title: Cellular localization of THIK-1 (K(2P)13.1) and THIK-2 (K(2P)12.1) K channels in the mammalian kidney.
abstract: K(+)-channels fulfill several important functions in the mammalian kidney such as volume regulation, recirculation and secretion of K(+) ions, and maintaining the resting potential. In this study we used immunocytochemical methods, in situ hybridization, and nephron segment-specific RT-PCR to obtain a detailed picture of the cellular localization of two tandem pore domain potassium (K(2P)) channels, THIK-1 (K(2P)13.1, KCNK13) and THIK-2 (K(2P)12.1, KCNK12). Monospecific antibodies against C-terminal domains of rat THIK-1 and THIK-2 proteins (GST-fusion proteins) were raised in rabbits, freed from cross-reactivity, and affinity purified. All antibodies were validated by Western blot analysis, competitive ELISA, and preabsorption experiments. The expression of THIK channels in specific nephron segments was confirmed by double staining with marker proteins. Results indicate that in rat and mouse THIK-1 and THIK-2 were expressed in the proximal tubule (PT), thick ascending limb (TAL), connecting tubule (CNT), and cortical collecting duct (CCD). In human kidney THIK-1 and THIK-2 were localized in PT, TAL and CCD. Immunostaining of rat tissue revealed an intracellular expression of THIK-1 and THIK-2 throughout the identified nephron segments. However in mouse kidney THIK-2 was identified in basolateral membranes. Overall, the glomerulus, thin limbs and medullary collecting ducts were devoid of THIK-1 and THIK-2 signal. In summary, THIK-1 and THIK-2 are abundantly expressed in the proximal and distal nephron of the mammalian kidney.
authors.affiliation: Institute of Anatomy, Cardio-Renal Unit, Charite Universitatsmedizin Berlin, Berlin, Germany. franziska.theilig@charite.de
authors.forename: Franziska
authors.initials: F
authors.lastname: Theilig
authors.forename: Irena
authors.initials: I
authors.lastname: Goranova
authors.forename: Jochen R
authors.initials: JR
authors.lastname: Hirsch
authors.forename: Martin
authors.initials: M
authors.lastname: Wieske
authors.forename: Semanur
authors.initials: S
authors.lastname: Unsal
authors.forename: Sebastian
authors.initials: S
authors.lastname: Bachmann
authors.forename: Rudiger W
authors.initials: RW
authors.lastname: Veh
authors.forename: Christian
authors.initials: C
authors.lastname: Derst
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002460:Cell Line; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007668:Kidney / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D008954:Models, Biological; D009893:Opossums; D024683:Potassium Channels, Tandem Pore Domain / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000906:Antibodies; C486603:KCNK13 protein, human; C430726:Kcnk12 protein, rat; C486604:Kcnk13 protein, mouse; C430725:Kcnk13 protein, rat; D024683:Potassium Channels, Tandem Pore Domain