Stimulatory effect of splicing factors on transcriptional elongation.
Transcription and pre-mRNA splicing are tightly coupled gene expression events in eukaryotic cells. An interaction between the carboxy-terminal domain of the largest subunit of RNA polymerase (Pol) II and components of the splicing machinery is postulated to mediate this coupling. Here, we show that splicing factors function directly to promote transcriptional elongation, demonstrating that transcription is more intimately coupled to splicing than previously thought. The spliceosomal U small nuclear ribonucleoproteins (snRNPs) interact with human transcription elongation factor TAT-SF1 (refs 6,7,8,9) and strongly stimulate polymerase elongation when directed to an intron-free human immunodeficiency virus-1 (HIV-1) template. This effect is likely to be mediated through the binding of TAT-SF1 to elongation factor P-TEFb, a proposed component of the transcription elongation complex. Inclusion of splicing signals in the nascent transcript further stimulates transcription, supporting the notion that the recruitment of U snRNPs near the elongating polymerase is important for transcription. Because the TAT-SF1-U snRNP complex also stimulates splicing in vitro, it may serve as a dual-function factor to couple transcription and splicing and to facilitate their reciprocal activation.
Fong
Y W
YW
Department of Molecular Biology, University of California at Berkeley, California, 94720-3206, USA.
Zhou
Q
Q
D056906:Cyclin T; D016213:Cyclins / Q000378:metabolism*; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D017354:Point Mutation; D042925:Positive Transcriptional Elongation Factor B; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012319:RNA Polymerase II / Q000378:metabolism; D012326:RNA Splicing; D016601:RNA-Binding Proteins / Q000378:metabolism; D017411:Ribonucleoproteins, Small Nuclear / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
C503684:CCNT1 protein, human; C114067:CUS2 protein, S cerevisiae; D056906:Cyclin T; D016213:Cyclins; C101819:HTATSF1 protein, human; D016601:RNA-Binding Proteins; D017411:Ribonucleoproteins, Small Nuclear; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D042925:Positive Transcriptional Elongation Factor B; D017346:Protein Serine-Threonine Kinases; D012319:RNA Polymerase II