KLHL12-mediated ubiquitination of the dopamine D4 receptor does not target the receptor for degradation.
In previous studies, we identified KLHL12 as a novel interaction partner of the dopamine D4 receptor that functions as an adaptor in a Cullin3-based E3 ubiquitin ligase complex to target the receptor for ubiquitination. In this study, we show that KLHL12 promotes poly-ubiquitination of the receptor by performing ubiquitination assays in eukaryotic cells. Furthermore, we demonstrate that KLHL12 not only interacts with both immature, ER-associated and mature, plasma membrane-associated D4 receptors, but also promotes ubiquitination of both receptor subpools. Unexpectedly, however, KLHL12-mediated receptor ubiquitination does not promote proteasomal degradation of newly synthesized receptors through the ER-associated degradation pathway or lysosomal degradation of mature receptors. Moreover, our data reveal that D4 receptors do not undergo agonist-promoted ubiquitination or degradation, in contrast to many other G-protein-coupled receptors (GPCRs) indicating that ubiquitination of GPCRs does not defaultly lead to receptor degradation. Interestingly, KLHL12 does also interact with beta-arrestin2 but this has no effect on the ubiquitination or localization of beta-arrestin2 nor on the internalization of the D4 receptor.
Rondou
Pieter
P
Laboratory of Eukaryotic Gene Expression and Signal Transduction, Department of Physiology, Ghent University-UGent, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium.
Skieterska
Kamila
K
Packeu
Ann
A
Lintermans
Béatrice
B
Vanhoenacker
Peter
P
Vauquelin
Georges
G
Haegeman
Guy
G
Van Craenenbroeck
Kathleen
K
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D019390:Arrestins / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006801:Humans; D050638:Receptors, Dopamine D4 / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D054875:Ubiquitination; D000071557:beta-Arrestins
D048868:Adaptor Proteins, Signal Transducing; D019390:Arrestins; D000071557:beta-Arrestins; D050638:Receptors, Dopamine D4