A novel 14-3-3 gene is osmoregulated in gill epithelium of the euryhaline teleost Fundulus heteroclitus.
We have cloned and analyzed the full-length coding sequence and 3' untranslated region (UTR) of a unique 14-3-3 gene of the euryhaline teleost Fundulus heteroclitus, which we named 14-3-3.a. Phylogenetic analysis of the deduced amino acid sequence revealed that the 14-3-3.a gene product is most similar to vertebrate 14-3-3 zeta and beta, yet it displays considerable divergence to known classes of vertebrate 14-3-3 isoforms. The N and C termini of 14-3-3.a are the most unique regions, whereas the amino acid residues forming the amphipathic ligand-binding groove are highly conserved. F. heteroclitus 14-3-3.a mRNA expression is high in gill epithelium, moderate in intestine and brain, and low in gonads, white muscle and heart. Because 14-3-3 proteins are important molecular scaffolds and cofactors for phosphoproteins and signaling complexes, the high level of 14-3-3.a expression in gill epithelium of the euryhaline teleost F. heteroclitus suggests that it is crucial for signal transduction in gill epithelial cells. We provide evidence that 14-3-3.a is involved in osmosensory signal transduction by showing that its mRNA and protein levels in gill epithelium, but not in any other tissue analyzed, increase two- to fourfold within 24h of salinity transfer of fish from sea water to fresh water. These data are clear evidence for an important role of 14-3-3.a in the remodeling of gill epithelium during transition of euryhaline fish between plasma-hyperosmotic and plasma-hypoosmotic environments.
Kültz
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The Whitney Laboratory, University of Florida, 9505 Ocean Shore Boulevard, St Augustine, FL 32080, USA. dkkw@whitney.ufl.edu
Chakravarty
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Adilakshmi
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D048948:14-3-3 Proteins; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004848:Epithelium / Q000378:metabolism; D023781:Fundulidae / Q000235:genetics*; D005786:Gene Expression Regulation; D005880:Gills / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014446:Tyrosine 3-Monooxygenase / Q000737:chemistry / Q000235:genetics*; D014882:Water-Electrolyte Balance
D048948:14-3-3 Proteins; D014446:Tyrosine 3-Monooxygenase