Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2014 Jan;109(1):399.
doi: 10.1007/s00395-013-0399-0. Epub 2013 Dec 27.

Deletion of Sirt3 does not affect atherosclerosis but accelerates weight gain and impairs rapid metabolic adaptation in LDL receptor knockout mice: implications for cardiovascular risk factor development

Stephan Winnik  1 , Daniel S Gaul, Frédéric Preitner, Christine Lohmann, Julien Weber, Melroy X Miranda, Yilei Liu, Lambertus J van Tits, José María Mateos, Chad E Brokopp, Johan Auwerx, Bernard Thorens, Thomas F Lüscher, Christian M Matter
Affiliations

Deletion of Sirt3 does not affect atherosclerosis but accelerates weight gain and impairs rapid metabolic adaptation in LDL receptor knockout mice: implications for cardiovascular risk factor development

Stephan Winnik et al. Basic Res Cardiol. 2014 Jan.

Abstract

Sirt3 is a mitochondrial NAD(+)-dependent deacetylase that governs mitochondrial metabolism and reactive oxygen species homeostasis. Sirt3 deficiency has been reported to accelerate the development of the metabolic syndrome. However, the role of Sirt3 in atherosclerosis remains enigmatic. We aimed to investigate whether Sirt3 deficiency affects atherosclerosis, plaque vulnerability, and metabolic homeostasis. Low-density lipoprotein receptor knockout (LDLR(-/-)) and LDLR/Sirt3 double-knockout (Sirt3(-/-)LDLR(-/-)) mice were fed a high-cholesterol diet (1.25 % w/w) for 12 weeks. Atherosclerosis was assessed en face in thoraco-abdominal aortae and in cross sections of aortic roots. Sirt3 deletion led to hepatic mitochondrial protein hyperacetylation. Unexpectedly, though plasma malondialdehyde levels were elevated in Sirt3-deficient mice, Sirt3 deletion affected neither plaque burden nor features of plaque vulnerability (i.e., fibrous cap thickness and necrotic core diameter). Likewise, plaque macrophage and T cell infiltration as well as endothelial activation remained unaltered. Electron microscopy of aortic walls revealed no difference in mitochondrial microarchitecture between both groups. Interestingly, loss of Sirt3 was associated with accelerated weight gain and an impaired capacity to cope with rapid changes in nutrient supply as assessed by indirect calorimetry. Serum lipid levels and glucose tolerance were unaffected by Sirt3 deletion in LDLR(-/-) mice. Sirt3 deficiency does not affect atherosclerosis in LDLR(-/-) mice. However, Sirt3 controls systemic levels of oxidative stress, limits expedited weight gain, and allows rapid metabolic adaptation. Thus, Sirt3 may contribute to postponing cardiovascular risk factor development.

