Dynamic eIF3a O-GlcNAcylation controls translation reinitiation during nutrient stress

Nat Chem Biol. 2022 Feb;18(2):134-141. doi: 10.1038/s41589-021-00913-4. Epub 2021 Dec 9.

Abstract

In eukaryotic cells, many messenger RNAs (mRNAs) possess upstream open reading frames (uORFs) in addition to the main coding region. After uORF translation, the ribosome could either recycle at the stop codon or resume scanning for downstream start codons in a process known as reinitiation. Accumulating evidence suggests that some initiation factors, including eukaryotic initiation factor 3 (eIF3), linger on the early elongating ribosome, forming an eIF3-80S complex. Very little is known about how eIF3 is carried along with the 80S during elongation and whether the eIF3-80S association is subject to regulation. Here, we report that eIF3a undergoes dynamic O-linked N-acetylglucosamine (O-GlcNAc) modification in response to nutrient starvation. Stress-induced de-O-GlcNAcylation promotes eIF3 retention on the elongating ribosome and facilitates activating transcription factor 4 (ATF4) reinitiation. Eliminating the modification site from eIF3a via CRISPR genome editing induces ATF4 reinitiation even under the nutrient-rich condition. Our findings illustrate a mechanism in balancing ribosome recycling and reinitiation, thereby linking the nutrient stress response and translational reprogramming.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Proliferation
  • Codon, Terminator
  • Culture Media / chemistry
  • DNA, Complementary
  • Eukaryotic Initiation Factor-3 / genetics
  • Eukaryotic Initiation Factor-3 / metabolism*
  • Gene Expression Regulation / physiology*
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Peptide Chain Initiation, Translational
  • Stress, Physiological

Substances

  • Codon, Terminator
  • Culture Media
  • DNA, Complementary
  • EIF3A protein, human
  • Eukaryotic Initiation Factor-3