title: 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.
authors.affiliation: RNA group and Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
authors.forename: Bruno
authors.initials: B
authors.lastname: Lemieux
authors.affiliation: Stowers Institute for Medical Research, Kansas City, Missouri, United States of America.
authors.forename: Marco
authors.initials: M
authors.lastname: Blanchette
authors.affiliation: Lady Davis Institute for Medical Research-Sir Mortimer B. Davis Jewish General Hospital, McGill University, Montreal, Quebec, Canada.
authors.forename: Anne
authors.initials: A
authors.lastname: Monette
authors.affiliation: Lady Davis Institute for Medical Research-Sir Mortimer B. Davis Jewish General Hospital, McGill University, Montreal, Quebec, Canada.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Mouland
authors.affiliation: RNA group and Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
authors.forename: Raymund J
authors.initials: RJ
authors.lastname: Wellinger
authors.affiliation: RNA group and Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
authors.forename: Benoit
authors.initials: B
authors.lastname: Chabot
mesh_terms: D017398:Alternative Splicing; D002460:Cell Line; D042863:Cyclin-Dependent Kinase 9 / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004004:Dichlororibofuranosylbenzimidazole / Q000494:pharmacology; D017930:Genes, Reporter; D045325:HCT116 Cells; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D009997:Osmotic Pressure; D042925:Positive Transcriptional Elongation Factor B / Q000378:metabolism; D034622:RNA Interference; D012319:RNA Polymerase II / Q000037:antagonists & inhibitors / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D061805:Transcription Elongation, Genetic
chemical_list: D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D034741:RNA, Small Interfering; C439768:hnRNP A2; D004004:Dichlororibofuranosylbenzimidazole; D042925:Positive Transcriptional Elongation Factor B; C467969:CDK9 protein, human; D042863:Cyclin-Dependent Kinase 9; D012319:RNA Polymerase II