Target of rapamycin (TOR) mediates the transduction of nutritional signals into juvenile hormone production.
Anautogeny is a reproductive strategy by which females do not reproduce until they feed. Therefore, nutritional signals must inform the reproductive tissues, and cells that the organism has reached a nutritional status suitable for triggering reproductive processes. One of the possible pathways involved in anautogeny is the "target of rapamycin" (TOR) pathway, which has been described as connecting the nutritional status with growth, proliferation, and cancer. The German cockroach, Blattella germanica, is an anautogenous species whose vitellogenesis is governed by juvenile hormone. In the present report, we describe the cloning of TOR cDNA from B. germanica (BgTOR). Expression studies showed that BgTOR is expressed in adult female corpora allata and fat body. BgTOR knockdown using systemic RNAi in vivo produced a severe inhibition of juvenile hormone synthesis in adult female corpora allata, together with a reduction of mRNA levels corresponding to 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthase-1, HMG-CoA synthase-2, and HMG-CoA reductase. In addition, there was a reduction of vitellogenin mRNA in the fat body, and ovaries did not grow. Analysis of TOR expression in corpora allata of fed and starved females suggested that TOR is not regulated at the transcriptional level. Nevertheless, there was a reduction in HMG-CoA synthases and reductase mRNA in corpora allata (but not in the fat body) of starved females, together with a dramatic reduction of juvenile hormone production and ovary development. Taken together, our results indicate that TOR knockdown mimics starvation in terms of corpora allata activity, and suggest that nutritional signals that activate juvenile hormone biosynthesis and vitellogenin production are mediated by the TOR pathway.
Maestro
José L
JL
Institut de Biologia Evolutiva (CSIC-UPF), Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Spain. joseluis.maestro@ibe.upf-csic.es
Cobo
Juliana
J
Bellés
Xavier
X
D000818:Animals; D015139:Blotting, Southern; D003001:Cloning, Molecular; D003058:Cockroaches; D003335:Corpora Allata / Q000502:physiology*; D005216:Fat Body / Q000378:metabolism; D005260:Female; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism; D006904:Hydroxymethylglutaryl-CoA Synthase / Q000378:metabolism; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism*; D007605:Juvenile Hormones / Q000378:metabolism*; D010053:Ovary / Q000166:cytology / Q000378:metabolism; D010802:Phylogeny; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D012098:Reproduction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D020123:Sirolimus / Q000494:pharmacology; D013217:Starvation; D014818:Vitellogenesis / Q000502:physiology*; D014819:Vitellogenins / Q000235:genetics
D019476:Insect Proteins; D007605:Juvenile Hormones; D012333:RNA, Messenger; D014819:Vitellogenins; D006903:Hydroxymethylglutaryl CoA Reductases; D006904:Hydroxymethylglutaryl-CoA Synthase; D020123:Sirolimus