Membrane cholesterol depletion reduces downstream signaling activity of the adenosine A 2A receptor

Biochim Biophys Acta Biomembr. 2019 Apr 1;1861(4):760-767. doi: 10.1016/j.bbamem.2019.01.001. Epub 2019 Jan 8.

Abstract

Cholesterol has been shown to modulate the activity of multiple G Protein-coupled receptors (GPCRs), yet whether cholesterol acts through specific interactions, indirectly via modifications to the membrane, or via both mechanisms is not well understood. High-resolution crystal structures of GPCRs have identified bound cholesterols; based on a β2-adrenergic receptor (β2AR) structure bound to cholesterol and the presence of conserved amino acids in class A receptors, the cholesterol consensus motif (CCM) was identified. Here in mammalian cells expressing the adenosine A2A receptor (A2AR), ligand dependent production of cAMP is reduced following membrane cholesterol depletion with methyl-beta-cyclodextrin (MβCD), indicating that A2AR signaling is dependent on cholesterol. In contrast, ligand binding is not dependent on cholesterol depletion. All-atom molecular simulations suggest that cholesterol interacts specifically with the CCM when the receptor is in an active state, but not when in an inactive state. Taken together, the data support a model of receptor state-dependent binding between cholesterol and the CCM, which could facilitate both G-protein coupling and downstream signaling of A2AR.

Keywords: Downstream signaling; G-protein coupled receptor; Ligand binding; Membrane protein; Simulation.

Publication types

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

MeSH terms

  • Cholestyramine Resin* / chemistry
  • Cholestyramine Resin* / metabolism
  • HEK293 Cells
  • Humans
  • Molecular Dynamics Simulation*
  • Receptor, Adenosine A2A* / chemistry
  • Receptor, Adenosine A2A* / metabolism
  • Signal Transduction*
  • beta-Cyclodextrins / chemistry

Substances

  • ADORA2A protein, human
  • Receptor, Adenosine A2A
  • beta-Cyclodextrins
  • methyl-beta-cyclodextrin
  • Cholestyramine Resin