Drob-1, a Drosophila member of the Bcl-2/CED-9 family that promotes cell death

• DOI: 10.1073/pnas.97.2.662
• Publication Date: 2002-07-26T14:38:21Z
• Authors: Tatsushi Igaki; Hirotaka Kanuka; Naohiro Inohara; Kazunobu Sawamoto; Gabriel Núñez; Hideyuki Okano; Masayuki Miura
• Keywords: 0301 basic medicine; DNA, Complementary; Cell Death; Gene Expression Regulation, Developmental; Membrane Proteins; Helminth Proteins; Intracellular Membranes; Blotting, Northern; Eye; 3. Good health; Animals, Genetically Modified; Enzyme Activation; 03 medical and health sciences; Caspases; COS Cells; Animals; Drosophila Proteins; Insect Proteins; Drosophila; Amino Acid Sequence; Apoptosis Regulatory Proteins; Caenorhabditis elegans Proteins; In Situ Hybridization

The Bcl-2/CED-9 family of proteins, which includes both antiapoptotic and proapoptotic members, plays key regulating roles in programmed cell death. We report here the identification and characterization of Drob-1, the first Drosophila member of the Bcl-2/CED-9 family to be isolated. Drob-1 contains four conserved Bcl-2 homology domains (BH1, BH2, BH3, and BH4) and a C-terminal hydrophobic domain. Ectopic expression of Drob-1 in the developing Drosophila eye resulted in a rough-eye phenotype. Furthermore, when overexpressed in Drosophila S2 cells, Drob-1 induced apoptosis accompanied by elevated caspase activity. This Drob-1-induced cell death, however, could not be antagonized by baculovirus p35, a broad-spectrum caspase inhibitor. Drob-1 was localized to the intracytoplasmic membranes, predominantly to the mitochondrial membranes, and a mutant Drob-1 lacking the hydrophobic C terminus lost both its mitochondrial localization and its proapoptotic activity. These results suggest that Drob-1 promotes cell death by inducing both caspase-dependent and -independent pathways at the mitochondria. Our identification of Drob-1 and further genetic analysis should provide increased understanding of the universal mechanisms by which the Bcl-2/CED-9 family members and other related proteins regulate apoptosis.