Neurofibromin is a novel regulator of Ras-induced reactive oxygen species production in mice and humans.
Neurofibromatosis type 1 (NF1) predisposes individuals to early and debilitating cardiovascular disease. Loss of function mutations in the NF1 tumor suppressor gene, which encodes the protein neurofibromin, leads to accelerated p21(Ras) activity and phosphorylation of multiple downstream kinases, including Erk and Akt. Nf1 heterozygous (Nf1(+/-)) mice develop a robust neointima that mimics human disease. Monocytes/macrophages play a central role in NF1 arterial stenosis as Nf1 mutations in myeloid cells alone are sufficient to reproduce the enhanced neointima observed in Nf1(+/-) mice. Though the molecular mechanisms underlying NF1 arterial stenosis remain elusive, macrophages are important producers of reactive oxygen species (ROS) and Ras activity directly regulates ROS production. Here, we use compound mutant and lineage-restricted mice to demonstrate that Nf1(+/-) macrophages produce excessive ROS, which enhance Nf1(+/-) smooth muscle cell proliferation in vitro and in vivo. Further, use of a specific NADPH oxidase-2 inhibitor to limit ROS production prevents neointima formation in Nf1(+/-) mice. Finally, mononuclear cells from asymptomatic NF1 patients have increased oxidative DNA damage, an indicator of chronic exposure to oxidative stress. These data provide genetic and pharmacologic evidence that excessive exposure to oxidant species underlie NF1 arterial stenosis and provide a platform for designing novels therapies and interventions.
Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis 46202, United States; Department of Pediatrics and Neonatal-Perinatal Medicine, Indiana University School of Medicine, Indianapolis 46202, United States; Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis 46202, United States.
Waylan K
WK
Bessler
Department of Pediatrics and Neonatal-Perinatal Medicine, Augusta University, Augusta, GA 30912, United States; Vascular Biology Center, Augusta University, Augusta, GA 30912, United States.
Farlyn Z
FZ
Hudson
Department of Pediatrics and Neonatal-Perinatal Medicine, Augusta University, Augusta, GA 30912, United States; Vascular Biology Center, Augusta University, Augusta, GA 30912, United States.
Hanfang
H
Zhang
Department of Pediatrics and Neonatal-Perinatal Medicine, Augusta University, Augusta, GA 30912, United States; Vascular Biology Center, Augusta University, Augusta, GA 30912, United States.
Valerie
V
Harris
Vascular Biology Center, Augusta University, Augusta, GA 30912, United States; Department of Pharmacology and Toxicology, Augusta University, Augusta, GA 30912, United States.
Yusi
Y
Wang
Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis 46202, United States; Department of Pediatrics and Neonatal-Perinatal Medicine, Indiana University School of Medicine, Indianapolis 46202, United States; Melvin and Bren Simon Cancer Center, Indiana University School of Medicine, Indianapolis 46202, United States.
Julie A
JA
Mund
Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis 46202, United States; Department of Pediatrics and Neonatal-Perinatal Medicine, Indiana University School of Medicine, Indianapolis 46202, United States.
Brandon
B
Downing
Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis 46202, United States; Department of Pediatrics and Neonatal-Perinatal Medicine, Indiana University School of Medicine, Indianapolis 46202, United States; Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis 46202, United States.
David A
DA
Ingram
Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis 46202, United States; Melvin and Bren Simon Cancer Center, Indiana University School of Medicine, Indianapolis 46202, United States; Scripps Clinic Medical Group, Center for Organ and Cell Transplantation, La Jolla, CA 92037, United States.
Jamie
J
Case
Vascular Biology Center, Augusta University, Augusta, GA 30912, United States; Department of Pharmacology and Toxicology, Augusta University, Augusta, GA 30912, United States.
David J
DJ
Fulton
Department of Pediatrics and Neonatal-Perinatal Medicine, Augusta University, Augusta, GA 30912, United States; Vascular Biology Center, Augusta University, Augusta, GA 30912, United States. Electronic address: bstansfield@augusta.edu.
Brian K
BK
Stansfield
D000818:Animals; D016893:Carotid Stenosis / Q000235:genetics / Q000503:physiopathology; D049109:Cell Proliferation / Q000235:genetics; D004249:DNA Damage / Q000235:genetics; D006579:Heterozygote; D006801:Humans; D008264:Macrophages / Q000378:metabolism / Q000473:pathology; D051379:Mice; D032389:Myocytes, Smooth Muscle / Q000378:metabolism / Q000473:pathology; D000074662:NADPH Oxidase 2 / Q000235:genetics* / Q000378:metabolism; D058426:Neointima / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D009456:Neurofibromatosis 1 / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology; D025542:Neurofibromin 1 / Q000235:genetics*; D018384:Oxidative Stress / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
D025542:Neurofibromin 1; D017382:Reactive Oxygen Species; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; C495971:Hras protein, mouse; D016283:Proto-Oncogene Proteins p21(ras)
Apocynin; Macrophage; Monocyte; NADPH oxidase; Neointima; Neurofibromatosis; Ras; Reactive oxygen species; Smooth muscle cell; Superoxide