Loss of flfl Triggers JNK-Dependent Cell Death in Drosophila

falafel (flfl) encodes a Drosophila homolog of human SMEK whose in vivo functions remain elusive. In this study, we performed gain-of-function and loss-of-function analysis in Drosophila and identified flfl as a negative regulator of JNK pathway-mediated cell death. While ectopic expression of flfl suppresses TNF-triggered JNK-dependent cell death, loss of flfl promotes JNK activation and cell death in the developing eye and wing. These data report for the first time an essential physiological function of flfl in maintaining tissue homeostasis and organ development. As the JNK signaling pathway has been evolutionary conserved from fly to human, a similar role of PP4R3 in JNK-mediated physiological process is speculated.