A serpin mutant links Toll activation to melanization in the host defence of Drosophila.
A prominent response during the Drosophila host defence is the induction of proteolytic cascades, some of which lead to localized melanization of pathogen surfaces, while others activate one of the major players in the systemic antimicrobial response, the Toll pathway. Despite the fact that gain-of-function mutations in the Toll receptor gene result in melanization, a clear link between Toll activation and the melanization reaction has not been firmly established. Here, we present evidence for the coordination of hemolymph-borne melanization with activation of the Toll pathway in the Drosophila host defence. The melanization reaction requires Toll pathway activation and depends on the removal of the Drosophila serine protease inhibitor Serpin27A. Flies deficient for this serpin exhibit spontaneous melanization in larvae and adults. Microbial challenge induces its removal from the hemolymph through Toll-dependent transcription of an acute phase immune reaction component.
Ligoxygakis
Petros
P
Institut de Biologie Moléculaire and Cellulaire, UPR 9022 du CNRS, 15, rue René Descartes, F-67084 Strasbourg Cedex, France.
Pelte
Nadège
N
Ji
Chuanyi
C
Leclerc
Vincent
V
Duvic
Bernard
B
Belvin
Marcia
M
Jiang
Haobo
H
Hoffmann
Jules A
JA
Reichhart
Jean-Marc
JM
D000818:Animals; D004330:Drosophila / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D029721:Drosophila Proteins / Q000097:blood / Q000235:genetics* / Q000378:metabolism*; D006458:Hemolymph / Q000378:metabolism; D007239:Infections / Q000276:immunology; D008543:Melanins / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D015843:Serpins / Q000097:blood / Q000235:genetics* / Q000378:metabolism; D051193:Toll-Like Receptors
D029721:Drosophila Proteins; D008543:Melanins; D011956:Receptors, Cell Surface; D015843:Serpins; C468118:Spn27A protein, Drosophila; C068721:Tl protein, Drosophila; D051193:Toll-Like Receptors