scholarly journals Transcription elongation in the human c-myc gene is governed by overall transcription initiation levels in Xenopus oocytes.

1993 ◽  
Vol 13 (2) ◽  
pp. 1296-1305 ◽  
Author(s):  
C A Spencer ◽  
M A Kilvert
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Incubation Time ◽  
Transcription Initiation ◽  
Xenopus Oocytes ◽  
Transcription Termination ◽  
Transcription Elongation ◽  
Threshold Level ◽  
Specific Effects ◽  
Myc Gene

Both transcription initiation and transcription elongation contribute to the regulation of steady-state c-myc RNA levels. We have used the Xenopus oocyte transcription assay to study premature transcription termination which occurs in the first exon and intron of the human c-myc gene. Previous studies showed that after injection into Xenopus oocytes transcription from the c-myc P1 promoter resulted in read-through transcripts whereas transcription from the stronger P2 promoter resulted in a combination of prematurely terminated and read-through transcripts. We now demonstrate that this promoter-specific processivity results from the overall amount of RNA polymerase II transcription occurring from either promoter. Parameters that reduce the amount of transcription from P1 or P2, such as decreased concentration of template injected or decreased incubation time, result in a reduction in the ratio of terminated to read-through c-myc transcripts. Conversely, when transcription levels are increased by higher concentrations of injected template, increased incubation time, or coinjection with competing template, the ratio of terminated to read-through transcripts increases. We hypothesize that an RNA polymerase II processivity function is depleted above a threshold level of transcription initiation, resulting in high levels of premature transcription termination. These findings account for the promoter-specific effects on transcription elongation previously seen in this assay system and suggest a mechanism whereby limiting transcription elongation factors may contribute to transcription regulation in other eukaryotic cells.

Transcription elongation in the human c-myc gene is governed by overall transcription initiation levels in Xenopus oocytes

1993 ◽  
Vol 13 (2) ◽  
pp. 1296-1305
Author(s):  
C A Spencer ◽  
M A Kilvert
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Incubation Time ◽  
Transcription Initiation ◽  
Xenopus Oocytes ◽  
Transcription Termination ◽  
Transcription Elongation ◽  
Threshold Level ◽  
Specific Effects ◽  
Myc Gene

Both transcription initiation and transcription elongation contribute to the regulation of steady-state c-myc RNA levels. We have used the Xenopus oocyte transcription assay to study premature transcription termination which occurs in the first exon and intron of the human c-myc gene. Previous studies showed that after injection into Xenopus oocytes transcription from the c-myc P1 promoter resulted in read-through transcripts whereas transcription from the stronger P2 promoter resulted in a combination of prematurely terminated and read-through transcripts. We now demonstrate that this promoter-specific processivity results from the overall amount of RNA polymerase II transcription occurring from either promoter. Parameters that reduce the amount of transcription from P1 or P2, such as decreased concentration of template injected or decreased incubation time, result in a reduction in the ratio of terminated to read-through c-myc transcripts. Conversely, when transcription levels are increased by higher concentrations of injected template, increased incubation time, or coinjection with competing template, the ratio of terminated to read-through transcripts increases. We hypothesize that an RNA polymerase II processivity function is depleted above a threshold level of transcription initiation, resulting in high levels of premature transcription termination. These findings account for the promoter-specific effects on transcription elongation previously seen in this assay system and suggest a mechanism whereby limiting transcription elongation factors may contribute to transcription regulation in other eukaryotic cells.

