Juvenile hormone biosynthesis in adult Blattella germanica requires nuclear receptors Seven-up and FTZ-F1

Abstract

In insects, the transition from juvenile development to the adult stage is controlled by juvenile hormone (JH) synthesized from the corpora allata (CA) glands. Whereas a JH-free period during the last juvenile instar triggers metamorphosis and the end of the growth period, the reappearance of this hormone after the imaginal molt marks the onset of reproductive adulthood. Despite the importance of such transition, the regulatory mechanism that controls it remains mostly unknown. Here, using the hemimetabolous insect Blattella germanica, we show that nuclear hormone receptors Seven-up-B (BgSvp-B) and Fushi tarazu-factor 1 (BgFTZ-F1) have essential roles in the tissue- and stage-specific activation of adult CA JH-biosynthetic activity. Both factors are highly expressed in adult CA cells. Moreover, RNAi-knockdown of either BgSvp-B or BgFTZ-F1 results in adult animals with a complete block in two critical JH-dependent reproductive processes, vitellogenesis and oogenesis. We show that this reproductive blockage is the result of a dramatic impairment of JH biosynthesis, due to the CA-specific reduction in the expression of two key JH biosynthetic enzymes, 3-hydroxy-3-methylglutaryl coenzyme A synthase-1 (BgHMG-S1) and HMG-reductase (BgHMG-R). Our findings provide insights into the regulatory mechanisms underlying the specific changes in the CA gland necessary for the proper transition to adulthood.

Dissecting the roles of FTZ‐F1 in larval molting and pupation, and the sublethal effects of methoxyfenozide on Helicoverpa armigera

“…Actually, as a key molecule in 20E‐induced signaling cascade, FTZ‐F1 is induced immediately after the decline in 20E level and activates many developmental events 48 . We also observed the high expression of HaFTZ‐F1 in adult, which was consistent with the essential roles of FTZ‐F1 in reproduction 25,27,49 …”

“…In B. mori , BmFTZ‐F1 was involved in the regulation of silk protein synthesis by binding to the FTZ‐F1 response element 23 . In T. castaneum and adult B. germanica , knockdown of FTZ‐F1 resulted in severe block in vitellogenesis and oogenesis, thereby leading to the impaired reproductive capacity 24,25 . Likewise in A. aegypti , βFTZ‐F1 and EcR/USP worked in concert to achieve the precise and dynamic production of yolk protein precursors (YPPs) after a blood meal 26 .…”

Epigenetic modifications acetylation and deacetylation play important roles in juvenile hormone action

“…A similar RNAi-based study from our lab further disclosed the importance of TcSVP in reproduction, as indicated by the observation that newly eclosed T. castaneum females injected with dsTcSVP caused a decrease in TcVg transcript levels and egg production [84]. Recently, the contribution of SVP and Ftz-f1 in JH biosynthesis was also documented in B. germanica [85].…”

Genome-Wide Screening and Functional Analysis Reveal That the Specific microRNA nlu-miR-173 Regulates Molting by Targeting Ftz-F1 in Nilaparvata lugens

“…Mounting evidence suggests that Ftz-F1 acts importantly responsed by the 20E and JH signaling pathways during molting (Broadus et al, 1999; Bernardo and Dubrovsky, 2012; Cho et al, 2013; Borras-Castells et al, 2017). Ftz-F1 is induced after the decrease in the 20-hydroxyecdysone level (Woodard et al, 1994; Yamada et al, 2000; Hiruma and Riddiford, 2001), and the function of Ftz-F1 during metamorphosis in several insects was reported.…”