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. 2016 Aug 9;7(37):59519–59534. doi: 10.18632/oncotarget.11148

Figure 2. U3 and U8 are required for pre-rRNA processing in human cells.

Figure 2

Total RNA extracted from H1944 or MCF-7 cells depleted of U3 or U8 for 1, 2, or 3 days was resolved on denaturing gels and analyzed by Northern blotting with specific probes (see Materials and Methods). As a control, cells were treated with a non-targeting silencer (SCR). Blots were probed with oligonucleotide LD1844 (panels I and II), LD2612 (panel III), LD1827 (panel IV), and LD1828 (panel V). The pre-rRNA species detected are indicated and represented as schematics with the probes used highlighted. A detailed pre-rRNA processing pathway and a description of all the RNA species detected are provided in Figure S1. Note that several abundant truncated forms of the 36S RNA are detected (highlighted with stars in panel V). We suggest that in the absence of ITS2/3′-ETS processing after U8 depletion, large subunit precursors are targeted for degradation, and that this is manifested by activation of cryptic cleavage sites within the 28S-coding part of the precursor, leading to production of these abnormal dead-end intermediates.