Factors modulating p63 expression in cultured limbal epithelial cells

Area of Science:

• Ophthalmology
• Stem Cell Biology
• Molecular Biology

Background:

• The transcription factor p63 is a homologue of p53.
• Its role as a specific marker for corneal epithelial stem cells is debated.
• Understanding p63 expression is crucial for limbal stem cell research.

Purpose of the Study:

• To investigate the expression pattern of p63 in cultured limbal epithelial cells.
• To determine if p63 can serve as a specific marker for corneal epithelial stem cells.
• To analyze p63 expression under various culture conditions.

Main Methods:

• Cultured limbal epithelial cells were analyzed at different time points and densities.
• p63 expression was assessed in sparse, confluent, and starved cultures, and single-cell colonies.
• Expression of keratin 3 (K3), a differentiation marker, was correlated with p63 levels.

Main Results:

• Over 85% of cells expressed p63 initially, regardless of density.
• Sparsely plated cells maintained high p63 expression, while confluent cultures showed significantly reduced expression (16.9%).
• p63 expression persisted in starved cells and in most cells within single-cell-derived colonies.

Conclusions:

• p63 expression in most corneal limbal epithelial cells in culture, particularly in subconfluent conditions, indicates it is not a reliable stem cell marker.
• Reduced p63 expression in confluent cultures correlates with increased cell-cell contact.
• A subpopulation of p63-expressing cells in confluent cultures may possess proliferative potential, analogous to in vivo stem cells.