BS69 cooperates with TRAF3 in the regulation of Epstein-Barr virus-derived LMP1/CTAR1-induced NF-kappaB activation.

Epstein-Barr virus latent membrane protein 1 (LMP1) activates NF-kappaB signaling pathways through two C-terminal regions, CTAR1 and CTAR2. Previous studies have demonstrated that BS69, a multidomain cellular protein, regulates LMP1/CTAR2-mediated NF-kappaB activation by interfering with the complex formation between TRADD and LMP1/CTAR2. Here, we found that BS69 directly interacted with the LMP1/CTAR1 domain and regulated LMP1/CTAR1-mediated NF-kappaB activation and subsequent IL-6 production. Regarding the mechanisms involved, we found that BS69 directly interacted with TRAF3, a negative regulator of NF-kappaB activation. Furthermore, small-interfering RNA-mediated knockdown experiments revealed that TRAF3 was involved in the BS69-mediated suppression of LMP1/CTAR1-induced NF-kappaB activation.