Zebrafish etv2 knock-in line labels vascular endothelial and blood progenitor cells

ETS transcription factor Etv2/Etsrp is one of the earliest markers for vascular and hematopoietic progenitors and functions as a key regulator of hematovascular development in multiple vertebrates, including zebrafish. Therefore, transgenic etv2 reporter lines provide a valuable tool to study vasculogenesis and hematopoiesis. However, previously generated zebrafish reporter lines do not fully recapitulate the endogenous pattern of etv2 expression.

Here we used CRISPR/Cas9-mediated homology-independent DNA repair approach to knock-in a Gal4 transcriptional activator into the zebrafish etv2 genomic locus, thus generating etv2 ^ci32Gt gene trap line. etv2 ^ci32Gt ; UAS:GFP embryos show GFP expression in vascular endothelial, myeloid and red blood cells. Because gal4 insertion interrupts the etv2 locus, homozygous etv2 ^ci32Gt embryos display defects in vasculogenesis and myelopoiesis, and enable visualizing etv2-deficient hematovascular progenitors in live embryos. Furthermore, we performed differential transcriptome analysis of sorted GFP-positive cells from heterozygous and homozygous etv2 ^ci32Gt embryos. Approximately 500 downregulated genes were identified in etv2 ^ci32Gt homozygous embryos, which include multiple genes expressed in vascular endothelial and myeloid cells.

The etv2 ^ci32Gt gene trap line and the data sets of misregulated genes will be valuable resources to study hematopoietic and vascular development.