Activation mechanism of NADPH oxidase by SDS in intact guinea pig neutrophils.
It is well known that sodium dodecyl sulfate (SDS) activates NADPH oxidase in a cell-free system independently of protein kinase C (PKC). However, in intact neutrophils, direct evidence has never been presented to show that O2- production by SDS is actually due to the NADPH oxidase activation observed in the cell-free system. So, in this paper, we investigated the activation mechanism by SDS in intact guinea pig neutrophils. We previously reported that hypotonic treatment reversibly enhanced O2- production stimulated by PKC activators in intact neutrophils (M. Hiura et al., 1991, Arch. Biochem. Biophys. 291, 31-37). In this paper, SDS also significantly stimulated O2- production in the intact cells under the hypotonic condition. This enhancement was gradual and was PKC inhibitor resistant. Furthermore, phosphorylation of the 46-kDa protein, one of cytosolic activation factors, was not detected by autoradiography of two-dimensional electrophoresis. Translocation of cytosolic activation factors was demonstrated by a decrease in the activity of the factors remained in the cytosol. In the presence of SDS, addition of 1-oleoyl-2-acetylglycerol, a PKC activator, further enhanced O2- production and translocation of the cytosolic activation factors. On the other hand, SDS remarkably increased membrane fluidity in intact neutrophils as well as in the cell-free system. These results indicate that activation of NADPH oxidase by SDS in intact neutrophils seems to be partly due to the same mechanism observed in cell-free activation, and that SDS alone slightly activates the oxidase and other stimulation, such as hypotonic and/or PKC activator treatments, is required for significant activation. The increase in the membrane fluidity may be one of the activation mechanisms of NADPH oxidase by SDS.
Sasaki
J
J
Department of Physiological Chemistry, Hiroshima University School of Medicine, Japan.
Hiura
M
M
Yamaguchi
M
M
Sakai
M
M
Aoki
K
K
Abe
H
H
Okamura
N
N
Ishibashi
S
S
D000818:Animals; D001692:Biological Transport; D003600:Cytosol / Q000378:metabolism; D004075:Diglycerides / Q000494:pharmacology; D004789:Enzyme Activation; D005260:Female; D006168:Guinea Pigs; D008565:Membrane Proteins / Q000187:drug effects; D009247:NADH, NADPH Oxidoreductases / Q000187:drug effects*; D009252:NADPH Dehydrogenase / Q000032:analysis; D019255:NADPH Oxidases; D009504:Neutrophils / Q000201:enzymology*; D009997:Osmotic Pressure; D010750:Phosphoproteins / Q000032:analysis; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology*; D013481:Superoxides
D004075:Diglycerides; D008565:Membrane Proteins; D010750:Phosphoproteins; C079789:neutrophil cytosol factor 67K; D013481:Superoxides; D012967:Sodium Dodecyl Sulfate; C038237:1-oleoyl-2-acetylglycerol; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D009252:NADPH Dehydrogenase; D011493:Protein Kinase C