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Marjorie F. Lou, Subhasree Basu, Yibo Yu, Hongli Wu, A S. Menko; Glutaredoxin (Grx2) Gene Knockout Suppresses Fiber Cell Differentiation and Delays De-nucleation of the Mouse Lens. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5592.
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© ARVO (1962-2015); The Authors (2016-present)
Glutaredoxin 2 (Grx2) is an enzyme with dethiolase and peroxidase activities and is present in the mitochondria where it may protect the organelle from oxidative damage and regulate its redox balances. Recently we developed a global Grx2 gene knockout (KO) mouse model with a phenotype of early age-dependent cataract development, compared with the wild type (WT) control. The purpose of this study is to examine how Grx2 gene deletion affects lens development and influence its transparency.
Histological slides were made using whole eye globe (5 m WT, Grx2 KO), fixed and sectioned into 5 micron thickness, followed with hematoxylin and eosin staining. Lens cryosections prepared from WT and Grx2 KO mice at 1.2 m were immunostained with the lens differentiation marker filensin, counterstained for F-actin (fluorescent-conjugated phalloidin) and nuclei (TO-PRO-3), and imaged by confocal microscopy. Filensin expression also was examined in 1, 7, and 16 m WT and KO mice by Western blot analysis.
Lenses from Grx2 null mice showed similar growth in size and weight as WT mice but developed nuclear opacity 3 months sooner than the age-matched control. Histological section at the polar region of the Grx2 KO lens (5 m) showed heavy nuclei staining deep into the fiber cell layers. Saggital cryosections of 1.2 m-old Grx2-/- mice stained for F-actin showed a normal anterior-posterior alignment of fiber cells in the lens cortex, but cross-sectional analysis revealed patches of aberrant organization of the normal hexagonal packed structure. Immunostaining showed a lower-level expression of filensin in the cortex of Grx2-/- lenses compared to controls that was confirmed by Western blot analysis. And, unlike control lenses in which nuclei are lost with fiber cell differentiation, in the Grx2-/- lens nuclei persisted in the centermost fiber cells.
Grx2 gene deletion interferes the lens fiber differentiation and also inhibits the process of de-nucleation during lens development. Aberration of both may contribute to the early nuclear cataract formation in the Grx2-/- lens.
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