Nakagawa Yuki, Okada Seiji, Hatano Masahiko, Ebara Masaaki, Saisho Hiromitsu, Tokuhisa Takeshi
Department of Developmental Genetics (H2), Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan.
J Biochem Mol Biol. 2002 Sep 30;35(5):452-8. doi: 10.5483/bmbrep.2002.35.5.452.
Exposure to ultraviolet light (UV) induces apoptosis in mammalian cells. The caspase group of proteases is required for the apoptosis. This pathway is initiated by a release of cytochrome c from the mitochondria into the cytosol. Several Bcl-2 family proteins can regulate the release of cytochrome c by stabilizing the mitochondrial membrane. Here we show that expression of the endogenous bcl-xL was strongly downregulated in NIH3T3 cells within 2 h after UV-C irradiation, and that of bax was upregulated from 8 h after irradiation. Apoptosis was induced in more than 50% of the NIH3T3 cells 48 h after irradiation. Constitutive overexpression of bcl-xL in NIH3T3 cells protected the UV-induced apoptosis by preventing the loss of mitochondrial membrane potential and the activation of caspase 9. These results suggest that downregulation of Bcl-xL is relevant to UV-induced apoptosis of fibroblasts.
