Center for Precision Environmental Health, Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
Development. 2023 May 1;150(9). 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.
在胚胎发育过程中，中胚层中的一组细胞被特化为造血祖细胞，然后分化为内皮细胞和造血干细胞和祖细胞。在斑马鱼中，转录因子 npas4l（cloche）是造血祖细胞特化所必需的。然而，npas4l 是否是造血特化级联的唯一因素尚不清楚。在这里，我们表明 arnt1 和 arnt2 基因是造血特化所必需的。我们发现，arnt1;arnt2 双突变斑马鱼胚胎，但不是 arnt1 或 arnt2 单突变体，缺乏血细胞和大多数内皮细胞。arnt1/2 突变体中，etsrp 和 tal1 的表达减少或缺失，etsrp 和 tal1 是最早已知的内皮和造血转录因子基因。我们发现 Npas4l 在体外与 Arnt1 和 Arnt2 蛋白结合，这与 PAS 结构域包含的 bHLH 转录因子在多聚体复合物中起作用以调节基因表达的观点一致。我们的结果表明，npas4l、arnt1 和 arnt2 共同作用调节内皮细胞和造血细胞命运，其中每个基因都是必需的，但不是充分的，以驱动造血特化。
