title: Co-expression of pendrin, vacuolar H+-ATPase alpha4-subunit and carbonic anhydrase II in epithelial cells of the murine endolymphatic sac.
abstract: The endolymph in the endolymphatic sac (ES) is acidic (pH 6.6-7). Maintaining this acidic lumen is believed to be important for the normal function of the ES. The acid-base regulation mechanisms of the ES are unknown. Here we investigated the expression patterns of acid-base regulators, including vacuolar (v)H+-ATPase (proton pump), carbonic anhydrase (CA) II, and pendrin in the murine ES epithelium by immunohistochemistry (IHC) and compared their expression patterns by double immunostaining. We found that pendrin and vH+-ATPase were co-localized in the apical membrane of a specific type of ES epithelial cell. Pendrin- and vH+-ATPase-positive cells also expressed cytoplasmic CA II. Co-expression of pendrin, vH+-ATPase, and CA II in the same subgroup of ES cells suggests that this specific type of ES cell is responsible for the acid-base balance processes in the ES and pendrin, vH+-ATPase, and CA II are involved in these processes.
authors.affiliation: Center for Hearing and Deafness Research, Department of Pediatric Otolaryngology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, USA.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Dou
authors.forename: Jie
authors.initials: J
authors.lastname: Xu
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Wang
authors.forename: Annabel N
authors.initials: AN
authors.lastname: Smith
authors.forename: Manoocher
authors.initials: M
authors.lastname: Soleimani
authors.forename: Fiona E
authors.initials: FE
authors.lastname: Karet
authors.forename: John H
authors.initials: JH
authors.lastname: Greinwald
authors.forename: Daniel
authors.initials: D
authors.lastname: Choo
mesh_terms: D000818:Animals; D024402:Carbonic Anhydrase II / Q000096:biosynthesis*; D002352:Carrier Proteins / Q000096:biosynthesis*; D004712:Endolymphatic Sac / Q000166:cytology / Q000201:enzymology*; D004847:Epithelial Cells / Q000201:enzymology*; D005455:Fluorescent Antibody Technique; D007150:Immunohistochemistry; D026901:Membrane Transport Proteins; D051379:Mice; D021122:Protein Subunits / Q000096:biosynthesis; D000076988:Sulfate Transporters; D025262:Vacuolar Proton-Translocating ATPases / Q000096:biosynthesis*
chemical_list: D002352:Carrier Proteins; D026901:Membrane Transport Proteins; D021122:Protein Subunits; C085609:SLC26A4 protein, human; D000076988:Sulfate Transporters; D025262:Vacuolar Proton-Translocating ATPases; D024402:Carbonic Anhydrase II