Increased superoxide and endothelial NO synthase uncoupling in blood vessels of Bmal1-knockout mice

Ciprian B. Anea, Bo Cheng, Shruti Sharma, Sanjiv Kumar, R. William Caldwell, Lin Yao, M. Irfan Ali, Ana M. Merloiu, David W. Stepp, Stephen M. Black, David J.R. Fulton, R. Daniel Rudic

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

RATIONALE: Disruption of the circadian clock in mice produces vascular dysfunction as evidenced by impairments in endothelium-dependent signaling, vasomotion, and blood vessel remodeling. Although the altered function of endothelial NO synthase and the overproduction of reactive oxygen species are central to dysfunction of the endothelium, to date, the impact of the circadian clock on endothelial NO synthase coupling and vascular reactive oxygen species production is not known. OBJECTIVE: The goals of the present study were to determine whether deletion of a critical component of the circadian clock, Bmal1, can influence endothelial NO synthase coupling and reactive oxygen species levels in arteries from Bmal1-knockout (KO) mice. METHODS AND RESULTS: Endothelial function was reduced in aortae from Bmal1-KO mice and improved by scavenging reactive oxygen species with polyethylene glycol-superoxide dismutase and nonselectively inhibiting cyclooxygenase isoforms with indomethacin. Aortae from Bmal1-KO mice exhibited enhanced superoxide levels as determined by electron paramagnetic resonance spectroscopy and dihydroethidium fluorescence, an elevation that was abrogated by administration of nitro-L-arginine methyl ester. High-performance liquid chromatography analysis revealed a reduction in tetrahydrobiopterin and an increase in dihydrobiopterin levels in the lung and aorta of Bmal1-KO mice, whereas supplementation with tetrahydrobiopterin improved endothelial function in the circadian clock KO mice. Furthermore, levels of tetrahydrobiopterin, dihydrobiopterin, and the key enzymes that regulate biopterin bioavailability, GTP cyclohydrolase and dihydrofolate reductase exhibited a circadian expression pattern. CONCLUSIONS: Having an established influence in the metabolic control of glucose and lipids, herein, we describe a novel role for the circadian clock in metabolism of biopterins, with a significant impact in the vasculature, to regulate coupling of endothelial NO synthase, production of superoxide, and maintenance of endothelial function.

Original languageEnglish (US)
Pages (from-to)1157-1165
Number of pages9
JournalCirculation research
Volume111
Issue number9
DOIs
StatePublished - Oct 12 2012

Fingerprint

Circadian Clocks
Knockout Mice
Nitric Oxide Synthase
Superoxides
Blood Vessels
Reactive Oxygen Species
Biopterin
Aorta
Endothelium
GTP Cyclohydrolase
Tetrahydrofolate Dehydrogenase
Fluorescence Spectrometry
Electron Spin Resonance Spectroscopy
Prostaglandin-Endoperoxide Synthases
Indomethacin
Biological Availability
Protein Isoforms
Arteries
High Pressure Liquid Chromatography
Maintenance

Keywords

  • Bmal1
  • circadian
  • endothelial NO synthase
  • superoxide
  • uncoupling

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

Cite this

Increased superoxide and endothelial NO synthase uncoupling in blood vessels of Bmal1-knockout mice. / Anea, Ciprian B.; Cheng, Bo; Sharma, Shruti; Kumar, Sanjiv; Caldwell, R. William; Yao, Lin; Ali, M. Irfan; Merloiu, Ana M.; Stepp, David W.; Black, Stephen M.; Fulton, David J.R.; Rudic, R. Daniel.

In: Circulation research, Vol. 111, No. 9, 12.10.2012, p. 1157-1165.

Research output: Contribution to journalArticle

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AU - Cheng, Bo

AU - Sharma, Shruti

AU - Kumar, Sanjiv

AU - Caldwell, R. William

AU - Yao, Lin

AU - Ali, M. Irfan

AU - Merloiu, Ana M.

