Int. J. Dev. Biol. 60: 13 - 19 (2016)

https://doi.org/10.1387/ijdb.150193yx

Vol 60, Issue 1-2-3

Coordinate involvement of Nodal-dependent inhibition and Wnt-dependent activation in the maintenance of organizer-specific bmp2b in zebrafish

Original Article | Published: 15 January 2016

Yu Xue¹, Cencan Xing^2,3, Wenjuan Zhang¹, Canbin Chen¹, Jingjin Xu¹, Anming Meng*^,3 and Yutian Pan*^,1

¹The Engineering Technological Center of Mushroom Industry, Minnan Normal University, Zhangzhou, Fujian, ²Institute of Agro-products Processing Science and Technology, Chinese Academy of Agricultural Sciences, Beijing and ³State Key Laboratory of Biomembrane and Membrane Engineering, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China

Abstract

A vertebrate signaling center, known in zebrafish as the organizer, is essential for axis patterning and formation and is regulated by multiple cell signaling pathways, including Wnt, Nodal, and Bmp. Organizer-specific Bmp2b plays important roles in the maintenance of the Bmp activity gradient and dorsal-ventral patterning. However, it is unknown how transcription of bmp2b in the organizer is regulated. In this study, we generated a bmp2b transgenic line Tsg(-2.272bmp2b:gfp) that reproduced organizer-specific bmp2b expression. Dissection analysis revealed that a 0.273-kb minimal promoter was indispensable for bmp2b expression in the dorsal organizer. Reporter assays showed that organizer-specific bmp2b is negatively regulated by the Nodal signal and positively regulated by the Wnt signal in both embryos and cell lines. Promoter analysis and chromatin-immunoprecipitation (ChIP) indicated that one consensus Smad-binding element (SBE) (CAGAC) and one Lef/Tcf-binding element (LBE) (AGATAA) were present in the 0.273-kb promoter, and could be directly bound by Smad2 and β-catenin proteins. Together, these results suggest that maintenance of organizer-specific bmp2b expression involves opposite and concerted regulation by Nodal and Wnt signaling.

Keywords

zebrafish, organizer-specific bmp2b, transcriptional regulation, Nodal, Wnt