CHARACTERIZATION OF TUMOR NECROSIS FACTOR RECEPTOR ASSOCIATED FACTOR 3 (TRAF3) IN NILE TILAPIA: EXPRESSION PROFILES AND FUNCTIONS IN NF-κB PATHWAY

Tumor necrosis factor receptor (TNFR)-associated factor 3 (TRAF3) is a highly versatile regulator in many immune pathways, including TNFR and Toll-like receptor (TLRs)/RIG-I-like receptors (RLRs) signal pathway. In this study, a TRAF3 gene was cloned from Oreochromis niloticus (named OnTRAF3), (GenBank No. MN258118), which contained a RING finger, a zinc finger, a coiled-coil and MATH domain. Multiple sequence alignment showed that OnTRAF3 shares a relatively high identity with other known TRAF3 proteins. Quantitative real-time PCR (qRT-PCR) analysis showed OnTRAF3 transcripts were highly expressed in brain, skin, intestine and gill, and it could be induced by Streptococcus agalactiae. In HEK293T cells, OnTRAF3 presented both in the cytoplasm and nucleus. In addition, wide type (WT) OnTRAF3, activated NF-κB signal significantly, RING or Zinc finger was important for this activation. This study provides significant insights into the functions of TRAF3 in tilapia.