A plant diterpene counteracts juvenile hormone-mediated gene regulation during Drosophila melanogaster larval development

Sang Woon Shin,Doo-Sang Park,Jun Hyoung Jeon,Hyun-Woo Oh,Yunhee Shin,Seon Ah Jeong,Ji-Ae Kim,Erjun Ling

doi:10.1371/journal.pone.0200706

Sang Woon Shin, Doo-Sang Park + Show 6 more

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https://doi.org/10.1371/journal.pone.0200706

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Abstract

Many plant species possess compounds with juvenile hormone disruptor (JHD) activity. In some plant species, such activity has been attributed to diterpene secondary metabolites. Plant JHD diterpenes disrupt insect development by interfering with the juvenile hormone (JH)-mediated formation of JH receptor complexes. Here, we demonstrate that a plant extract and a diterpene from Lindera erythrocarpa (methyl lucidone) interfere with the formation of both methoprene-tolerant (Met)/Taiman and Germ cell-expressed (GCE)/Taiman heterodimer complexes in yeast two-hybrid assays in vitro. In addition to the in vitro JHD activity, the diterpene and the plant extract from L. erythrocarpa also disrupt the development of larvae and pupae in Drosophila melanogaster. Comparing the transcriptomes of juvenile hormone analog (JHA, methoprene)- and JHD (methyl lucidone)-fed wandering third-instar larvae revealed a large number of genes that were coregulated by JHA and JHD. Moreover, most (83%) of the genes that were repressed by methyl lucidone were significantly activated by methoprene, indicating that JHDs and JHAs have opposing effects on the transcriptional regulation of many JH-dependent genes. Gene ontology analysis also suggested that some of the genes activated-by-JHA/repressed-by-JHD play roles in spermatogenesis. Affymetrix microarray-based analysis indicated that the expression of genes activated-by-JHA/repressed-by-JHD was testis-specific. Together, these results suggest that JH is involved in testis-specific gene expression and that plant JHD diterpenes function as JH antagonists in such JHA-mediated gene regulation.

Highlights

Insect juvenile hormone (JH) regulates larval development and prevents premature metamorphosis [1]
The cDNAs encoding full open reading frames (ORFs) of Met and Germ cell-expressed (GCE) from D. melanogaster were introduced in a yeast two-hybrid (Y2H) bait plasmid, whereas the cDNA encoding a partial ORF of the D. melanogaster Taiman gene was introduced in a Y2H prey plasmid
The plant extracts disrupted both Met-Taiman and GCE-Taiman binding (Fig 2, R2 = 0.6001). These results demonstrate that GCE-Taiman binding occurs independently of JH/juvenile hormone analog (JHA) and that the binding can be disrupted by plant extracts with in vitro juvenile hormone disruptor (JHD) activity, which suggests that plant JHDs may be non-structural antagonists of JH/JHA and do not directly compete with JH/JHA in the JH-binding pocket of JH receptor complexes

Summary

Introduction

Insect juvenile hormone (JH) regulates larval development and prevents premature metamorphosis [1]. The JH-dependent heterodimer-binding properties of Met and CYC/ SRC were used to develop the in vitro assay system to quantify the disruption caused by plant extracts and diterpenes on the JH-mediated Met-CYC/SRC heterodimer formation in the mosquito A. aegypti and the Indian meal moth Plodia interpunctella [29, 30]. D. melanogaster Y2H screening systems for Met-Taiman and SRC-Taiman binding were constructed In these in vitro systems, Met-Taiman binding was induced by JH III or JHAs, whereas GCE-Taiman binding is constitutive and occurs independent of JH or JHAs. Both, the Met-Taiman and GCE-Taiman binding can be disrupted by plant extracts or JHD diterpenes, especially methyl lucidone. The Met-Taiman and GCE-Taiman binding can be disrupted by plant extracts or JHD diterpenes, especially methyl lucidone Both L. erythrocarpa extracts and methyl lucidone strongly blocked the larval and pupal development of D. melanogaster, thereby preventing the formation of pupae and emergence of adults. The comparison of transcriptomes from methoprene- and methyl lucidone-fed wandering third-instar larvae revealed that many testis-specific genes were up-regulated by JHA and down-regulated by JHD, indicating that JHD counteracts the role of JHA during the JH-mediated regulation of testis-specific genes

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