The G protein-coupled receptor 182 (GPR182) is an orphan GPCR, the expression of which is enriched in embryonic endothelial cells (ECs). However, the physiological role and molecular mechanism of action of GPR182 are unknown. Here, we show that GPR182 negatively regulates definitive hematopoiesis in zebrafish and mice. In zebrafish, gpr182 expression is enriched in the hemogenic endothelium (HE), and gpr182^–/– display an increased expression of HE and hematopoietic stem cell (HSC) marker genes. Notably, we find an increased number of myeloid cells in gpr182^–/– compared to wild-type. Further, by time-lapse imaging of zebrafish embryos during the endothelial-to-hematopoietic transition, we find that HE/HSC cell numbers are increased in gpr182^–/– compared to wild-type. GPR182^–/– mice also exhibit an increased number of myeloid cells compared to wild-type, indicating a conserved role for GPR182 in myelopoiesis. Using cell-based small molecule screening and transcriptomic analyses, we further find that GPR182 regulates the leukotriene B4 (LTB4) biosynthesis pathway. Taken together, these data indicate that GPR182 is a negative regulator of definitive hematopoiesis in zebrafish and mice, and provide further evidence for LTB4 signaling in HSC biology.

中文翻译：

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孤儿G蛋白偶联受体182是通过白三烯B4信号传导确定性造血作用的负调节剂。

G蛋白偶联受体182（GPR182）是一种孤儿GPCR，其表达在胚胎内皮细胞（EC）中富集。但是，GPR182的生理作用和分子作用机理尚不清楚。在这里，我们显示GPR182负调控斑马鱼和小鼠的确定性造血功能。在斑马鱼中，gpr182的表达在造血内皮（HE）中富集，而gpr182 ^{– / –}显示HE和造血干细胞（HSC）标记基因的表达增加。值得注意的是，我们发现gpr182 ^{– / –中}的髓样细胞数量增加相比野生型。此外，通过在内皮细胞到造血细胞的过渡过程中对斑马鱼胚胎的延时成像，我们发现与野生型相比，gpr182 ^{– / –}中的HE / HSC细胞数量增加了。与野生型相比，GPR182 ^{– / –}小鼠还显示出更多的髓样细胞数量，表明GPR182在骨髓生成中的保守作用。使用基于细胞的小分子筛选和转录组分析，我们进一步发现GPR182调节白三烯B4（LTB4）生物合成途径。综上所述，这些数据表明，GPR182是斑马鱼和小鼠中确定性造血的负调节剂，并为HSC生物学中LTB4信号提供了进一步的证据。