Abstract
Purpose::
Ceramide is a second messenger sphingolipid that has been shown previously in this lab to induce apoptosis in the lens epithelial cells. The purpose of the present study is to determine how insuline-like growth factor-1 (IGF-1)/PI-3 kinase affects C2-ceramide-induced apoptosis.
Methods::
Primary bovine lens epithelial cells are used to study the effect of IGF-1 on C2-ceramide induced apoptosis. Measurement of apoptosis is done by DAPI method. Western blotting was performed to study the ceramide-mediated mitochondrial release of cytochrome C. Caspase-3 activation was measured by cleavage of substrate DEVD-MCA.
Results::
IGF-1 inhibited C2-ceramide induced lens epithelial cell apoptosis. This inhibitory action of IGF-1 was blocked by a phosphatidylinositol-3 (PI-3) kinase inhibitor wortmannin. IGF-1 treatment restored ceramide-depleted catalse function. A catalse inhibitor 3-amino-1h-1,2,4-triazole(ATZ) blocked the inhibitory action of IGF-1 on ceramide-induced apoptosis. Ceramide-activated caspase-3 was inhibitied by IGF-1/PI-3 kinase.
Conclusions::
Results from the present study suggest that IGF-1/PI-3 kinase inhibited C2-ceramide-induced apoptosis due to oxidative damage in the lens epithelial cells. IGF-1/PI-3 kinase restored ceramide-induced inhibition of catalse.
Keywords: apoptosis/cell death • signal transduction • lipids