Author:
Ge Mingli,Wu Li,He Feng,Tai Yu,Fang Ruhong,Han Dafei,Guo Paipai,Liu Hao,Hu Yong,Xu Shenglin,Wei Wei,Wang Qingtong
Abstract
AbstractIn essence, the β2 adrenergic receptor (β2AR) plays an antiproliferative role by increasing the intracellular cyclic 3’,5’-adenosine monophosphate (cAMP) concentration through Gαs coupling, but interestingly, β2AR antagonists are able to effectively inhibit fibroblast-like synoviocytes (FLSs) proliferation, thus ameliorating experimental RA, indicating that the β2AR signalling pathway is impaired in RA FLSs via unknown mechanisms. The local epinephrine (Epi) level was found to be much higher in inflammatory joints than in normal joints, and high-level stimulation with Epi or isoproterenol (ISO) directly promoted FLSs proliferation and migration due to impaired β2AR signalling and cAMP production. By applying inhibitor of receptor internalization, and small interfering RNA (siRNA) of Gαs and Gαi, and by using fluorescence resonance energy transfer and coimmunoprecipitation assays, a switch in Gαs-Gαi coupling to β2AR was observed in inflammatory FLSs as well as in FLSs with chronic ISO stimulation. This Gαi coupling was then revealed to be initiated by G protein coupled receptor kinase 2 (GRK2) but not β-arrestin2 or protein kinase A-mediated phosphorylation of β2AR. Inhibiting the activity of GRK2 with the novel GRK2 inhibitor paeoniflorin-6′-O-benzene sulfonate (CP-25), a derivative of paeoniflorin, or the accepted GRK2 inhibitor paroxetine effectively reversed the switch in Gαs-Gαi coupling to β2AR during inflammation and restored the intracellular cAMP level in ISO-stimulated FLSs. As expected, CP-25 significantly inhibited the hyperplasia of FLSs in a collagen-induced arthritis (CIA) model (CIA FLSs) and normal FLSs stimulated with ISO and finally ameliorated CIA in rats. Together, our findings revealed the pathological changes in β2AR signalling in CIA FLSs, determined the underlying mechanisms and identified the pharmacological target of the GRK2 inhibitor CP-25 in treating CIA.
Funder
the Program for Upgrading Basic and Clinical Collaborative Research of Anhui Medical University
the National Natural Science Foundation of China
the Anhui Provincial Natural Science Foundation for Distinguished Young Scholars
Collaborative Innovation Project of Key Scientific Research Platform in Anhui Universities
Anhui Provincial Key R&D Programs
Program for Upgrading Scientific Research Level of Anhui Medical University
Academic Funding for Top-notch Talents in University Disciplines (Majors) of Anhui Province
Publisher
Springer Science and Business Media LLC
Subject
Cell Biology,Molecular Biology,Biochemistry