Dataset Information

Vascular Smooth Muscle Sirtuin-1 Protects Against Diet-Induced Aortic Stiffness.

ABSTRACT: Arterial stiffness, a major cardiovascular risk factor, develops within 2 months in mice fed a high-fat, high-sucrose (HFHS) diet, serving as a model of human metabolic syndrome, and it is associated with activation of proinflammatory and oxidant pathways in vascular smooth muscle (VSM) cells. Sirtuin-1 (SirT1) is an NAD(+)-dependent deacetylase regulated by the cellular metabolic status. Our goal was to study the effects of VSM SirT1 on arterial stiffness in the context of diet-induced metabolic syndrome. Overnight fasting acutely decreased arterial stiffness, measured in vivo by pulse wave velocity, in mice fed HFHS for 2 or 8 months, but not in mice lacking SirT1 in VSM (SMKO). Similarly, VSM-specific genetic SirT1 overexpression (SMTG) prevented pulse wave velocity increases induced by HFHS feeding, during 8 months. Administration of resveratrol or S17834, 2 polyphenolic compounds known to activate SirT1, prevented HFHS-induced arterial stiffness and were mimicked by global SirT1 overexpression (SirT1 bacterial artificial chromosome overexpressor), without evident metabolic improvements. In addition, HFHS-induced pulse wave velocity increases were reversed by 1-week treatment with a specific, small molecule SirT1 activator (SRT1720). These beneficial effects of pharmacological or genetic SirT1 activation, against HFHS-induced arterial stiffness, were associated with a decrease in nuclear factor kappa light chain enhancer of activated B cells (NF?B) activation and vascular cell adhesion molecule (VCAM-1) and p47phox protein expressions, in aorta and VSM cells. In conclusion, VSM SirT1 activation decreases arterial stiffness in the setting of obesity by stimulating anti-inflammatory and antioxidant pathways in the aorta. SirT1 activators may represent a novel therapeutic approach to prevent arterial stiffness and associated cardiovascular complications in overweight/obese individuals with metabolic syndrome.

SUBMITTER: Fry JL

PROVIDER: S-EPMC4982825 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature

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Vascular Smooth Muscle Sirtuin-1 Protects Against Diet-Induced Aortic Stiffness.

Fry Jessica L JL Al Sayah Leona L Weisbrod Robert M RM Van Roy Isabelle I Weng Xiang X Cohen Richard A RA Bachschmid Markus M MM Seta Francesca F

Hypertension (Dallas, Tex. : 1979) 20160718 3

Arterial stiffness, a major cardiovascular risk factor, develops within 2 months in mice fed a high-fat, high-sucrose (HFHS) diet, serving as a model of human metabolic syndrome, and it is associated with activation of proinflammatory and oxidant pathways in vascular smooth muscle (VSM) cells. Sirtuin-1 (SirT1) is an NAD(+)-dependent deacetylase regulated by the cellular metabolic status. Our goal was to study the effects of VSM SirT1 on arterial stiffness in the context of diet-induced metaboli ...[more]

