The ADP ribosylation factor nucleotide exchange factor ARNO promotes beta-arrestin release necessary for luteinizing hormone/choriogonadotropin receptor desensitization

Proc Natl Acad Sci U S A. 2000 May 23;97(11):5901-6. doi: 10.1073/pnas.100127097.

Abstract

Desensitization of guanine nucleotide binding protein-coupled receptors is a ubiquitous phenomenon characterized by declining effector activity upon persistent agonist stimulation. The luteinizing hormone/choriogonadotropin receptor (LH/CGR) in ovarian follicles exhibits desensitization of effector adenylyl cyclase activity in response to the mid-cycle surge of LH. We have previously shown that uncoupling of the agonist-activated LH/CGR from the stimulatory G protein (G(s)) is dependent on GTP and attributable to binding of beta-arrestin present in adenylyl cyclase-rich follicular membrane fraction to the third intracellular (3i) loop of the receptor. Here, we report that LH/CGR-dependent desensitization is mimicked by ADP ribosylation factor nucleotide-binding site opener, a guanine nucleotide exchange factor of the small G proteins ADP ribosylation factors (Arfs) 1 and 6, and blocked by synthetic N-terminal Arf6 peptide, suggesting that the GTP-dependent step of LH/CGR desensitization is receptor-dependent Arf6 activation. Arf activation by GTP and ADP ribosylation factor nucelotide-binding site opener promotes the release of docked beta-arrestin from the membrane, making beta-arrestin available for LH/CGR; Arf6 but not Arf1 peptides block beta-arrestin release from the membrane. Thus, LH/CGR appears to activate two membrane delimited signaling cascades via two types of G proteins: heterotrimeric G(s) and small G protein Arf6. Arf6 activation releases docked beta-arrestin necessary for receptor desensitization, providing a feedback mechanism for receptor self-regulation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • ADP-Ribosylation Factor 6
  • ADP-Ribosylation Factors / chemistry
  • ADP-Ribosylation Factors / pharmacology
  • ADP-Ribosylation Factors / physiology
  • Adenylyl Cyclases / metabolism
  • Animals
  • Arrestins / metabolism*
  • Cell-Free System
  • Chorionic Gonadotropin / pharmacology*
  • Feedback
  • Female
  • GTP-Binding Protein alpha Subunits, Gs / physiology
  • GTPase-Activating Proteins / physiology*
  • Gonadotropins, Equine / pharmacology
  • Granulosa Cells / drug effects
  • Granulosa Cells / metabolism
  • Guanosine Triphosphate / physiology
  • Luteinizing Hormone / pharmacology*
  • Ovarian Follicle / metabolism
  • Ovulation Induction
  • Peptide Fragments / pharmacology
  • Protein Binding
  • Rats
  • Receptors, LH / metabolism*
  • Recombinant Fusion Proteins / physiology
  • Signal Transduction
  • Swine
  • beta-Arrestins

Substances

  • ADP-Ribosylation Factor 6
  • Arrestins
  • Chorionic Gonadotropin
  • GTPase-Activating Proteins
  • Gonadotropins, Equine
  • Peptide Fragments
  • Receptors, LH
  • Recombinant Fusion Proteins
  • beta-Arrestins
  • cytohesin-2
  • Guanosine Triphosphate
  • Luteinizing Hormone
  • GTP-Binding Protein alpha Subunits, Gs
  • ADP-Ribosylation Factors
  • Arf6 protein, rat
  • Adenylyl Cyclases