Progesterone receptor induces bcl-x expression through intragenic binding sites favoring RNA polymerase II elongation

Abstract

Steroid receptors were classically described for regulating transcription by binding to target gene promoters. However, genome-wide studies reveal that steroid receptors-binding sites are mainly located at intragenic regions. To determine the role of these sites, we examined the effect of progestins on the transcription of the bcl-x gene, where only intragenic progesterone receptor-binding sites (PRbs) were identified. We found that in response to hormone treatment, the PR is recruited to these sites along with two histone acetyltransferases CREB-binding protein (CBP) and GCN5, leading to an increase in histone H3 and H4 acetylation and to the binding of the SWI/SNF complex. Concomitant, a more relaxed chromatin was detected along bcl-x gene mainly in the regions surrounding the intragenic PRbs. PR also mediated the recruitment of the positive elongation factor pTEFb, favoring RNA polymerase II (Pol II) elongation activity. Together these events promoted the re-distribution of the active Pol II toward the 3′-end of the gene and a decrease in the ratio between proximal and distal transcription. These results suggest a novel mechanism by which PR regulates gene expression by facilitating the proper passage of the polymerase along hormone-dependent genes.

Ulipristal Acetate Inhibits Progesterone Receptor Isoform A-Mediated Human Breast Cancer Proliferation and BCl2-L1 Expression

“…To better elucidate the molecular mechanisms by which P4-activated PRA regulated BCL 2- L 1 gene expression in MDA-iPRA cells and based on previous studies performed in T47D cells [ 27 ], ChIP assays were performed to examine PRA recruitment on one genomic target motif, already established on BCL 2 -L 1 gene [ 31 ]. We chose the intragenic PR-binding sequence located at +58 kb downstream Transcription Start Site (TSS) of BCL 2 -L 1 gene as schematically depicted in the genomic structure of the human BCL 2 -L 1 gene ( Fig 6A ).…”

Argonaute-1 binds transcriptional enhancers and controls constitutive and alternative splicing in human cells

“…ChIP was performed as published (5). Library preparation and sequencing were carried out following standard protocols.…”

“…Recently, amid an avalanche of papers reporting various connections between the chromatin context and splicing (3)(4)(5)(6)(7)(8)(9), a relationship between splicing and small RNAs has emerged. The convergence of these previously unrelated areas (RNA interference, chromatin, and splicing) has been studied by our laboratory, showing that siRNAs (20-25 nt long) targeting both intronic and exonic regions near the cassette exon 33 (E33, also known as EDI) of the fibronectin gene were able to regulate its alternative splicing by affecting the chromatin context at the target region, with an increase of histone tail modifications associated with gene silencing (H3K9me2 and H3K27me3, i.e., dimethylation of lysine 9 and trimethylation of lysine 27 of histone H3 respectively).…”

Heregulin Co-opts PR Transcriptional Action Via Stat3 Role As a Coregulator to Drive Cancer Growth

“…We have here reported that HRG␤1-activated Stat3 regulation on bcl-X transcription occurs via an intact PRE (Supplemental Figure 5A). Recently, ligand-activated PR was shown to regulate the transcription of human bcl-X by modulating the RNA polymerase II elongation process through binding to intragenic PREs (57). It remains to be determined whether unliganded PR exerts the latter regulation in the transcription of the murine bcl-X gene in spite of the divergence of the intronic sequences between both species.…”