title: Control of Drosophila blood cell activation via Toll signaling in the fat body.
abstract: The Toll signaling pathway, first discovered in Drosophila, has a well-established role in immune responses in insects as well as in mammals. In Drosophila, the Toll-dependent induction of antimicrobial peptide production has been intensely studied as a model for innate immune responses in general. Besides this humoral immune response, Toll signaling is also known to activate blood cells in a reaction that is similar to the cellular immune response to parasite infections, but the mechanisms of this response are poorly understood. Here we have studied this response in detail, and found that Toll signaling in several different tissues can activate a cellular immune defense, and that this response does not require Toll signaling in the blood cells themselves. Like in the humoral immune response, we show that Toll signaling in the fat body (analogous to the liver in vertebrates) is of major importance in the Toll-dependent activation of blood cells. However, this Toll-dependent mechanism of blood cell activation contributes very little to the immune response against the parasitoid wasp, Leptopilina boulardi, probably because the wasp is able to suppress Toll induction. Other redundant pathways may be more important in the defense against this pathogen.
authors.affiliation: Department of Molecular Biology, Umeå University, Umeå, Sweden.
authors.forename: Martin R
authors.initials: MR
authors.lastname: Schmid
authors.affiliation: Department of Molecular Biology, Umeå University, Umeå, Sweden; Institute of Biomedical Technology (BioMediTech), University of Tampere, Tampere, Finland.
authors.forename: Ines
authors.initials: I
authors.lastname: Anderl
authors.affiliation: Institute of Biomedical Technology (BioMediTech), University of Tampere, Tampere, Finland.
authors.forename: Laura
authors.initials: L
authors.lastname: Vesala
authors.affiliation: Institute of Biomedical Technology (BioMediTech), University of Tampere, Tampere, Finland.
authors.forename: Leena-Maija
authors.initials: LM
authors.lastname: Vanha-aho
authors.affiliation: Department of Molecular Biology, Umeå University, Umeå, Sweden; College of Animal Science, South China Agricultural University, Guangzhou, China.
authors.forename: Xiao-Juan
authors.initials: XJ
authors.lastname: Deng
authors.affiliation: Institute of Biomedical Technology (BioMediTech), University of Tampere, Tampere, Finland; Department of Pediatrics, Tampere University Hospital, Tampere, Finland.
authors.forename: Mika
authors.initials: M
authors.lastname: Rämet
authors.affiliation: Department of Molecular Biology, Umeå University, Umeå, Sweden; Institute of Biomedical Technology (BioMediTech), University of Tampere, Tampere, Finland.
authors.forename: Dan
authors.initials: D
authors.lastname: Hultmark
mesh_terms: D000818:Animals; D004330:Drosophila / Q000276:immunology* / Q000378:metabolism / Q000469:parasitology; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005216:Fat Body / Q000378:metabolism*; D006434:Hemocytes / Q000378:metabolism*; D006790:Host-Parasite Interactions / Q000276:immunology*; D007111:Immunity, Cellular; D007814:Larva / Q000276:immunology* / Q000378:metabolism / Q000469:parasitology; D015398:Signal Transduction; D051193:Toll-Like Receptors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014863:Wasps / Q000502:physiology
chemical_list: D029721:Drosophila Proteins; C068721:Tl protein, Drosophila; D051193:Toll-Like Receptors
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