title: Ectopic expression of ecdysone oxidase impairs tissue degeneration in Bombyx mori.
abstract: Metamorphosis in insects includes a series of programmed tissue histolysis and remolding processes that are controlled by two major classes of hormones, juvenile hormones and ecdysteroids. Precise pulses of ecdysteroids (the most active ecdysteroid is 20-hydroxyecdysone, 20E), are regulated by both biosynthesis and metabolism. In this study, we show that ecdysone oxidase (EO), a 20E inactivation enzyme, expresses predominantly in the midgut during the early pupal stage in the lepidopteran model insect, Bombyx mori. Depletion of BmEO using the transgenic CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/RNA-guided Cas9 nucleases) system extended the duration of the final instar larval stage. Ubiquitous transgenic overexpression of BmEO using the Gal4/UAS system induced lethality during the larval-pupal transition. When BmEO was specifically overexpressed in the middle silk gland (MSG), degeneration of MSG at the onset of metamorphosis was blocked. Transmission electron microscope and LysoTracker analyses showed that the autophagy pathway in MSG is inhibited by BmEO ectopic expression. Furthermore, RNA-seq analysis revealed that the genes involved in autophagic cell death and the mTOR signal pathway are affected by overexpression of BmEO. Taken together, BmEO functional studies reported here provide insights into ecdysone regulation of tissue degeneration during 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, People's Republic of China.
authors.forename: Zhiqian
authors.initials: Z
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, People's Republic of China.
authors.forename: Lang
authors.initials: L
authors.lastname: You
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, People's Republic of China.
authors.forename: Baosheng
authors.initials: B
authors.lastname: Zeng
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, People's Republic of China.
authors.forename: Lin
authors.initials: L
authors.lastname: Ling
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, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Xu
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, People's Republic of China.
authors.forename: Xu
authors.initials: X
authors.lastname: Chen
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, People's Republic of China.
authors.forename: Zhongjie
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Entomology, College of Agriculture, University of Kentucky, S-225 Agriculture Science Center North, Lexington, KY 40546, USA.
authors.forename: Subba Reddy
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, People's Republic of China yphuang@sibs.ac.cn.
authors.forename: Yongping
authors.initials: Y
authors.lastname: Huang
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, People's Republic of China ajtan01@sibs.ac.cn.
authors.forename: Anjiang
authors.initials: A
authors.lastname: Tan
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D030801:Animals, Genetically Modified / Q000235:genetics / Q000254:growth & development; D012831:Bombyx / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure; D000066630:Ectopic Gene Expression; D005088:Exocrine Glands / Q000378:metabolism / Q000648:ultrastructure; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D007814:Larva / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000648:ultrastructure; D008675:Metamorphosis, Biological; D046529:Microscopy, Electron, Transmission; D011679:Pupa / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000648:ultrastructure; D047011:Silk / Q000378:metabolism
chemical_list: D019476:Insect Proteins; D047011:Silk; D015096:3-Hydroxysteroid Dehydrogenases; C020096:ecdysone oxidase
keywords: Bombyx mori; CRISPR/Cas9; Gal4/UAS; autophagy; ecdysone oxidase