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

Abstract

The retinoid-related orphan nuclear receptor gamma (RORγ) plays critical roles in regulation of development, immunity and metabolism. As transcription factor usually forms a protein complex to function, thus capturing and dissecting of the RORγ protein complex will be helpful for exploring the mechanisms underlying those functions. After construction of the recombinant tandem affinity purification (TAP) plasmid, pMSCVpuro RORγ-CTAP(SG), the nuclear localization of RORγ-CTAP(SG) fusion protein was verified. Following isolation of RORγ protein complex by TAP strategy, seven candidate interacting proteins were identified. Finally, the heat shock protein 90 (HSP90) and receptor-interacting protein 140 (RIP140) were confirmed to interplay with RORγ by co-immunoprecipitation. Interference of HSP90 or/and RIP140 genes resulted in dramatically decreased expression of CYP2C8 gene, the RORγ target gene. Data from this study demonstrate that HSP90 and RIP140 proteins interact with RORγ protein in a complex format and function as co-activators in the RORγ-mediated regulatory processes of HepG2 cells. © 2012 by the The Korean Society for Biochemistry and Molecular Biology.