Myosin light chain kinase- and PKC-dependent contraction of LES and esophageal smooth muscle.
Myosin light chain kinase- and PKC-dependent contraction of LES and esophageal smooth muscle.
复制标题
LES 和食管平滑肌的肌球蛋白轻链激酶和 PKC 依赖性收缩。
DOI：
10.1152/ajpgi.2001.281.2.g467
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Biancani,P
中科院分区：
文献类型：
--
作者：
Sohn,UD;Cao,W;Tang,DC;Stull,JT;Haeberle,JR;Wang,CL;Harnett,KM;Behar,J;Biancani,P
在用酶法分离的食管环肌(ESO)和下食道括约肌(LES)的平滑肌细胞中，ACh引起的收缩和肌球蛋白轻链(MLC)的磷酸化是相似的。纯化的MLC激酶(MLCK)对LES的收缩和磷酸化作用明显强于ESO。在LES中，钙调素和MLCK抑制剂可抑制ACh引起的收缩和MLC的磷酸化，而在ESO中则可被蛋白激酶C(PKC)抑制剂所抑制。MLCK抑制剂不影响PKC激动剂1，2-二辛酰甘油(DG)引起的LES和ESO收缩。Caldesmon和Calponin浓度依赖地抑制ACh诱导的ESO收缩，而不抑制LES。在ESO中，钙离子通道阻断剂GS17C可逆转钙离子通道阻断剂的作用，但不能逆转钙粘蛋白对ACh的抑制作用。GS17C使通透性ESO收缩，但对LES的影响较小。MLCK抑制剂不影响GS17C诱导的收缩，提示MLCK可能不调节钙离子介导的收缩。CaDesmon和calponinin抑制DG引起的ESO和LES的收缩，提示这些蛋白可能调节PKC依赖的收缩。我们认为钙调蛋白和MLCK在ACh诱导的LES收缩中起作用，而经典的MLCK可能不是ESO中MLC收缩和磷酸化的主要激酶。ESO收缩依赖于PKC。Caldesmon和/或Calponin可能在PKC依赖的收缩中发挥作用。
In smooth muscle cells enzymatically isolated from circular muscle of the esophagus (ESO) and lower esophageal sphincter (LES), ACh-induced contraction and myosin light chain (MLC) phosphorylation were similar. Contraction and phosphorylation induced by purified MLC kinase (MLCK) were significantly greater in LES than ESO. ACh-induced contraction and MLC phosphorylation were inhibited by calmodulin and MLCK inhibitors in LES and by protein kinase C (PKC) inhibitors in ESO. Contraction of LES and ESO induced by the PKC agonist 1,2-dioctanoylglycerol (DG) was unaffected by MLCK inhibitors. Caldesmon and calponin concentration-dependently inhibited ACh-induced contraction of ESO and not LES. In ESO, caldesmon antagonist GS17C reversed caldesmon- but not calponin-induced ACh inhibition. GS17C caused contraction of permeabilized ESO but had much less effect on LES. GS17C-induced contraction was not affected by MLCK inhibitors, suggesting that MLCK may not regulate caldesmon-mediated contraction. DG-induced contraction of ESO and LES was inhibited by caldesmon and calponinin, suggesting that these proteins may regulate PKC-dependent contraction. We conclude that calmodulin and MLCK play a role in ACh-induced LES contraction, whereas the classical MLCK may not be the major kinase responsible for contraction and phosphorylation of MLC in ESO. ESO contraction is PKC dependent. Caldesmon and/or calponin may play a role in PKC-dependent contraction.