Epithelial localization of a reptilian Na+/H+ exchanger homologous to NHE-1

Samantha P. Harris, Theresa V. Strong, Noel Wys, Neil W. Richards, Jacques Pouysségur, Stephen A. Ernst, David C. Dawson

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Basolateral membranes of turtle (Pseudemys scripta) colon epithelial cells exhibit robust Na+/H+ exchange activity that can be activated by cell shrinkage and is blocked by amiloride [M. A. Post and D. C. Dawson. Am. J. Physiol. 262 (Cell Physiol. 31): C1089-C1094, 1992]. The colonic epithelium actively absorbs Na+ and secretes K+ and HCO3, but the role of basolateral Na+/H+ exchange, if any, in transepithelial transport is unknown. The current studies were undertaken to identify the gene product(s) responsible for the observed basolateral Na+/H+ exchange activity and to determine the cellular localization of the reptilian Na+/H+ exchange protein. We cloned and sequenced partial-length cDNAs that are likely to encode a reptilian homologue of the mammalian NHE-1 Na+/H+ exchanger isoform. The partial- length cDNAs were >80% identical to mammalian NHE-1 homologues at the nucleotide level and recognized a transcript (~5.8-6.0 kb) in RNA isolated from turtle colon, small intestine, stomach, kidney, urinary bladder, heart, and liver. In situ hybridization showed that mRNA encoding the reptile homologue of NHE-1 was expressed predominantly in the epithelial cells of these tissues. Immunofluorescent localization of the reptilian Na+/H+ exchanger protein using an antibody raised against a human NHE-1 fusion protein confirmed that protein expression paralleled abundant mRNA expression in epithelial cells of turtle stomach and colon, as well as in some nephron segments, and showed that the reptile NHE-1 homologue was localized exclusively to the basolateral membranes of these cells. The relatively high level of NHE-1 expression in epithelial cells, particularly those of the colon and stomach, suggests that NHE-1 function is important for the maintenance or regulation of ion transport processes that occur in these cell types.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume272
Issue number6 35-6
StatePublished - Jun 1997
Externally publishedYes

Fingerprint

Sodium-Hydrogen Antiporter
Turtles
Colon
Epithelial Cells
Stomach
Reptiles
Epithelium
Complementary DNA
Messenger RNA
Proteins
Amiloride
Nephrons
Ion Transport
Small Intestine
In Situ Hybridization
Protein Isoforms
Urinary Bladder
Nucleotides
Maintenance
Cell Membrane

Keywords

  • Epithelia
  • Immunofluorescence
  • in situ hybridization
  • Na/H exchange
  • Pseudemys scripta

ASJC Scopus subject areas

  • Gastroenterology
  • Physiology
  • Physiology (medical)

Cite this

Harris, S. P., Strong, T. V., Wys, N., Richards, N. W., Pouysségur, J., Ernst, S. A., & Dawson, D. C. (1997). Epithelial localization of a reptilian Na+/H+ exchanger homologous to NHE-1. American Journal of Physiology - Gastrointestinal and Liver Physiology, 272(6 35-6).

Epithelial localization of a reptilian Na+/H+ exchanger homologous to NHE-1. / Harris, Samantha P.; Strong, Theresa V.; Wys, Noel; Richards, Neil W.; Pouysségur, Jacques; Ernst, Stephen A.; Dawson, David C.

In: American Journal of Physiology - Gastrointestinal and Liver Physiology, Vol. 272, No. 6 35-6, 06.1997.

Research output: Contribution to journalArticle

Harris, SP, Strong, TV, Wys, N, Richards, NW, Pouysségur, J, Ernst, SA & Dawson, DC 1997, 'Epithelial localization of a reptilian Na+/H+ exchanger homologous to NHE-1', American Journal of Physiology - Gastrointestinal and Liver Physiology, vol. 272, no. 6 35-6.
Harris SP, Strong TV, Wys N, Richards NW, Pouysségur J, Ernst SA et al. Epithelial localization of a reptilian Na+/H+ exchanger homologous to NHE-1. American Journal of Physiology - Gastrointestinal and Liver Physiology. 1997 Jun;272(6 35-6).
Harris, Samantha P. ; Strong, Theresa V. ; Wys, Noel ; Richards, Neil W. ; Pouysségur, Jacques ; Ernst, Stephen A. ; Dawson, David C. / Epithelial localization of a reptilian Na+/H+ exchanger homologous to NHE-1. In: American Journal of Physiology - Gastrointestinal and Liver Physiology. 1997 ; Vol. 272, No. 6 35-6.
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abstract = "Basolateral membranes of turtle (Pseudemys scripta) colon epithelial cells exhibit robust Na+/H+ exchange activity that can be activated by cell shrinkage and is blocked by amiloride [M. A. Post and D. C. Dawson. Am. J. Physiol. 262 (Cell Physiol. 31): C1089-C1094, 1992]. The colonic epithelium actively absorbs Na+ and secretes K+ and HCO3, but the role of basolateral Na+/H+ exchange, if any, in transepithelial transport is unknown. The current studies were undertaken to identify the gene product(s) responsible for the observed basolateral Na+/H+ exchange activity and to determine the cellular localization of the reptilian Na+/H+ exchange protein. We cloned and sequenced partial-length cDNAs that are likely to encode a reptilian homologue of the mammalian NHE-1 Na+/H+ exchanger isoform. The partial- length cDNAs were >80{\%} identical to mammalian NHE-1 homologues at the nucleotide level and recognized a transcript (~5.8-6.0 kb) in RNA isolated from turtle colon, small intestine, stomach, kidney, urinary bladder, heart, and liver. In situ hybridization showed that mRNA encoding the reptile homologue of NHE-1 was expressed predominantly in the epithelial cells of these tissues. Immunofluorescent localization of the reptilian Na+/H+ exchanger protein using an antibody raised against a human NHE-1 fusion protein confirmed that protein expression paralleled abundant mRNA expression in epithelial cells of turtle stomach and colon, as well as in some nephron segments, and showed that the reptile NHE-1 homologue was localized exclusively to the basolateral membranes of these cells. The relatively high level of NHE-1 expression in epithelial cells, particularly those of the colon and stomach, suggests that NHE-1 function is important for the maintenance or regulation of ion transport processes that occur in these cell types.",
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