Talk Abstracts

Talk on Friday 01:24-01:36pm submitted by Thomas Gallagher

Pnrc2 is required for rapid decay of oscillating transcripts via their 3’ UTR

Thomas L. Gallagher (Molecular Genetics, The Ohio State University), Nicolas L. Derr, Kiel T. Tietz (Molecular Genetics, The Ohio State University), Courtney E. French, Jasmine M. McCammon, Michael L. Goldrich (Molecular and Cell Biology, University of California, Berkeley), Steven E. Brenner (Molecular and Cell Biology, University of California, Berkeley), Sharon L. Amacher (Molecular Genetics, The Ohio State University)

Abstract:
The vertebrate segmentation clock controls segment formation by regulating oscillating gene expression. The clock cycles rapidly with a period of 30-120 minutes, depending upon the vertebrate model. At the core of the clock are a family of auto-inhibitory transcriptional repressors encoded by the hairy/Enhancer of split-related (her or Hes) genes. Although many studies have elucidated transcriptional mechanisms important for oscillatory expression, fewer have investigated mechanisms of post-transcriptional processing that promote rapid clearance of Hes/her transcripts. In a zebrafish screen for genes involved in cyclic transcript regulation, we uncovered the tortuga mutation. tortuga^b644 mutants accumulate cyclic transcripts post-splicing. The gene affected in tortuga mutants is pnrc2, which encodes a proline-rich nuclear receptor co-activator implicated in promoting mRNA decay. We hypothesize that Pnrc2 is part of an mRNA decay complex that recognizes elements and/or structural features of developmentally-regulated transcripts. In support of this hypothesis, we find that pnrc2 genetically interacts with upf1, a nonsense-mediated decay (NMD) core component.
In order to define the instability feature(s) recognized by the Pnrc2 decay complex, we have developed an inducible in vivo reporter system to test transcript stability in zebrafish embryos. We show that the 3’ UTR of her1 is sufficient to confer instability to an otherwise stable heterologous transcript in a Pnrc2-dependent manner. Deletion constructs reveal that important features reside in the proximal half of the her1 3’ UTR and studies are underway to define the instability determinants. In parallel, we are comparing the her1 3’ UTR with other potential Prnc2-regulated targets that we identified via RNA-seq of Pnrc2-depleted embryos. Our goal is to define the regulatory logic controlling targeted degradation of oscillating transcripts.

Keywords: mRNA decay, pnrc2, oscillating expression