Effects of IFN-γ on intracellular trafficking and activity of macrophage NADPH oxidase flavocytochrome b558

Amy Jo Casbon, Matthew E. Long, Kenneth Dunn, Lee Ann H Allen, Mary C. Dinauer

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

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.

Original languageEnglish (US)
Pages (from-to)869-882
Number of pages14
JournalJournal of Leukocyte Biology
Volume92
Issue number4
DOIs
StatePublished - Oct 2012
Externally publishedYes

Fingerprint

NADPH Oxidase
Macrophages
Intracellular Membranes
Endosomes
Phagocytes
NADP
Superoxides
cytochrome b558
Catalytic Domain
Electrons
Cytokines
Oxygen
Membranes
Proteins

Keywords

  • Cytokine
  • Gp91
  • Membrane
  • P22
  • Phagocytosis
  • Superoxide

ASJC Scopus subject areas

  • Cell Biology
  • Immunology

Cite this

Effects of IFN-γ on intracellular trafficking and activity of macrophage NADPH oxidase flavocytochrome b558. / Casbon, Amy Jo; Long, Matthew E.; Dunn, Kenneth; Allen, Lee Ann H; Dinauer, Mary C.

In: Journal of Leukocyte Biology, Vol. 92, No. 4, 10.2012, p. 869-882.

Research output: Contribution to journalArticle

Casbon, Amy Jo ; Long, Matthew E. ; Dunn, Kenneth ; Allen, Lee Ann H ; Dinauer, Mary C. / Effects of IFN-γ on intracellular trafficking and activity of macrophage NADPH oxidase flavocytochrome b558. In: Journal of Leukocyte Biology. 2012 ; Vol. 92, No. 4. pp. 869-882.
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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.

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