title: MicroRNA genes are transcribed by RNA polymerase II.
abstract: MicroRNAs (miRNAs) constitute a large family of noncoding RNAs that function as guide molecules in diverse gene silencing pathways. Current efforts are focused on the regulatory function of miRNAs, while little is known about how these unusual genes themselves are regulated. Here we present the first direct evidence that miRNA genes are transcribed by RNA polymerase II (pol II). The primary miRNA transcripts (pri-miRNAs) contain cap structures as well as poly(A) tails, which are the unique properties of class II gene transcripts. The treatment of human cells with alpha-amanitin decreased the level of pri-miRNAs at a concentration that selectively inhibits pol II activity. Furthermore, chromatin immunoprecipitation analyses show that pol II is physically associated with a miRNA promoter. We also describe, for the first time, the detailed structure of a miRNA gene by determining the promoter and the terminator of mir-23a approximately 27a approximately 24-2. These data indicate that pol II is the main, if not the only, RNA polymerase for miRNA gene transcription. Our study offers a basis for understanding the structure and regulation of miRNA genes.
authors.affiliation: Institute of Molecular Biology and Genetics and School of Biological Science, Seoul National University, Seoul, Korea.
authors.forename: Yoontae
authors.initials: Y
authors.lastname: Lee
authors.forename: Minju
authors.initials: M
authors.lastname: Kim
authors.forename: Jinju
authors.initials: J
authors.lastname: Han
authors.forename: Kyu-Hyun
authors.initials: KH
authors.lastname: Yeom
authors.forename: Sanghyuk
authors.initials: S
authors.lastname: Lee
authors.forename: Sung Hee
authors.initials: SH
authors.lastname: Baek
authors.forename: V Narry
authors.initials: VN
authors.lastname: Kim
mesh_terms: D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D001483:Base Sequence; D002460:Cell Line; D002843:Chromatin / Q000378:metabolism; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006151:Guanosine / Q000031:analogs & derivatives / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D035683:MicroRNAs / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D012315:RNA Caps / Q000737:chemistry; D034622:RNA Interference; D012319:RNA Polymerase II / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D043244:Ribonuclease III / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D002843:Chromatin; D035683:MicroRNAs; D012315:RNA Caps; D034741:RNA, Small Interfering; D006151:Guanosine; D008156:Luciferases; D012319:RNA Polymerase II; D043244:Ribonuclease III