title: Hypotonic stress promotes ATP release, reactive oxygen species production and cell proliferation via TRPV4 activation in rheumatoid arthritis rat synovial fibroblasts.
abstract: Rheumatoid arthritis (RA) is a chronic and systemic autoimmune-disease with complex and unclear etiology. Hypotonicity of synovial fluid is a typical characteristic of RA, which may play pivotal roles in RA pathogenesis. In this work, we studied the responses of RA synovial fibroblasts to hypotonic stress in vitro and further explored the underlying mechanisms. Data showed that hyposmotic solutions significantly triggered increases in cytosolic calcium concentration ([Ca2+]c) of synoviocytes. Subsequently, it caused rapid release of ATP, as well as remarkable production of intracellular reactive oxygen species (ROS). Meanwhile, hypotonic stimulus promoted the proliferation of synovial fibroblasts. These effects were almost abolished by calcium-free buffer and significantly inhibited by gadolinium (III) chloride (a mechanosensitive Ca2+channel blocker) and ruthenium red (a transient receptor potential vanilloid 4 (TRPV4) blocker). 4α-phorbol 12,13-didecanoate, a specific agonist of TRPV4, also mimicked hypotonic shock-induced responses shown above. In contrast, voltage-gated channel inhibitors verapamil and nifedipine had little influences on these responses. Furthermore, RT-PCR and western blotting evidently detected TRPV4 expression at mRNA and protein level in isolated synoviocytes. Taken together, our results indicated that hypotonic stimulus resulted in ATP release, ROS production, and cell proliferation depending on Ca2+entry through activation of TRPV4 channel in synoviocytes.
authors.affiliation: The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, TEDA Institute of Applied Physics, School of Physics, Nankai University, Tianjin, China.
authors.forename: Fen
authors.initials: F
authors.lastname: Hu
authors.affiliation: The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, TEDA Institute of Applied Physics, School of Physics, Nankai University, Tianjin, China.
authors.forename: Zhenhai
authors.initials: Z
authors.lastname: Hui
authors.affiliation: The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, TEDA Institute of Applied Physics, School of Physics, Nankai University, Tianjin, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wei
authors.affiliation: The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, TEDA Institute of Applied Physics, School of Physics, Nankai University, Tianjin, China.
authors.forename: Jianyu
authors.initials: J
authors.lastname: Yang
authors.affiliation: The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, TEDA Institute of Applied Physics, School of Physics, Nankai University, Tianjin, China.
authors.forename: Ziyuan
authors.initials: Z
authors.lastname: Chen
authors.affiliation: The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, TEDA Institute of Applied Physics, School of Physics, Nankai University, Tianjin, China.
authors.forename: Bu
authors.initials: B
authors.lastname: Guo
authors.affiliation: The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, TEDA Institute of Applied Physics, School of Physics, Nankai University, Tianjin, China.
authors.forename: Fulin
authors.initials: F
authors.lastname: Xing
authors.affiliation: The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, TEDA Institute of Applied Physics, School of Physics, Nankai University, Tianjin, China; Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi, China.
authors.forename: Xinzheng
authors.initials: X
authors.lastname: Zhang
authors.affiliation: The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, TEDA Institute of Applied Physics, School of Physics, Nankai University, Tianjin, China; The 2011 Project Collaborative Innovation Center for Biological Therapy, Nankai University, Tianjin, China. Electronic address: plt@nankai.edu.cn.
authors.forename: Leiting
authors.initials: L
authors.lastname: Pan
authors.affiliation: The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, TEDA Institute of Applied Physics, School of Physics, Nankai University, Tianjin, China.
authors.forename: Jingjun
authors.initials: J
authors.lastname: Xu
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001169:Arthritis, Experimental / Q000473:pathology; D001172:Arthritis, Rheumatoid / Q000473:pathology; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D007038:Hypotonic Solutions / Q000494:pharmacology*; D008297:Male; D009997:Osmotic Pressure; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013583:Synovial Membrane / Q000473:pathology; D050916:TRPV Cation Channels / Q000235:genetics / Q000378:metabolism*
chemical_list: D007038:Hypotonic Solutions; D017382:Reactive Oxygen Species; D050916:TRPV Cation Channels; C486577:Trpv4 protein, rat; D000255:Adenosine Triphosphate; D002118:Calcium
keywords: Hypotonic stimulus; Rheumatoid arthritis; Synovial fibroblasts; TRPV4 channel