G protein specificity of inhibitory adrenergic a2a receptor‐mediated modulation of synaptic transmission

Abstract

Modulation of neurotransmitter exocytosis by activated Gi/o‐type G‐protein coupled receptors (GPCRs) is a universal regulatory mechanism used both to avoid overstimulation and to influence circuitry. One of the known modulation mechanisms is Gβγ and soluble N‐ethylmaleimide‐sensitive factor attachment protein receptor (SNARE) complex interaction. There are 5 Gβ and 12 Gγ subunits, but specific Gβγs activated by a given GPCR in vivo are not known. Presynaptic α2a‐adrenergic receptors (α2a‐ARs) in both adrenergic (auto α2a‐ARs) and non‐adrenergic neurons (hetero α2a‐ARs) inhibit neurotransmitter release and affect various physiological function such as anesthetic sparing and working memory enhancement. Here, we investigate whether auto α2a‐ARs in sympathetic neurons use the same Gbg subunits as hetero α2a‐ARs in other neuronal types to inhibit exocytosis by interacting with SNARE. Using several mice models including transgenic Flag‐α2a‐ARs, knock‐in HA‐α2a‐ARs, co‐immunoprecipitation, mass spectrometry analysis, we have determined the Gb and Gg subunits that interact with α2a‐ARs and SNARE complexes. So far, we find Gβ2 preferentially interacting with activated auto α2a‐ARs. We also see a basal Gβγ‐SNARE interaction and the 2 fold enhancement of this interaction upon the auto α2a‐ARs activation. Further understanding Gβγ specificity and Gβγ‐SNARE interaction may offer new insights into the normal functioning of the brain, as well as better understanding of disease progression.Support or Funding InformationThis work was supported by the National Institutes of Health (EY10291, MH101679, DK109204, and T32)