ADP-ribosylation factor-like 4aa (Arl4aa) is a member of the ADP-ribosylation factor family. It is expressed in hematopoietic tissue during embryonic development, but its function was unknown. Zebrafish arl4aa is preferentially expressed in the ventral wall of the dorsal aorta (VDA) at 24 and 36 hpf and in caudal hematopoietic tissue at 48 hpf. Morpholino knockdown and transcription activator-like effector nuclease (TALEN) knockout of arl4aa significantly reduced expression of genes associated with definitive hematopoietic stem cells (HSCs). Golgi complex integrity in VDA was disrupted as shown by transmission electron microscopy and immunostaining of Golgi membrane Giantin. Mechanistically, arl4aa knockdown reduced Notch signaling in the VDA and its target gene expression. Protein expression of NICD was also reduced. Effects of arl4aa knockdown on definitive hematopoiesis could be restored by NICD expression. This study identified arl4aa as a factor regulating initiation of definitive HSCs by maintaining the integrity of Golgi complex and, secondarily, maturation of the Notch receptor.

类似ADP-核糖基化因子的4aa（Arl4aa）是ADP-核糖基化因子家族的成员。它在胚胎发育过程中在造血组织中表达，但其功能尚不清楚。斑马鱼arl4aa在24和36 hpf时优先在背主动脉（VDA）的腹壁中表达，在48 hpf时在尾部造血组织中表达。敲除arl4aa的吗啉代敲除和转录激活因子样效应子核酸酶（TALEN）大大降低了与定型造血干细胞（HSC）相关的基因的表达。如透射电子显微镜和高尔基膜巨蛋白的免疫染色所示，VDA中的高尔基复合体完整性被破坏。从机械上讲，arl4aa组合式降低了VDA及其靶基因表达中的Notch信号传导。NICD的蛋白质表达也降低。可以通过NICD表达恢复arl4aa敲低对确定性造血作用的作用。这项研究确定arl4aa是通过维持高尔基复合体的完整性以及其次是Notch受体的成熟来调节确定的HSC起始的因子。