The Ran-binding protein RanBPM can depress the NF-κB pathway by interacting with TRAF6

Ran-binding protein in microtubule-organizing center (RanBPM) has been reported to interact with the neurotrophin receptors p75NTR and TrkA, meanwhile p75NTR and TrkA can also interact with TRAF6. Whether RanBPM interacts directly with TRAF6 has not yet been established. In this study, using a yeast two-hybrid system and glutathione-s-transferase pull-down assays, we determined that RanBPM binds to the TRAF6 C-terminus through its SPRY motif. Complex formation between overexpressed RanBPM and TRAF6 was also confirmed with a co-immunoprecipitation assay, laser scanning confocal and fluorescence resonance energy transfer. Additional co-immunoprecipitation experiments verified that endogenous RanBPM and TRAF6 interact in several mammalian cell lines. A series of experiments revealed that RanBPM influences TRAF6 ubiquitination and the TRAF6-triggered NF-kappa B signaling pathway through RanBPM's interaction with TRAF6. These data suggest that RanBPM participates in gene transcription by binding to TRAF6.