Poster abstracts
Poster number 25 submitted by Monica Mannings
Does Pnrc2 promotes oscillatory mRNA decay independent of translational regulation of oscillatory protein?
Monica C. Mannings (The Ohio State University Molecular Genetics Department), Kiel T. Tietz (The Ohio State University Molecular Genetics Department), Thomas L. Gallagher (The Ohio State University Molecular Genetics Department)
Abstract:
Vertebrate segmentation is regulated by the segmentation clock, a biological oscillator that regulates embryonic segment formation. The segmentation clock controls oscillatory gene expression in the presomitic mesoderm (PSM) with the same periodicity as segment formation. Cyclically-expressed genes include genes encoding the Her/Hes family of transcriptional repressors. Our work investigates regulatory mechanisms governing cyclic expression during zebrafish segmentation. Previously, we showed that Proline-rich nuclear receptor coactivator 2 (Pnrc2) promotes decay of clock transcripts like her1, her7, and deltaC. pnrc2 mutants accumulate oscillatory transcripts, yet oscillatory protein expression is normal, suggesting that an additional layer of regulation ensures proper oscillatory protein expression. Using reporter-based assays, we showed that the her1 3’UTR drives rapid turnover of reporter transcripts in a Pnrc2-dependent manner and that a 3’UTR Pumilio (Pum) response element (PRE) functions as a decay element. Because PREs are present in other clock-associated transcript 3’UTRs, we hypothesize that Pum promotes oscillatory expression. Both zebrafish pum genes, pum1 and pum2, are expressed during segmentation and share extensive homology with mammalian Pum1 and Pum2. Because Pum proteins promote translational repression and mRNA decay, we hypothesize that oscillatory protein levels may be unaffected in pnrc2 mutants due to Pum-mediated translational repression of accumulated clock-associated transcripts. To address the potential role of Pum during segmentation, we are characterizing pum single mutants and pum;pnrc2 double and triple mutants. In parallel, we are performing ribosomal profiling to assess the translational status of accumulated oscillatory transcripts in pnrc2 mutants. Using genetic and biochemical approaches, our goal is to uncover mechanisms that underlie Pnrc2-mediated decay of oscillatory transcripts during segmentation.
Keywords: segmentation, Pumilio, translation