Abstract
Purpose: :
Lens sphingolipid composition increases with age. In addition, the sphingolipid content of cataract lens is higher than noncataractogenic lens. Sphingomyelin is the substrate for ceramide production in many cell types. The goal of this report is to determine the effect of ceramide on lens epithelial cell viability and cell death.
Methods: :
Primary bovine lens epithelial cells (BLEC) and human lens epithelial cell line SRA01/04 grown in vitro were treated with C2–D–erythro–ceramide, C6–D–erythro–Ceramide and C2–D–erythro–dihydroceramide. Cell viability was measured by MTT assay. Cell death was identified by staining the cells with DAPI and DNA fragmentation test. Activation of caspase 3 enzyme was examined by PARP immunoblotting.
Results: :
C2– and C6–Ceramide decreased cell viability of BLEC and SRA01/04. C2–ceramide reduced lens cell viability by 40–60%. In addition, ceramide increased cell death in a dose dependent manner. The exposure of lens epithelial cells to ceramide resulted in the detachment of the adherent cells. The adherent cells exhibited cell shrinkage, blebbing and chromatin condensation. C2–ceramide (50uM) treatment for 48 hours induced DNA fragmentation in lens epithelial cells. Cell death associated with ceramide treatment was caspase 3 dependent.
Conclusions: :
The abundance of membrane sphingolipids in aging lens and cataractous lens likely accounts for increased production of ceramide. Ceramide is shown to reduce cell viability and increase cell death in the cell epithelial cells.
Keywords: apoptosis/cell death • signal transduction • aging