Article

Visualization and exploration of Tcf/Lef function using a highly responsive Wnt/Β-catenin signaling-reporter transgenic zebrafish

Division of Cell Regulation Systems, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Developmental Biology (Impact Factor: 3.64). 07/2012; 370(1):71-85. DOI: 10.1016/j.ydbio.2012.07.016
Source: PubMed

ABSTRACT Evolutionarily conserved Tcf/Lef transcription factors (Lef1, Tcf7, Tcf7l1, and Tcf7l2) mediate gene expression regulated by Wnt/β-catenin signaling, which has multiple roles in early embryogenesis, organogenesis, adult tissue homeostasis, and tissue regeneration. However, the spatiotemporal dynamics of Tcf/Lef activity during these events remain poorly understood. We generated stable transgenic zebrafish lines carrying a new Wnt/β-catenin signaling reporter, Tcf/Lef-miniP:dGFP. The reporter revealed the transcriptional activities of four Tcf/Lef members controlled by Wnt/β-catenin signaling, which were expressed in known Wnt/β-catenin signaling-active sites during embryogenesis, organ development and growth, and tissue regeneration. We used the transgenic lines to demonstrate the contribution of Tcf/Lef-mediated Wnt/β-catenin signaling to the development of the anterior lateral line, dorsal and secondary posterior lateral lines, and gill filaments. Thus, these reporter lines are highly useful tools for studying Tcf/Lef-mediated Wnt/β-catenin signaling-dependent processes.

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    • "These results suggest that Hipk2 is essential for endogenous b-catenin stability in zebrafish embryos. To monitor the specific role of Hipk2 in the Wnt/b-catenin pathway, we used a transgenic zebrafish line carrying a Wnt/b-catenin signaling reporter construct (OTM:d2EGFP) comprising a destabilized GFP (d2EGFP) driven by a promoter containing multiple Tcf/Lef binding sites (Shimizu et al., 2012). d2EGFP expression was attenuated by hipk2 knockdown using MOs at 4, 8, and 10 hr postfertilization (hpf) (Figures 1B, S2B, and S2C), suggesting that Hipk2 is required for b-catenin pathway activation throughout early zebrafish embryogenesis. "
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    • "Thus, we speculate that the accumulative process of í µí»½-catenin is not primarily mediated by í µí»½catenin mRNA but instead by the state of í µí»½-catenin, such as phosphorylation or dephosphorylation. The role of Tcf7/Lef1 as either a repressor or activator in Wnt/í µí»½-catenin signaling is controversial [41] [42]. We found that the treatment of BMSCs with SP led to an increased expression of Lef1 and Tcf7, which appeared to exert a positive effect on the activation of SPinduced Wnt/í µí»½-catenin signaling. "
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