title: Identification and functional characterization of a novel locust peptide belonging to the family of insect growth blocking peptides.
abstract: Growth blocking peptides (GBPs) are recognized as insect cytokines that take part in multifaceted functions including immune system activation and growth retardation. The peptides induce hemocyte spreading in vitro, which is considered as the initial step in hemocyte activation against infection in many insect species. Therefore, in this study, we carried out a series of in vitro bioassay driven fractionations of Locusta migratoria hemolymph combined with mass spectrometry to identify locust hemocyte activation factors belonging to the family of insect GBPs. We identified the locust hemocyte spreading peptide (locust GBP) as a 28-mer peptide encoded at the C-terminus of a 64 amino acid long precursor polypeptide. As demonstrated by QRT-PCR, the gene encoding the locust GBP precursor (proGBP) was expressed in large quantities in diverse locust tissues including fat body, endocrine glands, central nervous system, reproductive tissues and flight muscles. In contrary, hemocytes, gut tissues and Malpighian tubules displayed little expression of the proGBP transcript. The bioactive peptide induces transient depletion of hemocytes in vivo and when injected in last instar nymphs it extends the larval growth phase and postpones adult molting. In addition, we identified a functional homologous hemocyte spreading peptide in Schistocerca gregaria.
authors.affiliation: Insect Physiology and Molecular Ethology, Biology Department, KU Leuven, Naamsestraat 59, B-3000 Leuven, Belgium. Electronic address: TewodrosFirdissa.Duressa@bio.kuleuven.be.
authors.forename: Tewodros Firdissa
authors.initials: TF
authors.lastname: Duressa
authors.affiliation: Functional Genomics and Proteomics, Biology Department, KU Leuven, B-3000 Leuven, Belgium. Electronic address: kurt.boonen@bio.kuleuven.be.
authors.forename: Kurt
authors.initials: K
authors.lastname: Boonen
authors.affiliation: Department of Applied Biological Sciences, Saga University, Saga 840-8502, Japan. Electronic address: hayakayo@cc.saga-u.ac.jp.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Hayakawa
authors.affiliation: Insect Physiology and Molecular Ethology, Biology Department, KU Leuven, Naamsestraat 59, B-3000 Leuven, Belgium. Electronic address: Roger.Huybrechts@bio.kuleuven.be.
authors.forename: Roger
authors.initials: R
authors.lastname: Huybrechts
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005260:Female; D015870:Gene Expression; D007301:Insect Hormones / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D048188:Locusta migratoria / Q000378:metabolism* / Q000502:physiology; D008297:Male; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009928:Organ Specificity; D036361:Peptide Hormones / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D016415:Sequence Alignment
chemical_list: D007301:Insect Hormones; D036361:Peptide Hormones
keywords: Cytokine; Growth; Immunity; Locusta migratoria; Schistocerca gregaria