Subcloning, localization, and expression of the rat intestinal sodium-hydrogen exchanger isoform 8

Hua Xu, Rongji Chen, Fayez K. Ghishan

Research output: Contribution to journalArticlepeer-review

72 Scopus citations

Abstract

Apically expressed intestinal and renal sodium-hydrogen exchangers (NHEs) play a major role in Na+ absorption. Our previous studies on NHE ontogeny have shown that NHE-2 and NHE-3 are expressed at very low levels in young animals. Furthermore, single and/or double NHE-2 and NHE-3 knockout mice display no obvious abnormalities before weaning. These observations suggest that other transporter(s) may be involved in intestinal Na+ absorption during early life. The present studies were designed to clone the novel rat intestinal NHE-8 cDNA and to decipher the NHE-8 protein localization and gene expression pattern during different developmental stages. The rat NHE-8 cDNA has 2,160 bp and encodes a 575-amino acid protein. An antibody against NHE-8 protein was developed. Immunohistochemistry staining indicated apical localization of NHE-8 protein in rat intestinal epithelial cells. The apical localization of NHE-8 was also confirmed by its presence in brush-border membrane and its absence in basolateral membrane preparations. Northern blotting utilizing a NHE-8-specific probe demonstrated higher NHE-8 mRNA expression in young animals compared with adult animals. Western blot analysis revealed a similar pattern. Tissue distribution with multiple human tissue RNA blot showed that NHE-8 was expressed in multiple tissues including the gastrointestinal tract. In conclusion, we have cloned the full-length NHE-8 cDNA from rat intestine and further showed its apical localization in intestinal epithelial cells. We have also shown that NHE-8 gene expression and protein expression were regulated during ontogeny. Our data suggests that NHE-8 may play an important role in intestinal Na+ absorption during early life.

Original languageEnglish (US)
Pages (from-to)G36-G41
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume289
Issue number1 52-1
DOIs
StatePublished - Jul 2005

Keywords

  • Intestine
  • Ontogeny
  • SLC9A8

ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

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