PMID: 27432859

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Project description:BackgroundThoracic aortic aneurysms (TAAs) are abnormal aortic dilatations and a major cardiovascular complication of Marfan syndrome. We previously demonstrated a critical role for vascular smooth muscle (VSM) SirT1 (sirtuin-1), a lysine deacetylase, against maladaptive aortic remodeling associated with chronic oxidative stress and aberrant activation of MMPs (matrix metalloproteinases).MethodsIn this study, we investigated whether redox dysregulation of SirT1 contributed to the pathogenesis of TAA using fibrillin-1 hypomorphic mice (Fbn1mgR/mgR), an established model of Marfan syndrome prone to aortic dissection/rupture.ResultsOxidative stress markers 3-nitrotyrosine and 4-hydroxynonenal were significantly elevated in aortas of patients with Marfan syndrome. Moreover, reversible oxidative post-translational modifications (rOPTM) of protein cysteines, particularly S-glutathionylation, were dramatically increased in aortas of Fbn1mgR/mgR mice, before induction of severe oxidative stress markers. Fbn1mgR/mgR aortas and VSM cells exhibited an increase in rOPTM of SirT1, coinciding with the upregulation of acetylated proteins, an index of decreased SirT1 activity, and increased MMP2/9 activity. Mechanistically, we demonstrated that TGFβ (transforming growth factor beta), which was increased in Fbn1mgR/mgR aortas, stimulated rOPTM of SirT1, decreasing its deacetylase activity in VSM cells. VSM cell-specific deletion of SirT1 in Fbn1mgR/mgR mice (SMKO-Fbn1mgR/mgR) caused a dramatic increase in aortic MMP2 expression and worsened TAA progression, leading to aortic rupture in 50% of SMKO-Fbn1mgR/mgR mice, compared with 25% of Fbn1mgR/mgR mice. rOPTM of SirT1, rOPTM-mediated inhibition of SirT1 activity, and increased MMP2/9 activity were all exacerbated by the deletion of Glrx (glutaredoxin-1), a specific deglutathionylation enzyme, while being corrected by overexpression of Glrx or of an oxidation-resistant SirT1 mutant in VSM cells.ConclusionsOur novel findings strongly suggest a causal role of S-glutathionylation of SirT1 in the pathogenesis of TAA. Prevention or reversal of SirT1 rOPTM may be a novel therapeutic strategy to prevent TAA and TAA dissection/ruptures in individuals with Marfan syndrome, for which, thus far, no targeted therapy has been developed.

Project description:Background: Abdominal aortic aneurysm (AAA) is a potentially life-threatening condition, but approved medical therapies to prevent AAA progression and rupture are currently lacking. Sphingolipids metabolism disorders are associated with the occurrence and development of AAA. It has been discovered that ganglioside GM3, a sialic acid-containing type of glycosphingolipid, plays a protective role in atherosclerosis which is an important risk factor for AAA, but the potential contribution of GM3 to AAA development has not been investigated. Methods: We performed a metabolomics study to evaluated GM3 level in plasma of human AAA patients. We profiled GM3 synthase (ST3GAL5) expression in the mouse model of aneurysm and human AAA tissues through western blotting and immunofluorescence staining. RNA sequencing, proteomic analysis, affinity purification and mass spectrometry, surface plasmon resonance (SPR) analysis, and functional studies were used to dissect the molecular mechanism of GM3-regulating ferroptosis. We conditionally deleted and overexpressed St3gal5 in smooth muscle cells (SMCs) in vivo to investigate its role in AAA. Results: We found significantly reduced plasma levels of the GM3 in human AAA patients. GM3 content and ST3GAL5 expression were all decreased in abdominal aortic VSMCs in AAA patients and mouse model. RNA-sequencing analysis showed that ST3GAL5 silencing in human aortic SMCs (HASMCs) induced ferroptosis. Importantly, we showed that GM3 interacted directly with the extracellular domain of transferrin receptor 1 (TFR1), a cell membrane protein critical for cellular iron uptake, disrupted its interaction with holo-transferrin. SMC-specific St3gal5 knockout exacerbated iron accumulation at lesion sites and significantly promoted AAA development, while GM3 supplementation suppressed lipid peroxidation, reduced iron deposition in aortic VSMCs and markedly decreased AAA incidence. Conclusions: Together, these results suggest that GM3 dysregulation promotes ferroptosis of VSMCs in AAA. Furthermore, GM3 may constitute a new therapeutic target for the treatment of AAA.

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Dataset Information

Vascular Smooth Muscle Sirtuin-1 Protects Against Diet-Induced Aortic Stiffness.

Publications

Vascular Smooth Muscle Sirtuin-1 Protects Against Diet-Induced Aortic Stiffness.

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