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Aihua Hou, Louis Tong; Transglutaminase-2 Knockdown Effect Epithelial-Mesenchymal Transition during Corneal Wound Healing. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3872.
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Transglutaminase-2 (TGM-2) is a multifunctional cross-linking enzyme involved in wound healing. Cornea wound closure was delayed in TGM-2-/- knockout mice. Also, Knockdown of TGM-2 reduced epithelial cell adhesion and migration. Epithelial-mesenchymal transition (EMT) was suggested to be involved in wound healing in cornea epithelial cells. This study aimed to investigate whether TGM2 defect perturbs EMT during corneal wound healing.
The central cornea of anesthetized mice was marked by a trephine, and the epithelium was peeled off using forceps under a dissecting microscope. Mouse eyes were harvest at different time points and embedded in OCT, and then were sectioned with cryostat at 8µM thickness. Immunofluorescent staining was performed on mouse eye sections using anti-Slug, anti-Twist and anti-β-Catenin antibodies.
In TGM2+/+ mice, EMT marker Slug was observed 4hrs following corneal abrasion, while in TGM2-/- mice, slug was observed at 24hours. Interestingly, in both TGM2+/+ and TGM2-/- mice, Slug was expressed only in the nuclei of cells at basal layer of the impaired epithelium. By immunostaining, at both naive and wounded cornea epithelium, TGM2 +/+ mice had stronger β-catenin expression than TGM2-/- mice. In TGM2+/+ mice, strong β-Catenin staining was observed at the advancing edge of corneal epithelium 4 hrs after abrasion, this phenomenon was absent at the wound edge in TGM2-/- mice. Weak Twist staining was observed in both naive and wounded corneal epithelium, but no obvious difference between TGM2+/+ and TGM2-/- mice.
TGM-2 knockdown delayed Slug expression in wounded corneal epithelium, and also reduced β-Catenin expression. These findings may suggest perturbation of EMT, which has implications for wound response. The therapeutic significance is in the modulation of wound healing via TGM-2 in ocular surface diseases.
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