Functional coupling of mu-receptor-Galphai-tethered proteins in AtT20 cells.

Billy C. Chieng (1) , David J. Lee (1) , Yan P. Du (1) , Peregrine B. Osborne (1) , Macdonald J. Christie (1) , Dominique Massotte (2)

1 Pain Management Research Institute,
2 IGBMC - Institut de génétique et biologie moléculaire et cellulaire

Opioid efficacy on mu-receptor may be influenced by various Gi/o-G-protein subunits interacting with intracellular face of receptor. Pertussis toxin-insensitive Galphai1 and Galphai2 subunits tethered with mu-receptor were stably transfected into AtT20 cells to (i) determine coupling of different alpha-subunits on opioid efficacy, and (ii) determine coupling to downstream effectors, for example, calcium and potassium channels. After pertussis toxin, stimulation of [35S]GTP-gamma-S incorporation persisted. Both constructs were able to couple to native calcium and potassium channels, with endomorphins 1 and 2 equally effective. However, pertussis toxin abolished opioid actions on calcium and potassium channels suggesting strong coupling to endogenous G-proteins, and that differences in coupling efficacy to Galphai1 and Galphai2 previously observed are restricted to initial step of signaling cascade.

Billy C. Chieng, David J. Lee, Yan P. Du, Peregrine B. Osborne, Macdonald J. Christie, et al.. Functional coupling of mu-receptor-Galphai-tethered proteins in AtT20 cells.. NeuroReport, 2008, 19 (18), pp.1793-6. ⟨10.1097/WNR.0b013e3283196b55⟩. ⟨inserm-00384590⟩