Calreticulin regulates TGF-β1-induced epithelial mesenchymal transition through modulating Smad signaling and calcium signaling
Calreticulin regulates TGF-β1-induced epithelial mesenchymal transition through modulating Smad signaling and calcium signaling
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钙网蛋白通过调节 Smad 信号和钙信号来调节 TGF-β1 诱导的上皮间质转化
DOI：
10.1016/j.biocel.2017.07.023
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发表时间：
2017-09-01
影响因子：
4
通讯作者：
Tang, Liling
中科院分区：
文献类型：
--
作者：
Wu, Yanjiao;Xu, Xiaoli;Tang, Liling
钙网蛋白（calreticulin，CRT）作为一种钙离子结合蛋白，具有多种功能，在多种肿瘤中发挥重要作用。CRT在TGF-β 1诱导的EMT中的作用尚不清楚。在这项研究中，我们证明了在体外，TGF-β 1诱导EMT提高CRT在A549肺癌细胞的表达。随后，我们证实过表达CRT没有单独诱导A549细胞EMT的能力，但成功地增强了TGF-β 1诱导的EMT。此外，A549细胞中CRT的敲低显著抑制TGF-β 1诱导的EMT标志物表达的变化。在TGF-β 1治疗时，CRT的过表达可增强Smad 2和Smad 3的磷酸化。因此，通过siRNA-CRT基因敲低CRT，可以抑制TGF-β 1激活的Smad信号通路。这些结果表明CRT通过Smad信号通路调节TGF-β 1诱导的EMT。最后，TGF-β 1诱导的EMT增强了A549细胞中钙池操作的Ca 2+内流。CRT敲除能够消除TGF-β 1对毒胡萝卜素（TG）诱导的Ca 2+释放的作用，但未能减少钙池操作的Ca 2+内流。TG或BAPTA-AM改变细胞内Ca ~（2+）浓度可通过Smad信号通路调节TGF-β 1诱导的EMT。总之，这些数据表明CRT通过调节Smad信号传导调节TGF-β 1诱导的EMT。此外，TGF-β 1诱导的EMT具有高度的钙依赖性，CRT部分参与其中。
As a Ca2+ binding protein, calreticulin (CRT) has many functions and plays an important role in a variety of tumors. The role of CRT in TGF-beta 1-induced EMT is unknown. In this study, we demonstrated in vitro that TGF-beta 1-induced EMT elevated the expression of CRT in A549 lung cancer cells. Subsequently, we confirmed that overexpression CRT had no capacity to induce A549 cells EMT alone, but successfully enhanced TGF-beta 1-induced-EMT. Furthermore, knockdown of CRT in A549 cells significantly suppressed changes of EMT marks expression induced by TGF-beta 1. On treatment with TGF-beta 1, overexpression of CRT could enhance the phosphorylation of both Smad2 and Smad3. Consistently, the knockdown of CRT by siRNA-CRT could inhibit Smad signaling pathway activated by TGF-beta 1. These results indicated that CRT regulates EMT induced by TGF-beta 1 through Smad signaling pathway. Finally, TGF-beta 1-induced-EMT enhanced store-operated Ca2+ influx in A549 cells. CRT knockdown was able to abolish the effect of TGF-beta 1 on thapsigargin (TG) - induced Ca2+ release, but had failed to reduce store-operated Ca2+ influx. The alteration of intracellular Ca2+ concentration by TG or BAPTA-AM was able to regulate EMT induced by TGF-beta 1 through Smad signaling pathway. Together, these data identify that CRT regulates TGF-beta 1-induced-EMT through modulating Smad signaling. Furthermore, TGF-beta 1-induced-EMT is highly calcium-dependent, CRT was partly involved in it.