Abstract
Objective:
Adenosine monophosphate activated protein kinase (AMPK) has been identified as a regulator of vascular function via the preservation of endothelial cell (EC) function. In this study, we examined whether the beneficial effects of AMPK on ECs are dependent on its involvement in cholesterol efflux and its impact on hypercholesterolemia-induced endothelial dysfunction.
Methods and results:
Using human aortic ECs and bovine aortic ECs, we show that AMPK activation upregulates ATP binding cassette G1 (ABCG1) expression independently of liver X receptor alpha (LXR alpha) transcriptional activity but through a posttranscriptional mechanism that increases mRNA stability. Using a heterologous system and a luciferase reporter, we further identify that the 3'-untranslated region of the ABCG1 mRNA is responsible for the regulatory effects of AMPK activation. 5-Aminoimidazole-4-carboxamide-1-beta-D-riboside treatment promotes endothelial 7-ketocholesterol efflux and prevents 7-ketocholesterol (7-KC)-induced reactive oxygen species production in an ABCG1-dependent manner, thus preserving endothelial nitric oxide synthase activity and nitric oxide bioavailability. Notably, in vivo studies using C57BL/6J mice receiving a high-cholesterol diet revealed that the infusion of 5-aminoimidazole-4-carboxamide-1-beta-d-riboside increases vascular ABCG1 expression and improves vascular reactivity. These effects are abrogated by the AMPK antagonist compound C and by the vascular gene transfer of ABCG1 small interfering RNA.
Conclusions:
Our current findings uncover a novel mechanism by which AMPK protects against hypercholesterolemia-mediated endothelial dysfunction.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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3' Untranslated Regions
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AMP-Activated Protein Kinases / antagonists & inhibitors
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AMP-Activated Protein Kinases / genetics
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AMP-Activated Protein Kinases / metabolism*
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ATP Binding Cassette Transporter, Subfamily G, Member 1
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ATP-Binding Cassette Transporters / genetics
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ATP-Binding Cassette Transporters / metabolism*
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Acetylcholine / pharmacology
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Aminoimidazole Carboxamide / analogs & derivatives
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Aminoimidazole Carboxamide / pharmacology
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Animals
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Biological Transport
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Cattle
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Cells, Cultured
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Disease Models, Animal
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Dose-Response Relationship, Drug
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Endothelial Cells / drug effects
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Endothelial Cells / enzymology*
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Endothelium, Vascular / drug effects
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Endothelium, Vascular / enzymology*
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Endothelium, Vascular / physiopathology
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Enzyme Activation
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Enzyme Activators
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Genes, Reporter
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Humans
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Hypercholesterolemia / enzymology*
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Hypercholesterolemia / physiopathology
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Ketocholesterols / metabolism*
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Male
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Mice
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Mice, Inbred C57BL
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Nitric Oxide / metabolism
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Nitric Oxide Synthase Type III / metabolism
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Nitroprusside / pharmacology
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Oxidative Stress
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Protein Kinase Inhibitors / pharmacology
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Pyrazoles / pharmacology
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Pyrimidines / pharmacology
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RNA Interference
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RNA Processing, Post-Transcriptional
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RNA Stability
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RNA, Messenger / metabolism
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Reactive Oxygen Species / metabolism
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Ribonucleotides / pharmacology
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Transfection
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Up-Regulation
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Vasodilation* / drug effects
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Vasodilator Agents / pharmacology
Substances
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3' Untranslated Regions
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ABCG1 protein, human
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ATP Binding Cassette Transporter, Subfamily G, Member 1
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ATP-Binding Cassette Transporters
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Enzyme Activators
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Ketocholesterols
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Protein Kinase Inhibitors
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Pyrazoles
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Pyrimidines
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RNA, Messenger
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Reactive Oxygen Species
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Ribonucleotides
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Vasodilator Agents
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dorsomorphin
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Nitroprusside
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Nitric Oxide
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Aminoimidazole Carboxamide
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Nitric Oxide Synthase Type III
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AMP-Activated Protein Kinases
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AICA ribonucleotide
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Acetylcholine
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7-ketocholesterol