Substance P-induced trafficking of beta-arrestins - The role of beta-arrestins in endocytosis of the neutrokinin-1 receptor

Agonist-induced redistribution of G-protein-coupled receptors (GPCRs) and b eta-arrestins determines the subsequent cellular responsiveness to agonists and is important for signal transduction. We examined substance P (SP)-ind uced trafficking of beta-arrestin1 and the neurokinin-1 receptor (NK1R) in KNRK cells in real time using green fluorescent protein. Green fluorescent protein did not alter function or localization of the NK1R or beta-arrestin 1, SP induced (a) striking and rapid (<1 min) translocation of beta-arresti n1 from the cytosol to the plasma membrane, which preceded NK1R endocytosis ; (b) redistribution of the NK1R and beta-arrestin1 into the same endosomes containing SP and the transferrin receptor (2-10 min); (c) prolonged coloc alization of the NK1R and beta-arrestin1 in endosomes (>60 min); (d) gradua l resumption of the steady state distribution of the NK1R at the plasma mem brane and beta-arrestin1 in the cytosol (4-6 h), SP stimulated a similar re distribution of immunoreactive beta-arrestin1 and beta-arrestin2. In contra st, SP did not affect G alpha(q/11) distribution, which remained at the pla sma membrane. Expression of the dominant negative beta-arrestin(319-418) in hibited SP-induced endocytosis of the NK1R, Thus, SP induces rapid transloc ation of beta-arrestins to the plasma membrane, where they participate in N K1R endocytosis. beta-Arrestins colocalize with the NK1R in endosomes until the NK1R recycles and beta-arrestins return to the cytosol.