Intrinsic sites of transcription termination and pausing in the c-myc gene

1988 ◽  
Vol 8 (10) ◽  
pp. 4389-4394
Author(s):  
T K Kerppola ◽  
C M Kane
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Xenopus Oocytes ◽  
Transcription Termination ◽  
Transcription Elongation ◽  
Rna Polymerase Iii ◽  
Intron 1 ◽  
Exon 1 ◽  
Myc Gene

We have studied transcription elongation and termination in the human c-myc gene. Transcription of c-myc gene sequences with purified mammalian RNA polymerase II revealed several sites of transcription termination and pausing in the vicinity of the exon 1-intron 1 junction. This region previously has been shown to block transcription elongation in vivo by nuclear run-on analysis (D. Bentley and M. Groudine, Nature [London] 321:702-706, 1986). These sites were recognized by purified RNA polymerase II, and we therefore designated them intrinsic sites of termination and pausing. Two of these sites cause termination of RNA polymerase III transcription as well. RNA polymerase II terminated transcription in a cluster of seven consecutive T residues in the nontranscribed strand and paused during transcription at three additional sites in this region. The intrinsic sites of transcription termination and pausing described here correspond closely to the 3' ends of transcripts synthesized in Xenopus oocytes injected with plasmids containing the c-myc termination region (D. Bentley and M. Groudine, Cell 53:245-256, 1988). This correspondence suggests that the intrinsic recognition of these termination and pause sites by purified RNA polymerase II may play a role in the transcription elongation block observed in vivo.

scholarly journals Intrinsic sites of transcription termination and pausing in the c-myc gene.

1988 ◽  
Vol 8 (10) ◽  
pp. 4389-4394 ◽  
Author(s):  
T K Kerppola ◽  
C M Kane
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Xenopus Oocytes ◽  
Transcription Termination ◽  
Transcription Elongation ◽  
Rna Polymerase Iii ◽  
Intron 1 ◽  
Exon 1 ◽  
Myc Gene

We have studied transcription elongation and termination in the human c-myc gene. Transcription of c-myc gene sequences with purified mammalian RNA polymerase II revealed several sites of transcription termination and pausing in the vicinity of the exon 1-intron 1 junction. This region previously has been shown to block transcription elongation in vivo by nuclear run-on analysis (D. Bentley and M. Groudine, Nature [London] 321:702-706, 1986). These sites were recognized by purified RNA polymerase II, and we therefore designated them intrinsic sites of termination and pausing. Two of these sites cause termination of RNA polymerase III transcription as well. RNA polymerase II terminated transcription in a cluster of seven consecutive T residues in the nontranscribed strand and paused during transcription at three additional sites in this region. The intrinsic sites of transcription termination and pausing described here correspond closely to the 3' ends of transcripts synthesized in Xenopus oocytes injected with plasmids containing the c-myc termination region (D. Bentley and M. Groudine, Cell 53:245-256, 1988). This correspondence suggests that the intrinsic recognition of these termination and pause sites by purified RNA polymerase II may play a role in the transcription elongation block observed in vivo.

scholarly journals Genome-wide R-loop analysis defines unique roles for DDX5, XRN2, and PRMT5 in DNA/RNA hybrid resolution

2020 ◽  
Vol 3 (10) ◽  
pp. e202000762
Author(s):  
Oscar D Villarreal ◽  
Sofiane Y Mersaoui ◽  
Zhenbao Yu ◽  
Jean-Yves Masson ◽  
Stéphane Richard
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Transcription Start Site ◽  
Transcription Initiation ◽  
Transcription Termination ◽  
Start Site ◽  
Loop Gain ◽  
Transcription Start ◽  
Genome Wide ◽  
Rna Polymerase Ii Transcription

DDX5, XRN2, and PRMT5 have been shown to resolve DNA/RNA hybrids (R-loops) at RNA polymerase II transcription termination sites at few genomic loci. Herein, we perform genome-wide R-loop mapping using classical DNA/RNA immunoprecipitation and high-throughput sequencing (DRIP-seq) of loci regulated by DDX5, XRN2, and PRMT5. We observed hundreds to thousands of R-loop gains and losses at transcribed loci in DDX5-, XRN2-, and PRMT5-deficient U2OS cells. R-loop gains were characteristic of highly transcribed genes located at gene-rich regions, whereas R-loop losses were observed in low-density gene areas. DDX5, XRN2, and PRMT5 shared many R-loop gain loci at transcription termination sites, consistent with their coordinated role in RNA polymerase II transcription termination. DDX5-depleted cells had unique R-loop gain peaks near the transcription start site that did not overlap with those of siXRN2 and siPRMT5 cells, suggesting a role for DDX5 in transcription initiation independent of XRN2 and PRMT5. Moreover, we observed that the accumulated R-loops at certain loci in siDDX5, siXRN2, and siPRMT5 cells near the transcription start site of genes led to antisense intergenic transcription. Our findings define unique and shared roles of DDX5, XRN2, and PRMT5 in DNA/RNA hybrid regulation.

scholarly journals Distinct properties of c-myc transcriptional elongation are revealed in Xenopus oocytes and mammalian cells and by template titration, 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB), and promoter mutagenesis.

