Generation of transaldolase knockdown Drosophila in the apoptosis study and screening for the apoptosis modifiers. Yi-Chun Chen, Tzu-Li Yen, Ju-Ching Yu, Horng-Dar Wang. Institute of Biotechnology, HsinChu, Taiwan.

   Transaldolase is the rate-limiting enzyme in the non-oxidative branch of pentose phosphate pathway. While deficiency of transaldolase has been implicated in enhancing apoptosis in cell culture, yet there is no reported genetic phenotypic study of transaldolase knockdown mediated apoptosis in Drosophila. Here, we showed the novel phenotypes, the posterior bulgy eyes and the wrinkled wings, upon RNAi knockdown of transaldolase by eye-specific GMR-Gal4 and wing-specific MS1096-Gal4 drivers respectively. In order to examine whether the phenotypes by the knockdown of transaldolase are due to apoptosis, we knockdown each of the apoptosis-related genes, p53, hid, and Dronc, simultaneously in the transaldolase knockdown flies. Blocking the expression of the apoptosis-related genes rescues the phenotypes by the knockdown of transaldolase back to normal, suggesting the specific phenotypes are triggered by apoptosis. Biochemical analysis by acridine orange confirms the phenotypes are consequences of apoptosis. We have generated the viable GMR-Gal4;UAS-TalRNAi homozygous line to screen about 400 RNAi knockdown fly lines for the modifiers either suppressing and enhancing the bulgy apoptotic eye by transaldolase knockdown. We have identified a number of novel modifiers which genetically interact with the transaldolase knockdown induced apoptosis. Future large-scale screening will further provide more new novel molecular targets for the treatment and prevention of metabolic diseases and cancer.