title: Developmental regulation and antifungal activity of a growth-blocking peptide from the beet armyworm Spodoptera exigua.
abstract: Insect cytokine growth-blocking peptides (GBPs) are involved in growth regulation and the innate immune response. However, the microbial binding and antimicrobial activities of GBPs remain unclear. Here, we investigate the developmental role and antifungal activity of a GBP from the beet armyworm Spodoptera exigua (SeGBP). Sequence analysis predicted that mature SeGBP consists of 24 amino acid residues, including 2 cysteine residues. During S. exigua development, SeGBP is constitutively expressed in the fat body during the larval and adult stages but not in pupae. SeGBP expression is up-regulated by 20-hydroxyecdysone and down-regulated by juvenile hormone analog. Recombinant SeGBP purified from baculovirus-infected insect cells retards the growth of S. exigua larvae. Additionally, SeGBP expression is acutely induced in the fat body after injection with Escherichia coli, Bacillus thuringiensis, or Beauveria bassiana. Recombinant SeGBP can bind to B. bassiana but not to E. coli or B. thuringiensis. Consistent with these findings, SeGBP shows antifungal activity against B. bassiana. Therefore, these results provide insight into the role of SeGBP during the innate immune response following microbial infection, and furthermore, they suggest a novel function for SeGBP as a direct antifungal agent against entomopathogenic fungi, such as B. bassiana.
authors.affiliation: Department of Plant Protection, Huazhong Agricultural University, Wuhan 430070, PR China.
authors.forename: Hu
authors.initials: H
authors.lastname: Wan
authors.forename: Kwang Sik
authors.initials: KS
authors.lastname: Lee
authors.forename: Bo Yeon
authors.initials: BY
authors.lastname: Kim
authors.forename: Miao
authors.initials: M
authors.lastname: Yuan
authors.forename: Sha
authors.initials: S
authors.lastname: Zhan
authors.forename: Yanhui
authors.initials: Y
authors.lastname: Lu
authors.forename: Hong
authors.initials: H
authors.lastname: You
authors.forename: Jianhong
authors.initials: J
authors.lastname: Li
authors.forename: Byung Rae
authors.initials: BR
authors.lastname: Jin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000935:Antifungal Agents / Q000378:metabolism* / Q000494:pharmacology; D001413:Bacillus thuringiensis / Q000187:drug effects / Q000502:physiology; D052982:Beauveria / Q000187:drug effects / Q000502:physiology; D015152:Blotting, Northern; D015153:Blotting, Western; D003001:Cloning, Molecular; D016207:Cytokines / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004441:Ecdysterone / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000502:physiology; D005216:Fat Body / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D015801:Helminth Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D054884:Host-Pathogen Interactions; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D007605:Juvenile Hormones / Q000494:pharmacology; D007814:Larva / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D061987:Sf9 Cells; D018411:Spodoptera / Q000235:genetics / Q000378:metabolism* / Q000821:virology
chemical_list: D000935:Antifungal Agents; D016207:Cytokines; D018076:DNA, Complementary; D015801:Helminth Proteins; D019476:Insect Proteins; D007605:Juvenile Hormones; D011994:Recombinant Proteins; D004441:Ecdysterone
keywords: Antifungal activity; Beet armyworm; Growth-blocking peptide; Hormonal regulation; Immunity; Spodoptera exigua