitized in cells expressing ET_B receptors only (t_1/2 = 17 ± 1 s). Desensitization was eliminated in cells cotransfected with ET receptors. We conclude that ET_A receptors localize to the cell membrane, whereas ET_B receptors are in the membrane and intracellular compartments. Coexpressed ET receptors are in the membrane. ET_B receptors desensitize faster than ET_A receptors, but receptor coexpression eliminates desensitization. Finally, ET_A and ET_B receptors interact to change receptor trafficking which may modify ET receptor function in vascular SMCs coexpressing these receptors.

Key Words: desensitization • endothelin receptor • trafficking

This article has been cited by other articles:

				N. J. Evans and J. W. Walker Endothelin Receptor Dimers Evaluated by FRET, Ligand Binding, and Calcium Mobilization Biophys. J., July 1, 2008; 95(1): 483 - 492. [Abstract] [Full Text] [PDF]