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Differences in corneal phenotypes between destrin mutants are due to allelic difference and modified by genetic background.

Kawakami-Schulz SV, Verdoni AM, Sattler SG, Ikeda A, Ikeda S - Mol. Vis. (2012)

Bottom Line: The goal of this study was to determine whether phenotypic differences are due to allelic differences between Dstn(corn1) and Dstn(corn1-2J), or are the result of genetic background effects.Actin accumulation, neovascularization, epithelial proliferation and inflammation in B6.Cg-Dstn(corn1) cornea are significantly reduced when compared to A.BY Dstn(corn1)cornea.Differences in the abnormal phenotypes of Dstn mutants result from allelic differences between Dstn(corn1) and Dstn(corn1-2J) .

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Genetics, University of Wisconsin, Madison, WI 53705, USA.

ABSTRACT

Purpose: Mutations in destrin (Dstn) cause corneal abnormalities in mice. A mutation, Dstn(corn1), results in corneal epithelial hyperproliferation, inflammation, and neovascularization in the A.BY background (A.BY Dstn(corn1)). Homozygosity for a point mutation, Dstn(corn1-2J), results in mild thickening of the corneal epithelium but no corneal neovascularization in a C57BL/6 (B6) background (B6 Dstn(corn1-2J)). The goal of this study was to determine whether phenotypic differences are due to allelic differences between Dstn(corn1) and Dstn(corn1-2J), or are the result of genetic background effects.

Methods: We generated two congenic (Cg) mouse lines, B6.Cg-Dstn(corn1) and A.BY.Cg-Dstn(corn1-2J), to compare to the original A.BY Dstn(corn1) and B6 Dstn(corn1-2J) lines. We performed immunohistochemistry to assay F-actin accumulation, neovascularization, proliferation, and inflammation. By western blot analysis we tested the expression of serum response factor (SRF), a known regulator of the Dstn(corn1) phenotype.

Results: The Dstn(corn1) mutation leads to neovascularization, hyperproliferation, and inflammation in the cornea of A.BY Dstn(corn1) as well as B6.Cg-Dstn(corn1) mice. We did not observe significant corneal neovascularization or hyperproliferation in either A.BY.Cg-Dstn(corn1-2J) or B6 Dstn(corn1-2J) mice. Actin accumulation, neovascularization, epithelial proliferation and inflammation in B6.Cg-Dstn(corn1) cornea are significantly reduced when compared to A.BY Dstn(corn1)cornea. SRF changes are consistent in Dstn(corn1) mutants, regardless of genetic background.

Conclusions: Differences in the abnormal phenotypes of Dstn mutants result from allelic differences between Dstn(corn1) and Dstn(corn1-2J) . Moreover, phenotypes of Dstn(corn1) mice are modified by genetic background, suggesting the existence of genetic modifiers. Protein analysis suggests that a genetic modifier affects phenotypic severity functionally downstream from or in a pathway independent from SRF. These data demonstrate that natural genetic variation affects phenotypic severity in Dstn(corn1) mice.

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Gross anatomic imaging of eyes of A.BY Dstncorn1, B6.Cg-Dstncorn1 , A.BY.Cg-Dstncorn1–2J, B6 Dstncorn1–2J, A.BY WT, and B6 WT mice. Corneal neovascularization occurs only in lines with the Dstncorn1mutation (arrowheads in B6.Cg-Dstncorn1). While all Dstn mutants display a roughened corneal surface, this phenotype is more severe in Dstncorn1. Cataract formation occurs in all four mutants, but is delayed in Dstncorn1–2J when compared to Dstncorn1.
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f1: Gross anatomic imaging of eyes of A.BY Dstncorn1, B6.Cg-Dstncorn1 , A.BY.Cg-Dstncorn1–2J, B6 Dstncorn1–2J, A.BY WT, and B6 WT mice. Corneal neovascularization occurs only in lines with the Dstncorn1mutation (arrowheads in B6.Cg-Dstncorn1). While all Dstn mutants display a roughened corneal surface, this phenotype is more severe in Dstncorn1. Cataract formation occurs in all four mutants, but is delayed in Dstncorn1–2J when compared to Dstncorn1.

Mentions: Even upon gross visual analysis, these two Dstn mutations exhibit phenotypic differences at P58 (Figure 1). The corneal surface of A.BY Dstncorn1 and B6.Cg-Dstncorn1 mice is roughened and blood vessels are clearly visible. Cataracts in the lens are another characteristic feature of Dstncorn1 eyes in both backgrounds at P58. The corneal surface of A.BY.Cg-Dstncorn1–2J and B6 Dstncorn1–2J also appears rough when compared to WT, but to a lesser degree. In mice with the Dstncorn1–2J mutation, a cataract has not fully formed by P58 but develops in all mice as they age (data not shown). Additionally, neither Dstncorn1-2J mutant displays corneal neovascularization (Figure 1).


