title: Biological responses of osteocytic connexin 43 hemichannels to simulated microgravity.
abstract: Connexin 43 (Cx43) hemichannels and gap junctions in osteocytes are responsive to mechanical loading, which is important for bone formation and remodeling. However, the mechanism of these Cx43-forming channels in the process of mechanical unloading is still not very clear. In this study, unloading caused by weightlessness was simulated by using a random position machine (RPM). Osteocytic MLO-Y4 cells were subjected to 2 h of RPM treatment, and levels of Cx43 mRNA and total and cell surface expressed protein were determined by quantitative real-time PCR, western blotting, and biotinylation analysis. Although mRNA was elevated by RPM, total protein level of Cx43 was not altered; however, surface biotinylated Cx43 was significantly reduced. Interestingly, RPM promoted the retention of Cx43 in the Golgi apparatus detected by co-immunofluorescence with antibodies against Cx43 and 58 K Golgi marker protein. Dye uptake assay showed that hemichannels were induced open after RPM for 2 h. Consistently, prostaglandin E2release was increased and this increase was completely attenuated with the treatment of a Cx43 hemichannel blocking antibody. Together, this study demonstrates increased activity of Cx43 hemichannels to RPM, and active Cx43 hemichannels with prostaglandin E2release are likely to module biological function under simulated weightless conditions. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1195-1202, 2017.
authors.affiliation: Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi, China.
authors.forename: Huiyun
authors.initials: H
authors.lastname: Xu
authors.affiliation: Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi, China.
authors.forename: Ruofei
authors.initials: R
authors.lastname: Liu
authors.affiliation: Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi, China.
authors.forename: Dandan
authors.initials: D
authors.lastname: Ning
authors.affiliation: Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi, China.
authors.forename: Ruixin
authors.initials: R
authors.lastname: Yang
authors.affiliation: Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
authors.forename: Manuel A
authors.initials: MA
authors.lastname: Riquelme
authors.affiliation: Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi, China.
authors.forename: Jingbao
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
authors.forename: Jean X
authors.initials: JX
authors.lastname: Jiang
authors.affiliation: Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Shang
mesh_terms: D000818:Animals; D002460:Cell Line; D018031:Connexin 43 / Q000378:metabolism*; D015232:Dinoprostone / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D051379:Mice; D010011:Osteocytes / Q000378:metabolism*; D018474:Weightlessness Simulation
chemical_list: D018031:Connexin 43; C543076:GJA1 protein, mouse; D015232:Dinoprostone
keywords: connexin43; hemichannel; osteocyte; random position machine