Agonist-induced internalization and mitogen-activated protein kinase activation of the human prostaglandin EP4 receptor

We examined the pathway of prostaglandin E-2 (PGE(2))-induced internalization of the prostaglandin EP4 receptor in HEK 293 cells. Co-expression of dominant negative beta -arrestin (319-418) or dynamin I (K44A) with the EP4 receptor reduced internalization. The activated receptor co-localized with GFP-arrestin 2 and GFP-arrestin 3, confirming the requirement for P-arrestins in internalization. Inhibition of clathrin-coated vesicle-mediated internalization resulted in inhibition of sequestration, whereas inhibition of caveola-mediated internalization had no effect. PGE2 stimulation of the EP4 receptor resulted in rapid mitogen-activated protein (MAP) kinase activation. Examination of an internalization-resistant mutant and co-expression of mutant accessory proteins with EP4 revealed that MAP kinase activation proceeds independently of internalization. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.