Functional roles of the Ripply-mediated suppression of segmentation gene expression at the anterior presomitic mesoderm in zebrafish

In this study, we generated ripply1 mutants and examined genetic interaction between ripply1/2 and tbx6. Zebrafish ripply1−/− embryos failed to form the somite boundaries as was observed in knockdown embryos. We found that somite segmentation defects in ripply1 mutants were suppressed by heterozygous mutation of tbx6 or partial translational inhibition of tbx6 by antisense morpholino. We further showed that somite boundaries that were recovered in tbx6+/−; ripply1−/− embryos were dependent on the function of ripply2, indicating that relative gene dosage between ripply1/2 and tbx6 plays a critical role in the somite formation. Interestingly, the expression of segmentation genes such mesp as was still not fully suppressed at the anterior PSM of tbx6+/−; ripply1−/− embryos although the somite formation and rostral-caudal polarity of somites were properly established. Furthermore, impaired myogenesis was observed in the segmented somites in tbx6+/−; ripply1−/− embryos. These results revealed that partial suppression of the segmentation gene expression by Ripply is sufficient to establish the rostral-caudal polarity of somites, and that stronger suppression of the segmentation gene expression by Ripply is required for proper myogenesis in zebrafish embryos.

Source: Mechanisms of Development - July 6, 2018 Category: Biology Source Type: research