During development, endothelial tip cells (ETCs) located at the leading edge of growing vascular plexus guide angiogenic sprouts to target vessels, and thus, ETC pathfinding is fundamental for vascular pattern formation in organs, including the brain. However, mechanisms of ETC pathfinding remain largely unknown. Here, we report that Piezo1-mediated Ca²⁺ activities at primary branches of ETCs regulate branch dynamics to accomplish ETC pathfinding during zebrafish brain vascular development. ETC branches display spontaneous local Ca²⁺ transients, and high- and low-frequency Ca²⁺ transients cause branch retraction through calpain and branch extension through nitric oxide synthase, respectively. These Ca²⁺ transients are mainly mediated by Ca²⁺-permeable Piezo1 channels, which can be activated by mechanical force, and mutating piezo1 largely impairs ETC pathfinding and brain vascular patterning. These findings reveal that Piezo1 and downstream Ca²⁺ signaling act as molecular bases for ETC pathfinding and highlight a novel function of Piezo1 and Ca²⁺ in vascular development.

在发育过程中，位于正在生长的血管丛前沿的内皮尖细胞（ETC）将血管新生芽引导至目标血管，因此，ETC寻路对于包括大脑在内的器官中的血管模式形成至关重要。但是，ETC寻路的机制仍然未知。在这里，我们报道在斑马鱼脑血管发育过程中，ETC初级分支中的Piezo1介导的Ca ²⁺活性调节分支动力学，以完成ETC寻路。ETC分支显示自发的局部Ca ²⁺瞬变，而高频和低频Ca ²⁺瞬变分别通过钙蛋白酶引起分支收缩和通过一氧化氮合酶引起分支扩展。这些钙²⁺瞬变主要由可渗透Ca ^2+的Piezo1通道介导，该通道可被机械力激活，并且使Piezo1突变会大大损害ETC寻路和脑血管模式。这些发现表明Piezo1和下游Ca ²⁺信号作为ETC寻路的分子基础，并突出了Piezo1和Ca ²⁺在血管发育中的新功能。