Talk abstracts
Talk on Friday 02:00-02:15pm submitted by Monica Mannings
Pnrc2-dependent mRNA decay and translational control mechanisms promote oscillatory gene expression during vertebrate segmentation
Monica Mannings (The Ohio State University Molecular Genetics Department), Thomas Gallagher (The Ohio State University Molecular Genetics Department), Sharon Amacher (The Ohio State University Molecular Genetics Department)
Abstract:
During early vertebrate embryogenesis, muscle and skeletal stem cells are grouped into reiterated segments, called somites, in a process called somitogenesis. Sequential somite formation is established by a genetic oscillator called the segmentation clock, comprised of a network of genes expressed rhythmically in the presomitic mesoderm. Precise control of segmentation clock oscillations is driven by robust temporal regulation of mRNA production, translation, and mRNA decay, and our work explores post-transcriptional mechanisms that regulate oscillatory expression. Previously, we demonstrated that Proline-rich nuclear receptor coactivator 2 (Pnrc2) regulates oscillatory mRNA decay in zebrafish and loss of pnrc2 results in stabilization and accumulation of clock transcripts. Surprisingly, pnrc2 mutant embryos exhibit normal protein expression and somite patterning is not disrupted. We are currently addressing this molecular phenotype by analyzing the translation status of clock transcripts in wild-type and pnrc2 mutant embryos using polysome profiling. We found segmentation clock transcripts her1, her7, dlc, and rhov are enriched in ribosome-unbound fractions in pnrc2 mutants, compared to wild type, which indicates that stabilized transcripts are translationally repressed. To further dissect the mechanism of clock transcript regulation, we performed in vivo reporter analyses that revealed that disruption of two RNA binding protein motifs, a Pumilio Response Element (PRE) and AU-rich Element (ARE), within the her1 3’UTR markedly increased stability and polysome association of reporter mRNAs, suggesting one or both elements are important for translational regulation of clock transcripts. Our work investigating the role of Pumilio and ARE-binding proteins in regulating segmentation clock mRNA stability and translation will demonstrate how essential, vertebrate patterning processes are robustly maintained through multiple layers of post-transcriptional regulation.
Keywords: decay, translation, oscillations