Figure 5.

Transcriptional regulation of hyx/CDC73 and Thor/4E-BP in response to caloric or serum starvation. Upregulation in w¹¹¹⁸ control or mutant flies of hyx/CDC73 and Thor/4E-BP, but not of Tor transcript, compared with fed controls following 48 h of starvation (a–d). The basal reduction of hyx transcript observed in Tor^+/− (Tor^MB0798/+) heterozygous flies was lost following 48 h of starvation, suggesting that nutritional cues may regulate hyx transcription independently of Tor activity (c). Conversely, the basal reduction in Thor/4E-BP transcript observed in hyx^+/− heterozygous flies persists following 48 h of starvation, suggesting that hyx is necessary for the starvation-induced increase in Thor/4E-BP transcript (d). Basal expression of Thor/4E-BP transcript was unchanged in Mnn1^+/− (Mnn1^DG30701/+) heterozygous flies compared with w¹¹¹⁸ controls; however, the level of Thor transcript was somewhat reduced following 48 h of starvation (e). Expression of human CDC73, EIF4EBP1, EIF4EBP2, and EIF4EBP3 transcript was significantly increased in HEK293 cells following 48 h of serum starvation (f–i). For b–i ^*P<0.05, ^**P<0.005; ^***P<0.0005 compared with control, using unpaired Student's t-test