The reactive oxygen species (ROS) producing enzyme, NADPH oxidase 4 (Nox4), is upregulated in response to TGFβ in lens epithelial cells in vitro, and its selective inhibition was shown to block aspects of TGFβ-induced epithelial-mesenchymal transition (EMT). In the present in situ study we validate the role(s) of Nox4 in TGFβ-induced lens EMT leading to anterior subcapsular cataract (ASC) formation. Mice overexpressing TGFβ in the lens, that develop ASC, were crossed to Nox4-deficient mice. When comparing mice overexpressing TGFβ in lens, to mice that were also deficient for Nox4, we see the delayed onset of cataract, along with a delay in EMT protein markers normally associated with TGFβ-induced fibrotic cataracts. In the absence of Nox4, we also see elevated levels of ERK1/2 activity that was shown to be required for TGFβ/Smad2/3-signaling. qRT-PCR revealed upregulation of Nox2 and its regulatory subunit in TGFβ-overexpressing lens epithelial cells devoid of Nox4. Taken together, these findings provide an improved platform to delineate putative Nox4 (and ROS) interactions with Smad2/3 and/or ERK1/2, in particular in the development of fibrotic diseases, such as specific forms of cataract.

中文翻译：

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涉及Nox4介导的ROS产生，但对于TGFβ诱导的晶状体EMT导致白内障不是必需的。

响应晶状体上皮细胞中的TGFβ，产生活性氧（ROS）的酶NADPH氧化酶4（Nox4）被上调，并且它的选择性抑制被证明可阻断TGFβ诱导的上皮-间质转化（EMT）的各个方面。在当前的原位研究中，我们验证了Nox4在TGFβ诱导的晶状体EMT中导致前囊下白内障（ASC）形成的作用。将在晶状体中过表达TGFβ的小鼠发展为ASC，将其与Nox4缺陷小鼠杂交。当将在晶状体中过表达TGFβ的小鼠与同样缺乏Nox4的小鼠进行比较时，我们发现白内障的发生延迟，以及通常与TGFβ诱导的纤维化白内障相关的EMT蛋白标记的延迟。在没有Nox4的情况下，我们还发现EGF1 / 2活性水平升高，这表明TGFβ/ Smad2 / 3-信号传导是必需的。qRT-PCR显示在没有Nox4的过表达TGFβ的晶状体上皮细胞中Nox2及其调节亚基的上调。综上所述，这些发现提供了一个改进的平台来描述推定的Nox4（和ROS）与Smad2 / 3和/或ERK1 / 2的相互作用，特别是在纤维化疾病的发展中，例如特定形式的白内障。