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Molecular cloning and expression of a TNF receptor and two TNF ligands in the fish ovary
1Institut National de la Recherche Agronomique, S.C.R.I.B.E., Campus de Beaulieu, 35042, Rennes Cedex, France.
Abstract:
Using degenerative primers, partial cDNAs of a TNF (tumor necrosis factor) receptor and two TNF ligands were obtained by PCR of zebrafish and trout cDNAs, or cDNA libraries. These fragments were then used to screen cDNA libraries of appropriate tissues to obtain clones containing full coding sequences. A zebrafish cDNA was obtained that presumably codes for a 438 amino acid ovarian TNF receptor (OTR) that was identified as a death-domain-containing member of the TNF receptor family. On Northern blots, the OTR cDNA hybridized with a 3.4-kb transcript that is abundant in the zebrafish ovary but lightly detected in all other tissues tested. A zebrafish cDNA presumably coding for a 214 amino acid protein with sequence similarity to mammalian TRAIL (TNF-related apoptosis inducing ligand), was also isolated. In addition, a fragment of the brook trout TRAIL homologue was obtained. Finally, a full-length brook trout cDNA, that presumably codes for a 255 amino acid protein with sequence similarity to mammalian TNF-alpha and lymphotoxin-alpha, was isolated. This study is the first report of a death-domain-containing TNF receptor and the first published report of a TNF ligand in fish.
Insights
Researchers identified novel fish tumor necrosis factor (TNF) receptor and ligand genes. This study reports the first fish death-domain-containing TNF receptor and TNF ligand, advancing comparative immunology and molecular biology.
Area of Science:
- Comparative immunology and molecular biology.
- Genomics and transcriptomics of teleost fish.
Background:
- Tumor necrosis factor (TNF) receptors and ligands are critical in immune responses and apoptosis.
- Limited information exists regarding TNF signaling pathways in fish species.
- Understanding fish immune systems is vital for aquaculture and conservation.
Purpose of the Study:
- To identify and characterize novel TNF receptor and ligand genes in zebrafish and trout.
- To investigate the expression patterns of these newly identified genes.
- To establish a foundation for studying TNF signaling in fish.
Main Methods:
- Polymerase chain reaction (PCR) using degenerate primers on zebrafish and trout cDNA.
- Screening of cDNA libraries to obtain full-length coding sequences.
- Northern blot analysis to determine gene expression patterns.
Main Results:
- Isolation of a zebrafish ovarian TNF receptor (OTR) cDNA, encoding a death-domain-containing receptor.
- Identification of a zebrafish cDNA with similarity to mammalian TNF-related apoptosis inducing ligand (TRAIL).
- Characterization of a brook trout cDNA homologous to mammalian TNF-alpha and lymphotoxin-alpha.
Conclusions:
- This study reports the first death-domain-containing TNF receptor identified in fish.
- It provides the first published description of TNF ligands in fish species.
- These findings significantly expand the understanding of TNF signaling in vertebrates.