title: Nox2-Mediated PI3K and Cofilin Activation Confers Alternate Redox Control of Macrophage Pinocytosis.
abstract: Internalization of extracellular fluid and its solute by macropinocytosis requires dynamic reorganization of actin cytoskeleton, membrane ruffling, and formation of large endocytic vacuolar compartments, called macropinosomes, inside the cell. Although instigators of macropinocytosis, such as growth factors and phorbol esters, stimulate NADPH oxidase (Nox) activation and signal transduction mediators upstream of Nox assembly, including Rac1 and protein kinase C (PKC), are involved in macropinocytosis, the role of Nox enzymes in macropinocytosis has never been investigated. This study was designed to examine the role of Nox2 and the potential downstream redox signaling involved in macropinocytosis.
  
  
  
  Phorbol myristate acetate activation of human and murine macrophages stimulated membrane ruffling, macropinosome formation, and subsequent uptake of macromolecules by macropinocytosis. Mechanistically, we found that pharmacological blockade of PKC, transcriptional knockdown of Nox2, and scavenging of intracellular superoxide anion abolished phorbol ester-induced macropinocytosis. We observed that Nox2-derived reactive oxygen species via inhibition of phosphatase and tensin homolog and activation of the phosphoinositide-3-kinase (PI3K)/Akt pathway lead to activation of actin-binding protein cofilin, membrane ruffling, and macropinocytosis. Similarly, activation of macropinocytosis by macrophage colony-stimulating factor involves Nox2-mediated cofilin activation. Furthermore, peritoneal chimera experiments indicate that macropinocytotic uptake of lipids in hypercholesterolemic ApoE-/-mice was attenuated in Nox2y/-macrophages compared with wild-type controls. Innovation and Conclusion: In summary, these findings demonstrate a novel Nox2-mediated mechanism of solute uptake via macropinocytosis, with broad implications for both general cellular physiology and pathological processes. The redox mechanism described here may also identify new targets in atherosclerosis and other disease conditions involving macropinocytosis. Antioxid. Redox Signal. 26, 902-916.
authors.affiliation: 1 Vascular Biology Center, Augusta University , Medical College of Georgia, Augusta, Georgia .
authors.forename: Pushpankur
authors.initials: P
authors.lastname: Ghoshal
authors.affiliation: 1 Vascular Biology Center, Augusta University , Medical College of Georgia, Augusta, Georgia .
authors.forename: Bhupesh
authors.initials: B
authors.lastname: Singla
authors.affiliation: 1 Vascular Biology Center, Augusta University , Medical College of Georgia, Augusta, Georgia .
authors.forename: Huiping
authors.initials: H
authors.lastname: Lin
authors.affiliation: 2 Vascular Medicine Institute, University of Pittsburgh , Pittsburgh, Pennsylvania.
authors.forename: Douglas M
authors.initials: DM
authors.lastname: Feck
authors.affiliation: 2 Vascular Medicine Institute, University of Pittsburgh , Pittsburgh, Pennsylvania.|3 Department of Pharmacology and Chemical Biology, University of Pittsburgh , Pittsburgh, Pennsylvania.
authors.forename: Nadiezhda
authors.initials: N
authors.lastname: Cantu-Medellin
authors.affiliation: 2 Vascular Medicine Institute, University of Pittsburgh , Pittsburgh, Pennsylvania.|3 Department of Pharmacology and Chemical Biology, University of Pittsburgh , Pittsburgh, Pennsylvania.
authors.forename: Eric E
authors.initials: EE
authors.lastname: Kelley
authors.affiliation: 1 Vascular Biology Center, Augusta University , Medical College of Georgia, Augusta, Georgia .
authors.forename: Stephen
authors.initials: S
authors.lastname: Haigh
authors.affiliation: 1 Vascular Biology Center, Augusta University , Medical College of Georgia, Augusta, Georgia .|4 Department of Pharmacology and Toxicology, Augusta University , Medical College of Georgia, Augusta, Georgia .
authors.forename: David
authors.initials: D
authors.lastname: Fulton
authors.affiliation: 1 Vascular Biology Center, Augusta University , Medical College of Georgia, Augusta, Georgia .|4 Department of Pharmacology and Toxicology, Augusta University , Medical College of Georgia, Augusta, Georgia .
authors.forename: Gábor
authors.initials: G
authors.lastname: Csányi
mesh_terms: D051339:Actin Depolymerizing Factors / Q000378:metabolism*; D000818:Animals; D050197:Atherosclerosis / Q000235:genetics / Q000378:metabolism*; D002784:Cholesterol / Q000378:metabolism; D004195:Disease Models, Animal; D006801:Humans; D008264:Macrophages / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D000074662:NADPH Oxidase 2 / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010873:Pinocytosis; D000067996:RAW 264.7 Cells; D015398:Signal Transduction; D000074084:THP-1 Cells
chemical_list: D051339:Actin Depolymerizing Factors; D002784:Cholesterol; C056558:CYBB protein, human; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; D019869:Phosphatidylinositol 3-Kinases
keywords: NADPH oxidase; atherosclerosis; cofilin; macrophage; macropinocytosis