title: Role of FKBP12.6 in hypoxia- and norepinephrine-induced Ca2+ release and contraction in pulmonary artery myocytes.
abstract: The cellular and molecular processes underlying the regulation of ryanodine receptor (RyR) Ca(2+) release in smooth muscle cells (SMCs) are incompletely understood. Here we show that FKBP12.6 proteins are expressed in pulmonary artery (PA) smooth muscle and associated with type-2 RyRs (RyR2), but not RyR1, RyR3, or IP(3) receptors (IP(3)Rs) in PA sarcoplasmic reticulum. Application of FK506, which binds to FKBPs and dissociates these proteins from RyRs, induced an increase in [Ca(2+)](i) and Ca(2+)-activated Cl(-) and K(+) currents in freshly isolated PASMCs, whereas cyclosporin, an agent known to inhibit calcineurin but not to interact with FKBPs, failed to induce an increase in [Ca(2+)](i). FK506-induced [Ca(2+)](i) increase was completely blocked by the RyR antagonist ruthenium red and ryanodine, but not the IP(3)R antagonist heparin. Hypoxic Ca(2+) response and hypoxic vasoconstriction were significantly enhanced in FKBP12.6 knockout mouse PASMCs. FK506 or rapamycin pretreatment also enhanced hypoxic increase [Ca(2+)](i), but did not alter caffeine-induced Ca(2+) release (SR Ca(2+) content) in PASMCs. Norepinephrine-induced Ca(2+) release and force generation were also markedly enhanced in PASMCs from FKBP12.6 null mice. These findings suggest that FKBP12.6 plays an important role in hypoxia- and neurotransmitter-induced Ca(2+) and contractile responses by regulating the activity of RyRs in PASMCs.
authors.affiliation: Center for Cardiovascular Sciences (MC-8), Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA.
authors.forename: Yun-Min
authors.initials: YM
authors.lastname: Zheng
authors.forename: Qi-Bing
authors.initials: QB
authors.lastname: Mei
authors.forename: Qing-Song
authors.initials: QS
authors.lastname: Wang
authors.forename: Iskandar
authors.initials: I
authors.lastname: Abdullaev
authors.forename: F Anthony
authors.initials: FA
authors.lastname: Lai
authors.forename: Hong-Bo
authors.initials: HB
authors.lastname: Xin
authors.forename: Michael I
authors.initials: MI
authors.lastname: Kotlikoff
authors.forename: Yong-Xiao
authors.initials: YX
authors.lastname: Wang
mesh_terms: D000818:Animals; D019703:Calcineurin / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D015687:Cell Hypoxia; D016572:Cyclosporine / Q000494:pharmacology; D006736:Horses; D007166:Immunosuppressive Agents / Q000378:metabolism; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology*; D011651:Pulmonary Artery / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology; D016559:Tacrolimus / Q000378:metabolism; D022021:Tacrolimus Binding Proteins / Q000235:genetics / Q000378:metabolism*; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology
chemical_list: D007166:Immunosuppressive Agents; D012333:RNA, Messenger; D019837:Ryanodine Receptor Calcium Release Channel; D016572:Cyclosporine; D019703:Calcineurin; D022021:Tacrolimus Binding Proteins; C403484:tacrolimus binding protein 1B; D002118:Calcium; D020123:Sirolimus; D016559:Tacrolimus; D009638:Norepinephrine