Putative binding sites for mir‐125 family miRNAs in the mouse Lfng 3′UTR affect transcript expression in the segmentation clock, but mir‐125a‐5p is dispensable for normal somitogenesis

• Published in: Developmental dynamics Vol. 246; no. 10; pp. 740 - 748
• Main Authors: Wahi, Kanu, Friesen, Sophia, Coppola, Vincenzo, Cole, Susan E.
• Format: Journal Article
• Language: English
• Published: 01.10.2017
• Subjects: 3′UTR; lunatic fringe; miRNA; mir‐125a‐5p; posttranscriptional regulation; segmentation clock; somitogenesis
• ISSN: 1058-8388; 1097-0177
• DOI: 10.1002/dvdy.24552

Background: In vertebrate embryos, a “segmentation clock” times somitogenesis. Clock‐linked genes, including Lunatic fringe (Lfng), exhibit cyclic expression in the presomitic mesoderm (PSM), with a period matching the rate of somite formation. The clock period varies widely across species, but the mechanisms that underlie this variability are not clear. The half‐lives of clock components are proposed to influence the rate of clock oscillations, and are tightly regulated in the PSM. Interactions between Lfng and mir‐125a‐5p in the embryonic chicken PSM promote Lfng transcript instability, but the conservation of this mechanism in other vertebrates has not been tested. Here, we examine whether this interaction affects clock activity in a mammalian species. Results: Mutation of mir‐125 binding sites in the Lfng 3′UTR leads to persistent, nonoscillatory reporter transcript expression in the caudal‐most mouse PSM, although dynamic transcript expression recovers in the central PSM. Despite this, expression of endogenous mir‐125a‐5p is dispensable for mouse somitogenesis. Conclusions: These results suggest that mir‐125a sites in the Lfng 3′ untranslated region influence transcript turnover in both mouse and chicken embryos, and support the existence of position‐dependent regulatory mechanisms in the PSM. They further suggest the existence of compensatory mechanisms that can rescue the loss of mir‐125a‐5p in mice. Developmental Dynamics 246:740–748, 2017. © 2017 Wiley Periodicals, Inc. Key Findings Lfng RNA stability can be influenced by mir‐125a‐5p in mouse cells. Mutation of putative mir‐125a binding sites in the Lfng 3′UTR causes persistent, non‐oscillatory reporter transcript expression in the caudal PSM. Transcripts with mutant mir‐125a sites in the 3′UTR exhibit restored dynamic expression in the central region of the PSM, supporting position‐dependent mechanisms that influence transcript turnover across the PSM. mir‐125a‐5p itself is not required for mouse somitogenesis.