Endothelial nitric oxide (NO) is a critical mediator of vascular function and vascular remodeling. NO is produced by endothelial nitric oxide synthase (eNOS), which is activated by calcium (Ca²⁺)-dependent and Ca²⁺-independent pathways. Here, we report that neurogranin (Ng), which regulates Ca²⁺-calmodulin (CaM) signaling in the brain, is uniquely expressed in endothelial cells (EC) of human and mouse vasculature, and is also required for eNOS regulation. To test the role of Ng in eNOS activation, Ng knockdown in human aortic endothelial cells (HAEC) was performed using Ng SiRNA along with Ng knockout (Ng ^−/−) in mice. Depletion of Ng expression decreased eNOS activity in HAEC and NO production in mice. We show that Ng expression was decreased by short-term laminar flow and long-them oscillating flow shear stress, and that Ng siRNA with shear stress decreased eNOS expression as well as eNOS phosphorylation at S1177. We further reveled that lack of Ng expression decreases both AKT-dependent eNOS phosphorylation, NF-κB-mediated eNOS expression, and promotes endothelial activation. Our findings also indicate that Ng modulates Ca²⁺-dependent calcineurin (CaN) activity, which suppresses Ca²⁺-independent AKT-dependent eNOS signaling. Moreover, deletion of Ng in mice also reduced eNOS activity and caused endothelial dysfunction in flow-mediated dilation experiments. Our results demonstrate that Ng plays a crucial role in Ca²⁺-CaM-dependent eNOS regulation and contributes to vascular remodeling, which is important for the pathophysiology of cardiovascular disease.

内皮一氧化氮 (NO) 是血管功能和血管重塑的关键介质。NO 由内皮一氧化氮合酶 (eNOS) 产生，该酶由钙 (Ca ²⁺ ) 依赖性和 Ca ²⁺非依赖性途径激活。在这里，我们报告了调节大脑中 Ca ²⁺ -钙调蛋白 (CaM) 信号传导的神经颗粒素 (Ng) 在人和小鼠脉管系统的内皮细胞 (EC) 中唯一表达，并且也是 eNOS 调节所必需的。为了测试 Ng 在 eNOS 激活中的作用，使用 Ng SiRNA 和 Ng 敲除（Ng ^-/-) 在老鼠身上。Ng 表达的消耗降低了 HAEC 中的 eNOS 活性和小鼠中 NO 的产生。我们表明，短期层流和长期振荡流剪切应力降低了 Ng 表达，并且具有剪切应力的 Ng siRNA 降低了 S1177 处的 eNOS 表达和 eNOS 磷酸化。我们进一步发现，缺乏 Ng 表达会降低 AKT 依赖性 eNOS 磷酸化、NF-κB 介导的 eNOS 表达，并促进内皮活化。我们的研究结果还表明，Ng 调节 Ca ²⁺依赖性钙调神经磷酸酶 (CaN) 活性，从而抑制 Ca ²⁺-独立的 AKT 依赖性 eNOS 信号传导。此外，小鼠中 Ng 的缺失也降低了 eNOS 活性，并在流动介导的扩张实验中导致内皮功能障碍。^{我们的研究结果表明，Ng 在 Ca 2+} -CaM 依赖性 eNOS 调节中起着至关重要的作用，并有助于血管重塑，这对于心血管疾病的病理生理学很重要。