Myosin light chain phosphorylation regulates barrier function by remodeling tight junction structure
Myosin light chain phosphorylation regulates barrier function by remodeling tight junction structure
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DOI：
10.1242/jcs.02915
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发表时间：
2006-05-15
影响因子：
4
通讯作者：
Turner, Jerrold R.
中科院分区：
文献类型：
--
作者：
Shen, Le;Black, Eric D.;Turner, Jerrold R.
上皮紧密连接形成了一个屏障，防止被动的细胞旁流动。这种屏障受到复杂的生理和病理生理信号的调节，这些信号可以对紧密连接的通透性进行精确的微调。虽然肌动球蛋白收缩和肌球蛋白轻链磷酸化明显参与了某些形式的紧密连接调节，但对其他信号事件的贡献和肌球蛋白轻链磷酸化在这种反应中的作用知之甚少。在这里，我们要问的是，单独激活肌球蛋白轻链激酶是否足以诱导下游紧密连接调节。我们使用汇合极化肠上皮细胞模型系统，其中组成型活性肌球蛋白轻链激酶，tMLCK，使用诱导型启动子表达。tMLCK表达增加肌球蛋白轻链磷酸化，重组连接周围的F-肌动蛋白，并增加紧密连接通透性。TJ蛋白ZO-1和occludin在形态学和生物化学上显著重新分布，但对claudin-1和claudin-2的影响有限。tMLCK抑制防止由tMLCK表达诱导的屏障功能和紧密连接组织的变化，表明这些事件都需要肌球蛋白轻链磷酸化。我们的结论是，肌球蛋白轻链磷酸化本身就足以诱导紧密连接调节，并提供了新的见解介导这种调节的分子机制。
Epithelial tight junctions form a barrier against passive paracellular flux. This barrier is regulated by complex physiologic and pathophysiologic signals that acutely fine-tune tight junction permeability. Although actomyosin contraction and myosin light chain phosphorylation are clearly involved in some forms of tight junction regulation, the contributions of other signaling events and the role of myosin light chain phosphorylation in this response are poorly understood. Here we ask if activation of myosin light chain kinase alone is sufficient to induce downstream tight junction regulation. We use a confluent polarized intestinal epithelial cell model system in which constitutively active myosin light chain kinase, tMLCK, is expressed using an inducible promoter. tMLCK expression increases myosin light chain phosphorylation, reorganizes perijunctional F-actin, and increases tight junction permeability. TJ proteins ZO-1 and occludin are markedly redistributed, morphologically and biochemically, but effects on claudin-1 and claudin-2 are limited. tMLCK inhibition prevents changes in barrier function and tight junction organization induced by tMLCK expression, suggesting that these events both require myosin light chain phosphorylation. We conclude that myosin light chain phosphorylation alone is sufficient to induce tight junction regulation and provide new insights into the molecular mechanisms that mediate this regulation.