title: Regulation and intracellular trafficking pathways of the endothelin receptors.
abstract: The effects of endothelin (ET) are mediated via the G protein-coupled receptors ET(A) and ET(B). However, the mechanisms of ET receptor desensitization, internalization, and intracellular trafficking are poorly understood. The aim of the present study was to investigate the molecular mechanisms of ET receptor regulation and to characterize the intracellular pathways of ET-stimulated ET(A) and ET(B) receptors. By analysis of ET(A) and ET(B) receptor internalization in transfected Chinese hamster ovary cells in the presence of overexpressed betaARK, beta-arrestin-1, beta-arrestin-2, or dynamin as well as dominant negative mutants of these regulators, we have demonstrated that both ET receptor subtypes follow an arrestin- and dynamin/clathrin-dependent mechanism of internalization. Fluorescence microscopy of Chinese hamster ovary and COS cells expressing green fluorescent protein (GFP)-tagged ET receptors revealed that the ET(A) and ET(B) subtypes were targeted to different intracellular routes after ET stimulation. While ET(A)-GFP followed a recycling pathway and colocalized with transferrin in the pericentriolar recycling compartment, ET(B)-GFP was targeted to lysosomes after ET-induced internalization. Both receptor subtypes colocalized with Rab5 in classical early endosomes, indicating that this compartment is a common early intermediate for the two ET receptors during intracellular transport. The distinct intracellular routes of ET-stimulated ET(A) and ET(B) receptors may explain the persistent signal response through the ET(A) receptor and the transient response through the ET(B) receptor. Furthermore, lysosomal targeting of the ET(B) receptor could serve as a biochemical mechanism for clearance of plasma endothelin via this subtype.
authors.affiliation: Merck Sharp & Dohme Cardiovascular Research Center and Institute of Surgical Research, University of Oslo, The National Hospital, 0027 Oslo, Norway.
authors.forename: T
authors.initials: T
authors.lastname: Bremnes
authors.forename: J D
authors.initials: JD
authors.lastname: Paasche
authors.forename: A
authors.initials: A
authors.lastname: Mehlum
authors.forename: C
authors.initials: C
authors.lastname: Sandberg
authors.forename: B
authors.initials: B
authors.lastname: Bremnes
authors.forename: H
authors.initials: H
authors.lastname: Attramadal
mesh_terms: D000818:Animals; D019390:Arrestins / Q000502:physiology; D016466:CHO Cells; D019556:COS Cells; D002467:Cell Nucleus / Q000502:physiology; D006224:Cricetinae; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D034281:Dynamins; D019332:Endothelin-1 / Q000494:pharmacology* / Q000502:physiology; D020558:GTP Phosphohydrolases / Q000502:physiology; D049452:Green Fluorescent Proteins; D006801:Humans; D007700:Kinetics; D008164:Luminescent Proteins / Q000032:analysis / Q000235:genetics; D008247:Lysosomes / Q000502:physiology; D016297:Mutagenesis, Site-Directed; D010716:Phosphatidylinositols / Q000378:metabolism; D010766:Phosphorylation; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection; D051552:beta-Adrenergic Receptor Kinases; D000071559:beta-Arrestin 1; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins
chemical_list: C000605253:ARRB1 protein, human; C000605254:ARRB2 protein, human; D019390:Arrestins; D019332:Endothelin-1; D008164:Luminescent Proteins; D010716:Phosphatidylinositols; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin; D011993:Recombinant Fusion Proteins; D000071559:beta-Arrestin 1; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins; D049452:Green Fluorescent Proteins; D017868:Cyclic AMP-Dependent Protein Kinases; D051552:beta-Adrenergic Receptor Kinases; D020558:GTP Phosphohydrolases; D034281:Dynamins