Myosin light chain kinase is central to smooth muscle contraction and required for gastrointestinal motility in mice
Myosin light chain kinase is central to smooth muscle contraction and required for gastrointestinal motility in mice
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DOI：
10.1053/j.gastro.2008.05.032
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发表时间：
2008-08-01
期刊：
影响因子：
29.4
通讯作者：
Zhu, Min-Sheng
中科院分区：
文献类型：
--
作者：
He, Wei-Qi;Peng, Ya-Jing;Zhu, Min-Sheng
背景与目的：平滑肌对维持机体许多功能的动态平衡是必不可少的，并对病理性疾病施加的压力提供适应性反应。已确定的细胞信号网络定义了许多潜在的机制，在肌球蛋白轻链激酶(MLCK)磷酸化或肌球蛋白调节轻链(RLC)磷酸化的情况下，启动肌球蛋白调节轻链(RLC)。我们建立了他莫昔芬诱导的和平滑肌特异的MLCK基因敲除(KO)小鼠，并提供了直接的功能丧失证据，表明MLCK在相性平滑肌收缩中的主要重要性。方法：利用Cre-loxP系统建立外显子23、24和25两侧分别带有2个loxP位点的Mlck小鼠。将Mlck系小鼠与SM-Creer(T2)(KI)小鼠杂交，然后用他莫昔芬治疗，获得了平滑肌特异的MLCK KO小鼠。通过组织学、生化、分子、细胞生物学和生理学分析评价其表型。结果：靶向缺失成年小鼠平滑肌MLCK可导致严重的肠道运动障碍，表现为胃肠蠕动减弱，消化道扩张，粪便排泄和摄食量减少。同时出现膀胱功能异常和血压下降。分离的肌肉显示K+去极化诱导的RLC磷酸化和力量发展的丧失。该激酶的敲除也显着降低了RLC的磷酸化，并迫使乙酰胆碱与激活钙敏感的信号通路的乙酰胆碱一起发展。结论：MLCK及其磷酸化的RLC在生理上是平滑肌收缩所必需的，也是正常胃肠运动所必需的。
Background & Aims: Smooth muscle is essential for maintaining homeostasis for many body functions and provides adaptive responses to stresses imposed by pathologic disorders. Identified cell signaling networks have defined many potential mechanisms for initiating smooth muscle contraction with or without myosin regulatory light chain (RLC) phosphorylation by myosin light chain kinase (MLCK). We generated tamoxifen-inducible and smooth muscle-specific MLCK knockout (KO) mice and provide direct loss-of-function evidence that shows the primary importance of MLCK in phasic smooth muscle contractions. Methods: We used the Cre-loxP system to establish Mlck floxed mice in which exons 23, 24, and 25 were flanked by 2 loxP sites. Smooth muscle-specific MLCK KO mice were generated by crossing Mlck floxed mice with SM-CreER(T2) (ki) mice followed by tamoxifen treatment. The phenotype was assessed by histologic, biochemical, molecular, cell biological, and physiologic analyses. Results: Targeted deletion of MLCK in adult mouse smooth muscle resulted in severe gut dysmotility characterized by weak peristalsis, dilation of the digestive tract, and reduction of feces excretion and food intake. There was also abnormal urinary bladder function and lower blood pressure. Isolated muscles showed a loss of RLC phosphorylation and force development induced by K+-depolarization. The kinase knockout also markedly reduced RLC phosphorylation and force development with acetylcholine which activates Ca2+-sensitizing signaling pathways. Conclusions: MLCK and its phosphorylation of RLC are required physiologically for smooth muscle contraction, and are essential for normal gastrointestinal motility.