Age-dependent endothelial nitric oxide synthase uncoupling in pulmonary arteries of endoglin heterozygous mice.
Endoglin is a TGF-beta superfamily receptor critical for endothelial cell function. Mutations in this gene are associated with hereditary hemorrhagic telangiectasia type I (HHT1), and clinical signs of disease are generally more evident later in life. We previously showed that systemic vessels of adult Eng heterozygous (Eng(+/-)) mice exhibit increased vasorelaxation due to uncoupling of endothelial nitric oxide synthase (eNOS). We postulated that these changes may develop with age and evaluated pulmonary arteries from newborn and adult Eng(+/-) mice for eNOS-dependent, acetylcholine (ACh-induced) vasorelaxation, compared with that of age-matched littermate controls. While ACh-induced vasorelaxation was similar in all newborn mice, it was significantly increased in the adult Eng(+/-) vs. control vessels. The vasodilatory responses were inhibited by l-NAME suggesting eNOS dependence. eNOS uncoupling was observed in lung tissues of adult, but not newborn, heterozygous mice and was associated with increased production of reactive O(2) species (ROS) in adult Eng(+/-) vs. control lungs. Interestingly, ROS generation was higher in adult than newborn mice and so were the levels of NADPH oxidase 4 and SOD 1, 2, 3 isoforms. However, enzyme protein levels and NADPH activity were normal in adult Eng(+/-) lungs indicating that the developmental maturation of ROS generation and scavenging cannot account for the increased vasodilatation observed in adult Eng(+/-) mice. Our data suggest that eNOS-dependent H(2)O(2) generation in Eng(+/-) lungs accounts for the heightened pulmonary vasorelaxation. To the extent that these mice mimic human HHT1, age-associated pulmonary vascular eNOS uncoupling may explain the late childhood and adult onset of clinical lung manifestations.
Belik
J
J
The Hospital for Sick Children, University of Toronto, Ontario, Canada. Jaques.Belik@SickKids.ca
Jerkic
M
M
McIntyre
B A S
BA
Pan
J
J
Leen
J
J
Yu
L X
LX
Henkelman
R M
RM
Toporsian
M
M
Letarte
M
M
D000375:Aging / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D001696:Biomechanical Phenomena / Q000187:drug effects; D000071063:Endoglin; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism; D006579:Heterozygote; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D008168:Lung / Q000187:drug effects / Q000201:enzymology; D051379:Mice; D019255:NADPH Oxidases / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000187:drug effects / Q000201:enzymology*; D013482:Superoxide Dismutase / Q000378:metabolism; D014057:Tomography, X-Ray Computed; D014664:Vasodilation / Q000187:drug effects
D000071063:Endoglin; C502004:Eng protein, mouse; D018841:HSP90 Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D006861:Hydrogen Peroxide; D052250:Nitric Oxide Synthase Type III; D013482:Superoxide Dismutase; D019255:NADPH Oxidases