Identification of interacting proteins of retinoid-related orphan nuclear receptor gamma in HepG2 cells

The retinoid-related orphan nuclear receptor gamma (RORγ)plays critical roles in regulation of development, immunity andmetabolism. As transcription factor usually forms a proteincomplex to function, thus capturing and dissecting of theRORγ protein complex will be helpful for exploring themechanisms underlying those functions. After construction ofthe recombinant tandem affinity purification (TAP) plasmid,pMSCVpuro RORγ-CTAP(SG), the nuclear localization ofRORγ-CTAP(SG) fusion protein was verified. Followingisolation of RORγ protein complex by TAP strategy, sevencandidate interacting proteins were identified. Finally, the heatshock protein 90 (HSP90) and receptor-interacting protein 140(RIP140) were confirmed to interplay with RORγ byco-immunoprecipitation. Interference of HSP90 or/and RIP140genes resulted in dramatically decreased expression ofCYP2C8 gene, the RORγ target gene. Data from this studydemonstrate that HSP90 and RIP140 proteins interact withRORγ protein in a complex format and function asco-activators in the RORγ-mediated regulatory processes ofHepG2 cells.