title: FXYD11 mediated modulation of Na(+)/K(+)-ATPase activity in gills of the brackish medaka (Oryzias dancena) when transferred to hypoosmotic or hyperosmotic environments.
abstract: FXYD proteins regulate Na(+)/K(+)-ATPase (NKA), which is a primary active pump that provides the driving force that triggers osmoregulatory systems in teleosts. To explore the regulatory mechanisms between FXYD and NKA in euryhaline teleosts, the expression of NKA (mRNA, protein, and activity) and FXYD11 and their interaction were examined in the gills of brackish medaka (Oryzias dancena) when transferred from brackish water (BW; 15‰) to fresh water (FW) or seawater (SW; 35‰). The mRNA expression of Odfxyd11 and Odnka-α was elevated 48h post-hypoosmotic transfer. Moreover, FXYD11 protein and NKA activity were upregulated 12h after transfer to FW. When transferred to SW, the protein abundance of FXYD11 and the NKA α-subunit did not show apparent changes, while Odfxyd11 and Odnka-α mRNA expression and NKA activity increased significantly 12h and 1h post-transfer, respectively. To clarify the FXYD11 mechanisms involved in modulating NKA activity via their interaction, co-immunoprecipitation was further applied to O. dancena gills. The results revealed that the levels of protein-protein interaction between branchial NKA and FXYD11 increased acutely 12h after the transfer from BW to FW. However, immediate upregulation of NKA activity 1h following post-exposure to SW, without the elevation of protein-protein interaction levels, was found. Hence, branchial NKA activity of O. dancena was suggested to be rapidly regulated by FXYD11 interaction with NKA when acclimated to hypoosmotic environments. To the best of our knowledge, this is the first study that focuses on the efficacy of interactions between FXYD11 and NKA in the gills of euryhaline teleosts.
authors.affiliation: Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan.
authors.forename: Chia-Hao
authors.initials: CH
authors.lastname: Chang
authors.affiliation: Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan.
authors.forename: Wen-Kai
authors.initials: WK
authors.lastname: Yang
authors.affiliation: National Institute for Basic Biology, NINS, Okazaki, Aichi 444-0864, Japan.
authors.forename: Chia-Hao
authors.initials: CH
authors.lastname: Lin
authors.affiliation: Tainan Hydraulics Laboratory, National Cheng Kung University, Tainan 709, Taiwan.
authors.forename: Chao-Kai
authors.initials: CK
authors.lastname: Kang
authors.affiliation: Graduate Institute of Marine Biology, National Dong Hwa University, Pingtung 944, Taiwan; National Museum of Marine Biology and Aquarium, Pingtung 944, Taiwan. Electronic address: wtang@mail.ndhu.edu.tw.
authors.forename: Cheng-Hao
authors.initials: CH
authors.lastname: Tang
authors.affiliation: Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan; Department of Biological Science and Technology, China Medical University, Taichung 404, Taiwan. Electronic address: thlee@email.nchu.edu.tw.
authors.forename: Tsung-Han
authors.initials: TH
authors.lastname: Lee
mesh_terms: D000818:Animals; D005880:Gills / Q000201:enzymology*; D009990:Oryzias; D009994:Osmolar Concentration; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
chemical_list: D000254:Sodium-Potassium-Exchanging ATPase
keywords: FXYD11; Gills; NKA; Oryzias dancena; Salinity