Key Points HLA I signaling induces robust activation of YAP in human ECs. Src kinases mediate YAP activation in response to HLA I signaling in ECs. Src/YAP plays a critical role in HLA I–induced proliferation and migration of ECs. Ab cross-linking of HLA class I (HLA I) molecules on the surface of endothelial cells (EC) triggers proliferative and prosurvival intracellular signaling, which is implicated in the process of chronic allograft rejection, also known as transplant vasculopathy. Despite the importance of Ab-mediated rejection in transplantation, the mechanisms involved remain incompletely understood. In this study, we examined the regulation of yes-associated protein (YAP) localization, phosphorylation, and transcriptional activity in human ECs challenged with Abs that bind HLA I. In unstimulated ECs, YAP localized mainly in the cytoplasm. Stimulation of these cells with Ab W6/32 induced marked translocation of YAP to the nucleus. The nuclear import of YAP was associated with a rapid decrease in YAP phosphorylation at Ser127 and Ser397, sites targeted by LATS1/2 and with the expression of YAP-regulated genes, including connective tissue growth factor (CTGF), and cysteine-rich angiogenic inducer 61 (CYR61). Transfection of small interfering RNAs targeting YAP/TAZ blocked the migration of ECs stimulated by ligation of HLA I, indicating that YAP mediates the increase in EC migration induced by HLA I ligation. Treatment of intact ECs with Src family inhibitors induced cytoplasmic localization of YAP in unstimulated ECs and, strikingly, blocked the nuclear import of YAP induced by Ab-induced HLA I activation in these cells and the increase in the expression of the YAP-regulated genes CTGF and CYR61 induced by HLA I stimulation. Our results identify the Src/YAP axis as a key player in promoting the proliferation and migration of ECs that are critical in the pathogenesis of transplant vasculopathy.

中文翻译：

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HLA I 类分子的连接通过人内皮细胞中的 Src 诱导 YAP 激活

关键点 HLA I 信号诱导人类内皮细胞中 YAP 的强烈激活。Src 激酶响应于 EC 中的 HLA I 信号传导介导 YAP 激活。Src/YAP 在 HLA I 诱导的内皮细胞增殖和迁移中起关键作用。内皮细胞 (EC) 表面上 HLA I 类 (HLA I) 分子的 Ab 交联触发增殖和促存活细胞内信号传导，这与慢性同种异体移植排斥过程有关，也称为移植血管病。尽管 Ab 介导的排斥在移植中很重要，但所涉及的机制仍未完全了解。在这项研究中，我们检查了受结合 HLA I 的 Ab 攻击的人类 ECs 中 yes 相关蛋白 (YAP) 定位、磷酸化和转录活性的调节。在未受刺激的 ECs 中，YAP 主要位于细胞质中。用 Ab W6/32 刺激这些细胞诱导 YAP 显着易位至细胞核。YAP 的核输入与 Ser127 和 Ser397、LATS1/2 靶向位点的 YAP 磷酸化迅速降低以及 YAP 调节基因的表达有关，包括结缔组织生长因子 (CTGF) 和富含半胱氨酸的血管生成诱导剂61 (CYR61)。靶向 YAP/TAZ 的小干扰 RNA 的转染阻止了 HLA I 连接刺激的 EC 迁移，表明 YAP 介导了 HLA I 连接诱导的 EC 迁移增加。用 Src 家族抑制剂处理完整的 ECs 诱导了 YAP 在未受刺激的 ECs 中的细胞质定位，并且令人惊讶的是，阻断了这些细胞中 Ab 诱导的 HLA I 激活诱导的 YAP 的核输入，以及 HLA I 刺激诱导的 YAP 调节基因 CTGF 和 CYR61 表达的增加。我们的研究结果表明，Src/YAP 轴是促进 EC 增殖和迁移的关键因素，而 EC 对移植血管病变的发病机制至关重要。