title: Regulation of lipid metabolism genes, lipid carrier protein lipophorin, and its receptor during immune challenge in the mosquito Aedes aegypti.
abstract: In the mosquito Aedes aegypti, the expression of two fat body genes involved in lipid metabolism, a lipid carrier protein lipophorin (Lp) and its lipophorin receptor (LpRfb), was significantly increased after infections with Gram (+) bacteria and fungi, but not with Gram (-) bacteria. The expression of these genes was enhanced after the infection with Plasmodium gallinaceum. RNA interference (RNAi) knockdown of Lp strongly restricted the development of Plasmodium oocysts, reducing their number by 90%. In Vg-DeltaREL1-A transgenic mosquitoes, with gain-of-function phenotype of Toll/REL1 immune pathway activated after blood feeding, both the Lp and LpRfb genes were overexpressed independently of septic injury. The same phenotype was observed in the mosquitoes with RNAi knockdown of Cactus, an IkappaB inhibitor in the Toll/REL1 pathway. These results showed that, in the mosquito fat body, both Lp and LpRfb gene expression were regulated by the Toll/REL1 pathway during immune induction by pathogen and parasite infections. Indeed, the proximal region of the LpRfb promoter contained closely linked binding motifs for GATA and NF-kappaB transcription factors. Transfection and in vivo RNAi knockdown experiments showed that the bindings of both GATA and NF-kappaB transcription factors to the corresponding motif were required for the induction of the LpRfb gene. These findings suggest that lipid metabolism is involved in the mosquito systemic immune responses to pathogens and parasites.
authors.affiliation: Center for Disease-Vector Research, Department of Entomology and the Institute for Integrative Genome Biology, University of California, Riverside, California 92521, USA.
authors.forename: Hyang-Mi
authors.initials: HM
authors.lastname: Cheon
authors.forename: Sang Woon
authors.initials: SW
authors.lastname: Shin
authors.forename: Guowu
authors.initials: G
authors.lastname: Bian
authors.forename: Jong-Hwa
authors.initials: JH
authors.lastname: Park
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Raikhel
mesh_terms: D000330:Aedes / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D000818:Animals; D030801:Animals, Genetically Modified; D005216:Fat Body / Q000276:immunology; D005786:Gene Expression Regulation / Q000235:genetics* / Q000276:immunology; D017344:Genes, Insect; D050356:Lipid Metabolism; D008074:Lipoproteins / Q000235:genetics* / Q000276:immunology; D010964:Plasmodium gallinaceum / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000276:immunology; D034622:RNA Interference; D018160:Receptors, Cytoplasmic and Nuclear / Q000276:immunology*; D014157:Transcription Factors / Q000276:immunology
chemical_list: D008074:Lipoproteins; C501431:REL1 protein, Aedes aegypti; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; C032830:lipophorin; C432945:lipophorin receptor