Etv6 activates vegfa expression through positive and negative transcriptional regulatory networks in Xenopus embryos

Lei Li,Catherine Porcher,Roger Patient,Rossella Rispoli,Aldo Ciau-Uitz

doi:10.1038/s41467-019-09050-y

Abstract

VEGFA signaling controls physiological and pathological angiogenesis and hematopoiesis. Although many context-dependent signaling pathways downstream of VEGFA have been uncovered, vegfa transcriptional regulation in vivo remains unclear. Here, we show that the ETS transcription factor, Etv6, positively regulates vegfa expression during Xenopus blood stem cell development through multiple transcriptional inputs. In agreement with its established repressive functions, Etv6 directly inhibits expression of the repressor foxo3, to prevent Foxo3 from binding to and repressing the vegfa promoter. Etv6 also directly activates expression of the activator klf4; reflecting a genome-wide paucity in ETS-binding motifs in Etv6 genomic targets, Klf4 then recruits Etv6 to the vegfa promoter to activate its expression. These two mechanisms (double negative gate and feed-forward loop) are classic features of gene regulatory networks specifying cell fates. Thus, Etv6’s dual function, as a transcriptional repressor and activator, controls a major signaling pathway involved in endothelial and blood development in vivo.

Highlights

Vascular endothelial growth factor A (VEGFA) signaling controls physiological and pathological angiogenesis and hematopoiesis
Indexed libraries were generated from immunoprecipitated DNA and control input, samples were pooled and sequenced, and reads mapped to the X. laevis genome
We show that expression of the important signaling molecule vegfa is under tight transcriptional control by the ETS transcription factors (TFs) Etv[6] during the early stages of hematovascular development

Summary

Introduction

VEGFA signaling controls physiological and pathological angiogenesis and hematopoiesis. Etv[6] directly activates expression of the activator klf[4]; reflecting a genome-wide paucity in ETS-binding motifs in Etv[6] genomic targets, Klf[4] recruits Etv[6] to the vegfa promoter to activate its expression. These two mechanisms (double negative gate and feed-forward loop) are classic features of gene regulatory networks specifying cell fates. Vascular endothelial growth factor A (VEGFA) signaling is critical for both physiological and pathological processes in the adult, including hematopoiesis, angiogenesis and solid tumour progression. Because developmental and tumour biology and, in particular, angiogenic and metastatic processes share signaling and transcriptional pathways[13], a better understanding of the regulatory networks lying upstream of VEGFA during specification of the hematovascular lineage may help identify new druggable targets relevant to VEGFA-dependent diseases

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Conclusion