MYC binding to nascent RNA suppresses innate immune signaling by R-loop-derived RNA-DNA hybrids

In response to perturbed transcription elongation, the MYC oncoprotein multimerizes and undergoes a phase transition. Here, we demonstrate that MYC globally relocalizes from its canonical positions on DNA to nascent RNA upon accumulation of intronic RNA. Upon binding to RNA, MYC forms multimers that concentrate the nuclear exosome, an RNA exonuclease, and its targeting complexes around double-stranded RNA and R-loops. MYC harbors four RNA-binding regions (RBRI-IV). RBRIII promotes MYC multimerization and is necessary for recruiting the exosome to R-loops. RBRIII is dispensable for transcriptional activation and pancreatic tumor cell proliferation in culture, but it is indispensable for sustaining tumor growth…

• HH
  Howard Hughes Medical Institute
• AL
  Alex's Lemonade Stand Foundation for Childhood Cancer
• DF
  Deutsche Forschungsgemeinschaft
• DK
  Deutsche Krebshilfe