Differences in corneal phenotypes between destrin mutants are due to allelic difference and modified by genetic background.

Kawakami-Schulz SV, Verdoni AM, Sattler SG, Ikeda A, Ikeda S - Mol. Vis. (2012)

Gross anatomic imaging of eyes of A.BY Dstncorn1, B6.Cg-Dstncorn1 , A.BY.Cg-Dstncorn1–2J, B6 Dstncorn1–2J, A.BY WT, and B6 WT mice. Corneal neovascularization occurs only in lines with the Dstncorn1mutation (arrowheads in B6.Cg-Dstncorn1). While all Dstn mutants display a roughened corneal surface, this phenotype is more severe in Dstncorn1. Cataract formation occurs in all four mutants, but is delayed in Dstncorn1–2J when compared to Dstncorn1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3298451&req=5

f1: Gross anatomic imaging of eyes of A.BY Dstncorn1, B6.Cg-Dstncorn1 , A.BY.Cg-Dstncorn1–2J, B6 Dstncorn1–2J, A.BY WT, and B6 WT mice. Corneal neovascularization occurs only in lines with the Dstncorn1mutation (arrowheads in B6.Cg-Dstncorn1). While all Dstn mutants display a roughened corneal surface, this phenotype is more severe in Dstncorn1. Cataract formation occurs in all four mutants, but is delayed in Dstncorn1–2J when compared to Dstncorn1.
Mentions: Even upon gross visual analysis, these two Dstn mutations exhibit phenotypic differences at P58 (Figure 1). The corneal surface of A.BY Dstncorn1 and B6.Cg-Dstncorn1 mice is roughened and blood vessels are clearly visible. Cataracts in the lens are another characteristic feature of Dstncorn1 eyes in both backgrounds at P58. The corneal surface of A.BY.Cg-Dstncorn1–2J and B6 Dstncorn1–2J also appears rough when compared to WT, but to a lesser degree. In mice with the Dstncorn1–2J mutation, a cataract has not fully formed by P58 but develops in all mice as they age (data not shown). Additionally, neither Dstncorn1-2J mutant displays corneal neovascularization (Figure 1).

Bottom Line: The goal of this study was to determine whether phenotypic differences are due to allelic differences between Dstn(corn1) and Dstn(corn1-2J), or are the result of genetic background effects.Actin accumulation, neovascularization, epithelial proliferation and inflammation in B6.Cg-Dstn(corn1) cornea are significantly reduced when compared to A.BY Dstn(corn1)cornea.Differences in the abnormal phenotypes of Dstn mutants result from allelic differences between Dstn(corn1) and Dstn(corn1-2J) .

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Genetics, University of Wisconsin, Madison, WI 53705, USA.

ABSTRACT

Purpose: Mutations in destrin (Dstn) cause corneal abnormalities in mice. A mutation, Dstn(corn1), results in corneal epithelial hyperproliferation, inflammation, and neovascularization in the A.BY background (A.BY Dstn(corn1)). Homozygosity for a point mutation, Dstn(corn1-2J), results in mild thickening of the corneal epithelium but no corneal neovascularization in a C57BL/6 (B6) background (B6 Dstn(corn1-2J)). The goal of this study was to determine whether phenotypic differences are due to allelic differences between Dstn(corn1) and Dstn(corn1-2J), or are the result of genetic background effects.

Methods: We generated two congenic (Cg) mouse lines, B6.Cg-Dstn(corn1) and A.BY.Cg-Dstn(corn1-2J), to compare to the original A.BY Dstn(corn1) and B6 Dstn(corn1-2J) lines. We performed immunohistochemistry to assay F-actin accumulation, neovascularization, proliferation, and inflammation. By western blot analysis we tested the expression of serum response factor (SRF), a known regulator of the Dstn(corn1) phenotype.

Results: The Dstn(corn1) mutation leads to neovascularization, hyperproliferation, and inflammation in the cornea of A.BY Dstn(corn1) as well as B6.Cg-Dstn(corn1) mice. We did not observe significant corneal neovascularization or hyperproliferation in either A.BY.Cg-Dstn(corn1-2J) or B6 Dstn(corn1-2J) mice. Actin accumulation, neovascularization, epithelial proliferation and inflammation in B6.Cg-Dstn(corn1) cornea are significantly reduced when compared to A.BY Dstn(corn1)cornea. SRF changes are consistent in Dstn(corn1) mutants, regardless of genetic background.

Conclusions: Differences in the abnormal phenotypes of Dstn mutants result from allelic differences between Dstn(corn1) and Dstn(corn1-2J) . Moreover, phenotypes of Dstn(corn1) mice are modified by genetic background, suggesting the existence of genetic modifiers. Protein analysis suggests that a genetic modifier affects phenotypic severity functionally downstream from or in a pathway independent from SRF. These data demonstrate that natural genetic variation affects phenotypic severity in Dstn(corn1) mice.

Show MeSH
Related in: MedlinePlus