title: TLR-Activated Gap Junction Channels Protect Mice against Bacterial Infection through Extracellular UDP Release.
abstract: Extracellular UDP (eUDP), released as a danger signal by stressed or apoptotic cells, plays an important role in a series of physiological processes. Although the mechanism of eUDP release in apoptotic cells has been well defined, how the eUDP is released in innate immune responses remains unknown. In this study, we demonstrated that UDP was released in both Escherichia coli-infected mice and LPS- or Pam3CSK4-treated macrophages. Also, LPS-induced UDP release could be significantly blocked by selective TLR4 inhibitor Atractylenolide I and selective gap junction inhibitors carbenoxolone and flufenamic acid (FFA), suggesting the key role of TLR signaling and gap junction channels in this process. Meanwhile, eUDP protected mice from peritonitis by reducing invaded bacteria that could be rescued by MRS2578 (selective P2Y6 receptor inhibitor) and FFA. Then, connexin 43, as one of the gap junction proteins, was found to be clearly increased by LPS in a dose- and time-dependent manner. Furthermore, if we blocked LPS-induced ERK signaling by U0126, the expression of connexin 43 and UDP release was also inhibited dramatically. In addition, UDP-induced MCP-1 secretion was significantly reduced by MRS2578, FFA, and P2Y6 mutation. Accordingly, pretreating mice with U0126 and Gap26 increased invaded bacteria and aggravated mice death. Taken together, our study reveals an internal relationship between danger signals and TLR signaling in innate immune responses, which suggests a potential therapeutic significance of gap junction channel-mediated UDP release in infectious diseases.
authors.affiliation: Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China.
authors.forename: Juliang
authors.initials: J
authors.lastname: Qin
authors.affiliation: Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China.
authors.forename: Guangxu
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China.
authors.forename: Binghe
authors.initials: B
authors.lastname: Tan
authors.affiliation: Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China.
authors.forename: Zhangsheng
authors.initials: Z
authors.lastname: Lv
authors.affiliation: Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China.
authors.forename: Mingyao
authors.initials: M
authors.lastname: Liu
authors.affiliation: Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Ren
authors.affiliation: Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China.
authors.forename: Min
authors.initials: M
authors.lastname: Qian
authors.affiliation: Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China bdu.ecnu@gmail.com.
authors.forename: Bing
authors.identifier: http://orcid.org/0000-0002-5402-6527
authors.initials: B
authors.lastname: Du
mesh_terms: D000818:Animals; D015153:Blotting, Western; D018031:Connexin 43 / Q000276:immunology* / Q000378:metabolism; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D004927:Escherichia coli Infections / Q000276:immunology*; D005260:Female; D017629:Gap Junctions / Q000276:immunology; D007113:Immunity, Innate; D017737:Macrophages, Peritoneal / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000276:immunology*; D051197:Toll-Like Receptor 4 / Q000276:immunology* / Q000378:metabolism; D051193:Toll-Like Receptors / Q000276:immunology / Q000378:metabolism; D014530:Uridine Diphosphate / Q000276:immunology* / Q000378:metabolism*
chemical_list: D018031:Connexin 43; C543076:GJA1 protein, mouse; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014530:Uridine Diphosphate