PubMed Disclaimer

Figures

Fig. 1
Fig. 1
Loss of Sirt3 does not affect atherosclerosis in LDLR knockout mice after a high-cholesterol diet. 8-week old male Sirt3 −/− LDLR −/− and Sirt3 +/+ LDLR −/− mice were fed a high-cholesterol diet (1.25 % w/w) for 12 weeks before aortae were excised. a Plaque burden of thoraco-abdominal aortae en face, stained with Oil Red O (ORO), n = 10 per group. b–e Cryosections of aortic roots, n = 6 per group, stained with Oil red O (ORO) (b), or immunohistochemically for CD68 (C), CD3 (d), or vascular cell adhesion molecule-1 (VCAM-1) (e). Images are representative micrographs, box plots display interquartile ranges, whiskers indicate minima and maxima, scale bars are 1 mm (a) and 500 μm (b–e)
Fig. 2
Fig. 2
Deletion of Sirt3 does not affect features of plaque stability. Sirt3 −/− LDLR −/− and Sirt3 +/+ LDLR −/− mice were treated as described and aortae excised. a Cryosections of aortic roots, stained for collagen with Sirius red, n = 6 per group. b Quantification of fibrous cap thickness, necrotic core diameter and area. Images are representative micrographs, box plots display interquartile ranges, whiskers indicate minima and maxima, scale bars are 500 μm
Fig. 3
Fig. 3
Sirt3 deficiency does not affect endothelial mitochondrial architecture in the aortic wall. Sirt3 −/− LDLR −/− and Sirt3 +/+ LDLR −/− mice were treated as described and aortae excised and cross sections of the thoracic descending aorta were imaged using electron microscopy. a, b Overview of the inner vascular wall (from left to right): endothelial monolayer with endothelial nuclei (Ncl) protruding towards the lumen, elastica interna, vascular smooth muscle cell layer. c, d Magnification of an endothelial cell, allowing the differentiation of its subcellular components, including mitochondria (M). e, f Magnification of a single endothelial mitochondrion, showing mitochondrial microarchitecture. Images are representative micrographs of n = 5 per group and 100 mitochondria per aortic phenotype, and serve for qualitative comparisons only. M mitochondrion, Ncl nucleus, ER endoplasmic reticulum
Fig. 4
Fig. 4
Loss of Sirt3 increases systemic oxidative stress without affecting vascular oxidative DNA damage. Sirt3 −/− LDLR −/− and Sirt3 +/+ LDLR −/− mice were treated as described, blood was drawn and aortas were explanted. a Malondialdehyde (MDA) levels as surrogate for systemic oxidative stress, n = 8 per group. b Aortic DNA was isolated and relative oxidative damage of genomic (b) and mitochondrial DNA c was assessed using quantitative PCR. b Lesion frequency and the resulting copy number of DNA polymerase b as surrogate for genomic DNA damage, n = 10 per group. c Lesion frequency and the resulting copy number of a 1 kb mitochondrial DNA fragment as surrogate for mitochondrial DNA damage, n = 10 per group. d–f Expression of catalase (cat) and superoxide dismutase 2 (SOD2) were assessed using quantitative PCR, n = 9 per group (d, e) and by western blot, n = 5 per group (f). g Plasma isocitrate dehydrogenase 2 (IDH2) activity, n = 9 per group. h Plasma glutathione reductase (GR) activity, n = 6 per group. i Plasma NADP/NADPH ratio, n = 5 per group. Box plots display interquartile ranges, whiskers indicate minima and maxima
Fig. 5
Fig. 5
Loss of Sirt3 lead to global mitochondrial hyperacetylation. Hepatic mitochondria were isolated and protein was extracted, separated by electrophoresis and probed for Sirt3 (α-Sirt3), acetylated lysine residues (α-AcK) and the beta-subunit of ATP-Synthase (α-ATPB, loading control). Data are mean ± SEMs with superimposition of individual data points
Fig. 6
Fig. 6
Deletion of Sirt3 accelerates weight gain and increases plasma glucose levels. Sirt3 −/− LDLR −/− and Sirt3 +/+ LDLR −/− mice were fed a high-cholesterol diet (1.25 % w/w) for 12 weeks. a Weight gain during treatment (left panel) and its quantification comparing areas under the curve (AUC, right panel). b Plasma glucose levels, fed (left panel) and fasted (right panel). c Plasma glucose levels upon intraperitoneal glucose challenge (2 g/kg body weight) (left panel), quantification comparing areas under the curve (AUC, right panel). d Plasma free fatty acid (FFA) content, fed (left panel) and fasted (right panel). Data are means ± SEMs with superimposition of individual data points in all panels except for a and c, left panels
Fig. 7
Fig. 7
Loss of Sirt3 impairs metabolic adaptation to rapid changes in energy supply. After a 12-week high-cholesterol diet (1.25 % w/w) different metabolic parameters were assessed in individually caged Sirt3 −/− LDLR −/− and Sirt3 +/+ LDLR −/− mice during five light cycles. a, b Metabolic rate (heat production): circadian profile during an ad libitum fed state (night 1 to day 3), during a 15-h overnight fasting period (5 pm, day 3 through 8 am, day 4) and during subsequent refeeding (day 4, night 5), N night, D day. b Average metabolic rates per day/night (left panel); metabolic drop during fasting (“delta night 3 vs. night 4”, center panel), and metabolic rebound upon refeeding (“delta night 4 vs. night 5”, right panel). c Average oxygen consumption (VO2) per day/night (left panel); VO2 drop during fasting (“delta night 3 vs. night 4”, center panel), and VO2 rebound upon refeeding (“delta night 4 vs. night 5”, right panel). d Average locomotor activity per day/night. e Average food intake per day/night. Data are means ± SEM, with superimposition of individual data points in “delta” panels. *) p < 0.01 compared with LDLR −/− Sirt3 −/− mice
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Ahn B-H, Kim H-S, Song S, Lee IH, Liu J, Vassilopoulos A, Deng C-X, Finkel T. A role for the mitochondrial deacetylase Sirt3 in regulating energy homeostasis. Proc Natl Acad Sci USA. 2008;105:14447–14452. doi: 10.1073/pnas.0803790105. - DOI - PMC - PubMed
    1. Alberti KGMM, Eckel RH, Grundy SM, Zimmet PZ, Cleeman JI, Donato KA, Fruchart JC, James WPT, Loria CM, Smith SC. Harmonizing the Metabolic Syndrome: a joint interim statement of the international diabetes federation task force on epidemiology and prevention; National Heart, Lung, and Blood Institute; American Heart Association; World Heart Federation; International Atherosclerosis Society; and International Association for the Study of Obesity. Circulation. 2009;120:1640–1645. doi: 10.1161/CIRCULATIONAHA.109.192644. - DOI - PubMed
    1. Bellizzi D, Rose G, Cavalcante P, Covello G, Dato S, De Rango F, Greco V, Magiolini M, Feraco E, Mari V, Franceschi C, Passarino G, De Benidictis G. A novel VNTR enhancer within the SIRT3 gene, a human homologue of SIR2, is associated with survival at oldest ages. Genomics. 2005;85:258–263. doi: 10.1016/j.ygeno.2004.11.003. - DOI - PubMed
    1. Chen Y, Zhang J, Lin Y, Lei Q, Guan K-L, Zhao S, Xiong Y. Tumour suppressor SIRT3 deacetylates and activates manganese superoxide dismutase to scavenge ROS. EMBO Rep. 2011;12:534–541. doi: 10.1038/embor.2011.65. - DOI - PMC - PubMed
    1. Cimen H, Han M-J, Yang Y, Tong Q, Koc H, Koc EC. Regulation of succinate dehydrogenase activity by SIRT3 in mammalian mitochondria. Biochemistry. 2010;49:304–311. doi: 10.1021/bi901627u. - DOI - PMC - PubMed

Publication types