Calcium/calmodulin-dependent protein kinase II supports morphine antinociceptive tolerance by phosphorylation of glycosylated phosducin-like protein.
The long isoform of the phosducin-like protein (PhLPl) is widely expressed in the brain and it is thought to influence G-protein signalling by regulating the activity of Gbetagamma dimers. We show that in the mature nervous system, PhLPl exists as both a 38kDa non-glycosylated isoform and as glycosylated isoforms of about 45, 100 and 150kDa. Additionally, neural PhLPl is subject to serine phosphorylation, which augments upon the activation of Mu-opioid receptors (MORs), as does its association with Gbetagamma subunits and 14-3-3 proteins. While the intracerebroventricular (icv) administration of morphine to mice rapidly reduced the association of MORs with G proteins, it increased the serine phosphorylation of these receptors. Moreover, activated Ca2+/calmodulin-dependent protein kinase II (CaMKII) accumulated in the MOR environment and phosphorylated PhLPl was seen to co-precipitate with these opioid receptors. Opioid-induced phosphorylation of PhLPl was impaired by inhibiting the activity of CaMKII and, in these circumstances, the association of PhLPl with Gbetagamma dimers and 14-3-3 proteins was diminished. Furthermore, these events were coupled with the recovery of G protein regulation by the MORs, while there was a decrease in serine phosphorylation of these receptors and morphine antinociceptive tolerance diminished. It seems that CaMKII phosphorylation of PhLPl stabilizes the PhLPl.Gbetagamma complex by promoting its binding to 14-3-3 proteins. When this complex fails to bind to 14-3-3 proteins, the association of PhLPl with Gbetagamma is probably disrupted by GalphaGDP subunits and the MORs recover control on G proteins.
Sánchez-Blázquez
Pilar
P
Neuropharmacology, Cajal Institute, Avd. Doctor Arce 37, Madrid E28002, Spain.
Rodríguez-Muñoz
María
M
Montero
Carlos
C
de la Torre-Madrid
Elena
E
Garzón
Javier
J
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D004361:Drug Tolerance / Q000502:physiology; D015180:Electrophoresis, Gel, Two-Dimensional; D054769:G-Protein-Coupled Receptor Kinase 2 / Q000378:metabolism; D006031:Glycosylation; D007074:Immunoglobulin G / Q000096:biosynthesis / Q000235:genetics; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D018832:Molecular Chaperones; D009020:Morphine / Q000494:pharmacology*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010147:Pain Measurement / Q000187:drug effects; D010766:Phosphorylation; D011930:Reaction Time / Q000187:drug effects; D017450:Receptors, Opioid, mu / Q000187:drug effects / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism
D000701:Analgesics, Opioid; D002352:Carrier Proteins; D007074:Immunoglobulin G; D018832:Molecular Chaperones; D009419:Nerve Tissue Proteins; C498319:Pdcl protein, mouse; D017450:Receptors, Opioid, mu; D012694:Serine; D009020:Morphine; C496568:GRK2 protein, mouse; D054769:G-Protein-Coupled Receptor Kinase 2; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2