Identification of a TRAF (TNF receptor-associated factor) gene in Caenorhabditis elegans

Many members of the tumor necrosis factor (TNF) receptor superfamily and the interleukin-l (IZ-I) receptor engage intracellular signaling pathways including the nuclear factor kappa B (NF-kappa B)-, c-jun N-terminal kinase (JNK)-, and extracellular signal-regulated kinase (ERK) pathways by direct or indirect interaction with TNF receptor-associated factor (TRAF) molecules. To dale, six mammalian members of the TRAF family have been identified. Searching public databases with a sequence pattern comprising 19 conserved amino acid residues derived from the carboxyl-terminal part of the TRAF homology domain, we found significant sequence homologies to a stretch of genomic DNA from Caenorhabditis elegans which encodes 1 of 12 exons of a putative protein. The sequence of this putative protein shows up to 29% sequence identity to the mammalian TRAFs and is therefore designated C. elegans TRAF (CeTRAF). The CeTRAF molecule has an aminoterminal RING finger motif followed by four zinc finger structures and a carboxyl-terminal TRAF domain, a composition which is also found in most of the mammalian TRAFs. Reverse transcription-PCR and sequencing analysis of the respective amplicon clearly demonstrates that CeTRAF is in fact transcribed in C. elegans. The existence of a member of the TRAF family in C. elegans provides strong evidence for evolutionary conserved pathways linking cell surface receptors to activation of JNK, ERK, and NF-kappa B.