Membrane cholesterol depletion reduces downstream signaling activity of the adenosine A2a receptor

Publication date: Available online 8 January 2019Source: Biochimica et Biophysica Acta (BBA) - BiomembranesAuthor(s): Claire McGraw, Lewen Yang, Ilya Levental, Edward Lyman, Anne Skaja-RobinsonAbstractCholesterol 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 A2aR, ligand dependent production of cAMP is reduced following membrane cholesterol depletion with methyl-beta-cyclodextrin (MβCD), indicating that adenosine A2a receptor (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.Graphical abstract

Source: Biochimica et Biophysica Acta (BBA) Biomembranes - January 8, 2019 Category: Biochemistry Source Type: research