Phospholipid scramblase 1 functionally interacts with angiogenin and regulates angiogenin-enhanced rRNA transcription.

BACKGROUND Angiogenin (ANG) can translocate to the target cell nucleus and accumulate in the nucleolus to enhance rRNA transcription, thus promoting cell proliferation. However, the regulation of ANG-enhanced rRNA transcription remains unknown. Previously we identified phospholipid scramblase 1 (PLSCR1) as a potential ANG-interacting protein in yeast two-hybrid screening. METHODS The interaction was re-confirmed in yeast cells and further verified by in vitro pull down, in vivo co-immunoprecipitation (Co-IP), fluorescent resonance energy transfer (FRET) and immunofluorescence analyses. The rRNA transcription level was determined by real-time quantitative PCR and Northern blot. RESULTS PLSCR1 was identified as a novel ANG-interacting protein. Notably, PLSCR1 interacted with ANG in the cell nucleus and regulated rRNA transcription. Furthermore, depletion of cellular ANG expression abolished PLSCR1-enhanced rRNA transcription, which could be rescued by exogenous ANG. CONCLUSION Our data suggest that PLSCR1 positively regulates rRNA transcription through interacting with ANG, thus deepening our understanding on rRNA transcription regulation.