Homo- and hetero-oligomerization of thyrotropin-releasing hormone (TRH) receptor subtypes. Differential regulation of beta-arrestins 1 and 2.

Published

Journal Article

G-protein-coupled receptors (GPCRs) are regulated by a complex network of mechanisms such as oligomerization and internalization. Using the GPCR subtypes for thyrotropin-releasing hormone (TRHR1 and TRHR2), the aim of this study was to determine if subtype-specific differences exist in the trafficking process. If so, we wished to determine the impact of homo- and hetero-oligomerization on TRHR subtype trafficking as a potential mechanism for the differential cellular responses induced by TRH. Expression of either beta-arrestin 1 or 2 promoted TRHR1 internalization. In contrast, only beta-arrestin 2 could enhance TRHR2 internalization. The preference for beta-arrestin 2 by TRHR2 was supported by the impairment of TRHR2 trafficking in mouse embryonic fibroblasts (MEFs) from either a beta-arrestin 2 knockout or a beta-arrestin 1/2 knockout, while TRHR1 trafficking was only abolished in MEFs lacking both beta-arrestins. The differential beta-arrestin-dependence of TRHR2 was directly measured in live cells using bioluminescence resonance energy transfer (BRET). Both BRET and confocal microscopy were also used to demonstrate that TRHR subtypes form hetero-oligomers. In addition, these hetero-oligomers have altered internalization kinetics compared with the homo-oligomer. The formation of TRHR1/2 heteromeric complexes increased the interaction between TRHR2 and beta-arrestin 1. This may be due to conformational differences between TRHR1/2 hetero-oligomers versus TRHR2 homo-oligomers as a mutant TRHR1 (TRHR1 C335Stop) that does not interact with beta-arrestins, could also enhance TRHR2/beta-arrestin 1 interaction. This study demonstrates that TRHR subtypes are differentially regulated by the beta-arrestins and also provides the first evidence that the interactions of TRHRs with beta-arrestin may be altered by hetero-oligomer formation.

Full Text

Duke Authors

Cited Authors

  • Hanyaloglu, AC; Seeber, RM; Kohout, TA; Lefkowitz, RJ; Eidne, KA

Published Date

  • December 27, 2002

Published In

Volume / Issue

  • 277 / 52

Start / End Page

  • 50422 - 50430

PubMed ID

  • 12393857

Pubmed Central ID

  • 12393857

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.M209340200

Language

  • eng

Conference Location

  • United States