Department of Medical Microbiology and Immunology, Creighton University School of Medicine, Omaha, Nebraska, United States of America.
PLoS One. 2012;7(12):e51371. doi: 10.1371/journal.pone.0051371. Epub 2012 Dec 7.
Recent studies have suggested that proliferating cholangiocytes have an important role in the induction of fibrosis, either directly via epithelial-to-mesenchymal transition (EMT), or indirectly via activation of other liver cell types. Transforming growth factor beta 1 (TGF-β1), a critical fibrotic cytokine for hepatic fibrosis, is a potent EMT inducer. This study aimed to clarify the potential contributions of TGF-β1-induced EMT-like cholangiocyte phenotype to collagen production and cell survival of cholangiocytes in vitro. Mouse cholangiocytes (603B cells) were treated with TGF-β1 and EMT-like phenotype alterations were monitored by morphological changes and expression of EMT-associated genes. Alterations in Col1A1 gene, Col1A1-associated miR-29s, and pro-apoptotic genes were measured in TGF-β1-treated 603B cells. Snail1 knockdown was achieved using shRNA to evaluate the contribution of EMT-associated changes to Col1A1 production and cell survival. We found TGF-β1 treatment induced partial EMT-like phenotype transition in 603B cells in a Snail1-dependent manner. TGF-β1 also stimulated collagen α1(I) expression in 603B cells. However, this induction was not parallel to the EMT-like alterations and independent of Snail1 or miR-29 expression. Cells undergoing EMT-like changes showed a modest down-regulation of multiple pro-apoptotic genes and displayed resistance to TNF-α-induced apoptosis. TGF-β1-induced apoptosis resistance was attenuated in Snail1 knockdown 603B cells. TGF-β1-induced Col1A1 production seems to be independent of EMT-like transition and miR-29 expression. Nevertheless, TGF-β1-induced EMT may contribute to the increased survival capacity of cholangiocytes via modulating the expression of pro-apoptotic genes.
最近的研究表明，增殖的胆管细胞通过上皮-间充质转化（EMT）直接或通过激活其他肝实质细胞间接在纤维化的诱导中起重要作用。转化生长因子β1（TGF-β1）是肝纤维化的关键纤维化细胞因子，是一种有效的 EMT 诱导剂。本研究旨在阐明 TGF-β1 诱导的 EMT 样胆管细胞表型对胆管细胞胶原产生和细胞存活的潜在贡献。用 TGF-β1 处理鼠胆管细胞（603B 细胞），通过形态变化和 EMT 相关基因的表达监测 EMT 样表型改变。在 TGF-β1 处理的 603B 细胞中测量 Col1A1 基因、Col1A1 相关 miR-29 和促凋亡基因的改变。使用 shRNA 敲低 Snail1，以评估 EMT 相关变化对 Col1A1 产生和细胞存活的贡献。我们发现 TGF-β1 处理以 Snail1 依赖的方式诱导 603B 细胞中部分 EMT 样表型转化。TGF-β1 还刺激 603B 细胞中胶原 α1(I)的表达。然而，这种诱导与 EMT 样改变不平行，且不依赖于 Snail1 或 miR-29 的表达。发生 EMT 样变化的细胞显示多个促凋亡基因的适度下调，并对 TNF-α诱导的凋亡表现出抗性。Snail1 敲低的 603B 细胞中 TGF-β1 诱导的凋亡抗性减弱。TGF-β1 诱导的 Col1A1 产生似乎独立于 EMT 样转变和 miR-29 表达。然而，TGF-β1 诱导的 EMT 可能通过调节促凋亡基因的表达来增加胆管细胞的存活能力。
