SPI1 suppresses YAP phosphorylation in vascular endothelial cells to prevent intracranial aneurysm progression

This study aims to elucidate the mechanism by which YAP mediates the activity of vascular endothelial cells (ECs) in the biological process of intracranial aneurysms (IAs) and to provide a novel target for noninvasive IAs treatment. Single-nuclei RNA profiling of aneurysmal cells revealed that ECs within aneurysms exhibit an intermediate identity between arterial and venous/capillary cells, rather than clustering within the normal arterial population. These specific human ECs showed downregulated YAP expression under turbulent flow. Immunostaining of human IA tissues demonstrated reduced YAP and increased phosphorylated YAP (p-YAP) compared with superficial temporal artery walls. Using YAP-knockdown human brain microvascular endothelial cells (HBMECs), we observed elevated expression of senescence markers p21 and p16, accompanied by diminished proliferation and migration capacities. Furthermore, SPI1 (also known as PU.1) overexpression alleviated EC degeneration induced by turbulent flow through suppression of YAP phosphorylation. Collectively, our findings indicate that turbulent flow markedly reduces YAP expression while promoting its phosphorylation, thereby accelerating endothelial senescence. Importantly, SPI1 overexpression effectively mitigated turbulent-flow-induced endothelial senescence, suggesting that SPI1 may serve as a potential therapeutic target for preventing aneurysmal progression.