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A function for the hnRNP A1/A2 proteins in transcription elongation

ABSTRACT: The hnRNP A1 and A2 proteins regulate processes such as alternative pre-mRNA splicing and mRNA stability. Here, we report that a reduction in the levels of hnRNP A1 and A2 by RNA interference or their cytoplasmic retention by osmotic stress drastically increases the transcription of a reporter gene. Based on previous work, we propose that this effect may be linked to a decrease in the activity of the transcription elongation factor P-TEFb. Consistent with this hypothesis, the transcription of the reporter gene was stimulated when the catalytic component of P-TEFb, CDK9, was inhibited with DRB. While low levels of A1/A2 stimulated the association of RNA polymerase II with the reporter gene, they also increased the association of CDK9 with the repressor 7SK RNA, and compromised the recovery of promoter-distal transcription on the Kitlg gene after the release of pausing. Transcriptome analysis revealed that more than 50% of the genes whose expression was affected by the siRNA-mediated depletion of A1/A2 were also affected by DRB. RNA polymerase II-chromatin immunoprecipitation assays on DRB-treated and A1/A2-depleted cells identified a common set of repressed genes displaying increased occupancy of polymerases at promoter-proximal locations, consistent with pausing. Overall, our results suggest that lowering the levels of hnRNP A1/A2 elicits defective transcription elongation on a fraction of P-TEFb-dependent genes, hence favoring the transcription of P-TEFb-independent genes.

ORGANISM(S): Homo sapiens

PROVIDER: GSE67617 | GEO | 2015/04/07

SECONDARY ACCESSION(S): PRJNA280492

REPOSITORIES: GEO

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A function for the hnRNP A1/A2 proteins in transcription elongation

Project description:The hnRNP A1 and A2 proteins regulate processes such as alternative pre-mRNA splicing and mRNA stability. Here, we report that a reduction in the levels of hnRNP A1 and A2 by RNA interference or their cytoplasmic retention by osmotic stress drastically increases the transcription of a reporter gene. Based on previous work, we propose that this effect may be linked to a decrease in the activity of the transcription elongation factor P-TEFb. Consistent with this hypothesis, the transcription of the reporter gene was stimulated when the catalytic component of P-TEFb, CDK9, was inhibited with DRB. While low levels of A1/A2 stimulated the association of RNA polymerase II with the reporter gene, they also increased the association of CDK9 with the repressor 7SK RNA, and compromised the recovery of promoter-distal transcription on the Kitlg gene after the release of pausing. Transcriptome analysis revealed that more than 50% of the genes whose expression was affected by the siRNA-mediated depletion of A1/A2 were also affected by DRB. RNA polymerase II-chromatin immunoprecipitation assays on DRB-treated and A1/A2-depleted cells identified a common set of repressed genes displaying increased occupancy of polymerases at promoter-proximal locations, consistent with pausing. Overall, our results suggest that lowering the levels of hnRNP A1/A2 elicits defective transcription elongation on a fraction of P-TEFb-dependent genes, hence favoring the transcription of P-TEFb-independent genes. two treatements and one control

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Total RNA Pol2 ChIP-seq in mES cells treated with flavopiridol (Cdk9 inhibitor) after DSIF and NELF knockdown

Project description:Recent studies have found that promoter-proximal pausing occurs at most Pol2-regulated genes. DSIF and NELF function as negative elongation factors and promote Pol2 pausing. P-TEFb, whose enzymatic activity lies in the kinase Cdk9, positively regulates the transition into productive elongation by phosphorylating subunits in DSIF, NELF and Pol2. To gain insights into the interplay between these factors in regulating transcriptional pause release, we tested if knockdown of either pausing factor could bypass P-TEFb function. We find that P-TEFb function is still required for transcriptional elongation after DSIF or NELF knockdown. mES cells were infected with a shRNA hairpin to knockdown Spt5, Spt4, NelfE or control. The resulting cells were then treated with flavopiridol (1uM for 60 minutes). DNA was enriched by chromatin immunoprecipitation (ChIP) and analyzed by Solexa sequencing. A sample of whole cell extract was sequenced and used as the background to determine enrichment. ChIP was performed using an antibody against total RNA Pol2 (Rpb1 N-terminus, Santa Cruz sc-899).

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Total RNA Pol2 ChIP-seq in mES cells treated with flavopiridol (Cdk9 inhibitor) after DSIF and NELF knockdown

2011-01-19 | GSE26658 | GEO

Homo sapiens

Project description:A function for the hnRNP A1/A2 proteins in transcription elongation

| PRJNA280492 | ENA