Bound to splice

Abstract

Messenger RNAs don't usually correspond exactly to DNA — portions of the primary transcript, known as introns, are removed by splicing. A study reveals new ways in which splicing can be regulated. Genome-wide analyses in yeast have shown that the switch from mitosis to gamete-forming meiosis is associated with a dramatic change in gene expression profiles. One protein expressed only during meiosis is the cyclin Rem1, which enhances pre-meiotic intragenic recombination and ensures progression through meiosis. Moldon et al. now show that Rem1 expression in the fission yeast Saccharomyces pombe is controlled not only at the level of transcription, but also by splicing. In mitotic cells, binding of the Fkh2 transcription factor to the Rem1 promoter yields a transcript that retains its introns so that only a short protein is produced; this protein affects recombination levels. In meiotic cells, binding of a meiosis-specific transcription factor, Mei4, to the Rem1 promoter results in splicing of Rem1, and the active cyclin. Thus two transcription factors can differentially modify splicing of the same gene.