title: Roles of Slc13a1 and Slc26a1 sulfate transporters of eel kidney in sulfate homeostasis and osmoregulation in freshwater.
abstract: Sulfate is required for proper cell growth and development of all organisms. We have shown that the renal sulfate transport system has dual roles in euryhaline eel, namely, maintenance of sulfate homeostasis and osmoregulation of body fluids. To clarify the physiological roles of sulfate transporters in teleost fish, we cloned orthologs of the mammalian renal sulfate transporters Slc13a1 (NaSi-1) and Slc26a1 (Sat-1) from eel (Anguilla japonica) and assessed their functional characteristics, tissue localization, and regulated expression. Full-length cDNAs coding for ajSlc13a1 and ajSlc26a1 were isolated from a freshwater eel kidney cDNA library. Functional expression in Xenopus oocytes revealed the expected sulfate transport characteristics; furthermore, both transporters were inhibited by mercuric chloride. Northern blot analysis, in situ hybridization, and immunohistochemistry demonstrated robust apical and basolateral expression of ajSlc13a1 and ajSlc26a1, respectively, within the proximal tubule of freshwater eel kidney. Expression was dramatically reduced after the transfer of eels from freshwater to seawater; the circulating sulfate concentration in eels was in turn markedly elevated in freshwater compared with seawater conditions (19 mM vs. 1 mM). The reabsorption of sulfate via the apical ajSlc13a1 and basolateral ajSlc26a1 transporters may thus contribute to freshwater osmoregulation in euryhaline eels, via the regulation of circulating sulfate concentration.
authors.affiliation: Dept. of Biological Sciences, Tokyo Institute of Technology, 4259-B-19 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Nakada
authors.forename: Kambiz
authors.initials: K
authors.lastname: Zandi-Nejad
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Kurita
authors.forename: Hisayuki
authors.initials: H
authors.lastname: Kudo
authors.forename: Vadjista
authors.initials: V
authors.lastname: Broumand
authors.forename: Charles Y
authors.initials: CY
authors.lastname: Kwon
authors.forename: Adriana
authors.initials: A
authors.lastname: Mercado
authors.forename: David B
authors.initials: DB
authors.lastname: Mount
authors.forename: Shigehisa
authors.initials: S
authors.lastname: Hirose
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D027321:Anion Transport Proteins / Q000235:genetics / Q000502:physiology*; D027682:Cation Transport Proteins / Q000235:genetics / Q000502:physiology; D004524:Eels / Q000097:blood / Q000378:metabolism / Q000502:physiology*; D005618:Fresh Water; D006706:Homeostasis / Q000502:physiology*; D007668:Kidney / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000378:metabolism; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000378:metabolism; D012623:Seawater; D000077003:Sodium Sulfate Cotransporter; D013431:Sulfates / Q000097:blood / Q000378:metabolism*; D027981:Symporters / Q000235:genetics / Q000502:physiology; D014018:Tissue Distribution; D014882:Water-Electrolyte Balance / Q000502:physiology*
chemical_list: D027321:Anion Transport Proteins; D027682:Cation Transport Proteins; D012333:RNA, Messenger; D000077003:Sodium Sulfate Cotransporter; D013431:Sulfates; D027981:Symporters