Abstract
The Wnt/β-catenin transcriptional activation complex requires the adapter protein Pygopus (Pygo), which links the basal transcription machine to β-catenin to regulate the transcription of target genes. Previous studies revealed that the Pygo genes were broadly involved in the embryonic development of Drosophila, Xenopus and mouse, however, their functions in the embryonic development of amphioxus and zebrafish remain to be investigated. Here, we cloned and characterized one Pygo gene from amphioxus Branchiostoma belcheri (BbPygo) and two from zebrafish Danio rerio (DrPygo1 and DrPygo2). The spatial–temporal expression profiles showed that all these genes were maternally expressed. BbPygo expression was distributed ubiquitously in the amphioxus embryos before the gastrula stage and became restricted in the pharyngeal region in late stages. Similar to BbPygo, DrPygo2 was also expressed throughout whole embryos before the early gastrula stage, but limited in the pharyngeal region and central nervous system (CNS) in subsequent developing stages. Further knockdown of the DrPygo2 resulted in developmental defects of the body axis, CNS and cartilage segments in zebrafish. In contrast, the expression signal of the DrPygo1 gene was not detectable using the in situ hybridization method, which is consistent with its extremely low expression level detected by RT-qPCR. The expression patterns and function investigations revealed in this study suggest that the three Pygo genes probably function differentially though all of them show a conserved maternal expression pattern during the early embryonic stages of amphioxus and zebrafish.
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Acknowledgments
We thank Dr. Qiang Wang (Institute of Zoology, Chinese Academy of Sciences) and Dr. Zongbin Cui (Institute of Hydrobiology, Chinese Academy of Sciences) for kindly providing the plasmids Emx1, Krox20, Pax2a and Shha of zebrafish. This work was supported by a Grant from the National Natural Science Foundation of China (Nos. 31071110 and 31101631) and also from China Postdoctoral Science Foundation funded project (2014M561711).
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Guanghui Qian and Liyan Zhu have contributed equally to this work.
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Qian, G., Zhu, L., Li, G. et al. Distinct expression patterns and functions of the pygopus genes in amphioxus and zebrafish early embryogenesis. Genes Genom 37, 375–386 (2015). https://doi.org/10.1007/s13258-015-0266-5
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DOI: https://doi.org/10.1007/s13258-015-0266-5