Translational fidelity screens in mammalian cells reveal eIF3 and eIF4G2 as regulators of start codon selectivity.
Nucleic Acids Res
; 51(12): 6355-6369, 2023 07 07.
Article
em En
| MEDLINE
| ID: mdl-37144468
ABSTRACT
The translation initiation machinery and the ribosome orchestrate a highly dynamic scanning process to distinguish proper start codons from surrounding nucleotide sequences. Here, we performed genome-wide CRISPRi screens in human K562 cells to systematically identify modulators of the frequency of translation initiation at near-cognate start codons. We observed that depletion of any eIF3 core subunit promoted near-cognate start codon usage, though sensitivity thresholds of each subunit to sgRNA-mediated depletion varied considerably. Double sgRNA depletion experiments suggested that enhanced near-cognate usage in eIF3D depleted cells required canonical eIF4E cap-binding and was not driven by eIF2A or eIF2D-dependent leucine tRNA initiation. We further characterized the effects of eIF3D depletion and found that the N-terminus of eIF3D was strictly required for accurate start codon selection, whereas disruption of the cap-binding properties of eIF3D had no effect. Lastly, depletion of eIF3D activated TNFα signaling via NF-κB and the interferon gamma response. Similar transcriptional profiles were observed upon knockdown of eIF1A and eIF4G2, which also promoted near-cognate start codon usage, suggesting that enhanced near-cognate usage could potentially contribute to NF-κB activation. Our study thus provides new avenues to study the mechanisms and consequences of alternative start codon usage.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fator de Iniciação 3 em Eucariotos
/
RNA Guia de Sistemas CRISPR-Cas
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Ano de publicação:
2023
Tipo de documento:
Article