Immune response and anti-microbial peptides expression in Malpighian tubules of Drosophila melanogaster is under developmental regulation.
Malpighian tubules (MT) of Drosophila melanogaster are osmoregulatory organs that maintain the ionic balance and remove toxic substances from the body. Additionally they act as autonomous immune sensing organs, which secrete antimicrobial peptides in response to invading microbial pathogens. We show that the antimicrobial peptides (AMP) diptericin, cecropinA, drosocin and attacinA are constitutively expressed and are regulated in developmental stage specific manner. Their developmental expression begins from 3(rd) instar larval stage and an immune challenge increases the expression several folds. Spatial variations in the level of expression along the MT tissue are observed. The mortality of 3(rd) instar larvae fed on bacterial food is much less than that of the earlier larval stages, coinciding with the onset of innate immunity response in MT. Ectopic expression of AMP imparts better resistance to infection while, loss of function of one of the AMP through directed RNAi reduces host survival after immune challenge. The AMP secreted from the MT exhibit bactericidal activity. Expression of the NF-κB transcription factor, Relish, also coincides with activation of immune responsive genes in MT, demonstrating that immune regulation in MT is under developmental control and is governed by the Imd pathway.
Cytogenetics Laboratory, Department of Zoology, Banaras Hindu University, Varanasi, Índia. madhu@bhu.ac.in
Puja
P
Verma
Madhu G
MG
Tapadia
D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000235:genetics / Q000378:metabolism*; D001424:Bacterial Infections / Q000276:immunology; D060467:Disease Resistance / Q000187:drug effects / Q000276:immunology; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000276:immunology*; D004926:Escherichia coli / Q000166:cytology / Q000187:drug effects; D005216:Fat Body / Q000187:drug effects / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006458:Hemolymph / Q000187:drug effects / Q000378:metabolism; D007814:Larva / Q000254:growth & development / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008317:Malpighian Tubules / Q000187:drug effects / Q000254:growth & development* / Q000276:immunology*; D008826:Microbial Sensitivity Tests; D016019:Survival Analysis; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D023181:Antimicrobial Cationic Peptides; C054756:DptA protein, Drosophila; D029721:Drosophila Proteins; D008070:Lipopolysaccharides; C101626:Rel protein, Drosophila; D014157:Transcription Factors; D049452:Green Fluorescent Proteins