Figure 3

In vitro cleavage assay demonstrates that all DICER1 RNase IIIb mutations affect the production of 5p miRNAs. Using pre-miR122 as a surrogate for all DICER1-dependent pre-miRNAs, either the presence of 5p+loop and/or absence of 5p could be responsible for altering the transcriptome to initiate aberrant cellular signaling cascades to result in anaplastic sarcoma of the kidney. The somatic mutation in case 4 (c.5425G>A) is the same as that was previously reported for case 7, which results in 5p+loop and 3p.⁷ The somatic mutation (c.5425G>A) in cases 6 and 8 has been evaluated and results in 5p+loop and 3p. The somatic mutation in case 1 (c.5438A>G) is the same as that was reported for case 9, which can either result in 5p+loop and 3p (if it behaves as a missense mutation) or no miRNA generation (if it results in exon skipping).⁸