A divergent CFTR homologue: highly regulated salt transport in the euryhaline teleost F. heteroclitus

The killifish, Fundulus heteroclitus, is a euryhaline teleost fish capable of adapting rapidly to transfer from freshwater (FW) to four times seawater (SW). To investigate osmoregulation at a molecular level, a 5.7-kilobase cDNA homologous to human cystic fibrosis transmembrane conductance regulator...

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Bibliographic Details
Published inAmerican Journal of Physiology: Cell Physiology Vol. 274; no. 3; p. C715
Main Authors Singer, Thomas D, Tucker, Stephen J, Marshall, William S, Higgins, Christopher F
Format Journal Article
LanguageEnglish
Published United States 01.03.1998
Subjects
gill
osmoregulation
chloride channel
Xenopusexpression
cystic fibrosis
cystic fibrosis transmembrane conductance regulator
killifish
Fundulus heteroclitus
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Summary:The killifish, Fundulus heteroclitus, is a euryhaline teleost fish capable of adapting rapidly to transfer from freshwater (FW) to four times seawater (SW). To investigate osmoregulation at a molecular level, a 5.7-kilobase cDNA homologous to human cystic fibrosis transmembrane conductance regulator (hCFTR) was isolated from a gill cDNA library from SW-adapted killifish. This cDNA encodes a protein product (kfCFTR) that is 59% identical to hCFTR, the most divergent form of CFTR characterized to date. Expression of kfCFTR in Xenopus oocytes generated adenosine 3',5'-cyclic monophosphate-activated, Cl -selective currents similar to those generated by hCFTR. In SW-adapted killifish, kfCFTR was expressed at high levels in the gill, opercular epithelium, and intestine. After abrupt exposure of FW-adapted killifish to SW, kfCFTR expression in the gill increased severalfold, suggesting a role for kfCFTR in salinity adaptation. Under similar conditions, plasma Na levels rose significantly after 8 h and then fell, although it is not known whether these changes are directly responsible for the changes in kfCFTR expression. The killifish provides a unique opportunity to understand teleost osmoregulation and the role of CFTR.
ISSN:1522-1563