title: Depletion of key protein components of the RISC pathway impairs pre-ribosomal RNA processing.
abstract: Little is known about whether components of the RNA-induced silencing complex (RISC) mediate the biogenesis of RNAs other than miRNA. Here, we show that depletion of key proteins of the RISC pathway by antisense oligonucleotides significantly impairs pre-rRNA processing in human cells. In cells depleted of Drosha or Dicer, different precursors to 5.8S rRNA strongly accumulated, without affecting normal endonucleolytic cleavages. Moderate yet distinct processing defects were also observed in Ago2-depleted cells. Physical links between pre-rRNA and these proteins were identified by co-immunoprecipitation analyses. Interestingly, simultaneous depletion of Dicer and Drosha led to a different processing defect, causing slower production of 28S rRNA and its precursor. Both Dicer and Ago2 were detected in the nuclear fraction, and reduction of Dicer altered the structure of the nucleolus, where pre-rRNA processing occurs. Together, these results suggest that Drosha and Dicer are implicated in rRNA biogenesis.
authors.affiliation: Department of Core Antisense Research, ISIS Pharmaceuticals, Inc., 1896 Rutherford Rd, Carlsbad, CA 92008, USA. lliang@isisph.com
authors.forename: Xue-Hai
authors.initials: XH
authors.lastname: Liang
authors.forename: Stanley T
authors.initials: ST
authors.lastname: Crooke
mesh_terms: D060565:Argonaute Proteins; D002466:Cell Nucleolus / Q000648:ultrastructure; D002467:Cell Nucleus / Q000737:chemistry / Q000201:enzymology; D003593:Cytoplasm / Q000737:chemistry / Q000201:enzymology; D015852:Eukaryotic Initiation Factor-2 / Q000032:analysis / Q000037:antagonists & inhibitors; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D012322:RNA Precursors / Q000302:isolation & purification / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012335:RNA, Ribosomal / Q000302:isolation & purification / Q000378:metabolism*; D012340:RNA, Ribosomal, 5.8S / Q000378:metabolism; D034743:RNA-Induced Silencing Complex / Q000037:antagonists & inhibitors / Q000378:metabolism*; D043244:Ribonuclease III / Q000032:analysis / Q000037:antagonists & inhibitors / Q000502:physiology*
chemical_list: C466422:AGO2 protein, human; D060565:Argonaute Proteins; D015852:Eukaryotic Initiation Factor-2; D012322:RNA Precursors; D012335:RNA, Ribosomal; D012340:RNA, Ribosomal, 5.8S; D034743:RNA-Induced Silencing Complex; C517918:DROSHA protein, human; D043244:Ribonuclease III