Expression of Na+/H+ exchanger isoforms in normal human nasal epithelial cells and functional activity of Na+/H+ exchanger 1 in intracellular pH regulation

• Published in: Acta oto-laryngologica 2005-03, Vol.125 (3), p.286-292
• Main Authors: Shin, Ji-Hyun, Namkung, Wan, Kim, Chang-Hoon, Choi, Jae Young, Yoo, Jong-Bum, Lee, Kyung-Dong, Lee, Jeung-Gweon, Lee, Min Goo, Yoon, Joo-Heon
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Blotting, Western; Cation Transport Proteins - antagonists & inhibitors; Cation Transport Proteins - metabolism; Cell Differentiation; Cells, Cultured; Differentiation; Epithelial Cells - metabolism; Epithelial Cells - pathology; Guanidines - pharmacology; Humans; Hydrogen-Ion Concentration; Intracellular Fluid - chemistry; Medical sciences; Membrane Proteins - antagonists & inhibitors; Membrane Proteins - metabolism; Na+/H+ exchanger; nasal epithelial cells; Nasal Mucosa - cytology; Otorhinolaryngology. Stomatology; Protein Isoforms - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - metabolism; Sodium-Hydrogen Exchanger 1; Sodium-Hydrogen Exchangers - antagonists & inhibitors; Sodium-Hydrogen Exchangers - metabolism; Sulfones - pharmacology
• ISSN: 0001-6489; 1651-2251
• DOI: 10.1080/00016480410022976

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. Material and 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 μM and by 85% at 5 μM in the NHNE cells.