Chromatin structure is implicated in "late" elongation checkpoints on the U2 snRNA and beta-actin genes.
The negative elongation factor NELF is a key component of an early elongation checkpoint generally located within 100 bp of the transcription start site of protein-coding genes. Negotiation of this checkpoint and conversion to productive elongation require phosphorylation of the carboxy-terminal domain of RNA polymerase II (pol II), NELF, and DRB sensitivity-inducing factor (DSIF) by positive transcription elongation factor b (P-TEFb). P-TEFb is dispensable for transcription of the noncoding U2 snRNA genes, suggesting that a NELF-dependent checkpoint is absent. However, we find that NELF at the end of the 800-bp U2 gene transcription unit and RNA interference-mediated knockdown of NELF causes a termination defect. NELF is also associated 800 bp downstream of the transcription start site of the beta-actin gene, where a "late" P-TEFb-dependent checkpoint occurs. Interestingly, both genes have an extended nucleosome-depleted region up to the NELF-dependent control point. In both cases, transcription through this region is P-TEFb independent, implicating chromatin in the formation of the terminator/checkpoint. Furthermore, CTCF colocalizes with NELF on the U2 and beta-actin genes, raising the possibility that it helps the positioning and/or function of the NELF-dependent control point on these genes.
Egloff
Sylvain
S
Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, United Kingdom.
Al-Rawaf
Hadeel
H
O'Reilly
Dawn
D
Murphy
Shona
S
D000199:Actins / Q000235:genetics* / Q000378:metabolism*; D001665:Binding Sites; D000076246:CCCTC-Binding Factor; D002843:Chromatin / Q000235:genetics* / Q000378:metabolism*; D004257:DNA Polymerase II / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006609:High Mobility Group Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008954:Models, Biological; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D009707:Nucleosomes / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D042925:Positive Transcriptional Elongation Factor B / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D012342:RNA, Small Nuclear / Q000235:genetics* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic; D035602:Transcriptional Elongation Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
D000199:Actins; D000076246:CCCTC-Binding Factor; C000619697:CTCF protein, human; D002843:Chromatin; D004268:DNA-Binding Proteins; D006609:High Mobility Group Proteins; D009687:Nuclear Proteins; D009707:Nucleosomes; D034741:RNA, Small Interfering; D012342:RNA, Small Nuclear; D011994:Recombinant Proteins; D012097:Repressor Proteins; C073537:SSRP1 protein, human; C112224:SUPT5H protein, human; D014157:Transcription Factors; D035602:Transcriptional Elongation Factors; C405484:U2 small nuclear RNA; C118437:negative elongation factor; C018648:transcription factor S-II; D042925:Positive Transcriptional Elongation Factor B; D004257:DNA Polymerase II