Peptidoglycan recognition in Drosophila : Figure 1

Division of Infectious Diseases, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01720, USA.
Biochemical Society Transactions (Impact Factor: 3.19). 01/2008; 35(Pt 6):1496-500. DOI: 10.1042/BST0351496
Source: PubMed


Drosophila rely primarily on innate immune responses to effectively combat a wide array of microbial pathogens. The hallmark of the Drosophila humoral immune response is the rapid production of AMPs (antimicrobial peptides) by the fat body, the insect homologue of the mammalian liver. Production of these AMPs is controlled at the level of transcription by two NF-kappaB (nuclear factor kappaB) signalling pathways. The Toll pathway is activated by fungal and many Gram-positive bacterial microbes, whereas the IMD (immune deficiency) pathway responds to Gram-negative bacteria and certain Gram-positive bacilli. In the present review, we discuss the mechanisms involved in bacterial recognition, in particular the differential recognition of various types of bacterial PGN (peptidoglycan) by different members of the PGRP (PGN recognition protein) family of receptors.

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    • "In this study, we provide novel insights into the expression of PGRPs in honey bee larvae by showing that pesticide treatments or simultaneous pesticide and mite treatments induce increased transcript levels for an apparent ortholog to Drosophila short-chain Peptidoglycan Recognition Protein PGRP-SC (PGRPSC 4300). PGRPs are pathogen recognition genes defined by a conserved 160-amino- acid domain (Aggrawal and Silverman, 2007). Our results show that elevated expression levels for PGRPs are associated with mite infestations and that the PGRP family member SC4300 can be associated with mite parasitism, and potentially with DWV pathology. "
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    ABSTRACT: Honey bee (Apis mellifera) larvae reared in vitro were exposed to one of nine pesticides and/or were challenged with the parasitic mite, Varroa destructor. Total RNA was extracted from individual larvae and first strand cDNAs were generated. Gene-expression changes in larvae were measured using quantitative PCR (qPCR) targeting transcripts for pathogens and genes involved in physiological processes, bee health, immunity, and/or xenobiotic detoxification. Transcript levels for Peptidoglycan Recognition Protein (PGRPSC), a pathogen recognition gene, increased in larvae exposed to Varroa mites (P<0.001) and were not changed in pesticide treated larvae. As expected, Varroa-parasitized brood had higher transcripts of Deformed Wing Virus than did control larvae (P<0.001). Varroa parasitism, arguably coupled with virus infection, resulted in significantly higher transcript abundances for the antimicrobial peptides abaecin, hymenoptaecin, and defensin1. Transcript levels for Prophenoloxidase-activating enzyme (PPOact), an immune end product, were elevated in larvae treated with myclobutanil and chlorothalonil (both are fungicides) (P<0.001). Transcript levels for Hexameric storage protein (Hsp70) were significantly upregulated in imidacloprid, fluvalinate, coumaphos, myclobutanil, and amitraz treated larvae. Definitive impacts of pesticides and Varroa parasitism on honey bee larval gene expression were demonstrated. Interactions between larval treatments and gene expression for the targeted genes are discussed.
    Full-text · Article · Apr 2012 · Journal of insect physiology
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    • "Hemocytes participate in immune signaling to the fat body, phagocytosis, damaged tissue surveillance, encapsulation of foreign intruders, and remodeling of cells during development and also respond to aberrant self-cells to form melanotic tumors/pseudotumors (Babcock et al. 2008; Brennan et al. 2007; Gateff 1994; Rizki and Rizki 1983; Tepass et al. 1994; Vass and Nappi 2000). The fat body, like the mammalian liver, produces abundant humoral response molecules, including antimicrobial peptides released into the hemolymph (Aggrawal and Silverman 2007). "
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    ABSTRACT: A major category of mutant hematopoietic phenotypes in Drosophila is melanotic tumors or nodules, which consist of abnormal and overproliferated blood cells, similar to granulomas. Our analyses of the melanotic mutant dappled have revealed a novel type of gene involved in blood cell regulation. The dappled gene is an essential gene that encodes cytochrome b5, a conserved hemoprotein that participates in electron transfer in multiple biochemical reactions and pathways. Viable mutations of dappled cause melanotic nodules and hemocyte misregulation during both hematopoietic waves of development. The sexes are similarly affected, but hemocyte number is different in females and males of both mutants and wild type. Additionally, initial tests show that curcumin enhances the dappled melanotic phenotype and establish screening of endogenous and xenobiotic compounds as a route for analysis of cytochrome b5 function. Overall, dappled provides a tractable genetic model for cytochrome b5, which has been difficult to study in higher organisms.
    Preview · Article · Jun 2011 · Biochemical Genetics
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    • "The collective data suggest that fish lack the TLR4 receptor-mediated recognition of LPS present in mammals (Iliev et al., 2005b), but given the robust cytokine response that can be stimulated in fish immune cells by crude LPS preparation, some other component of the LPS is likely to be responsible for this stimulation. At least in trout, it appears that peptidoglycans may be the component of G-negative bacteria being recognised by macrophages (Mackenzie et al., 2010; Boltã na et al., 2011), similar to what is observed in invertebrates such as Drosophila (Aggrawal and Silverman, 2007; Royet and Dziarski, 2007). Yet the recognition of LPS in fish may be more involved and exhibit phylogenetic specificities that are just being uncovered. "
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    ABSTRACT: Understanding the mechanisms that underpin pathogen recognition and subsequent orchestration of the immune response in fish is an area of significant importance for both basic research and management of health in aquaculture. In recent years much attention has been given to the identification of pattern recognition receptors (PRRs) in fish, however, characterisation of interactions with specific pathogen-associated molecular patterns (PAMPs) is still incomplete. Microarray studies have significantly contributed to functional studies and early descriptions of PAMP-PRR driven activation of specific response cassettes in the genome have been obtained although much is left to be done. In this review we will address gram negative (G-negative) bacterial recognition in fish addressing contributing factors such as structure-function relationships between G-negative PAMPs, current knowledge of fish PRRs and the input achieved by microarray-based studies ranging from in vivo infection studies to directed in vitro PAMP-cell studies. Finally we revisit the endotoxic recognition paradigm in fish and suggest a series of future perspectives that could contribute toward the further elucidation of G-negative bacterial recognition across the highly diverse group of vertebrates that encompass the fishes.
    Full-text · Article · Mar 2011 · Developmental and comparative immunology
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