Department of Molecular Physiology, College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, 525-8577, Japan.
Department of Molecular Physiology, College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, 525-8577, Japan.
Biochem Biophys Res Commun. 2024 Apr 9;703:149685. doi: 10.1016/j.bbrc.2024.149685. Epub 2024 Feb 13.
Ciliary beating in the airway epithelium plays an important role in preventing infection by eliminating small particles and pathogens. Stimulation of β adrenergic receptor (βAR) increases [cAMP] levels and strongly activates this ciliary beating. βAR is localized to the apical membrane of the airways by indirectly binding to ezrin, an actin-binding protein. Ezrin takes active phosphorylated and inactive dephosphorylated states at Thr-567. Previously we showed that procaterol-stimulated ciliary beating was impaired in the ezrin-knockdown mice. In this study, we examined the roles of ezrin and its phosphorylation in regulating ciliary beating by using NSC305787, an ezrin inhibitor, in normal human airway epithelial cells (NHBE). We found that NSC305787 inhibits the phosphorylation of ezrin with an IC of 50 μM in NHBE. Treatment with NSC305787 for 4 h or more decreased the expression of βAR in the cell membrane and induced vesicle- or dot-like expression of ezrin and βAR inside the cell. As a result, inhibition of ezrin phosphorylation by NSC305787 attenuated the effect of procaterol-induced activation of ciliary beating in both frequency and distance indices.
气道上皮纤毛的摆动对于防止感染具有重要作用，它可以清除小颗粒和病原体。β肾上腺素能受体（βAR）的刺激会增加[cAMP]水平，并强烈激活纤毛的摆动。βAR 通过间接与细胞骨架结合蛋白 ezrin 结合而定位在气道的顶膜上。ezrin 在 Thr-567 处处于活跃的磷酸化和非磷酸化状态。之前我们发现，在 ezrin 敲低的小鼠中，procaterol 刺激的纤毛摆动受损。在这项研究中，我们使用 ezrin 抑制剂 NSC305787 研究了 ezrin 及其磷酸化在调节纤毛摆动中的作用，该抑制剂在正常人呼吸道上皮细胞（NHBE）中起作用。我们发现，NSC305787 在 NHBE 中的 IC50 为 50μM，可抑制 ezrin 的磷酸化。用 NSC305787 处理 4 小时或更长时间会降低细胞膜中βAR 的表达，并在细胞内诱导 ezrin 和 βAR 的囊泡或点状表达。结果，NSC305787 抑制 ezrin 磷酸化减弱了 procaterol 诱导的纤毛摆动激活的作用，表现在频率和距离指数上。
