Coregulators:: transducing signal from transcription to alternative splicing

Cells respond to many external stimuli by modulating gene expression. A key step in this regulation is the control of transcription, which determines the concentrations of pre-mRNA that are produced. A second level of control involves maturation of pre-mRNAs; many are alternatively spliced, which changes the exon content of transcripts and therefore the 'message' of the genes. Recent data indicate that the two control levels are linked. Here, we describe how transcriptional regulators and coregulators influence alternative splicing, with a focus on genes that are controlled by steroid hormones. Recent technical advances that help to elucidate the impact of stimuli on the exon content of regulated gene transcripts are also discussed.