Abstract
Abstract: :
Purpose: During cataractogenesis, LEC on the anterior surface of the lens proliferate, transform into myofibroblast–like cells, and migrate posteriorly. These events resemble epithelial–mesenchymal transition (EMT), the transformation of anchored epithelial cells into migrating fibroblastic cells, occurring during development. EMT is initiated by growth factors like epidermal growth factor (EGF) that stimulate expression of the transcription factors Slug and Snail. These transcription factors then coordinate the many downstream events required for EMT. We hypothesize that enhanced expression of Slug or Snail due to EGF stimulation controls EMT–like changes in lens epithelial cells (LEC) during canine cataractogenesis. Methods: LEC were wounded in vitro and treated with EGF. Wound closure was monitored and real time RT–PCR was performed to measure Slug and Snail expression. Real–time RT–PCR was also used to examine the expression of Slug and Snail mRNA in canine cataracts and normal lenses. Results: EGF–treated LEC migrated faster to heal defects than untreated LEC. Following EGF treatment, Slug expression increased after 8 hours and remained elevated until 12 hours. Snail expression increased following 5 hours of EGF treatment and did not decrease until after 12 hours. Neither normal canine lenses nor cataracts expressed Slug or Snail mRNA. Conclusions: Cultured LEC treated with EGF express more Slug and Snail mRNA than normal LEC, suggesting enhanced stimulation of cell migration. Clinical cataracts do not express Slug or Snail, perhaps because stimulation of cell migration occurred during the initial stages of cataractogenesis, prior to sample collection. Future aims of this project are to treat whole lenses with EGF in vitro and measure Slug and Snail expression during early stages of cataract formation.
Keywords: cataract • growth factors/growth factor receptors • transcription factors