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

Many members of the tumor necrosis factor (TNF) receptor superfamily and th e interleukin-l (IZ-I) receptor engage intracellular signaling pathways inc luding the nuclear factor kappa B (NF-kappa B)-, c-jun N-terminal kinase (J NK)-, 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. Se arching public databases with a sequence pattern comprising 19 conserved am ino acid residues derived from the carboxyl-terminal part of the TRAF homol ogy domain, we found significant sequence homologies to a stretch of genomi c 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 id entity to the mammalian TRAFs and is therefore designated C. elegans TRAF ( CeTRAF). The CeTRAF molecule has an aminoterminal RING finger motif followe d by four zinc finger structures and a carboxyl-terminal TRAF domain, a com position which is also found in most of the mammalian TRAFs. Reverse transc ription-PCR and sequencing analysis of the respective amplicon clearly demo nstrates 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 evo lutionary conserved pathways linking cell surface receptors to activation o f JNK, ERK, and NF-kappa B.