Poster abstracts
Poster number 82 submitted by Monica Mannings
Pnrc2 promotes 3'UTR-dependent oscillatory transcript decay during vertebrate segmentation
Monica Mannings (The Ohio State University Molecular Genetics Department), Kiel Tietz (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:
Vertebrate segmentation is regulated by the segmentation clock, a biological oscillator that controls periodic formation of embryonic segments, or somites, within the presomitic mesoderm (PSM). Molecular components of the clock include the her/Hes family of transcriptional repressors, but additional transcripts also cycle. While transcriptional regulation of clock-associated genes has been studied comprehensively, post-transcriptional mechanisms governing oscillatory gene expression are not well-understood. Our previous work demonstrated that Proline rich nuclear receptor coactivator 2 (Pnrc2) promotes decay of clock-associated transcripts like her1 and dlc during segmentation, and loss of pnrc2 results in stabilization of oscillatory mRNAs. Microinjection of pnrc2 mRNA and pnrc1 mRNA, which codes for a protein that shares sequence similarity with Pnrc2, both restore normal her1 expression. Pnrc2 and Pnrc1 contain highly conserved C-terminal domains known to be important for mediating interactions among mRNA processing and decay factors, such as DCP1A and UPF1. Additionally, we utilized a reporter-based assay that showed that Pnrc2 promotes decay in a her1 and dlc 3'UTR-dependent manner. Regulatory motifs present within both 3’UTRs, a Pumilio Response Element and AU-rich Element, are known to bind to proteins that promote decay and translational repression. Mutation of the PRE and ARE within the full-length her1 3’UTR resulted in increased stability of reporter transcripts, suggesting both motifs likely bind to proteins that degrade cyclic transcripts. Interestingly, while cyclic transcripts accumulate in pnrc2 mutants, cyclic protein does not accumulate. Discordant expression of clock-associated mRNA and protein in pnrc2 mutants suggests that multiple levels of post-transcriptional gene regulation are implemented to sustain molecular oscillations during somitogenesis, and we are currently investigating trans factors that may be involved in decay and translation of oscillatory transcripts during vertebrate segmentation.
Keywords: decay, 3UTR, segmentation