title: E2F mediates enhanced alternative polyadenylation in proliferation.
abstract: BACKGROUND
  The majority of mammalian genes contain multiple poly(A) sites in their 3' UTRs. Alternative cleavage and polyadenylation are emerging as an important layer of gene regulation as they generate transcript isoforms that differ in their 3' UTRs, thereby modulating genes' response to 3' UTR-mediated regulation. Enhanced cleavage at 3' UTR proximal poly(A) sites resulting in global 3' UTR shortening was recently linked to proliferation and cancer. However, mechanisms that regulate this enhanced alternative polyadenylation are unknown.
  
  
  RESULTS
  Here, we explored, on a transcriptome-wide scale, alternative polyadenylation events associated with cellular proliferation and neoplastic transformation. We applied a deep-sequencing technique for identification and quantification of poly(A) sites to two human cellular models, each examined under proliferative, arrested and transformed states. In both cell systems we observed global 3' UTR shortening associated with proliferation, a link that was markedly stronger than the association with transformation. Furthermore, we found that proliferation is also associated with enhanced cleavage at intronic poly(A) sites. Last, we found that the expression level of the set of genes that encode for 3'-end processing proteins is globally elevated in proliferation, and that E2F transcription factors contribute to this regulation.
  
  
  CONCLUSIONS
  Our results comprehensively identify alternative polyadenylation events associated with cellular proliferation and transformation, and demonstrate that the enhanced alternative polyadenylation in proliferative conditions results not only in global 3' UTR shortening but also in enhanced premature cleavage in introns. Our results also indicate that E2F-mediated co-transcriptional regulation of 3'-end processing genes is one of the mechanisms that links enhanced alternative polyadenylation to proliferation.
authors: Ran
authors: R
authors: Elkon
authors: Jarno
authors: J
authors: Drost
authors: Gijs
authors: G
authors: van Haaften
authors: Mathias
authors: M
authors: Jenal
authors: Mariette
authors: M
authors: Schrier
authors: Joachim A F
authors: JA
authors: Oude Vrielink
authors: Reuven
authors: R
authors: Agami
mesh_terms: D020413:3' Untranslated Regions; D002460:Cell Line; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000378:metabolism; D050684:E2F Transcription Factors / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D020869:Gene Expression Profiling; D059014:High-Throughput Nucleotide Sequencing / Q000379:methods*; D006801:Humans; D011061:Poly A / Q000032:analysis*; D026723:Polyadenylation; D017423:Sequence Analysis, RNA / Q000379:methods*
chemical_list: D020413:3' Untranslated Regions; D050684:E2F Transcription Factors; D011061:Poly A