Probing Genes and Networks that Specify Cell Death

Acridine-stained apoptotic cells are prevalent in the wild-type embryo (top), absent in mutants that lack Rpr proteins, and severely reduced in animals that lack Dark, a component of the fly apoptosome.

The Drosophila apoptosome, like its mammalian counterparts, is a molecular machine that occupies a central position in networks that specify programmed cell death (PCD). We pursue unbiased genetic approaches to gain a comprehensive view of pivotal cell death regulators and to discover novel apoptogenic functions.  

Screening for Genes for Programmed Cell Death (PCD) in Vivo

We showed that lesions in canonical apoptotic pathways cause epithelial cells to persist past when they would normally die after eclosion. A uniquely characteristic late-onset phenotype results. Novel PCD genes, if similarly eliminated in the wing, show these same distinctive defects. Therefore, we are conducting a large-scale screening effort and have already recovered several promising mutants. Some mutations encode essential apoptotic determinants in distinct tissue types.

High-Throughput Gene Silencing Platforms

RNAi technology, combined with high-throughput cell-based assay systems, enable methodical testing of annotated genes for functional properties. We are exploiting cell-based RNAi screening platforms to capture novel effectors of apoptotic cell death using stimuli and drugs that simulate programmed signals (e.g. Reaper proteins) or stress from injury.

Stimulus-Induced Apoptosis and Rescue by Gene Silencing

Time-lapse studies follow apoptotic cell death in cultured Drosophila cells after lethal exposure to UV light.

Control sample: Acute apoptosis occurs  about 6 hours after UV challenge.
Rescue sample: Gene silencing was used to eliminate the apical caspase, Dronc, and cell death is prevented.