miRNA生成过程中Drosha-DGCR8复合物与Dicer通过不同方式识别其RNA底物

rosha/DGCR8 complex cleaves primary microRNAs (pri-miRNAs) to yield ~ 65 nucleotide (nt) precursor microRNAs (pre-miRNAs). Dicer cleaves pre-miRNAs to yield ~ 22 nt miRNA/miRNA* duplexes. Interactions of Drosha/DGCR8 and Dicer with their substrates are incompletely understood. By in vitro Drosha and Dicer assays, we proposed models that human Drosha/DGCR8 and Dicer recognize their substrates in different manners. The flanking sequences and the terminal loop structure of a pri-miRNA are critical for Drosha/DGCR8 processing pri-miRNAs. The terminal loop of a pre-miRNA is not essential for hDicer processing. The end side and the stem of the pre-miRNA contribute to the recognizing and binding with Dicer. This study improved our understanding on RNase III functional mechanism and miRNA processing.