Other approaches to RNAi include DNA-directed RNAi (ddRNAi) that is used to produce dsRNA inside the cell, which is cleaved into siRNA by the action of Dicer, a specific type of RNAse III
dsRNA can be intercepted by RNase III
Dicer acting in the RNA interference (RNAi) pathway, an ancient eukaryotic defense mechanism.
Structurally, Dicer1 has mainly two RNase III
domains along with helicase and Piwi/Argonaute/Zwille (PAZ) domains.
Many papers center around RNA, including nonsense-mediated mRNA decay, bacterial metabolic regulation, editing in plants, RNase III
, transcriptional elongation control, and adaptive translation.
In the first processing step, which occurs in the nucleus, the pri-miRNA is cleaved into pre-miRNA (an approximately 70-nucleotide hairpin stem loop intermediate) by a microprocessor complex that consists of Drosha, an RNase III
enzyme, and DGCR8, a double-stranded RNA-binding domain (dsRBD) protein .