title: Identification of conserved and novel microRNAs in Manduca sexta and their possible roles in the expression regulation of immunity-related genes.
abstract: The tobacco hornworm Manduca sexta has served as a model for insect biochemical and physiological research for decades. However, knowledge of the posttranscriptional regulation of gene expression by microRNAs is still rudimentary in this species. Our previous study (Zhang et al., 2012) identified 163 conserved and 13 novel microRNAs in M. sexta, most of which were present at low levels in pupae. To identify additional M. sexta microRNAs and more importantly to examine their possible roles in the expression regulation of immunity-related genes, we constructed four small RNA libraries using fat body and hemocytes from naïve or bacteria-injected larvae and obtained 32.9 million reads of 18-31 nucleotides by Illumina sequencing. Mse-miR-929 and mse-miR-1b (antisense microRNA of mse-miR-1) were predicted in the previous study and now found to be conserved microRNAs in the tissue samples. We also found four novel microRNAs, two of which result from a gene cluster. Mse-miR-281-star, mse-miR-965-star, mse-miR-31-star, and mse-miR-9b-star were present at higher levels than their respective mature strands. Abundance changes of microRNAs were observed after the immune challenge. Based on the quantitative data of mRNA levels in control and induced fat body and hemocytes as well as the results of microRNA target site prediction, we suggest that certain microRNAs and microRNA*s regulate gene expression for pattern recognition, prophenoloxidase activation, cellular responses, antimicrobial peptide synthesis, and conserved intracellular signal transduction (Toll, IMD, JAK-STAT, MAPK-JNK-p38, and small interfering RNA pathways). In summary, this study has enriched our knowledge on M. sexta microRNAs and how some of them may participate in the expression regulation of immunity-related genes.
authors: Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA. Electronic address: xiufeng.zhang@okstate.edu.
authors: Xiufeng
authors: X
authors: Zhang
authors: School of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan 650500, China. Electronic address: zhengyun5488@gmail.com.
authors: Yun
authors: Y
authors: Zheng
authors: Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA. Electronic address: guruswa@okstate.edu.
authors: Guru
authors: G
authors: Jagadeeswaran
authors: School of Life Sciences, Fudan University, Shanghai 200433, China. Electronic address: renren@fudan.edu.cn.
authors: Ren
authors: R
authors: Ren
authors: Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA. Electronic address: ramanjulu.sunkar@okstate.edu.
authors: Ramanjulu
authors: R
authors: Sunkar
authors: Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA. Electronic address: haobo.jiang@okstate.edu.
authors: Haobo
authors: H
authors: Jiang
mesh_terms: D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence; D005216:Fat Body / Q000737:chemistry; D005786:Gene Expression Regulation; D006434:Hemocytes / Q000737:chemistry; D007113:Immunity, Innate; D019476:Insect Proteins / Q000235:genetics* / Q000276:immunology; D018402:Manduca / Q000737:chemistry / Q000235:genetics* / Q000276:immunology*; D035683:MicroRNAs / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D016415:Sequence Alignment
chemical_list: D019476:Insect Proteins; D035683:MicroRNAs
keywords: Illumina sequencing; Insect immunity; Lepidoptera; Posttranscriptional regulation; Target site prediction