Nox4-mediated ROS production is involved, but not essential for TGFβ-induced lens EMT leading to cataract.
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.
['Das|S J|SJ|', 'Wishart|T F L|TFL|', 'Jandeleit-Dahm|K|K|', 'Lovicu|F J|FJ|']
D000818:Animals D015153:Blotting, Western D002386:Cataract D002478:Cells, Cultured D004591:Electrophoresis, Polyacrylamide Gel D004847:Epithelial Cells D058750:Epithelial-Mesenchymal Transition D005260:Female D005355:Fibrosis D019084:Fluorescent Antibody Technique, Indirect D060005:Genotyping Techniques D007908:Lens, Crystalline D008297:Male D051379:Mice D018345:Mice, Knockout D008822:Mice, Transgenic D019950:Mitogen-Activated Protein Kinase 1 D048052:Mitogen-Activated Protein Kinase 3 D000074663:NADPH Oxidase 4 D017382:Reactive Oxygen Species D060888:Real-Time Polymerase Chain Reaction D051899:Smad2 Protein D051900:Smad3 Protein D016212:Transforming Growth Factor beta
ROS Lens Cataract Nox4 Epithelial-mesenchymal transition (EMT) Anterior subcapsular cataract ERK1/2 Nox2 Fibrosis Myofibroblast Smad Transforming growth factor-beta (TGFβ)