Talk abstracts

Talk on Friday 02:50-03:10pm submitted by Jo Ann Wise

A meiotic gene regulatory cascade driven by alternative fates for newly synthesized transcripts

Nicole Cremona (Molecular Biology & Microbiology, Case Western Reserve Univ.), Kristine Potter (Molecular Biology & Microbiology, Case Western Reserve Univ.), Jo Ann Wise (Molecular Biology & Microbiology, Case Western Reserve Univ.)

Abstract:
To determine the relative importance of transcriptional regulation vs. RNA processing and turnover during the transition from proliferation to meiotic differentiation in the fission yeast Schizosaccharomyces pombe, we analyzed temporal profiles and effects of RNA surveillance factor mutants on expression of 32 meiotic genes. Comparing nascent transcription with steady state RNA accumulation reveals that the vast majority of these genes show a lag between maximal RNA synthesis and peak RNA accumulation. During meiosis, total RNA levels parallel 3' processing, which occurs in multiple temporally distinct waves that peak from 3-6 hours after meiotic induction. Most early genes and one middle gene, mei4, share a regulatory mechanism in which a specialized RNA surveillance factor targets newly synthesized transcripts for destruction. Mei4p, a member of the forkhead transcription factor family, in turn regulates a host of downstream genes. Remarkably, a spike in transcription is observed for less than one-third of the genes surveyed, and even these show evidence of RNA-level regulation. In aggregate, our findings lead us to propose that a regulatory cascade driven by changes in processing and stability of newly synthesized transcripts operates alongside the well-known transcriptional cascade as fission yeast cells enter meiosis.

Keywords: transcription, polyadenylation, meiosis