Human cells adapt to translational errors by modulating protein synthesis rate and protein turnover

Varanda, Ana Sofia; Santos, Mafalda; Soares, Ana Raquel; Vitorino, Rui; Oliveira, Patrícia; Oliveíra, Carla; Santos, Manuel A. S.

doi:10.1080/15476286.2019.1670039

Cited by 16 publications

(19 citation statements)

References 61 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous reports established a translation-inhibition response to mistranslating tRNAs expressed in mammalian cells ( 21 , 40 ). Through inhibition of mRNA translation initiation or elongation, general protein synthesis can be downregulated in response to mistranslation or tRNA dysfunction ( 21 , 57 ).…”

Section: Resultsmentioning

confidence: 99%

“…Previous studies established that certain tRNA anticodon variants expressed in mammalian cells lead to increased phosphorylation of eIF2α at Ser52 ( 21 , 28 , 40 ). Phospho-Ser52 in eIF2α prevents translation initiation of most cellular mRNAs and is a converging point of the integrated stress response stimulated by numerous cellular stresses.…”

Section: Resultsmentioning

confidence: 99%

“…Phospho-Ser52 in eIF2α prevents translation initiation of most cellular mRNAs and is a converging point of the integrated stress response stimulated by numerous cellular stresses. However, p-eIF2α levels vary substantially depending on the tRNA gene variant expressed ( 21 ), and how long cells have been expressing the tRNA variant ( 40 ). We used western blotting to measure p-eIF2α, eIF2α and GFP levels from cells expressing all combinations of EGFP-fused HTT-exon1 23Q and 74Q with wild-type tRNA Ser AGA or the tRNA Ser AAA variant.…”

Section: Resultsmentioning

confidence: 99%

“…Given the synthetic toxic effect we observed in mistranslating cells treated with MG132, and previous reports of tRNA anticodon variants promoting increased proteasome activity ( 40 ), we assayed protein turnover in mistranslating cells. Cycloheximide chase assays ( 64 ) were performed on N2a cells expressing no tRNA, wild-type tRNA Ser AGA , or the tRNA Ser AAA variant with EGFP-fused HTT-Exon1 23Q and 74Q (Figure 7A - D ).…”

Section: Resultsmentioning

confidence: 99%

“…Disorders characterized by protein folding stress or by impaired protein quality control may be particularly susceptible to the effects of mistranslating tRNAs, since mistranslation increases the synthesis of misfolded proteins to further burden the cellular protein folding stress responses ( 17 , 21 , 40 ). In the case of HD, proteinopathy is triggered by an expanded CAG (Gln) codon repeat in exon1 of the HTT gene encoding the huntingtin protein.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Formation and persistence of polyglutamine aggregates in mistranslating cells

Lant

Kiri

Duennwald

et al. 2021

Nucleic Acids Research

View full text Add to dashboard Cite

In neurodegenerative diseases, including pathologies with well-known causative alleles, genetic factors that modify severity or age of onset are not entirely understood. We recently documented the unexpected prevalence of transfer RNA (tRNA) mutants in the human population, including variants that cause amino acid mis-incorporation. We hypothesized that a mistranslating tRNA will exacerbate toxicity and modify the molecular pathology of Huntington's disease-causing alleles. We characterized a tRNA Pro mutant that mistranslates proline codons with alanine, and tRNA Ser mutants, including a tRNA Ser AGA G35A variant with a phenylalanine anticodon (tRNA Ser AAA ) found in ∼2% of the population. The tRNA Pro mutant caused synthetic toxicity with a deleterious huntingtin poly-glutamine (polyQ) allele in neuronal cells. The tRNA Ser AAA variant showed synthetic toxicity with proteasome inhibition but did not enhance toxicity of the huntingtin allele. Cells mistranslating phenylalanine or proline codons with serine had significantly reduced rates of protein synthesis. Mistranslating cells were slow but effective in forming insoluble polyQ aggregates, defective in protein and aggregate degradation, and resistant to the neuroprotective integrated stress response inhibitor (ISRIB). Our findings identify mistranslating tRNA variants as genetic factors that slow protein aggregation kinetics, inhibit aggregate clearance, and increase drug resistance in cellular models of neurodegenerative disease.

show abstract