Distinct expression patterns and functions of the pygopus genes in amphioxus and zebrafish early embryogenesis
2015
Qian, G., Soochow University, Suzhou, China | Zhu, L., Soochow University, Suzhou, China | Li, G., Xiamen University, Xiamen, China | Liu, X., Xiamen University, Xiamen, China | Wang, Y., Xiamen University, Xiamen, China
The Wnt/beta-catenin transcriptional activation complex requires the adapter protein Pygopus (Pygo), which links the basal transcription machine to b-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 fromzebrafish Danio rerio (DrPygo1 and DrPygo2). The spatialtemporal 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 RTqPCR. 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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