title: Lipopolysaccharide-induced serotonin transporter up-regulation involves PKG-I and p38MAPK activation partially through A3 adenosine receptor.
abstract: Serotonin transporter (SERT) is a critical determinant of synaptic serotonin (5-hydroxytryptamine, 5-HT) inactivation which plays a critical role in the pathology of depression and other mood disorders. Lipopolysaccharide (LPS), a potent activator of the inflammatory system, has been reported to cause depression symptoms by the modulation of SERT in vivo and in vitro. This study is aimed to investigate the underlying mechanism of LPS-induced SERT modulation. The 4-(4-(dimethylamino) styryl)-N-methylpyridinium iodide (ASP) assay was used to detect dynamic 5-HT uptake as read out of SERT activities in RBL-2H3 cells, and cytosol Ca(2+) concentrations ([Ca(2+)]i) and nitric oxide (NO) were examined. Using specific cyclic GMP-dependent protein kinase type I (PKG-I), p38 mitogen-activated protein kinases (p38MAPK) and A3 adenosine receptor (A3AR) inhibitors, SERT expression was evaluated by western blot and immunofluorescence analysis. Results showed that 24 h treatment with LPS stimulated 5-HT transport and up-regulate plasma membrane distribution of SERT in RBL-2H3 cells. LPS treatment increased NO and [Ca(2+)]i, and led to significant increases in levels of phosphorylated calcium/calmodulin-dependent protein kinase type II (CaMK-II), inducible NOS (iNOS) and PKG-I as well as active p38 MAPK. Moreover, PKG-I inhibitor KT5823 or p38MAPK inhibitor SB203580 respectively impaired SERT activation and transposition to plasma membrane by LPS. Notably, A3 adenosine receptor inhibitor MRS1191 also hindered SERT stimulation by LPS. In conclusion, LPS-induced 5-HT uptake and transposition to plasma membrane of SERT in RBL-2H3 cells involves CaMK-II/iNOS/PKG-I and p38 MAPK activation, which may be partially mediated by A3 adenosine receptor activation. This finding provides a novel insight into the interrelationship between LPS and depression.
authors.affiliation: Beijing Key Laboratory of Drug Target and Screening Research, Institute of Materia Medica, Chinese Academy of MedicalSciences & Peking Union Medical College.
authors.forename: Rui
authors.initials: R
authors.lastname: Zhao
authors.forename: Shoubao
authors.initials: S
authors.lastname: Wang
authors.forename: Zhonglin
authors.initials: Z
authors.lastname: Huang
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Xiuying
authors.initials: X
authors.lastname: Yang
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Bai
authors.forename: Dan
authors.initials: D
authors.lastname: Zhou
authors.forename: Zhizhen
authors.initials: Z
authors.lastname: Qin
authors.forename: Guanhua
authors.initials: G
authors.lastname: Du
mesh_terms: D058918:Adenosine A3 Receptor Antagonists / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D062965:Cyclic GMP-Dependent Protein Kinase Type I / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008954:Models, Biological; D009569:Nitric Oxide / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D043684:Receptor, Adenosine A3 / Q000502:physiology*; D012701:Serotonin / Q000378:metabolism; D050486:Serotonin Plasma Membrane Transport Proteins / Q000378:metabolism*; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D058918:Adenosine A3 Receptor Antagonists; D008070:Lipopolysaccharides; D043684:Receptor, Adenosine A3; D050486:Serotonin Plasma Membrane Transport Proteins; D009569:Nitric Oxide; D012701:Serotonin; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D048051:p38 Mitogen-Activated Protein Kinases; D002118:Calcium