title: Proteins homologous to p47phox and p67phox support superoxide production by NAD(P)H oxidase 1 in colon epithelial cells.
abstract: Superoxide production by phagocytes involves activation of a multi-component NADPH oxidase. Recently, several homologues of the catalytic component of the phagocyte oxidase, gp91phox, were identified in various tissues. Here we describe two proteins, p41 and p51, with significant homology to two cytosolic components of the phagocytic oxidase, p47phox and p67phox. Like p47phox, p41 contains an amino-terminal Phox homology domain, two SH3 domains, and a conserved carboxyl-terminal, proline-rich motif. Similarly, p51 is homologous to p67phox, containing four amino-terminal tetratrico-peptide repeats, a conserved "activation domain" motif, a PB1 domain, and a carboxyl-terminal SH3 domain. The highest levels of p41 transcript are detected in the colon and in other gastrointestinal tissues that express Nox1, the predominant gp91phox homologue in these tissues. In contrast, the p51 transcript showed a more widespread expression pattern, suggesting that it may support other tissue-specific oxidases. Mouse colon in situ hybridization detected both transcripts in the epithelial cells of colon crypts. Heterologous co-expression of p41 and p51 significantly enhances the superoxide-generating activity of Nox1-expressing cells; thus, p41 and p51 appear to be novel regulators of Nox1. These proteins also support the activity of gp91phox, albeit at much lower levels than the cytosolic phox counterparts. Our results suggest colon epithelial cells contain a multi-component NAD(P)H oxidase with a molecular architecture similar to the phagocytic oxidase.
authors.affiliation: Laboratory of Host Defenses, NIAID, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Miklós
authors.initials: M
authors.lastname: Geiszt
authors.forename: Kristen
authors.initials: K
authors.lastname: Lekstrom
authors.forename: Jassir
authors.initials: J
authors.lastname: Witta
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Leto
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003106:Colon / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D004847:Epithelial Cells / Q000201:enzymology / Q000378:metabolism; D016147:Genes, Tumor Suppressor; D017403:In Situ Hybridization; D051379:Mice; D008969:Molecular Sequence Data; D019255:NADPH Oxidases / Q000378:metabolism*; D010750:Phosphoproteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013481:Superoxides / Q000378:metabolism*; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins
chemical_list: D004268:DNA-Binding Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; C115051:TP63 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C079789:neutrophil cytosol factor 67K; C475299:p41 protein, mouse; D013481:Superoxides; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1