Spliceosome assembly is coupled to RNA polymerase II dynamics at the 3′ end of human genes

• Published in: Nature structural & molecular biology Vol. 18; no. 10; pp. 1115 - 1123
• Main Authors: Carmo-Fonseca, Maria, Martins, Sandra Bento, Rino, José, Carvalho, Teresa, Carvalho, Célia, Yoshida, Minoru, Klose, Jasmim Mona, de Almeida, Sérgio Fernandes
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.10.2011; Nature Publishing Group
• Subjects: 631/337/1645/1792; 631/337/572; beta-Globins - genetics; Biochemistry; Biological Microscopy; Biomedical and Life Sciences; Cell Line, Tumor; Enzymes; Eukaryotes; Genomics; Humans; In Situ Hybridization, Fluorescence; Life Sciences; Membrane Biology; Messenger RNA; Mutation; Physiological aspects; Protein Structure; Retention; Ribonucleic acid; RNA; RNA Polymerase II - metabolism; RNA polymerases; RNA, Messenger - genetics; Spliceosomes; Transcription, Genetic; United States
• ISSN: 1545-9993; 1545-9985
• DOI: 10.1038/nsmb.2124

Post-transcriptional maturation of pre-mRNAs involves a number of processes that are now known to interact with transcription itself. Mutations affecting early spliceosome assembly, but not a drug targeting a catalytic step of splicing, are now shown to lead to nascent transcript retention and pausing of RNA polymerase II predominantly at the 3′ end of the gene, suggesting cross-talk between splicing and transcriptional termination. In the nucleus of higher eukaryotes, maturation of mRNA precursors involves an orderly sequence of transcription-coupled interdependent steps. Transcription is well known to influence splicing, but how splicing may affect transcription remains unclear. Here we show that a splicing mutation that prevents recruitment of spliceosomal snRNPs to nascent transcripts causes co-transcriptional retention of unprocessed RNAs that remain associated with polymerases stalled predominantly at the 3′ end of the gene. In contrast, treatment with spliceostatin A, which allows early spliceosome formation but destabilizes subsequent assembly of the catalytic complex, abolishes 3′ end pausing of polymerases and induces leakage of unspliced transcripts to the nucleoplasm. Taken together, the data suggest that recruitment of splicing factors and correct assembly of the spliceosome are coupled to transcription termination, and this might ensure a proofreading mechanism that slows down release of unprocessed transcripts from the transcription site.