Hypoxia increases the abundance but not the assembly of extracellular fibronectin during epithelial cell transdifferentiation
Hypoxia increases the abundance but not the assembly of extracellular fibronectin during epithelial cell transdifferentiation
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DOI：
10.1242/jcs.155036
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发表时间：
2015-03-15
影响因子：
4
通讯作者：
Barber, Diane L.
中科院分区：
文献类型：
--
作者：
Rana, Manish K.;Srivastava, Jyoti;Barber, Diane L.
在上皮细胞转分化为间充质表型的过程中，细胞外基质蛋白的产生和组装增加，导致肾纤维化和肺纤维化等疾病。 TGF-β和缺氧是引发损伤诱导纤维化的两个因素，导致人肾细胞形成间充质表型，包括纤连蛋白表达和分泌增加。然而，缺氧时，组装的细胞外纤连蛋白原纤维大多不存在，而用 TGF-b 处理则产生丰富的原纤维。原纤维形成需要细胞产生的力和张力。 TGF-β（而非缺氧）增加了细胞收缩性，这是通过肌球蛋白轻链的磷酸化以及量化铺在工程弹性体微柱上的细胞产生的力和张力来确定的。此外，TGF-β（而非缺氧）增加了整合素的激活。然而，实验性激活整合素显着增加了缺氧时磷酸化肌球蛋白轻链和纤连蛋白原纤维组装的水平。我们的研究结果表明，整合素激活不足和随后的细胞收缩性缺乏是介导缺氧时纤维形成缺乏的机制，并且它们挑战了当前关于缺氧足以导致纤维化的观点。
Increased production and assembly of extracellular matrix proteins during transdifferentiation of epithelial cells to a mesenchymal phenotype contributes to diseases such as renal and pulmonary fibrosis. TGF-beta and hypoxia, two cues that initiate injury-induced fibrosis, caused human kidney cells to develop a mesenchymal phenotype, including increased fibronectin expression and secretion. However, upon hypoxia, assembled extracellular fibronectin fibrils were mostly absent, whereas treatment with TGF-b led to abundant fibrils. Fibrillogenesis required cell-generated force and tension. TGF-beta, but not hypoxia, increased cell contractility, as determined by phosphorylation of myosin light chain and quantifying force and tension generated by cells plated on engineered elastomeric microposts. Additionally, TGF-beta, but not hypoxia, increased the activation of integrins. However, experimentally activating integrins markedly increased the levels of phosphorylated myosin light chain and fibronectin fibril assembly upon hypoxia. Our findings show that deficient integrin activation and subsequent lack of cell contractility are mechanisms that mediate a lack of fibrillogenesis upon hypoxia and they challenge current views on oxygen deprivation being sufficient for fibrosis.