The multifunctional protein p54nrb/PSF recruits the exonuclease XRN2 to facilitate pre-mRNA 3' processing and transcription termination.
Termination of RNA polymerase II transcription frequently requires a poly(A) signal and cleavage/polyadenylation factors. Recent work has shown that degradation of the downstream cleaved RNA by the exonuclease XRN2 promotes termination, but how XRN2 functions with 3'-processing factors to elicit termination remains unclear. Here we show that XRN2 physically associates with 3'-processing factors and accumulates at the 3' end of a transcribed gene. In vitro 3'-processing assays show that XRN2 is necessary to degrade the downstream RNA, but is not required for 3' cleavage. Significantly, degradation of the 3'-cleaved RNA was stimulated when coupled to cleavage. Unexpectedly, while investigating how XRN2 is recruited to the 3'-processing machinery, we found that XRN2 associates with p54nrb/NonO(p54)-protein-associated splicing factor (PSF), multifunctional proteins involved in several nuclear processes. Strikingly, p54 is also required for degradation of the 3'-cleaved RNA in vitro. p54 is present along the length of genes, and small interfering RNA (siRNA)-mediated knockdown leads to defects in XRN2 recruitment and termination. Together, our data indicate that p54nrb/PSF functions in recruitment of XRN2 to facilitate pre-mRNA 3' processing and transcription termination.
Kaneko
Syuzo
S
Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
Rozenblatt-Rosen
Orit
O
Meyerson
Matthew
M
Manley
James L
JL
D001483:Base Sequence; D004268:DNA-Binding Proteins; D005095:Exoribonucleases / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D034521:Nuclear Matrix-Associated Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D050810:Octamer Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000072670:PTB-Associated Splicing Factor; D034622:RNA Interference; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D034741:RNA, Small Interfering / Q000235:genetics; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; C083214:NONO protein, human; D034521:Nuclear Matrix-Associated Proteins; D050810:Octamer Transcription Factors; D000072670:PTB-Associated Splicing Factor; D012322:RNA Precursors; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D005095:Exoribonucleases; C120903:XRN2 protein, human