Panel A shows a northern blot with a 5 prime ETS probe detecting 47S and 30S plus 1 transcripts. Panel B shows a northern blot with an ETS1-1399 probe detecting 45S and 30S transcripts. Panel C shows a northern blot with an ETS1-3636 probe detecting 45S and 30S transcripts. Panel D shows a northern blot with a 5 prime ITS1 probe detecting 45S, 43S, 41S, 30S, 26S, 21S, and 18S-E transcripts. Panel E shows a northern blot with an ITS1-5.8S probe detecting 45S, 43S, 36S, 32.5S, and 12S transcripts. Panel F shows a northern blot with an ITS2 probe detecting 45S, 43S, 32S, and 12S transcripts. Panel G is a bar graph showing the ratios of pre-rRNA products to precursors for different probes, with the x-axis labeled with probe names and the y-axis labeled with Log2(ratio(proband)) minus Log2(ratio(mean ctrl)). Panel H is a schematic representation of the 47S pre-rRNA indicating sequences for 18S, 5.8S, and 28S rRNAs, and flanking 5 prime ETS and 3 prime ETS, and internal ITS1, ITS2. Panel I is a schematic representation of 18S, 5.8S, and 28S rRNA precursors. The box plot in Panel G shows variations in pre-rRNA processing ratios between the patient and control samples, with significant differences marked by asterisks.
WDR75 variants affect pre-rRNA processing. Quantification of pre-rRNA precursors identified by northern blot analysis of LCLs derived from the patient and a control. Indicated radiolabeled probes were used to detect pre-rRNA precursors and mature rRNAs. Statistical analysis was performed using the Mann–Whitney U test; *P < 0.05. (A–C) 5′ETS probe, 47S transcript; 45S/47S ratio in conjunction with B and C. (B) ETS1-1,399 probe, 30S/45S ratio. (C) ETS1-3636 probe, 30S/45S ratio. (D) 5′ITS1 probe, 41S/45S, 30S/41S, 21S/30S, and 18S-E/21S ratios. (E) ITS1-5.8S probe, 32.5S/41S ratio. (F) ITS2 probe, 32S/41S and 12S/32S ratios. (G–I) Pre-rRNA product-to-precursor ratios obtained for the patient are shown relative to the control. Mean values ± standard error of the mean from n = 4 independent experiments, aside from 5S and 5.8S rRNA quantification, for which n = 3. Schematic representation of 47S pre-rRNA indicating the sequences for 18S, 5.8S, and 28S rRNAs, flanking 5′ETS and 3′ETS, and ITS1, ITS2 (H). Cleavage sites and probes for northern blots used for A–G are indicated. Schematic representation of 18S, 5.8S, and 28S rRNA precursors (I). Source data are available for this figure: SourceData F2.