Translation reinitiation at alternative open reading frames regulates gene expression in an integrated stress response

Stress-induced eukaryotic translation initiation factor 2 (eIF2) alpha phosphorylation paradoxically increases translation of the metazoan activating transcription factor 4 (ATF4), activating the integrated stress response (ISR), a pro-survival gene expression program. Previous studies implicated the 5' end of the ATF4 mRNA, with its two conserved upstream ORFs (uORFs), in this translational regulation. Here, we report on mutation analysis of the ATF4 mRNA which revealed that scanning ribosomes initiate translation efficiently at both uORFs and ribosomes that had translated uORF1 efficiently reinitiate translation at downstream AUGs. In unstressed cells, low levels of eIF2alpha phosphorylation favor early…

• EM
  Ellison Medical Foundation
• AP
  Ariad Pharmaceuticals
• NI
  National Institutes of Health

  Awards: ES08681, DK47119