Fig. 4. Translation repression is the primary cause of poly(PR)-induced NMD inhibition.

a Nuclear fractions of NMD targets, U1 snRNA, and GAPDH mRNA (cytoplasmic) in HEK293 cells expressing GFP, poly(GR), or poly(PR). n = 3 independent experiments. Data are presented as mean values ± SD. *P < 0.05; **P < 0.01, two-sided unpaired t tests. b Puromycin-labeled nascent peptides in HEK293 cells expressing GFP, poly(GR), or poly(PR). +CHX, CHX added 1 h before puromycin labeling. Similar results were obtained from three independent experiments. c Global translation levels in primary neurons treated with PR₂₀ for 24 h, quantified by the activity of a transfected luciferase reporter, normalized to mRNA levels and untreated control. n = 3 independent experiments. Data are presented as mean values ± SD. *P < 0.05; **P < 0.01; ***P < 0.001, two-sided ratio t tests. d Comparisons between the effects of PR₂₀ (red) and CHX (blue) on NMD targets. Degrees of translation repression and NMD target abundance were quantified in primary neurons treated with increasing concentrations of PR₂₀ or CHX. Zero-intercept linear functions were fit to normalized, log₂-transformed values. Source data and exact P values are provided in the Source Data file.