title: Innexin AGAP001476 is critical for mediating anti-Plasmodium responses in Anopheles mosquitoes.
abstract: The Toll and IMD pathways are known to be induced upon Plasmodium berghei and Plasmodium falciparum infection, respectively. It is unclear how Plasmodium or other pathogens in the blood meal and their invasion of the midgut epithelium would trigger the innate immune responses in immune cells, in particular hemocytes. Gap junctions, which can mediate both cell-to-cell and cell-to-extracellular communication, may participate in this signal transduction. This study examined whether innexins, gap junction proteins in insects, are involved in anti-Plasmodium responses in Anopheles gambiae. Inhibitor studies using carbenoxolone indicated that blocking innexons resulted in an increase in Plasmodium oocyst number and infection prevalence. This was accompanied by a decline in TEP1 levels in carbenoxolone-treated mosquitoes. Innexin AGAP001476 mRNA levels in midguts were induced during Plasmodium infection and a knockdown of AGAP001476, but not AGAP006241, caused an induction in oocyst number. Silencing AGAP001476 caused a concurrent increase in vitellogenin levels, a TEP1 inhibitor, in addition to a reduced level of TEP1-LRIM1-APL1C complex in hemolymph. Both vitellogenin and TEP1 are regulated by Cactus under the Toll pathway. Simultaneous knockdown of cactus and AGAP001476 failed to reverse the near refractoriness induced by the knockdown of cactus, suggesting that the AGAP001476-mediated anti-Plasmodium response is Cactus-dependent. These data demonstrate a critical role for innexin AGAP001476 in mediating innate immune responses against Plasmodium through Toll pathway in mosquitoes.
authors.affiliation: From the Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520 and the Howard Hughes Medical Institute, Chevy Chase, Maryland 20815 wingmanmichelle.li@yale.edu.
authors.forename: Michelle W M
authors.initials: MW
authors.lastname: Li
authors.affiliation: From the Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520 and.
authors.forename: Jiuling
authors.initials: J
authors.lastname: Wang
authors.affiliation: From the Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520 and the Howard Hughes Medical Institute, Chevy Chase, Maryland 20815.
authors.forename: Yang O
authors.initials: YO
authors.lastname: Zhao
authors.affiliation: From the Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520 and the Howard Hughes Medical Institute, Chevy Chase, Maryland 20815.
authors.forename: Erol
authors.initials: E
authors.lastname: Fikrig
mesh_terms: D000818:Animals; D000852:Anopheles / Q000276:immunology* / Q000469:parasitology; D002229:Carbenoxolone / Q000276:immunology / Q000494:pharmacology; D017630:Connexins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D005260:Female; D015870:Gene Expression / Q000276:immunology; D006458:Hemolymph / Q000276:immunology / Q000378:metabolism; D006790:Host-Parasite Interactions / Q000187:drug effects / Q000276:immunology; D007113:Immunity, Innate / Q000276:immunology; D019476:Insect Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D007303:Insect Vectors / Q000276:immunology* / Q000469:parasitology; D008288:Malaria / Q000097:blood / Q000276:immunology / Q000469:parasitology; D051379:Mice; D018613:Microscopy, Confocal; D033661:Oocysts / Q000276:immunology / Q000378:metabolism; D010961:Plasmodium / Q000276:immunology* / Q000502:physiology; D010962:Plasmodium berghei / Q000276:immunology / Q000502:physiology; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014819:Vitellogenins / Q000235:genetics / Q000276:immunology / Q000378:metabolism
chemical_list: D017630:Connexins; D019476:Insect Proteins; C540280:LRIM1 protein, Anopheles gambiae; C544265:TEP1 protein, Anopheles gambiae; D014819:Vitellogenins; D002229:Carbenoxolone
keywords: Gap Junction; Host-Pathogen Interaction; Innexin; Malaria; Microbial Pathogenesis; Plasmodium; Transmission Blocking