Nuclear receptor HR3 controls locust molt by regulating chitin synthesis and degradation genes of Locusta migratoria. (January 2018)

• Record Type: Journal Article
• Authors: Zhao, Xiaoming; Qin, Zhongyu; Liu, Weimin; Liu, Xiaojian; Moussian, Bernard; Ma, Enbo; Li, Sheng; Zhang, Jianzhen
• Is Part Of: Insect biochemistry and molecular biology. Volume 92(2018)
• Page Start: 1
• Page End: 11
• Publication Date: 2018-01
• Subjects: HR3 -- RNA interference -- Chitin synthesis genes -- Chitinase genes -- Locusta migratoria; Insect biochemistry -- Periodicals; Insects -- Physiology -- Periodicals; Insects -- Molecular aspects -- Periodicals; Biochemistry -- Periodicals; Insectes -- Biochimie -- Périodiques; Insectes -- Composition -- Périodiques; Insectes -- Physiologie -- Périodiques; Insectes -- Aspect moléculaire -- Périodiques; Biochimie -- Périodiques; Biochemistry; Insect biochemistry; Insects -- Molecular aspects; Insects -- Physiology; Periodicals; 572.8157
• DOI: 10.1016/j.ibmb.2017.11.001
• Languages: English
• ISSNs: 0965-1748

Abstract

Abstract: During growth and development of insects, the steroid hormone 20-Hydroxyecdysone (20E) regulates the molting process through activation of a series of genes including E74, E75 and HR3 by the 20E receptor EcR. Here, we analyzed the function of LmHR3 in the migratory locust Locusta migratoria . By sequence comparison, we first identified and characterized the putative nuclear receptor protein (LmHR3) based on L. migratoria transcriptome data. The full length cDNA is 2272 bp long encoding a protein of 455 amino acids that contains a DNA binding domain (zinc finger) and a ligand binding domain. Phylogenetic analyses showed that LmHR3 has a high homology with the ortholog from Blattaria . RT-qPCR results revealed that LmHR3 has a low level expression in the early days of 5th instar nymphs, and then increases and peaks at day 6, followed by a decrease to low levels before ecdysis. The LmHR3, hence, coincides with the profile of circulating 20E levels. Indeed, we show that transcription of LmHR3 is induced by 20E in vivo, and significantly suppressed by successfully knocking down expression of LmEcR . After injection of dsRNA for LmHR3 (ds LmHR3 ) at day 2 of earlier instar nymphs (3rd and 4th instar) and final instar nymphs (5th instar), none of the nymphs were able to molt normally, and eventually died. Chitin staining and ultra-structural analysis showed that both the synthesis of the new cuticle and the degradation of the old cuticle were blocked in the ds LmHR3 treated nymphs. Especially, chitin synthesis genes ( LmUAP1 and LmCHS1 ) and chitinase genes ( LmCHT5 and LmCHT10 ) were significantly down-regulated in the ds LmHR3 treatment group. Together, our results suggest that LmHR3 is involved in the control of chitin synthesis and degradation during L. migratoria molting. Graphical abstract: Highlights: We identified and characterized a nuclear receptor gene LmHR3 from Locusta migratoria transcriptome database. LmHR3 can be induced by 20E and repressed by ds LmEcR injection in vivo . The locusts failed to molt normally and died after RNAi of LmHR3 during nymphal-nymphal and nymphal-adult transition. RNAi of LmHR3 blocks the synthesis of new cuticle and degradation of old cuticle of L. migratoria . LmHR3 controls locust molt by regulating chitin synthesis and degradation genes of L. migratoria .