RT Journal Article SR Electronic T1 Vegetally localized Vrtn functions as a novel repressor to modulate bmp2b transcription during dorsoventral patterning in zebrafish JF bioRxiv FD Cold Spring Harbor Laboratory SP 119776 DO 10.1101/119776 A1 Ming Shao A1 Min Wang A1 Yi-Wen Ge A1 Yan-Jun Zhang A1 De-Li Shi YR 2017 UL http://biorxiv.org/content/early/2017/03/23/119776.abstract AB The vegetal pole cytoplasm represents a critical source of maternal signals for patterning the primary dorsoventral axis of the early embryo. Vegetally localized dorsal determinants are essential for the formation of the Spemann organizer, which expresses both bone morphogenetic proteins and their antagonists. The extracellular regulation of BMP signalling activity has been well characterized, however, transcriptional regulation of bmp genes along the dorsoventral axis remains largely unknown. Here, we report a novel mode of maternal regulation of BMP signalling in the lateral and ventral regions by analyzing the unexpected dorsalizing effect following vegetal yolk ablation experiment. We identified Vrtn as a novel vegetally localized maternal factor displaying dorsalizing activity. It functions as a novel transcriptional repressor to regulate bmp2b expression in the marginal region. Mechanistically, Vrtn binds bmp2b upstream sequence and inhibits its transcription independently of maternal Wnt/ß-catenin signalling. By creating vrtn loss-of-function mutation and analyzing maternal-zygotic mutant embryos, we further showed that Vrtn is required for the formation of dorsoventral axis. Our work thus unveils a novel maternal mechanism regulating BMP gradient during dorsoventral specification.