title: Expression of Na+/H+ exchanger isoforms in normal human nasal epithelial cells and functional activity of Na+/H+ exchanger 1 in intracellular pH regulation.
abstract: CONCLUSIONS
  Both the mRNA and protein of NHE1, -2 and -3 were expressed in NHNE cells. NHE1 is a major NHE isoform which is expressed in the basolateral membranes of NHNE cells.
  
  
  OBJECTIVE
  Na+/H+ exchangers are ubiquitous plasma membrane transport proteins implicated in the maintenance of intracellular pH. The aim of this study was to examine the expression of Na+/H+ exchangers as a function of the differentiation of normal human nasal epithelial (NHNE) cells. In addition, we investigated the functional activity of the Na+/H+ exchanger 1 (NHE1) in basolateral membranes.
  
  
  METHODS
  Cultured passage-2 NHNE cells were used. RNA and histological samples were collected on the day of confluence and on the 7th, 14th and 28th days after confluence in order to determine the effects of time. Cell lysates were collected on the day of confluence to investigate the presence of the proteins. Reverse transcriptase polymerase chain reaction and Western blotting were performed to investigate the presence of mRNA and protein, respectively. The functional activity of NHE1 was examined using 3-methylsulfonyl-4-piperidinobenzoyl guanidine methanesulfonate (HOE694), an NHE1-specific inhibitor, on the day of confluence.
  
  
  RESULTS
  The NHE1 mRNA expression level did not change as a function of differentiation. However, the NHE2 mRNA expression levels increased on the 7th, 14th and 28th days after confluence. The NHE3 mRNA expression levels increased on the 14th and 28th days after confluence. Western blot analysis confirmed the expression of NHE1 (91 kDa), NHE2 (90 kDa) and NHE3 (93 kDa). In addition, HOE694 inhibited basolateral NHE activity by 68% at 1 microM and by 85% at 5 microM in the NHNE cells.
authors.affiliation: Brain Korea 21 Project for Medical Sciences, Yonsei University College of Medicine, Seodaemun-gu, Seoul, South Korea.
authors.forename: Ji-Hyun
authors.initials: JH
authors.lastname: Shin
authors.forename: Wan
authors.initials: W
authors.lastname: Namkung
authors.forename: Chang-Hoon
authors.initials: CH
authors.lastname: Kim
authors.forename: Jae Young
authors.initials: JY
authors.lastname: Choi
authors.forename: Jong-Bum
authors.initials: JB
authors.lastname: Yoo
authors.forename: Kyung-Dong
authors.initials: KD
authors.lastname: Lee
authors.forename: Jeung-Gweon
authors.initials: JG
authors.lastname: Lee
authors.forename: Min Goo
authors.initials: MG
authors.lastname: Lee
authors.forename: Joo-Heon
authors.initials: JH
authors.lastname: Yoon
mesh_terms: D015153:Blotting, Western; D027682:Cation Transport Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000378:metabolism* / Q000473:pathology; D006146:Guanidines / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007424:Intracellular Fluid / Q000737:chemistry*; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009297:Nasal Mucosa / Q000166:cytology*; D020033:Protein Isoforms / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000074082:Sodium-Hydrogen Exchanger 1; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013450:Sulfones / Q000494:pharmacology
chemical_list: D027682:Cation Transport Proteins; D006146:Guanidines; D008565:Membrane Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; C490998:SLC9A1 protein, human; D000074082:Sodium-Hydrogen Exchanger 1; D017923:Sodium-Hydrogen Exchangers; D013450:Sulfones; C074107:3-methylsulfonyl-4-piperidinobenzoyl guanidine