Splicing, transcription, and chromatin: a ménage à trois

Alternative splicing allows for one gene to encode multiple proteins. This mechanism is regulated by dedicated splicing factors. However, recent data have shown that these factors contact the RNA polymerase II as well as transcription factors and chromatin remodeling enzymes present inside the coding region of the gene. These observations favor a model where cotranscriptional splice decisions are assisted by factors recruited at the promoter or by the elongating polymerase. We also suggest that chromatin could function as an RNA-binding matrix displaying the immature transcripts to the spliceosomes.