Feed-forward microprocessing and splicing activities at a microRNA-containing intron.
The majority of mammalian microRNA (miRNA) genes reside within introns of protein-encoding and non-coding genes, yet the mechanisms coordinating primary transcript processing into both mature miRNA and spliced mRNA are poorly understood. Analysis of melanoma invasion suppressor miR-211 expressed from intron 6 of melastatin revealed that microprocessing of miR-211 promotes splicing of the exon 6-exon 7 junction of melastatin by a mechanism requiring the RNase III activity of Drosha. Additionally, mutations in the 5' splice site (5'SS), but not in the 3'SS, branch point, or polypyrimidine tract of intron 6 reduced miR-211 biogenesis and Drosha recruitment to intron 6, indicating that 5'SS recognition by the spliceosome promotes microprocessing of miR-211. Globally, knockdown of U1 splicing factors reduced intronic miRNA expression. Our data demonstrate novel mutually-cooperative microprocessing and splicing activities at an intronic miRNA locus and suggest that the initiation of spliceosome assembly may promote microprocessing of intronic miRNAs.
Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, USA.
Maja M
MM
Janas
Mehdi
M
Khaled
Steffen
S
Schubert
Jacob G
JG
Bernstein
David
D
Golan
Rosa A
RA
Veguilla
David E
DE
Fisher
Noam
N
Shomron
Carmit
C
Levy
Carl D
CD
Novina
D045744:Cell Line, Tumor; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D007438:Introns / Q000235:genetics*; D008544:Melanocytes / Q000166:cytology; D035683:MicroRNAs / Q000235:genetics*; D016366:Open Reading Frames / Q000235:genetics; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D022821:RNA Splice Sites / Q000235:genetics; D012326:RNA Splicing; D034741:RNA, Small Interfering / Q000235:genetics; D016601:RNA-Binding Proteins; D043244:Ribonuclease III / Q000235:genetics / Q000378:metabolism; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000235:genetics / Q000378:metabolism; D017381:Spliceosomes / Q000235:genetics; D050053:TRPM Cation Channels / Q000235:genetics / Q000378:metabolism
C474043:DGCR8 protein, human; C549405:MIRN211 microRNA, human; D035683:MicroRNAs; D011506:Proteins; D022821:RNA Splice Sites; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D017412:Ribonucleoprotein, U1 Small Nuclear; D050053:TRPM Cation Channels; C492059:TRPM1 protein, human; C517918:DROSHA protein, human; D043244:Ribonuclease III