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Shannon J Das, Emma Collinson, Karin Jandeleit-Dahm, Harald Schmidt, Frank J Lovicu; TGFß-induced EMT leading to cataractogenesis requires Nox4 activity. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3787. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Transforming Growth Factor-β (TGFβ) can induce an epithelial to mesenchymal transition (EMT) in the lens that results in anterior subcapsular cataract (ASC) or posterior capsular opacification (PCO). We have previously shown that the reactive oxygen species (ROS) producing enzyme, NADPH oxidase 4 (Nox4), is upregulated in response to TGFβ-signaling in lens and that pharmacological inhibition of Nox4 abrogated aspects of EMT. To better elucidate the role(s) of Nox4 in lens EMT in situ, the present study utilised a mutant mouse line deficient for Nox4.
Mice overexpressing bioactive TGFβ specifically in the lens, that develop ASC, were crossed to Nox4 deficient mice. The eyes of the resultant progeny were grossly examined for the presence/absence of cataract, collected and processed for histological evaluation. Eye sections were Periodic-Acid Schiff stained, and immunofluorescence was used to assess for changes in EMT and cataract markers. Additionally, lenses from wild-type (WT) or Nox4-deficient mice were isolated, explanted and treated with exogenous TGFβ2 (200pg/ml) to assess for the progression of EMT in vitro.
When mice overexpressing bioactive TGFβ specifically in lens were crossed to the mutant mice deficient for Nox4, by postnatal day 21, lens from the resultant transgenic progeny were found to be transparent and did not present anterior subcapsular cataracts typically seen in TGFβ overexpressing lines. Histology and immunolabeling of these lenses revealed the absence of any significant EMT or cataractous plaques, in contrast to TGFβ overexpressing mice that presented subcapsular plaques. Our in vitro study validates these findings and lends itself to further characterise the specific molecular mechanisms involved in lens EMT.
These results indicate that in mice, Nox4 plays a role in the development of TGFß-induced EMT leading to cataract in situ. Taken together, these findings now provide a platform allowing us to delineate the specific targets of Nox4-derived ROS leading to EMT and cataract.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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