Transcriptional activity regulates alternative cleavage and polyadenylation

Molecular Systems Biology

Zhe Ji¹  Wenting Luo¹  Wencheng Li¹  Mainul Hoque¹  Zhenhua Pan¹  Yun Zhao¹ 

[1] Department of Biochemistry and Molecular Biology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, NJ, USA

关键词: 3′ end processing;    3′UTR;    alternative polyadenylation;    post‐transcriptional control;    transcription;   

DOI  :  10.1038/msb.2011.69

来源: Wiley

【 摘 要 】

Abstract

Genes containing multiple pre-mRNA cleavage and polyadenylation sites, or polyA sites, express mRNA isoforms with variable 3′ untranslated regions (UTRs). By systematic analysis of human and mouse transcriptomes, we found that short 3′UTR isoforms are relatively more abundant when genes are highly expressed whereas long 3′UTR isoforms are relatively more abundant when genes are lowly expressed. Reporter assays indicated that polyA site choice can be modulated by transcriptional activity through the gene promoter. Using global and reporter-based nuclear run-on assays, we found that RNA polymerase II is more likely to pause at the polyA site of highly expressed genes than that of lowly expressed ones. Moreover, highly expressed genes tend to have a lower level of nucleosome but higher H3K4me3 and H3K36me3 levels at promoter-proximal polyA sites relative to distal ones. Taken together, our results indicate that polyA site usage is generally coupled to transcriptional activity, leading to regulation of alternative polyadenylation by transcription.

Synopsis

Transcriptomic and epigenomic data, as well as reporter and nuclear run-on assays collectively show that transcriptional activity regulates the relative abundance of alternative polyadenylation isoforms, indicating general coupling of 3′ end processing to transcription.

• Using RNA-seq and exon array data for a large number of human and mouse tissues and cells, we identified a general correlation between relative expression of alternative polyadenylation (APA) isoforms and gene expression level: short 3′UTR isoforms are relatively more abundant when genes are highly expressed whereas long 3′UTR isoforms are relatively more abundant when genes are lowly expressed.
• Using reporter assays with different promoters, we found that induction of transcription leads to more usage of promoter-proximal polyA sites, suggesting modulation of 3′ end processing efficiency by transcriptional activity. Global analysis and reporter-based assays further revealed that regulation of polyA site choice by transcription takes place when genes are regulated under different cell conditions.
• Using global and reporter-based nuclear run-on assays, we found that highly expressed genes tend to have more RNA polymerase II pausing at promoter-proximal polyA sites, as compared with lowly expressed genes, supporting the notion that the efficiency of 3′ end processing is coupled to transcriptional activity.
• Highly expressed genes have a lower nucleosome level but higher H3K4me3 and H3K36me3 levels at promoter-proximal polyA sites relative to distal ones, as compared with lowly expressed genes, indicating that transcriptional activity impacts 3′ end processing and regulation of APA leaves epigenetic signatures.

【 授权许可】

CC BY-NC-SA   
Copyright © 2011 EMBO and Macmillan Publishers Limited

Creative Commons Attribution License, which permits distribution, and reproduction in any medium, provided the original author and source are credited. This license does not permit commercial exploitation without specific permission.