title: Modulation of mTOR Activity by μ-Opioid Receptor is Dependent upon the Association of Receptor and FK506-Binding Protein 12.
abstract: OBJECTIVE
  Mechanistic/mammalian target of rapamycin (mTOR) activation by μ-opioid receptor (OPRM1) participates in antinociceptive tolerance, hyperalgesia, and physical dependence. Our previous study also showed that mTOR activation by OPRM1 could attenuate β amyloid oligomers-induced neurotoxicity. OPRM1 is demonstrated to interact with FK506-binding protein 12 (FKBP12). It is our great interest to investigate whether OPRM1-mediated mTOR signaling is related to receptor-FKBP12 association.
  
  
  METHODS
  The activities of mTOR and its downstream effector p70 S6K were measured by immunoblotting their phosphorylation status. The interaction of receptor with mTOR was detected by co-immunoprecipitation and immunofluorescence.
  
  
  RESULTS
  OPRM1 activation by morphine-induced time-dependent mTOR activation. PI3K-specific inhibitor LY294002 only blocked the late phase of mTOR activation. However, morphine-induced mTOR activation was totally blocked at all time points in cells expressing FKBP12 association-deficient mutant receptor. FKBP12 knockdown also blocked morphine-induced mTOR activation. Further analysis demonstrated that morphine treatment enhanced the association of receptor with phosphorylated mTOR, whereas decreased association was observed after FKBP12 knockdown, mTOR inhibition or in cells expressing FKBP12 association-deficient mutant.
  
  
  CONCLUSIONS
  OPRM1-FKBP12 association played a key role in OPRM1-mediated mTOR activation, which could underlie the mechanisms of multiple physiological and pathological processes. Thus, our findings provide new avenue to modulating these processes.
authors.affiliation: Department of Pharmacology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China.|Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Pharmacology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Yan-Hui
authors.initials: YH
authors.lastname: Ge
authors.affiliation: Department of Pharmacology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Yan-Xia
authors.initials: YX
authors.lastname: Wang
authors.affiliation: Department of Pharmacology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Liu
authors.affiliation: Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Ping-Yee
authors.initials: PY
authors.lastname: Law
authors.affiliation: Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Horace H
authors.initials: HH
authors.lastname: Loh
authors.affiliation: Department of Pharmacology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Hong-Zhuan
authors.initials: HZ
authors.lastname: Chen
authors.affiliation: Department of Pharmacology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Qiu
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology*; D057809:HEK293 Cells; D006801:Humans; D047468:Immunoprecipitation; D009020:Morphine / Q000494:pharmacology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D017450:Receptors, Opioid, mu / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D022061:Tacrolimus Binding Protein 1A / Q000378:metabolism*; D014162:Transfection
chemical_list: D000701:Analgesics, Opioid; C485764:OPRM1 protein, human; D034741:RNA, Small Interfering; D017450:Receptors, Opioid, mu; D009020:Morphine; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D022061:Tacrolimus Binding Protein 1A
keywords: FK506-binding protein 12; Mechanistic/mammalian target of rapamycin; Protein interaction; μ-opioid receptor