title: Tweedle cuticular protein BmCPT1 is involved in innate immunity by participating in recognition of Escherichia coli.
abstract: Bombyx mori, a lepidopteran insect, is one of the earliest models for pattern recognition of Gram-negative bacteria, which may induce the IMD pathway for production of antibacterial peptides. So far, several recognition proteins have been reported in B. mori. However, the connection between pattern recognition of Gram negative bacteria and activation of BmRelish1, a transcription factor controlled by the IMD pathway remains largely unknown. In the present study, we identify BmCPT1, a cuticle protein bearing a Tweedle domain. Its gene expression is co-regulated by NF-kappaB and juvenile hormone signals. BmCPT1 is induced by Escherichia coli in fat bodies and hemocytes, but is constitutively expressed in the epidermis. In vitro binding assays indicate that BmCPT1 protein recognizes and binds to E. coli peptidoglycan. Post-transcriptionally modified BmCPT1 in the hemolymph binds to E. coli cells through interactions with peptidoglycan recognition protein-5 (BmPGRP5) and lipopolysaccharide binding protein (BmLBP). Transgenic overexpression of BmCPT1 causes the upregulated expression of BmRelish1 and clear induction of two gloverin genes. Therefore, BmCPT1 may work along with BmPGRP-S5 and BmLBP to recognize E. coli in the hemolymph and indirectly activate BmRelish1 to induce antimicrobial peptide synthesis.
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing 400715, China. Electronic address: jliang802@gmail.com.
authors.forename: Jiubo
authors.initials: J
authors.lastname: Liang
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing 400715, China. Electronic address: 924578463@qq.com.
authors.forename: Ting
authors.initials: T
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing 400715, China. Electronic address: xbxzh@swu.edu.cn.
authors.forename: Zhonghuai
authors.initials: Z
authors.lastname: Xiang
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing 400715, China. Electronic address: hejia@swu.edu.cn.
authors.forename: Ningjia
authors.initials: N
authors.lastname: He
mesh_terms: D000209:Acute-Phase Proteins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D012831:Bombyx / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D004926:Escherichia coli; D015870:Gene Expression; D006434:Hemocytes; D006458:Hemolymph / Q000276:immunology / Q000378:metabolism; D007113:Immunity, Innate; D019476:Insect Proteins / Q000096:biosynthesis / Q000235:genetics*; D036341:Intercellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins / Q000378:metabolism; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D010457:Peptidoglycan; D011499:Protein Processing, Post-Translational; D011506:Proteins; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation / Q000502:physiology; D000099231:Lipopolysaccharide-Binding Protein
chemical_list: D000209:Acute-Phase Proteins; D002352:Carrier Proteins; D019476:Insect Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D010457:Peptidoglycan; D011506:Proteins; D014157:Transcription Factors; D000099231:Lipopolysaccharide-Binding Protein; C107617:gloverin; C118897:peptidoglycan recognition protein
keywords: BmCPT1; Bombyx mori; Innate immunity; Pattern recognition