Background:Overexpression of connective tissue growth factor (CTGF) in alveolar type II epithelial (AT II) cells disrupts alveolar structure, causes interstitial fibrosis, and upregulates integrin-linked kinase (ILK). Whether CTGF-ILK signaling induces epithelial to mesenchymal transition (EMT) in AT II cells is unknown.Methods:Transgenic mice with targeted overexpression of CTGF in AT II cells were generated utilizing the surfactant protein C (SP-C) gene promoter and doxycycline-inducible system. AT II cells were isolated from 4-wk-old CTGF-overexpressing (CTGF+) mice and control littermates, and cultured on Matrigel. Cells were transfected with ILK siRNA, and cell morphology and expression of cell differentiation markers were analyzed.Results:The AT II cells from the control lungs grew in clusters and formed alveolar-like cysts and expressed SP-C. In contrast, the cells from CTGF+ lungs were spread and failed to form alveolar-like cysts. These cells expressed higher levels of CTGF, α smooth muscle actin (α-SMA), fibronectin and vimentin, the mesenchymal markers, suggesting EMT-like changes. Transfection with ILK siRNA not only dramatically attenuated ILK expression, but also decreased α-SMA expression as well as reversed cell morphological changes in CTGF+ AT II cells.Conclusion:Overexpression of CTGF induces EMT in mouse primary AT II cells and this is mediated by ILK.
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机译：背景：结缔组织生长因子（CTGF）在II型肺泡上皮细胞（AT II）中的过表达破坏了肺泡的结构，导致间质纤维化，并上调了整联蛋白连接激酶（ILK）。方法：利用表面活性剂蛋白C（SP-C）基因启动子和强力霉素-强力霉素-AT，产生ATGF细胞中靶向表达CTGF的过表达转基因小鼠。诱导系统。从4周大的CTGF过表达（CTGF +）小鼠和对照同窝幼仔中分离AT II细胞，并在Matrigel上培养。结果：来自对照肺的AT II细胞成簇生长，形成肺泡样囊肿并表达SP-C。结果显示：ILK siRNA转染了细胞，分析了细胞形态和细胞分化标志物的表达。相比之下，来自CTGF +肺的细胞扩散并且未能形成肺泡样囊肿。这些细胞表达较高水平的CTGF，α平滑肌肌动蛋白（α-SMA），纤连蛋白和波形蛋白（间充质标记），提示类似EMT的变化。 ILK siRNA转染不仅显着减弱了ILK表达，而且降低了CTGF + AT II细胞的α-SMA表达以及逆转的细胞形态学改变。 。
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