title: MicroRNA Let-7 regulates molting and metamorphosis in the silkworm, Bombyx mori.
abstract: MicroRNAs (miRNAs) are a class of endogenous, non-coding, regulatory RNA molecules that post-transcriptionally regulate gene expression by binding to the 3'UTRs of mRNA targets and thus cause their degradation or translational inhibition. In insects, important roles of miRNAs in various biological processes have been demonstrated in Drosophila melanogaster. However, biological roles of miRNAs are barely unveiled in the majority of insect species due to limited genetic tools. In the present study, we introduce the transgenic miRNA sponge (miR-SP) technology combining with the binary GAL4/UAS system in the domesticated silkworm, Bombyx mori, to exploit the biological function of an evolutionally conserved miRNA, let-7. We successfully established transgenic silkworm lines in which a miRNA sponge construct targeting BmLet-7 seed region was expressed in a ubiquitous manner directed by A3-GAL4 driver. Transgenic animals showed decreased expression of BmLet-7, leading to developmental arrestment during the larval-larval and larval-pupal transition. Simultaneously, expression levels of the predicted BmLet-7 target genes, FTZ-F1 and Eip74EF (E74), key regulatory factors in the ecdysone pathway, were elevated in transgenic animals. The current study is the first report on application of the transgenic miR-SP technology in non-drosophilid insects, which will not only contribute to better understanding of let-7 biological roles, but also greatly facilitate future miRNA functional analysis in insects.
authors.affiliation: Faculty of Life Sciences, Northwestern Polytechnical University, Xi'an 710072, China; 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; University of Chinese Academy of Sciences, Beijing 100049, 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, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Xie
authors.initials: X
authors.lastname: Ge
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; University of Chinese Academy of Sciences, Beijing 100049, 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, China; University of Chinese Academy of Sciences, Beijing 100049, 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, China; University of Chinese Academy of Sciences, Beijing 100049, 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, China.
authors.forename: Abu F M
authors.initials: AF
authors.lastname: Aslam
authors.affiliation: Division of Plant Sciences, University of Missouri, Columbia, MO, USA.
authors.forename: Qisheng
authors.initials: Q
authors.lastname: Song
authors.affiliation: Faculty of Life Sciences, Northwestern Polytechnical University, Xi'an 710072, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Shang
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: 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, China. Electronic address: tananjiang@sippe.ac.cn.
authors.forename: Anjiang
authors.initials: A
authors.lastname: Tan
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D012831:Bombyx / Q000235:genetics* / Q000254:growth & development*; D005786:Gene Expression Regulation; D007814:Larva; D008675:Metamorphosis, Biological / Q000235:genetics; D035683:MicroRNAs / Q000235:genetics / Q000502:physiology*; D018978:Molting / Q000235:genetics; D011679:Pupa
chemical_list: D035683:MicroRNAs
keywords: BmLet-7; Bombyx mori; Microrna; Microrna sponge