Arrestin-independent internalization and recycling of the urotensin receptor contribute to long-lasting urotensin II-mediated vasoconstriction

Item Type:	Article
Title:	Arrestin-independent internalization and recycling of the urotensin receptor contribute to long-lasting urotensin II-mediated vasoconstriction
Creators Name:	Giebing, G. and Toelle, M. and Juergensen, J. and Eichhorst, J. and Furkert, J. and Beyermann, M. and Neuschaefer-Rube, F. and Rosenthal, W. and Zidek, W. and van der Giet, M. and Oksche, A.
Abstract:	Urotensin II (UII), which acts on the G protein-coupled urotensin (UT) receptor, elicits long-lasting vasoconstriction. The role of UT receptor internalization and intracellular trafficking in vasoconstriction has yet not been analyzed. Therefore, UII-mediated contractile responses of aortic ring preparations in wire myography and rat UT (rUT) receptor internalization and intracellular trafficking in binding and imaging analyses were compared. UII elicited a concentration-dependent vasoconstriction of rat aorta (-log EC50, mol/L:9.0+/-0.1). A second application of UII after 30 minutes elicited a reduced contraction (36+/-4% of the initial response), but when applied after 60 minutes elicited a full contraction. In internalization experiments with radioactive labeled VII ((125)I-UII), approximately 70% of rUT receptors expressed on the cell surface of human embryonic kidney 293 cells were sequestered within 30 minutes (half life [t(h)]: 5.6+/-0.2 minutes), but recycled quantitatively within 60 minutes (t(h) 31.9+/-2.6 minutes). UII-bound rUT receptors were sorted to early and recycling endosomes, as evidenced by colocalization of rUT receptors with the early endosomal antigen and the transferrin receptor. Real-time imaging with a newly developed fluorescent UII (Cy3-UII) revealed that rUT receptors recruited arrestin3 green fluorescent protein to the plasma membrane. Arrestin3 was not required for the endocytosis of the rUT receptor, however, as internalization of Cy3-UII was not altered in mouse embryonic fibroblasts lacking endogenous arrestin2/arrestin3 expression. The data demonstrate that the rUT receptor internalizes arrestin independently and recycles quantitatively. The continuous externalization of rUT receptors provides the basis for repetitive and lasting UII-mediated vasoconstriction.
Keywords:	Urotensin II, Vascular Tone, Urotensin Receptor, Recycling, Internalization, Animals, Mice, Rats
Source:	Circulation Research
ISSN:	0009-7330
Publisher:	American Heart Association
Volume:	97
Number:	7
Page Range:	707-715
Date:	30 September 2005
Official Publication:	https://doi.org/10.1161/01.RES.0000184670.58688.9F
PubMed:	View item in PubMed

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