title: Lectin-induced activation of plasma membrane NADPH oxidase in cholesterol-depleted human neutrophils.
abstract: The gp91phox subunit of flavocytochrome b(558) is the catalytic core of the phagocyte plasma membrane NADPH oxidase. Its activation occurs within lipid rafts and requires translocation of four subunits to flavocytochrome b(558). gp91phox is the only glycosylated subunit of NADPH oxidase and no data exist about the structure or function of its glycans. Glycans, however, bind to lectins and this can stimulate NADPH oxidase activity. Given this information, we hypothesized that lectin-gp91phox interactions would facilitate the assembly of a functionally active NADPH oxidase in the absence of lipid rafts. To test this, we used lectins with different carbohydrate-binding specificity to examine the effects on H(2)O(2) generation by human neutrophils treated with the lipid raft disrupting agent methyl-β-cyclodextrin (MβCD). MβCD treatment removed membrane cholesterol, caused changes in cell morphology, inhibited lectin-induced cell aggregation, and delayed lectin-induced assembly of the NADPH oxidase complex. More importantly, MβCD treatment either stimulated or inhibited H(2)O(2) production in a lectin-dependent manner. Together, these results show selectivity in lectin binding to gp91phox, and provide evidence for the biochemical structures of the gp91phox glycans. Furthermore, the data also indicate that in the absence of lipid rafts, neutrophil NADPH oxidase activity can be altered by these select lectins.
authors: Department of Biophysics, Belarusian State University, Minsk.
authors: Irina V
authors: IV
authors: Gorudko
authors: Ann V
authors: AV
authors: Mukhortava
authors: Brendan
authors: B
authors: Caraher
authors: Melody
authors: M
authors: Ren
authors: Sergey N
authors: SN
authors: Cherenkevich
authors: Gregory M
authors: GM
authors: Kelly
authors: Alexander V
authors: AV
authors: Timoshenko
mesh_terms: D002449:Cell Aggregation / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D048430:Cell Shape / Q000187:drug effects; D002784:Cholesterol / Q000378:metabolism*; D003573:Cytochrome b Group / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D066298:In Vitro Techniques; D037102:Lectins / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000378:metabolism; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism*; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism*; D047392:beta-Cyclodextrins / Q000494:pharmacology
chemical_list: D003573:Cytochrome b Group; D037102:Lectins; D008562:Membrane Glycoproteins; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C036888:cytochrome b558; D002784:Cholesterol; D006861:Hydrogen Peroxide; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases