Hemato-vascular specification requires arnt1 and arnt2 genes in zebrafish embryos

Development. 2023 May 1;150(9):dev200500. doi: 10.1242/dev.200500. Epub 2023 Apr 28.


During embryonic development, a subset of cells in the mesoderm germ layer are specified as hemato-vascular progenitor cells, which then differentiate into endothelial cells and hematopoietic stem and progenitor cells. In zebrafish, the transcription factor npas4l (cloche) is required for the specification of hemato-vascular progenitor cells. However, it is unclear whether npas4l is the sole factor at the top of the hemato-vascular specification cascade. Here, we show that arnt1 and arnt2 genes are required for hemato-vascular specification. We found that arnt1;arnt2 double mutant zebrafish embryos, but not arnt1 or arnt2 single mutants, lack blood cells and most endothelial cells. arnt1/2 mutants have reduced or absent expression of etsrp and tal1, the earliest known endothelial and hematopoietic transcription factor genes. We found that Npas4l binds both Arnt1 and Arnt2 proteins in vitro, consistent with the idea that PAS domain-containing bHLH transcription factors act in a multimeric complex to regulate gene expression. Our results demonstrate that npas4l, arnt1 and arnt2 act together to regulate endothelial and hematopoietic cell fate, where each gene is necessary, but not sufficient, to drive hemato-vascular specification.

Keywords: Arnt; Hematopoiesis; Hematovascular specification; Npas4l; Zebrafish.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Aryl Hydrocarbon Receptor Nuclear Translocator* / genetics
  • Basic Helix-Loop-Helix Transcription Factors / metabolism
  • Endothelial Cells* / metabolism
  • Gene Expression Regulation
  • Transcription Factors / metabolism
  • Zebrafish Proteins* / genetics
  • Zebrafish*


  • Basic Helix-Loop-Helix Transcription Factors
  • Transcription Factors
  • arnt protein, zebrafish
  • arnt2 protein, zebrafish
  • Zebrafish Proteins
  • Aryl Hydrocarbon Receptor Nuclear Translocator