Reduced expression of laminin-5 in corneal epithelial cells under high glucose condition

Cornea. 2006 Jan;25(1):61-7. doi: 10.1097/01.ico.0000179932.21104.3c.

Abstract

Purpose: Laminin-5 (alpha3, beta3, gamma2 chains) is a major component of corneal basement membrane and has a crucial role in corneal epithelial cell adhesion. On the other hand, diabetic keratopathy has a varied degree of adhesive disturbance in corneal epithelial cells. Therefore, in this study, we investigated whether a high glucose condition altered the expression of laminin-5 in corneal epithelial cells in vitro.

Methods: Human corneal epithelial (HCE) cells were cultured in either normal (5 mmol/L) or high glucose (30 mmol/L) medium for 5 passages before being used in experiments. We first examined the effect of a high glucose condition on the expression of mRNA and proteins for 3 chains of laminin-5 in HCE cells by semiquantitative reverse transcriptase-polymerase chain reaction, Western blotting analysis, and immunofluorescence staining. Second, we tried a cell detachment assay. After 5 days of incubation in high or normal glucose medium, HCE cells were treated with a solution of 0.05% trypsin and EDTA (0.2 mmol/L), pH = 8. The number of detached cells at different times after treatment was determined using a cell count machine.

Results: We found that alpha3 chain expression was reduced at the mRNA level in a high glucose condition, whereas beta3 and gamma2 chains showed no change. The high glucose condition induced the inhibition in the synthesis of 190-kd, 160-kd alpha3 chain and 105-kd gamma2 chain proteins of laminin-5. The adhesion capacity of HCE cells in the high glucose medium was weaker than that of HCE cells in normal glucose medium. Soluble laminin-5 rescued the detachment of HCE cells in high glucose medium.

Conclusion: The loss of homeostatic levels of laminin-5 under a high glucose condition may correlate to weaken epithelial cell adhesion, resulting in the clinical manifestation of diabetic keratopathy.

MeSH terms

  • Blotting, Western
  • Cell Adhesion Molecules / genetics*
  • Cell Adhesion Molecules / metabolism
  • Cell Culture Techniques
  • Epithelium, Corneal / cytology
  • Epithelium, Corneal / drug effects
  • Epithelium, Corneal / metabolism*
  • Fluorescent Antibody Technique, Indirect
  • Gene Expression Regulation / drug effects*
  • Glucose / pharmacology*
  • Humans
  • Osmolar Concentration
  • RNA, Messenger / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction

Substances

  • Cell Adhesion Molecules
  • RNA, Messenger
  • kalinin
  • Glucose