Mosquito innate immunity: involvement of beta 1,3-glucan recognition protein in melanotic encapsulation immune responses in Armigeres subalbatus.
Beta 1,3-glucan recognition proteins (GRP) have specific affinity for beta 1,3-glucan, a component on the surface of fungi and bacteria. By interacting with beta 1,3-glucan, GRP initiates activation of prophenoloxidase, a key enzyme in the signaling pathway leading to melanotic encapsulation in invertebrates. In this study, we characterize a novel hemocyte-specific GRP from the mosquito, Armigeres subalbatus (AsGRP). The 1.57 kb cDNA clone encodes a 499 deduced amino acid sequence, which contains a region that displays significant similarity to the glucanase-like regions of other GRPs and Gram-negative bacteria binding proteins found in other organisms. AsGRP is constitutively expressed in the hemolymph of adult female mosquitoes, and is upregulated following challenge with Escherichia coli, Micrococcus luteus, and the filarial worm Dirofilaria immitis. AsGRP specifically recognizes curdlan (insoluble beta 1,3-glucan), but not mannose or N-acetyl-D-glucosamine. AsGRP binds a low percentage of E. coli, most M. luteus and D. immitis microfilariae. AsGRP double-stranded RNA interference strongly inhibits melanotic encapsulation of D. immitis in Ar. subalbatus. These results suggest that AsGRP has the capacity to bind to a variety of pathogens, functions as a pattern recognition receptor, and is required for effective melanotic encapsulation immune responses in Ar. subalbatus.
Wang
Xinguo
X
Department of Animal Health and Biomedical Sciences, University of Wisconsin-Madison, 1656 Linden Drive, Madison WI 53706, USA.
Fuchs
Jeremy F
JF
Infanger
Li-Chun
LC
Rocheleau
Thomas A
TA
Hillyer
Julián F
JF
Chen
Cheng-Chen
CC
Christensen
Bruce M
BM
D000117:Acetylglucosamine / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D003001:Cloning, Molecular; D009033:Culicidae / Q000276:immunology* / Q000382:microbiology / Q000469:parasitology; D018076:DNA, Complementary / Q000302:isolation & purification; D004183:Dirofilaria immitis / Q000276:immunology; D004926:Escherichia coli / Q000276:immunology; D005260:Female; D005786:Gene Expression Regulation; D007113:Immunity, Innate; D019476:Insect Proteins / Q000235:genetics / Q000502:physiology*; D008543:Melanins / Q000502:physiology; D016982:Micrococcus luteus / Q000276:immunology; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D011485:Protein Binding; D034622:RNA Interference; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D002352:Carrier Proteins; D018076:DNA, Complementary; D019476:Insect Proteins; D008543:Melanins; C405332:beta-1,3-glucan recognition protein, insect; D000117:Acetylglucosamine