Poster abstracts
Poster number 2 submitted by Rene Arvola
Investigating Regulators of Nonsense Mediated mRNA Decay in Zebrafish Neuromuscular Development
Rene Arvola (Department of Molecular Genetics, OSU), Pooja Gangras (Department of Molecular Genetics, OSU), Zhongxia Yi (Department of Molecular Genetics, OSU), Thomas Gallagher (Department of Molecular Genetics, OSU), Sharon Amacher (Department of Molecular Genetics, Department of Biological Chemistry and Pharmacology, OSU), Guramrit Singh (Department of Molecular Genetics, OSU)
Abstract:
Embryonic development requires highly specific spatiotemporal control of gene expression achieved, in part, by RNA binding proteins that regulate the stability and expression of mRNAs. The Exon Junction Complex (EJC) is a conserved multiprotein complex that is deposited on spliced mRNAs and is critical for many aspects of post-transcriptional gene regulation. In higher eukaryotes, the EJC serves as a regulator of mRNA quality control through stimulating Nonsense-Mediated Decay (NMD) of mRNAs bearing premature termination codons (PTCs). The EJC is necessary for murine brain development through supporting the proliferation of neural progenitors [1]; moreover EJC core components Rbm8a and Magoh are crucial for proper development of motor neurons and muscle during zebrafish embryogenesis [2]. The Cancer Susceptibility Candidate 3 (Casc3) protein is a peripheral EJC component that potentiates decay of a subset of transcripts [3]. Moreover, Casc3 has documented roles in mRNA localization, including in the murine brain [4]. Using human cell-based assays, we have demonstrated that CASC3 can stimulate decay of a PTC-bearing reporter and regulates endogenous PTC-containing mRNAs. To address how Casc3 modulates EJC function during development in vivo using zebrafish, we have generated casc3 mutants via CRISPR. Unlike rbm8a and magoh mutant zebrafish, casc3 homozygous mutants are viable; furthermore, preliminary studies suggest that several EJC-dependent NMD targets are not dysregulated in these mutants. Ongoing work includes investigating possible perturbations in motor neuron development in casc3 mutants. Future work will investigate whether Casc3 stimulates decay and/or localization of a subset of EJC-dependent targets, and whether this contributes to neuromuscular development or other tissue-specific roles.
References:
[1] Silver et al. (2010). The exon junction complex component Magoh controls brain size by regulating neural stem cell division. Nat Neurosci. 13(5):551-8
[2] Gangras et al. (2020). Zebrafish rbm8a and magoh mutants reveal EJC developmental functions and new 3′UTR intron-containing NMD targets. PLOS Genetics 16(6): e1008830
[3] Gerbracht et al. (2020). CASC3 promotes transcriptome-wide activation of nonsense-mediated decay by the exon junction complex, Nucleic Acids Research 48(15):8626-8644
[4] Fritzsche et al. (2013). Interactome of two diverse RNA granules links mRNA localization to translational repression in neurons. Cell Rep. 5(6):1749-62
Keywords: mRNA decay, embryonic development