AU - Stepp, David W.

AU - Black, Stephen M.

AU - Fulton, David J.R.

AU - Rudic, R. Daniel

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N2 - RATIONALE: Disruption of the circadian clock in mice produces vascular dysfunction as evidenced by impairments in endothelium-dependent signaling, vasomotion, and blood vessel remodeling. Although the altered function of endothelial NO synthase and the overproduction of reactive oxygen species are central to dysfunction of the endothelium, to date, the impact of the circadian clock on endothelial NO synthase coupling and vascular reactive oxygen species production is not known. OBJECTIVE: The goals of the present study were to determine whether deletion of a critical component of the circadian clock, Bmal1, can influence endothelial NO synthase coupling and reactive oxygen species levels in arteries from Bmal1-knockout (KO) mice. METHODS AND RESULTS: Endothelial function was reduced in aortae from Bmal1-KO mice and improved by scavenging reactive oxygen species with polyethylene glycol-superoxide dismutase and nonselectively inhibiting cyclooxygenase isoforms with indomethacin. Aortae from Bmal1-KO mice exhibited enhanced superoxide levels as determined by electron paramagnetic resonance spectroscopy and dihydroethidium fluorescence, an elevation that was abrogated by administration of nitro-L-arginine methyl ester. High-performance liquid chromatography analysis revealed a reduction in tetrahydrobiopterin and an increase in dihydrobiopterin levels in the lung and aorta of Bmal1-KO mice, whereas supplementation with tetrahydrobiopterin improved endothelial function in the circadian clock KO mice. Furthermore, levels of tetrahydrobiopterin, dihydrobiopterin, and the key enzymes that regulate biopterin bioavailability, GTP cyclohydrolase and dihydrofolate reductase exhibited a circadian expression pattern. CONCLUSIONS: Having an established influence in the metabolic control of glucose and lipids, herein, we describe a novel role for the circadian clock in metabolism of biopterins, with a significant impact in the vasculature, to regulate coupling of endothelial NO synthase, production of superoxide, and maintenance of endothelial function.

AB - RATIONALE: Disruption of the circadian clock in mice produces vascular dysfunction as evidenced by impairments in endothelium-dependent signaling, vasomotion, and blood vessel remodeling. Although the altered function of endothelial NO synthase and the overproduction of reactive oxygen species are central to dysfunction of the endothelium, to date, the impact of the circadian clock on endothelial NO synthase coupling and vascular reactive oxygen species production is not known. OBJECTIVE: The goals of the present study were to determine whether deletion of a critical component of the circadian clock, Bmal1, can influence endothelial NO synthase coupling and reactive oxygen species levels in arteries from Bmal1-knockout (KO) mice. METHODS AND RESULTS: Endothelial function was reduced in aortae from Bmal1-KO mice and improved by scavenging reactive oxygen species with polyethylene glycol-superoxide dismutase and nonselectively inhibiting cyclooxygenase isoforms with indomethacin. Aortae from Bmal1-KO mice exhibited enhanced superoxide levels as determined by electron paramagnetic resonance spectroscopy and dihydroethidium fluorescence, an elevation that was abrogated by administration of nitro-L-arginine methyl ester. High-performance liquid chromatography analysis revealed a reduction in tetrahydrobiopterin and an increase in dihydrobiopterin levels in the lung and aorta of Bmal1-KO mice, whereas supplementation with tetrahydrobiopterin improved endothelial function in the circadian clock KO mice. Furthermore, levels of tetrahydrobiopterin, dihydrobiopterin, and the key enzymes that regulate biopterin bioavailability, GTP cyclohydrolase and dihydrofolate reductase exhibited a circadian expression pattern. CONCLUSIONS: Having an established influence in the metabolic control of glucose and lipids, herein, we describe a novel role for the circadian clock in metabolism of biopterins, with a significant impact in the vasculature, to regulate coupling of endothelial NO synthase, production of superoxide, and maintenance of endothelial function.

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