title: Ligand directed signaling differences between rodent and human κ-opioid receptors.
abstract: KOR activation of Gβγ dependent signaling results in analgesia, whereas the dysphoric effects of KOR agonists are mediated by a different pathway involving G protein receptor kinase and non-visual arrestin. Based on this distinction, a partial KOR agonist that does not efficiently activate arrestin-dependent biased signaling may produce analgesia without dysphoria. No KOR-selective partial agonists are currently available, and preclinical assessment is complicated by sequence differences between rodent (r) and human (h) KOR. In this study, we compared the signaling initiated by the available partial agonists. Pentazocine was significantly more potent at activating p38 MAPK in hKOR than rKOR expressed in HEK293 cells but equally potent at arrestin-independent activation of ERK1/2 in hKOR and rKOR. Similarly, butorphanol increased phospho-p38-ir in hKOR-expressing cells but did not activate p38 in rKOR-HEK293. Like pentazocine, butorphanol was equally efficacious at activating ERK1/2 in rKOR and hKOR. In contrast, levorphanol, nalorphine, and U50,488 did not distinguish between hKOR and rKOR in p38 MAPK activation. Consistent with its low potency at p38 activation, pentazocine did not produce conditioned place aversion in mice. hKOR lacks the Ser-369 phosphorylation site in rKOR required for G protein receptor kinase/arrestin-dependent p38 activation, but mutation of the Ser-358 to asparagine in hKOR blocked p38 activation without affecting the acute arrestin-independent activation of ERK1/2. This study shows that hKOR activates p38 MAPK through a phosphorylation and arrestin-dependent mechanism; however, activation differs between hKOR and rKOR for some ligands. These functional selectivity differences have important implications for preclinical screening of partial KOR agonists.
authors.affiliation: Department of Pharmacology, University of Washington, Seattle, Washington98195, USA.
authors.forename: Selena S
authors.initials: SS
authors.lastname: Schattauer
authors.forename: Mayumi
authors.initials: M
authors.lastname: Miyatake
authors.forename: Haripriya
authors.initials: H
authors.lastname: Shankar
authors.forename: Chad
authors.initials: C
authors.lastname: Zietz
authors.forename: Jamie R
authors.initials: JR
authors.lastname: Levin
authors.forename: Lee-Yuan
authors.initials: LY
authors.lastname: Liu-Chen
authors.forename: Vsevolod V
authors.initials: VV
authors.lastname: Gurevich
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Rieder
authors.forename: Charles
authors.initials: C
authors.lastname: Chavkin
mesh_terms: D019943:Amino Acid Substitution; D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics; D057809:HEK293 Cells; D006801:Humans; D008024:Ligands; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000235:genetics; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D010766:Phosphorylation / Q000187:drug effects / Q000235:genetics; D017473:Receptors, Opioid, kappa / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D013045:Species Specificity; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D000701:Analgesics, Opioid; D008024:Ligands; C515653:OPRK1 protein, human; D017473:Receptors, Opioid, kappa; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases