Effects of a mosquitocidal toxin on a mammalian epithelial cell line expressing its target receptor.
The spread of diseases transmitted by Anopheles and Culex mosquitoes, such as malaria and West Nile fever, is a growing concern for human health. Bacillus sphaericus binary toxin (Bin) is one of the few available bioinsecticides able to control populations of these mosquitoes efficiently. We previously showed that Bin binds to Cpm1, an alpha-glucosidase located on the apical side of Culex larval midgut epithelium. We analysed the effects of Bin by expressing a construct encoding Cpm1 in the mammalian epithelial MDCK cell line. Cpm1 is targeted to the apical side of polarized MDCK, where it is anchored by glycosylphosphatidylinositol (GPI) and displays alpha-glucosidase activity. Bin bound to transfected cells and induced a non-specific current presumably related to the opening of pores. The formation of these pores may be related to the location of the toxin/receptor complex in lipid raft microdomains. Finally, Bin promoted the time-dependent appearance of intracytoplasmic vacuoles but did not drive cell lysis. Thus, the dual functionality (enzyme/toxin receptor) of Cpm1 is fully conserved in MDCK cells and Cpm1 is an essential target protein for Bin cytotoxicity in Culex mosquitoes.
Pauchet
Yannick
Y
Institut National de la Recherche Agronomique, UMR 1112 Réponses des Organismes aux Stress Environnementaux, 400 Route des Chappes, BP167, 06903 Sophia Antipolis Cedex, France.
Luton
Frédéric
F
Castella
Claude
C
Charles
Jean-François
JF
Romey
Georges
G
Pauron
David
D
D000818:Animals; D001427:Bacterial Toxins / Q000378:metabolism* / Q000494:pharmacology; D002460:Cell Line; D002463:Cell Membrane Permeability; D003465:Culex; D004285:Dogs; D004847:Epithelial Cells / Q000187:drug effects / Q000648:ultrastructure*; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D021962:Membrane Microdomains / Q000187:drug effects / Q000648:ultrastructure; D009032:Mosquito Control; D011869:Radioligand Assay; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014617:Vacuoles / Q000187:drug effects / Q000648:ultrastructure; D000520:alpha-Glucosidases / Q000235:genetics / Q000378:metabolism*
D001427:Bacterial Toxins; D017261:Glycosylphosphatidylinositols; D011994:Recombinant Proteins; C046134:binB protein, Bacillus sphaericus; D000520:alpha-Glucosidases