Disease relevance of CYBA

• Molecular analysis of 9 new families with chronic granulomatous disease caused by mutations in CYBA, the gene encoding p22(phox) [1].
• CONCLUSION: The C242T CYBA polymorphism is associated with essential hypertension [2].
• In conclusion, we identified a risk haplotype for nondiabetic ESRD in the CYBA gene using haplotype analysis [3].
• NADPH oxidase (CYBA) and FcgammaR polymorphisms as risk factors for aggressive periodontitis: a case-control association study [4].
• Association of NAD(P)H oxidase p22 phox gene variation with advanced carotid atherosclerosis in Japanese type 2 diabetes [5].

High impact information on CYBA

• We suggest that the binding of an SH3 domain of p47-phox to p22-phox, and thus activation of the oxidase, does not occur in the neutrophils of this patient, although under artificial conditions, electron flow from NADPH to oxygen in cytochrome b558 is possible [6].
• No detectable O2- was generated by untransfected p22phox-deficient lymphocytes [7].
• The genetic reconstitution of the respiratory burst in A22(0) CGD B lymphocytes by transfer of the wild-type p22phox cDNA represents a further step towards somatic gene therapy for this subgroup of A22(0) CGD [7].
• We report here that the capacity for O2- production and cytochrome b558 protein expression were restored to Epstein-Barr virus-transformed B lymphocytes from two A22(0) CGD patients by transfection with an expression plasmid containing a p22phox cDNA [7].
• Western blots of neutrophil extracts showed decreased immunoreactive cytochrome b558 components gp91-phox and p22-phox [8].

Chemical compound and disease context of CYBA

• We examined five polymorphisms in the CYBA gene encoding the p22 phox component of NAD(P)H oxidase, including 242C/T and 640A/G polymorphisms in 467 ESRD patients and 490 healthy individuals [3].
• The unmasking of p47-SH3 appears to play a crucial role in the assembly of the oxidase components, because p47-SH3 binds to both p22phox and p67phox but fails to interact with a mutant p22phox carrying a Pro-156-->Gln substitution in a proline-rich region, which has been found in a patient with chronic granulomatous disease [9].
• We studied 108 male Caucasians with angiographically documented CAD and 45 controls free of vascular disease under 60 years of age. p22 phox C242T genotypes and MDA levels were determined [10].
• This response was attenuated by antioxidants; the flavin inhibitor diphenylene-iodonium, Clostridium difficile toxin B, which inhibits Rho GTPases, p22phox antisense oligonucleotides, or the dominant-negative RacT17N mutant [11].
• Lack of association of eNOS(G894T) and p22phox NADPH oxidase submit (C242T) polymorphisms with systemic sclerosis in a cohort of French Caucasian patients [12].

Biological context of CYBA

• The CYBA locus was localized to 16q24, and the approximately 600-bp open reading frame determined to be encoded by six exons that span approximately 8.5 kb [13].
• One of the rarest forms of the disease is due to defects in the CYBA gene encoding p22(phox), which together with gp91(phox) forms flavocytochrome b(558), the catalytic core of NADPH oxidase [1].
• METHODS: CYBA polymorphisms were determined by restriction fragment length polymorphism (RFLP) or allelic discrimination [2].
• The C242T polymorphism was not in linkage disequilibrium with the -930A/G CYBA promoter variation, which also associates with hypertension [2].
• Haplotype analyses and homozygosity mapping with microsatellite markers around known CGD genes assigned the genetic defect to NCF1 in four patients, to NCF2 in four patients and to CYBA in two patients [14].

Anatomical context of CYBA

• C242T CYBA polymorphism of the NADPH oxidase is associated with reduced respiratory burst in human neutrophils [15].
• HL60 cells induced to differentiate in the presence of succinyl acetone (a inhibitor of heme synthesis) were unable to generate O2-., failed to express p22-phox but retained H+ channel activity [16].
• With respect to the catalytic flavoheme protein subunit, HaCaT membranes, which expressed p22phox, showed an absorbance peak at 558 nm indicative of a b-type cytochrome [17].
• We investigated the role of ANG II and platelet-derived growth factor (PDGF) AA induced ROS generation derived from p22phox-containing NAD(P)H oxidase in the activation of activator protein (AP) 1 in human vascular smooth muscle cells (SMCs) [18].
• Patients 2 and 3, but not patient 1, were demonstrated to have detectable p22-phox expression and significant granulocyte respiratory burst (ROB) activity [19].

