Finding a novel interacting protein of the hepatic carcinoma related gene MIP: NF-κB essential modulator (NEMO).

MafF interacting protein (MIP) is product of a candidate gene related to liver cancer development and progression. Here, we demonstrated that MIP could inhibit the proliferation of cancer cells through colony formation assays, and the inhibition ability of MIP to SMMC7721 cells was notably stronger than to HeLa cells. Using pGBKT7-MIP as bait, a human placenta cDNA library was screened using yeast two-hybrid system and a middle fragment of the NF-κB essential modulator (NEMO) was obtained as a novel important MIP interacting protein fragment, which contained 228 amino acid sequence from the 120 to 347 residue. Then the full coding sequence of NEMO was amplified from Clontech Placenta Marathon cDNA library and yeast mating assay verified the interaction of MIP and full length NEMO in yeast. GST pull-down assay and co-immunoprecipitation assay confirmed that MIP bound to NEMO specifically and directly. These results indicated that MIP interacted with NEMO and suggested that MIP could be involved in NF-κB signaling pathway, which is helpful to clarify the inhibition function of MIP to cancer cell proliferation.