Vascular Biology Laboratory, Department of Health Sciences, Boston University, Boston, Massachusetts, USA.
Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, Georgia, USA.
J Cell Mol Med. 2024 Jan;28(1):e18025. doi: 10.1111/jcmm.18025. Epub 2023 Dec 26.
Smooth muscle cell (SMC) contraction and vascular tone are modulated by phosphorylation and multiple modifications of the thick filament, and thin filament regulation of SMC contraction has been reported to involve extracellular regulated kinase (ERK). Previous studies in ferrets suggest that the actin-binding protein, calponin 1 (CNN1), acts as a scaffold linking protein kinase C (PKC), Raf, MEK and ERK, promoting PKC-dependent ERK activation. To gain further insight into this function of CNN1 in ERK activation and the regulation of SMC contractility in mice, we generated a novel Calponin 1 knockout mouse (Cnn1 KO) by a single base substitution in an intronic CArG box that preferentially abolishes expression of CNN1 in vascular SMCs. Using this new Cnn1 KO mouse, we show that ablation of CNN1 has two effects, depending on the cytosolic free calcium level: (1) in the presence of elevated intracellular calcium caused by agonist stimulation, Cnn1 KO mice display a reduced amplitude of stress and stiffness but an increase in agonist-induced ERK activation; and (2) during intracellular calcium depletion, in the presence of an agonist, Cnn1 KO mice exhibit increased duration of SM tone maintenance. Together, these results suggest that CNN1 plays an important and complex modulatory role in SMC contractile tone amplitude and maintenance.
平滑肌细胞 (SMC) 的收缩和血管张力受磷酸化和细肌丝、粗肌丝的多种修饰调节，已有研究报道，SMC 收缩的细肌丝调节涉及细胞外调节激酶 (ERK)。先前在雪貂中的研究表明，肌动蛋白结合蛋白钙调蛋白 1 (CNN1) 作为一种支架连接蛋白激酶 C (PKC)、Raf、MEK 和 ERK，促进 PKC 依赖性 ERK 激活。为了更深入地了解 CNN1 在 ERK 激活和小鼠 SMC 收缩调节中的这种作用，我们通过在一个内含子 CArG 盒中的单个碱基取代产生了一种新型的钙调蛋白 1 敲除小鼠 (Cnn1 KO)，该取代优先在血管 SMC 中消除 CNN1 的表达。使用这种新的 Cnn1 KO 小鼠，我们表明 CNN1 的缺失有两种作用，这取决于细胞质游离钙水平：(1) 在激动剂刺激引起的细胞内钙升高的情况下，Cnn1 KO 小鼠显示出应激和僵硬幅度减小，但激动剂诱导的 ERK 激活增加；(2) 在细胞内钙耗竭期间，在激动剂存在的情况下，Cnn1 KO 小鼠表现出维持 SM 张力的时间延长。总之，这些结果表明 CNN1 在 SMC 收缩张力幅度和维持中发挥重要而复杂的调节作用。
