TY - JOUR
T1 - Effects of IFN-γ on intracellular trafficking and activity of macrophage NADPH oxidase flavocytochrome b558
AU - Casbon, Amy Jo
AU - Long, Matthew E.
AU - Dunn, Kenneth W.
AU - Allen, Lee Ann H.
AU - Dinauer, Mary C.
PY - 2012/10
Y1 - 2012/10
N2 - Flavocytochrome b558, the catalytic core of the phagocyte NADPH oxidase (NOX2), mediates electron transfer from NADPH to molecular oxygen to generate superoxide, the precursor of highly ROS for host defense. Flavocytochrome b558 is an integral membrane heterodimer consisting of a large glycosylated subunit, gp91phox, and a smaller subunit, p22phox. We recently showed in murine macrophages that flavocytochrome b558 localizes to the PM and Rab11-positive recycling endosomes, whereas in primary hMDMs, gp91phox and p22phox reside in the PM and the ER. The antimicrobial activity of macrophages, including ROS production, is greatly enhanced by IFN-γ, but how this is achieved is incompletely understood. To further define the mechanisms by which IFN-γ enhances macrophage NADPH oxidase activity, we evaluated changes in flavocytochrome b558 expression and localization, along with NADPH oxidase activity, in IFN-γ stimulated RAW 264.7 cells and primary murine BMDMs and hMDMs. We found that enhanced capacity for ROS production is, in part, a result of increased protein expression of gp91phox and p22phox but also demonstrate that IFN-γ induced a shift in the predominant localization of gp91phox and p22phox from intracellular membrane compartments to the PM. Our results are the first to show that a cytokine can change the distribution of macrophage flavocytochrome b558 and provide a potential, new mechanism by which IFN-γ modulates macrophage antimicrobial activity. Altogether, our data suggest that the mechanisms by which IFN-γ regulates antimicrobial activity of macrophages are more complex than previously appreciated.
AB - Flavocytochrome b558, the catalytic core of the phagocyte NADPH oxidase (NOX2), mediates electron transfer from NADPH to molecular oxygen to generate superoxide, the precursor of highly ROS for host defense. Flavocytochrome b558 is an integral membrane heterodimer consisting of a large glycosylated subunit, gp91phox, and a smaller subunit, p22phox. We recently showed in murine macrophages that flavocytochrome b558 localizes to the PM and Rab11-positive recycling endosomes, whereas in primary hMDMs, gp91phox and p22phox reside in the PM and the ER. The antimicrobial activity of macrophages, including ROS production, is greatly enhanced by IFN-γ, but how this is achieved is incompletely understood. To further define the mechanisms by which IFN-γ enhances macrophage NADPH oxidase activity, we evaluated changes in flavocytochrome b558 expression and localization, along with NADPH oxidase activity, in IFN-γ stimulated RAW 264.7 cells and primary murine BMDMs and hMDMs. We found that enhanced capacity for ROS production is, in part, a result of increased protein expression of gp91phox and p22phox but also demonstrate that IFN-γ induced a shift in the predominant localization of gp91phox and p22phox from intracellular membrane compartments to the PM. Our results are the first to show that a cytokine can change the distribution of macrophage flavocytochrome b558 and provide a potential, new mechanism by which IFN-γ modulates macrophage antimicrobial activity. Altogether, our data suggest that the mechanisms by which IFN-γ regulates antimicrobial activity of macrophages are more complex than previously appreciated.
KW - Cytokine
KW - Gp91
KW - Membrane
KW - P22
KW - Phagocytosis
KW - Superoxide
UR - http://www.scopus.com/inward/record.url?scp=84868122360&partnerID=8YFLogxK
U2 - 10.1189/jlb.0512244
DO - 10.1189/jlb.0512244
M3 - Article
C2 - 22822009
AN - SCOPUS:84868122360
VL - 92
SP - 869
EP - 882
JO - Journal of Leukocyte Biology
JF - Journal of Leukocyte Biology
SN - 0741-5400
IS - 4
ER -