Ca2+-independent smooth muscle contraction -: A novel function for integrin-linked kinase
Ca2+-independent smooth muscle contraction -: A novel function for integrin-linked kinase
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DOI：
10.1074/jbc.m011634200
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发表时间：
2001-05-11
影响因子：
4.8
通讯作者：
Walsh, MP
中科院分区：
文献类型：
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作者：
Deng, JT;Van Lierop, JE;Walsh, MP
平滑肌收缩伴随着胞质Ca 2+浓度的增加、肌球蛋白轻链激酶的激活和肌球蛋白20-kDa轻链Ser的磷酸化（19）。通过G蛋白偶联受体作用的几种激动剂通过抑制肌球蛋白轻链磷酸酶和增加肌球蛋白磷酸化而引起收缩，而不改变[Ca 2 +]（i）。我们发现，微囊藻毒素（磷酸酶抑制剂）诱导的皮肤平滑肌收缩发生在Ca 2+的情况下，并与肌球蛋白轻链丝氨酸（19）和苏氨酸（18）的磷酸化的激酶不同的肌球蛋白轻链激酶。在这项研究中，我们确定这种激酶作为整合素连接激酶。对鸡砂囊整合素连接激酶cDNA进行克隆、测序，并在大肠杆菌中表达。在Ca ~（2+）缺乏的情况下，该酶可使肌球蛋白轻链的Ser（19）和Thr（18）磷酸化。亚细胞分离揭示了两个不同的群体的整合素连接的激酶，包括Triton X-100不溶性组分，磷酸化肌球蛋白在一个Ca 2 +-独立的方式。这些结果表明，一种新的功能，整合素连接的激酶在调节平滑肌收缩通过钙离子依赖性磷酸化的肌球蛋白，提高的可能性，整合素连接的激酶也可能发挥作用，在调节非肌肉运动，并确认整合素连接的激酶确实是一种功能性蛋白丝氨酸/苏氨酸激酶。
Smooth muscle contraction follows an increase in cytosolic Ca2+ concentration, activation of myosin light chain kinase, and phosphorylation of the 20-kDa light chain of myosin at Ser(19). Several agonists acting via G protein-coupled receptors elicit a contraction without a change in [Ca2+](i) via inhibition of myosin light chain phosphatase and increased myosin phosphorylation. We showed that microcystin (phosphatase inhibitor)-induced contraction of skinned smooth muscle occurred in the absence of Ca2+ and correlated with phosphorylation of myosin light chain at Ser(19) and Thr(18) by a kinase distinct from myosin light chain kinase. In this study, we identify this kinase as integrin-linked kinase. Chicken gizzard integrin-linked kinase cDNA was cloned, sequenced, expressed in E. coli, and shown to phosphorylate myosin light chain in the absence of Ca2+ at Ser(19) and Thr(18). Subcellular fractionation revealed two distinct populations of integrin-linked kinase, including a Triton X-100-insoluble component that phosphorylates myosin in a Ca2+-independent manner. These results suggest a novel function for integrin-linked kinase in the regulation of smooth muscle contraction via Ca2+-independent phosphorylation of myosin, raise the possibility that integrin-linked kinase may also play a role in regulation of nonmuscle motility, and confirm that integrin-linked kinase is indeed a functional protein-serine/threonine kinase.