title: Lower and upper stem-single-stranded RNA junctions together determine the Drosha cleavage site.
abstract: Microprocessor [Drosha-DGCR8 (DiGeorge syndrome critical region gene 8) complex] processing of primary microRNA (pri-miRNA) is the critical first step in miRNA biogenesis, but how the Drosha cleavage site is determined has been unclear. Previous models proposed that the Drosha-DGCR8 complex measures either ~22 nt from the upper stem-single-stranded RNA (ssRNA, terminal loop) junction or ~11 nt from the lower stem-ssRNA junction to determine the cleavage site. Here, using miRNA-offset RNAs to determine the Drosha cleavage site, we show that the Microprocessor measures the distances from both the lower and upper stem-ssRNA junctions to determine the cleavage site in human cells, and optimal distances from both structures are critical to the precision of Drosha processing. If the distances are not optimal, Drosha tends to cleave at multiple sites, which can, in turn, generate multiple 5' isomiRs. Thus, our results also reveal a mechanism of 5' isomiR generation.
authors.affiliation: Center of Excellence for Infectious Diseases, Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79905.
authors.forename: Hongming
authors.initials: H
authors.lastname: Ma
authors.forename: Yonggan
authors.initials: Y
authors.lastname: Wu
authors.forename: Jang-Gi
authors.initials: JG
authors.lastname: Choi
authors.forename: Haoquan
authors.initials: H
authors.lastname: Wu
mesh_terms: D002460:Cell Line; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D012323:RNA Processing, Post-Transcriptional / Q000502:physiology*; D043244:Ribonuclease III / Q000235:genetics / Q000378:metabolism*
chemical_list: D035683:MicroRNAs; C517918:DROSHA protein, human; D043244:Ribonuclease III
keywords: DcRNA; alternative Drosha processing; moR