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K. Terai, Y. Hayashi, T.–I. Chikama, W.W. Kao; Corneal Epithelial Wound Healing in the Absence of TGF–ß Type II Receptor . Invest. Ophthalmol. Vis. Sci. 2004;45(13):1433.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To examine the roles of TGF–ß signaling pathways on wound healing of corneal epithelium debridement. Methods: To prepare mice lacking TGF–ß receptor 2 (TbR2) in corneal epithelium, TbR2 floxed (TbR2f/f) mice were bred to Krt12Cre/+ mice to generate mice in which the TGF–ß receptor 2 gene was disrupted selectively in the corneal epithelium. Somatic genotype of epithelium was identified by PCR with specific primers for floxed TbR2 and excised ΔTbR2 alleles. A corneal epithelium debridement (2 mm diameter) was created in 2–month–old compound Krt12Cre/+/TbR2f/f, Krt12Cre/+/TbR2f/+ and Krt12+/+/TbR2f/f transgenic mice. The areas of corneal epithelium defect were measured by fluorescein staining. Cell proliferation was examined by BrdU incorporation. Immunohistochemistry was used to determine the distribution of TbR2, and p38 MAPK during wound healing. Results: Somatic genotyping indicated that both floxed TbR2 and excised ΔTbR2 alleles coexisted in corneal epithelium of Krt12Cre/+/TbR2f/f mice. Immune staining with anti–TbR2 antibodies exhibited a mosaic distribution of cells with and without the receptor. Epithelial wound healing was delayed in Krt12Cre/+/TbR2f/f mice as compared to that of Krt12Cre/+/TbR2f/+ and Krt12+/+/TbR2f/f mice. There is no significant difference in cell proliferation determined by BrdU incorporation or the activation of p38MAPK by immunohistochemistry. Conclusion: The mild defects in wound healing of corneal epithelium debridement in Krt12Cre/+/TbR2f/f mice can be explained by the fact that only one allele of Krt12 genes is activated when the limbal stem cells undergo differentiation. Thus, the ablation of TbR2 only occurs in cells that express Cre. Homozygous Krt12Cre/Cre/TbR2f/f mice are needed to determine the role of TGF–ß signaling in corneal epithelial wound healing.
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