title: FoxO inhibits juvenile hormone biosynthesis and vitellogenin production in the German cockroach.
abstract: The transcription factor Forkhead-box O (FoxO) is the main transcriptional effector of the Insulin Receptor/Phosphatidylinositol 3-kinase (InR/PI3K) pathway. In a situation of nutrient restriction, the pathway is inactive and FoxO translocates to the nucleus to exert its transcriptional action. In starved females of the cockroach Blattella germanica, the reproductive processes, and in particular the synthesis of juvenile hormone in the corpora allata and that of vitellogenin in the fat body, are arrested. In the present report we examine the possible role of FoxO in the transduction of the nutritional signals to these reproductive events. We first cloned FoxO cDNA from B. germanica (BgFoxO), and showed that its expression is not nutritionally regulated. BgFoxO knockdown using systemic RNAi in vivo in starved females elicited an increase of juvenile hormone biosynthesis, although without modifying mRNA levels of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthase-1, HMG-CoA synthase-2, HMG-CoA reductase or methyl farnesoate epoxidase (CYP15A1) in corpora allata. In addition, BgFoxO RNAi treatment produced a remarkable increase of vitellogenin mRNA levels in fat body and of vitellogenin protein in the haemolymph. Our results indicate that BgFoxO plays an inhibitory role on juvenile hormone biosynthesis and vitellogenin production in a situation of nutrient shortage.
authors.affiliation: Institut de Biologia Evolutiva (CSIC-UPF), Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Spain.
authors.forename: Songül
authors.initials: S
authors.lastname: Süren-Castillo
authors.forename: Marc
authors.initials: M
authors.lastname: Abrisqueta
authors.forename: José L
authors.initials: JL
authors.lastname: Maestro
mesh_terms: D000818:Animals; D020048:Blattellidae / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D005216:Fat Body / Q000378:metabolism; D005260:Female; D005508:Food Deprivation; D051858:Forkhead Transcription Factors / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism; D006904:Hydroxymethylglutaryl-CoA Synthase / Q000378:metabolism; D007605:Juvenile Hormones / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D010802:Phylogeny; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D012098:Reproduction; D016415:Sequence Alignment; D014819:Vitellogenins / Q000378:metabolism*
chemical_list: D018076:DNA, Complementary; D051858:Forkhead Transcription Factors; D007605:Juvenile Hormones; D012330:RNA, Double-Stranded; D012333:RNA, Messenger; D014819:Vitellogenins; D006903:Hydroxymethylglutaryl CoA Reductases; D006904:Hydroxymethylglutaryl-CoA Synthase