1993 ◽  
Vol 13 (9) ◽  
pp. 5647-5658 ◽  
Author(s):  
T Meulia ◽  
A Krumm ◽  
M Groudine
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Transcription Initiation ◽  
Mammalian Cells ◽  
Xenopus Oocytes ◽  
Premature Termination ◽  
Proximal Region ◽  
Transcriptional Elongation ◽  
Transcription Complexes ◽  
Rna Polymerase Ii Transcription

A block to c-myc transcription elongation has been observed in Xenopus oocytes and mammalian cells. Here, we show that the distribution of RNA polymerase II transcription complexes in the c-myc promoter proximal region in Xenopus oocytes is different from that observed previously in mammalian cells. Thus, there are major differences in the c-myc elongation block observed in the two systems. In addition, as first reported for a Xenopus tubulin gene (K. M. Middleton and G. T. Morgan, Mol. Cell. Biol. 10:727-735, 1990). c-myc template titration experiments reveal the existence of two classes of RNA polymerase II transcription complexes in oocytes: one (at low template concentration) that is capable of reading through downstream sites of premature termination, and another (high template concentration) that does not. We show that these classes of polymerases are distinct from those previously identified by 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB), which distinguishes transcription complexes on the basis of transcribed distance, rather than on the basis of differential elongation through sites of premature termination. We also show that mutations that affect the efficiency of initiation of transcription from the c-myc P2 promoter can influence premature termination by at least two mechanisms: TATA box mutations function by the titration effect (decrease in transcription initiation results in a relative decrease in premature termination), while an upstream activator (E2F) site functions by contributing to the assembly of polymerase complexes competent to traverse the downstream sites of premature termination.

Distinct properties of c-myc transcriptional elongation are revealed in Xenopus oocytes and mammalian cells and by template titration, 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB), and promoter mutagenesis

1993 ◽  
Vol 13 (9) ◽  
pp. 5647-5658
Author(s):  
T Meulia ◽  
A Krumm ◽  
M Groudine
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Transcription Initiation ◽  
Mammalian Cells ◽  
Xenopus Oocytes ◽  
Premature Termination ◽  
Proximal Region ◽  
Transcriptional Elongation ◽  
Transcription Complexes ◽  
Rna Polymerase Ii Transcription

A block to c-myc transcription elongation has been observed in Xenopus oocytes and mammalian cells. Here, we show that the distribution of RNA polymerase II transcription complexes in the c-myc promoter proximal region in Xenopus oocytes is different from that observed previously in mammalian cells. Thus, there are major differences in the c-myc elongation block observed in the two systems. In addition, as first reported for a Xenopus tubulin gene (K. M. Middleton and G. T. Morgan, Mol. Cell. Biol. 10:727-735, 1990). c-myc template titration experiments reveal the existence of two classes of RNA polymerase II transcription complexes in oocytes: one (at low template concentration) that is capable of reading through downstream sites of premature termination, and another (high template concentration) that does not. We show that these classes of polymerases are distinct from those previously identified by 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB), which distinguishes transcription complexes on the basis of transcribed distance, rather than on the basis of differential elongation through sites of premature termination. We also show that mutations that affect the efficiency of initiation of transcription from the c-myc P2 promoter can influence premature termination by at least two mechanisms: TATA box mutations function by the titration effect (decrease in transcription initiation results in a relative decrease in premature termination), while an upstream activator (E2F) site functions by contributing to the assembly of polymerase complexes competent to traverse the downstream sites of premature termination.

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