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E.I. Frolova, I. Frolov, V.M. Fokina; WNT Signaling Plays a Critical Role in Lens Morphogenesis . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1100.
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© ARVO (1962-2015); The Authors (2016-present)
Wnts are secreted glycoproteins that play important roles in the patterning of different organs during embryogenesis. Previously, we have shown that 6 Wnt ligands, 3 Frizzled receptors and 1 SFRP are expressed in the chick lens during development. In addition, overexpression of the Wnt antagonist Crescent led to abnormal lens development. These data imply that Wnts play a critical role in lens morphogenesis. To further understand the roles of Wnt signaling in lens development, we overexpressed several Wnts (Wnt2b, Wnt3a, Wnt7a and Wnt7b) in the embryonic chick lens using a Sindbis virus–based expression vector.
The entire coding seqiences for Wnt2b, Wnt3a, Wnt7a and Wnt7b were cloned in the Sindbis virus–based, replication–deficient expression vector, pSINm/GFP, which also encoded GFP under a separate subgenomic promoter to mark the Wnt–expressing cells. The vectors were packaged into the viral glycoproteins and used to infect the embryonic lenses in ovo at stages 18–21. Using different viral glycoproteins and/or injection protocols, we achieved the expression of Wnts either in the entire lens or only in the lens fiber cells. The embryos were sacrificed at different times post infection. To analyze the changes in the lens development induced by Wnt overexpression, the embryos were sectioned and processed for immunofluorescent staining with different antibodies.
When overexpressed, Wnt2b, Wnt7a and Wnt7b altered lens development. The observed phenotypes were different for each Wnt and correlated with the expected function that was suggested by the pattern of their expression, which we identified in the previous studies. As expected, Wnt3a, which is expressed in the embryonic chick cornea, but not the lens, did not alter lens differentiation, but had a strong effect on corneal morphogenesis.
These data suggest that several steps in lens morphogenesis are regulated by different Wnt signaling pathways.
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