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Sharolyn V. Kawakami-Schulz, Angela M. Verdoni, Akihiro Ikeda, Sakae Ikeda; Phenotypic Variations in the Cornea of Destrin Mutants Caused by Allelic Differences and Genetic Modifiers. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6400.
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© ARVO (1962-2015); The Authors (2016-present)
Mutations in the gene for Destrin (Dstn), an actin depolymerizing factor, lead to corneal abnormalities in mice. A null mutation in Dstn, termed Dstncorn1, isolated and maintained in the A.BY background (A.BY Dstncorn1), results in corneal hyperproliferation and neovascularization. Mice with a point mutation in the Dstn gene, termed Dstncorn1-2J, were maintained in a C57BL/6(B6) background (B6 Dstncorn1-2J) and display mild hyperproliferation in the corneal epithelium but not neovascularization. The goal of this study is to determine whether phenotypic differences in the cornea of these two Dstn mutants are due to the allelic differences between Dstncorn1 and Dstncorn1-2J, or are the result of genetic background effects from A.BY or B6.
We generated two congenic mouse lines, B6 Dstncorn1 and A.BY Dstncorn1-2J, to compare to the original A.BY Dstncorn1 and B6 Dstncorn1-2J lines. We performed immunohistochemistry on flat-mount cornea using CD31 as a marker for vasculature, and on frozen sections of the cornea using Ki67 as an indicator of proliferation, to assay differences in neovascularization and hyperproliferation between the four mouse lines.
The Dstncorn1 mutation leads to neovascularization in the cornea of A.BY Dstncorn1, as well as B6 Dstncorn1 mice. We did not observe this corneal neovascularization in A.BY Dstncorn1-2J mice. Therefore, neovascularization can be attributed to allelic differences between Dstncorn1 and Dstncorn1-2J. However, neovascularization in the cornea of B6 Dstncorn1, mice is significantly reduced when compared to A.BY Dstncorn1 mice, indicating the existence of genetic modifier(s) that affect the severity of neovascularization. Additionally, an F1 cross (A.BY Dstncorn1 x B6 Dstncorn1) yields an intermediate neovascularization phenotype, suggesting that the A.BY allele of the modifier(s) acts in a semi-dominant manner.
By comparing the original mutants to congenic lines with the Dstncorn1 or Dstncorn1-2J mutations, we found that the neovascularization phenotype results from the allelic difference between Dstncorn1 and Dstncorn1-2J and is also modified by genetic factors. Our results suggest that natural genetic variation affects the severity of neovascularization in Dstncorn1 mice.
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