Spinophilin stabilizes cell surface expression of α 2B-adrenergic receptors

Academic Article

Abstract

  • The third intracellular (3i) loops of the α - and α -adrenergic receptor (AR) subtypes are critical for retention of these receptors at the basolateral surface of polarized Madin-Darby canine kidney (MIICKII) cells at steady state. The third intracellular loops of the α , α , and α -AR subtypes interact with spinophilin, a multidomain protein that, like the three α -AR subtypes, is enriched at the basolateral surface of MDCKII cells. The present studies provide evidence that α -AR interaction with spinophilin contributes to cell surface stabilization of the receptor. We exploited the unique targeting profile of the α -AR subtype in MDCKII cells: random delivery to apical and basolateral surfaces with rapid (t ≤ 60 min) apical versus slower (t = 10-12 h) basolateral turnover. Apical delivery of a spinophilin subdomain containing the α -AR-interacting region (Sp151-483) by fusion with apically targeted p75 extended the half-life of α -AR at the apical surface to ∼3.6 h and eliminated the rapid phase (0-60 min) of α -AR turn-over on that surface. Furthermore, we examined α -AR turnover at the surface of mouse embryo fibroblasts derived from wild type (Sp ) or spinophilin knock-out (Sp ) mice. Two independent experimental approaches demonstrated that agonist-evoked internalization of HA-α -AR was accelerated in mouse embryo fibroblasts derived from Sp mice. These findings are consistent with the interpretation that endogenous spinophilin contributes to the stabilization of β -AR and presumably all three α -AR subtypes at the surface of target cells and may act as a scaffold that could link α -ARs to proteins interacting with spinophilin via other domains. 2A 2B 2A 2B 2C 2 2 2B 1/2 1/2 2 2B 2B 2B 2B 2B 2 2 NTR +/+ -/- -/-
  • Authors

    Published In

    Digital Object Identifier (doi)

    Author List

  • Brady AE; Wang Q; Colbran RJ; Allen PB; Greengard P; Limbird LE
  • Start Page

  • 32405
  • End Page

  • 32412
  • Volume

  • 278
  • Issue

  • 34