TNFAIP1 interacts with KCTD10 to promote the degradation of KCTD10 proteins and inhibit the transcriptional activities of NF-κB and AP-1.

The broad-complex, tramtrack, and bric-a-brac/poxvirus and zinc finger domain-containing protein tumor necrosis factor, alpha-induced protein 1 (TNFAIP1) was first identified as a gene whose expression can be induced by the tumor necrosis factor alpha. Some studies showed that TNFAIP1 may function in DNA replication, apoptosis and human diseases. However, the definite functions and the mechanisms of TNFAIP1 are poorly known. In this study, we performed a yeast two-hybrid assay and used TNFAIP1 as the bait to screen human brain cDNA library. Potassium channel tetramerisation domain containing 10 (KCTD10) was identified as TNFAIP1-interacting partner. The KCTD10-TNFAIP1 interaction was then confirmed by the in vitro GST pull-down assays and the in vivo co-immunoprecipitation and colocalization assays. In addition, protein degradation and ubiquitin assays revealed TNFAIP1 overexpression resulted in ubiquitin-mediated degradation of KCTD10 proteins, which was significantly alleviated with the proteasome inhibitor MG132 treatment. Furthermore, transient transfection assays with two reporters showed that TNFAIP1 and KCTD10 inhibited the transcriptional activities of nuclear factor kappa B (NF-κB) and activating protein-1 reporters. Taken together, our results indicated the novel interaction and function between KCTD10 and TNFAIP1 in human PDIP1 family.