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Updated: May 24, 2026
Investigating Scarless Tissue Regeneration in Embryonic Wounded Chick Corneas
Published on: May 2, 2022
Notch signaling promotes the corneal epithelium wound healing
Huayi Lu1, Qingxian Lu, Yajuan Zheng
1Department of Ophthalmology and Visual Sciences, James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, KY, USA.
Purpose:
The Notch signaling pathway plays crucial roles in regulation of cell proliferation, differentiation and cell fate decision in multiple tissues and cell types. This study was designed to test the effects of enhanced Notch activity on corneal epithelium homeostasis and wound healing using the transgenic mice that overexpressed an activated Notch1 (NICD) in cornea epithelium.
Methods:
The studies were performed on R26(fN1-ICD) transgenic mice that carry a NICD cDNA (cDNA) whose expression is prevented by a "Lox-STOP-Lox" cassette. When this transgenic mouse is bred to a mouse strain carrying a Cre recombinase expression cassette driven by a tissue-specific keratin 14 (K14) promoter, the floxed "STOP" cassette is excised and NICD is expressed in the cornea epithelium. The expression level of NICD and its downstream target genes, hairy and enhancer of split 1 (Hes1) and hairy/enhancer-of-split related with YRPW motif 1 (Hey1), in the transgenic corneal epithelium was examined by quantitative PCR (qPCR). The phenotypes and morphology of the transgenic corneal epithelium were compared with that of wild type (WT) controls. The proliferation rate of the epithelial cells was assessed by 5-bromo-2'-deoxyuridine (BrdU) incorporation and the differentiation statues were examined by K14, tumor protein p63 (p63), K12, and zona occludens 1 (ZO-1) immunoreactivity at either normal developmental condition or after corneal epithelial debridement. The corneal epithelial response to wound healing was studied by fluorescent staining and Richardson's staining macroscopically and by H&E staining at microscope level at 0, 6, 12, 18, and 24 h post injury.
Results:
Although overexpression of NICD in cornea epithelium led to upregulation of its downstream targets, i.e., Hes1 and Hey1, this did not alter corneal epithelial cell proliferation and differentiation. However, wound healing induced Notch activity and overexpression of NICD promoted corneal epithelial wound healing, which was in agreement with more rapid early proliferation response in NICD transgenic mice than in the wild type control mice.
Conclusions:
These findings further demonstrate the functional role of Notch signaling in corneal epithelium wound healing response.
Insights
Enhanced Notch activity, specifically Notch1 (NICD), promotes corneal epithelial wound healing. While it did not affect normal cell proliferation or differentiation, NICD overexpression accelerated wound repair in mice.
Area of Science:
- Ophthalmology
- Cell Biology
- Developmental Biology
Background:
- The Notch signaling pathway is vital for regulating cell proliferation, differentiation, and fate decisions across various tissues.
- Understanding Notch's role in the cornea is crucial for addressing its homeostasis and repair mechanisms.
Purpose of the Study:
- To investigate the impact of enhanced Notch signaling activity on corneal epithelium homeostasis and wound healing.
- To utilize transgenic mice overexpressing an activated form of Notch1 (NICD) in the corneal epithelium.
Main Methods:
- Generated transgenic mice with NICD expression in corneal epithelium using a Cre-lox system.
- Quantified NICD and its downstream targets (Hes1, Hey1) via qPCR.
- Assessed corneal epithelial cell proliferation (BrdU) and differentiation (K14, p63, K12, ZO-1).
- Evaluated wound healing response post-injury through macroscopic and microscopic staining.
Main Results:
- Overexpression of NICD upregulated Hes1 and Hey1 but did not alter basal corneal epithelial cell proliferation or differentiation.
- Wound healing induced endogenous Notch activity.
- NICD overexpression significantly promoted corneal epithelial wound healing.
- NICD transgenic mice exhibited a more rapid early proliferation response during wound healing compared to wild-type controls.
Conclusions:
- Notch signaling plays a significant functional role in the corneal epithelial wound healing process.
- Enhanced Notch activity, specifically NICD, accelerates corneal wound repair.
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