Journal: The EMBO Journal
Article Title: eIF3 mRNA selectivity profiling reveals eIF3k as a cancer‐relevant regulator of ribosome content
doi: 10.15252/embj.2022112362
Figure Lengend Snippet: 5′‐UTR sequences of RPS15A and RPS4X. 5′‐TOP element known to boost translation of ribosomal protein mRNAs (Meyuhas, ) are highlighted in gold prints, the eIF3‐binding sites mapped by Lee et al and Meyer et al are highlighted in red print. The alleles created by gene editing are shown (S15A‐eIF3KO, S4X‐eIF3KO). Note that the eIF3‐binding site in RPS4X is upstream of or overlapping with the major transcription start site. Thus, the S4X‐eIF3KO truncation we failed to generate most likely abolished the transcription of RPS4X mRNA. Parental eIF3k‐mAID cells or S15A‐eIF3KO cells (clones #45 and #361) were maintained in standard media, and cell numbers were determined at various time points. Data represent means ± SD, n = 3. Asterisks denote: * P < 0.005, ** P < 0.00005, *** P < 0.000005 (two‐stage step‐up method of Benjamini, Krieger, and Yekutieli). Relative levels of mRNAs encoding RPS15A , RPS4X , and RPL7A before and after depletion of eIF3k were determined in the indicated cell lines by RT–qPCR. Data were normalized to the signal obtained for GAPDH. Bars represent means ± SD, n = 3; numbers indicate P ‐values (unpaired Student's t ‐test). Relative translational efficiencies (TEs) of mRNAs encoding RPS15A , RPS4X , and RPL7A before and after depletion of eIF3k were determined in the indicated cell lines. RT–qPCR was performed on total RNA and on RNA contained within polysomal fractions > 2 ribosomes, and TE was calculated according to the formula TE = polysomal mRNA / total mRNA. Bars represent means ± SD, n = 3; numbers indicate P ‐values (unpaired Student's t ‐test). Basal expression of the indicated proteins was determined in parental eIF3k‐mAID cells or S15A‐eIF3KO cells (clones #45 and #361) by immunoblotting, followed by quantification of the blots. Bars represent means ± SD, n = 3 (Fig ). Numbers indicate P ‐values (unpaired Student's t ‐test). Data information: n = number of biological replicates. Source data are available online for this figure.
Article Snippet: Rabbit Polyclonal Anti‐ RPS4X (WB 1:2,000) , Abclonal , Cat # A6730; RRID: AB_2767314.
Techniques: Binding Assay, Clone Assay, Quantitative RT-PCR, Expressing, Western Blot