title: 20-Hydroxyecdysone (20E) Primary Response Gene E93 Modulates 20E Signaling to Promote Bombyx Larval-Pupal Metamorphosis.
abstract: As revealed in a previous microarray study to identify genes regulated by 20-hydroxyecdysone (20E) and juvenile hormone (JH) in the silkworm, Bombyx mori, E93 expression in the fat body was markedly low prior to the wandering stage but abundant during larval-pupal metamorphosis. Induced by 20E and suppressed by JH, E93 expression follows this developmental profile in multiple silkworm alleles. The reduction of E93 expression by RNAi disrupted 20E signaling and the 20E-induced autophagy, caspase activity, and cell dissociation in the fat body. Reducing E93 expression also decreased the expression of the 20E-induced pupal-specific cuticle protein genes and prevented growth and differentiation of the wing discs. Importantly, the two HTH domains in E93 are critical for inducing the expression of a subset of 20E response genes, including EcR, USP, E74, Br-C, and Atg1. By contrast, the LLQHLL and PLDLSAK motifs in E93 inhibit its transcriptional activity. E93 binds to the EcR-USP complex via a physical association with USP through its LLQHLL motif; and this association is enhanced by 20E-induced EcR-USP interaction, which attenuates the transcriptional activity of E93. E93 acts through the two HTH domains to bind to GAGA-containing motifs present in the Atg1 promoter region for inducing gene expression. In conclusion, E93 transcriptionally modulates 20E signaling to promote Bombyx larval-pupal metamorphosis.
authors.affiliation: Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China,; the State Key Laboratory of Silkworm Genome Biology and College of Biotechnology, Southwest University, Chongqing 400715, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Liu
authors.affiliation: the State Key Laboratory of Silkworm Genome Biology and College of Biotechnology, Southwest University, Chongqing 400715, China.
authors.forename: Fangyin
authors.initials: F
authors.lastname: Dai
authors.affiliation: Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China,; the Laboratory of Insect Molecular Biology and Biotechnology, Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Sciences, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Enen
authors.initials: E
authors.lastname: Guo
authors.affiliation: Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China,; the Laboratory of Insect Molecular Biology and Biotechnology, Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Sciences, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Kang
authors.initials: K
authors.lastname: Li
authors.affiliation: Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
authors.forename: Li
authors.initials: L
authors.lastname: Ma
authors.affiliation: Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Tian
authors.affiliation: the Laboratory of Insect Molecular Biology and Biotechnology, Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Sciences, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Cao
authors.affiliation: the Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang 212018, China.
authors.forename: Guozheng
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Department of Entomology, College of Agriculture, University of Kentucky, Lexington, Kentucky 40546.
authors.forename: Subba R
authors.initials: SR
authors.lastname: Palli
authors.affiliation: Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China,. Electronic address: lisheng01@sibs.ac.cn.
authors.forename: Sheng
authors.initials: S
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D012831:Bombyx / Q000235:genetics* / Q000254:growth & development* / Q000502:physiology; D004441:Ecdysterone / Q000502:physiology*; D005216:Fat Body / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D019476:Insect Proteins / Q000235:genetics / Q000502:physiology; D007605:Juvenile Hormones / Q000502:physiology; D007814:Larva / Q000254:growth & development; D008675:Metamorphosis, Biological / Q000235:genetics* / Q000502:physiology*; D008954:Models, Biological; D008969:Molecular Sequence Data; D011679:Pupa / Q000254:growth & development; D034622:RNA Interference; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014921:Wings, Animal / Q000254:growth & development
chemical_list: D019476:Insect Proteins; D007605:Juvenile Hormones; D004441:Ecdysterone
keywords: 20-hydroxyecdysone; Bombyx mori; E93; apoptosis; autophagy; fat body; juvenile hormone (JH); metamorphosis; transcription factor; wing disc