Poster abstracts
Poster number 5 submitted by Monica Blatnik
Pnrc2-dependent mRNA decay and translational control mechanisms promote oscillatory gene expression during vertebrate segmentation
Monica C. Blatnik (Department of Molecular Genetics, MCDB program), Thomas L. Gallagher (Department of Molecular Genetics), Sharon L. Amacher (Department of Molecular Genetics, Department of Biological Chemistry and Pharmacology)
Abstract:
During early vertebrate embryogenesis, muscle and skeletal stem cells are grouped into reiterated segments, called somites, in a process called somitogenesis. Somite formation is established by a genetic oscillator called the segmentation clock, comprised of a network of genes expressed periodically 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. proline-rich nuclear receptor coactivator 2 (pnrc2) regulates oscillatory mRNA decay in zebrafish embryos and loss of pnrc2 results in stabilization and accumulation of segmentation clock transcripts. However, pnrc2 mutant embryos exhibit normal segmentation clock protein expression and somite patterning is not disrupted. Polysome profiling analysis revealed that segmentation clock gene transcripts that are upregulated upon loss of pnrc2, including her1, her7, dlc, and rhov, are significantly increased in the ribosome-unbound (non-translating) fractions, indicating inefficient translation of accumulated transcripts. In addition, functional in vivo reporter analyses conducted to identify destabilizing cis-regulatory elements within the her1 3’UTR revealed that two RNA binding protein motifs, a Pumilio Response Element (PRE) and AU-rich Element (ARE), collectively drive rapid reporter transcript decay and repress reporter translation. Pumilio and a subclass of ARE-binding proteins are known to promote mRNA decay and repress translation of their target transcripts, and our work investigates the role of these RBPs in segmentation clock post-transcriptional regulation and somite patterning.
Keywords: decay, translation, oscillation