Nucleo-Cytoplasmic Trafficking of TRIM8, a Novel Oncogene, Is Involved in Positive Regulation of TNF Induced NF-κB Pathway

TNF induced nuclear factor kappa B (NF-kappa B) is one of the central signaling pathways that plays a critical role in carcinogenesis and inflammatory diseases. Post-translational modification through ubiquitin plays important role in the regulation of this pathway. In the current study, we investigated the role of TRIM8, member of RING family ubiquitin ligase in regulation of NF-kappa B pathway. We observed that TRIM8 positively regulates TNF induced NF-kappa B pathway. Different domains of TRIM8 showed discrete functions at the different steps in regulation of TNF induced NF-kappa B pathway. Ubiquitin ligase activity of TRIM8 is essential for regulation of NF-kappa B activation in both cytoplasm as well as nucleus. TRIM8 negates PIAS3 mediated negative repression of NF-kappa B at p65 by inducing translocation of PIAS3 from nucleus to cytoplasm as well as its turnover. TNF induces translocation of TRIM8 from nucleus to cytoplasm, which positively regulates NF-kappa B. The cytoplasmic translocation of TRIM8 is essential for TNF induced NF-kappa B but not for p65 mediated NF-kappa B regulation. TRIM8 also enhanced the clonogenic and migration ability of cells by modulating NF-kappa B. The further study will help to understand the role of TRIM8 in inflammation and cancer.