Associations of CYBA with chemical compounds

• CONCLUSIONS: The effect was inconsistent among the markers, but these results suggest that the CYBA C242T polymorphism is involved in NAD(P)H oxidase activity and affects oxidation of lipoproteins by altering the redox state in the vasculature [20].
• It is a heterodimer that consists of a large glycoprotein gp91phox (phox forphagocyte oxidase) (beta subunit) and a small protein p22phox (alpha subunit) [21].
• Role of p22phox in angiotensin II and platelet-derived growth factor AA induced activator protein 1 activation in vascular smooth muscle cells [18].
• Furthermore, we show that Pak translocates to the plasma membrane upon N-formyl-methionyl-leucyl-phenylalanine (fMLF) stimulation and colocalizes with translocated p47(phox) and with p22phox, a subunit of flavocytochrome b558 [22].
• The central region of the p22phox peptide forms a polyproline type II helix that is sandwiched by the N- and C-terminal SH3 domains, as was observed in the crystal structure, whereas the C-terminal region of the peptide takes on a short alpha-helical conformation that provides an additional binding site with the N-terminal SH3 domain [23].

Physical interactions of CYBA

• The mapping also confirmed a previously reported binding domain on gp91-phox (E554SGPRGVHFIF564) and putative Src homology 3 domain binding sites on p22-phox (P156PRPP160 and G177GPPGGP183) [24].
• Binding experiments using the isolated first SH3 domain also demonstrated its involvement in intramolecular interactions within p47phox and showed a requirement for five residues (residues 151 to 155) on its N-terminal boundary for binding to p22phox [25].

Co-localisations of CYBA

• In atherosclerotic arteries, there was an additional intense area of superoxide in the plaque shoulder, which is rich in macrophages and alpha-actin-positive cells. p22phox colocalized with gp91phox mainly in macrophages, whereas Nox4 was found only in nonphagocytic vascular cells [26].

Regulatory relationships of CYBA

• Antioxidant treatment with vitamin C or diphenyleneiodonium abrogated thrombin-induced ROS production and p22phox expression, whereas H2O2 elevated ROS production and p22phox levels [27].
• The effects of dexamethasone on DCHF oxidation, and p22 phox mRNA expression and PDGF-AB-stimulated O2. - production were inhibited by the glucocorticoid receptor antagonist RU486 [28].
• Multiple regression analysis revealed that medical treatment with statin and angiotensin II type 1 receptor blocker (ARB) suppressed p22phox expression in TAA [29].

Other interactions of CYBA

• On the basis of these observations we propose that while Rac2 can bind to a site distinct from either gp91phox or p22phox, it depends upon an interaction with the flavocytochrome b558 for maximal stability in the membrane [30].
• The novel homologue p41nox interacts with p22phox via the two tandem SH3 domains, as does p47phox [31].
• In the CYBA gene, encoding the p22phox subunit of the NADPH-oxidase, 2 polymorphisms were investigated [32].
• Nox4 associates with the protein p22phox on internal membranes, where ROS generation occurs [33].
• ANG II and PDGF AA both activated the redox-sensitive transcription factor AP-1, which was inhibited by p22phox antisense ODNs [18].

Analytical, diagnostic and therapeutic context of CYBA

• Immunoprecipitation of native Nox1 from human VSMC revealed co-precipitation of p22phox [34].
• Expression of p22phox was also confirmed by Northern blotting [35].
• Using NMR titration, we first identified the proline-rich region of p22phox that is essential for binding to the tandem SH3 domains of p47phox [23].
• The p22phox C242T and RAGE G1704T polymorphisms were examined by Taqman PCR methods [36].
• Two-photon confocal laser microscopy showed colocalization between p22phox and ROS production [27].

References