PT  - JOURNAL ARTICLE
AU  - Qin Wang
AU  - John R. Traynor
TI  - Modulation of Mu-Opioid Receptor Signaling by RGS19 in SH-SY5Y Cells
AID  - 10.1124/mol.112.081992
DP  - 2012 Nov 29
TA  - Molecular Pharmacology
PG  - mol.112.081992
4099  - http://molpharm.aspetjournals.org/content/early/2012/11/29/mol.112.081992.short
4100  - http://molpharm.aspetjournals.org/content/early/2012/11/29/mol.112.081992.full
AB  - Regulator of G protein signaling protein 19 (RGS19), also known as Gα interacting protein (GAIP) acts as a GTPase accelerating protein (GAP) for Gαz as well as Gαi/o subunits. Interactions with GIPN (GAIP-interacting protein N-terminus) and GIPC (GAIP-interacting protein C-terminus), link RGS19 to a variety of intracellular proteins. Here we show that RGS19 is abundantly expressed in human neuroblastoma SH-SY5Y cells that also express μ- and δ- opioid receptors (MOR and DOR, respectively) and nociceptin receptors (NOPR). Lentiviral delivery of short hairpin RNA (shRNA) specifically targeted to RGS19 reduced RGS19 protein levels by more than 69%, with a similar reduction in GIPC. In RGS19-depleted cells there was an increase in the ability of MOR (morphine) but not DOR (SNC80) or NOPR (nociceptin) agonists to inhibit forskolin-stimulated adenylyl cyclase and increase MAPK activity. Overnight treatment with either MOR (DAMGO or morphine) or DOR (DPDPE or SNC80) agonists increased RGS19 and GIPC protein levels in a time- and concentration-dependent manner. The MOR-induced increase in RGS19 protein was prevented by pretreatment with pertussis toxin or the opioid antagonist naloxone. PKC activation alone increased the level of RGS19 and inhibitors of PKC (Go6976) and MEK1 (PD98059), but not PKA (H89), completely blocked DAMGO-induced RGS19 protein accumulation. The findings show that RGS19 and GIPC are jointly regulated, that RGS19 is a GAP for MOR with selectivity over DOR and NOPR, and that chronic MOR or DOR agonist treatment increases RGS19 levels by a PKC and MAPK pathway-dependent mechanism.