Identification of a TRAF (TNF Receptor-Associated Factor) Gene in Caenorhabditis elegans

Abstract.

Many members of the tumor necrosis factor (TNF) receptor superfamily and the interleukin-1 (IL-1) receptor engage intracellular signaling pathways including the nuclear factor κB (NF-κB)-, 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 date, 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 amino-terminal 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-κB.