[Effects of organophosphorus insecticides on G protein-coupled receptor kinase-2 mediated phosphorylation of M2 muscarinic receptors].
OBJECTIVE
To explore the effect of organophosphorus insecticides (OPs) on G protein-coupled receptor kinase 2 mediated phosphorylation of M2 muscarinic receptors in vitro and to understand an alternative target of the OPs for human and other animals.


METHODS
The acetylcholine M2 muscarinic receptors (mAChR2) were purified from rat brain by single step affinity chromatography. In vitro experiments, the purified mAChR2, G-protein coupled receptor kinase 2 (GRK2) and the (gamma-p32) labeled ATP were incubated with paraoxon (PO), chlorpyrifos oxon (CPO) or chlorpyrifos (CPF) of varying concentrations. The proteins were separated by the polyacrylamide gel electrophoresis. The gels were dried and the phosphorylation of mAChR2 was detected with autoradiograms. Bands containing M2 receptor were excised and counted by liquid scintillation.


RESULTS
CPO inhibited phosphorylation of M2 muscarinic receptors by GRK2 with a median inhibition concentration (IC(50)) at 70 micromol/L. CPF also inhibited M2 receptors phosphorylation, but was less potent and less efficacious than that of CPO. PO and parathion (PT) had little effect on the receptor phosphorylation under the same conditions. CPO and CPF didn't inhibit the beta2 Adrenalin (beta2-AR) receptor phosphorylation also mediated by GRK2.


CONCLUSIONS
CPO and CPF can selectively inhibit the GRK2 mediated mAChR2 phosphorylation while PO and PT have no this effect.
Zou
Li-ming
LM
Department of Biochemistry and Molecular Biology, Shenyang Medical College, Shenyang 110034, China.
Li
Shu-yin
SY
Zhang
Jian
J
D000818:Animals; D004390:Chlorpyrifos / Q000031:analogs & derivatives* / Q000633:toxicity; D002800:Cholinesterase Inhibitors / Q000633:toxicity*; D054769:G-Protein-Coupled Receptor Kinase 2; D010261:Paraoxon / Q000633:toxicity*; D010766:Phosphorylation; D051381:Rats; D043585:Receptor, Muscarinic M2 / Q000378:metabolism*; D051552:beta-Adrenergic Receptor Kinases / Q000378:metabolism / Q000502:physiology*
D002800:Cholinesterase Inhibitors; D043585:Receptor, Muscarinic M2; C009618:O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphate; C496569:Grk2 protein, rat; D051552:beta-Adrenergic Receptor Kinases; D054769:G-Protein-Coupled Receptor Kinase 2; D004390:Chlorpyrifos; D010261:Paraoxon