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. 2018 Oct 1;315(4):E520-E530.
doi: 10.1152/ajpendo.00057.2018. Epub 2018 Apr 10.

NAD+-dependent deacetylase SIRT3 in adipocytes is dispensable for maintaining normal adipose tissue mitochondrial function and whole body metabolism

Lane C Porter  1 , Michael P Franczyk  1 , Terri Pietka  1 , Shintaro Yamaguchi  1 , Jonathan B Lin  2 , Yo Sasaki  3 , Eric Verdin  4   5 , Rajendra S Apte  1   2   6 , Jun Yoshino  1
Affiliations

NAD+-dependent deacetylase SIRT3 in adipocytes is dispensable for maintaining normal adipose tissue mitochondrial function and whole body metabolism

Lane C Porter et al. Am J Physiol Endocrinol Metab. .

Abstract

Mitochondrial dysfunction in adipose tissue is involved in the pathophysiology of obesity-induced systemic metabolic complications, such as type 2 diabetes, insulin resistance, and dyslipidemia. However, the mechanisms responsible for obesity-induced adipose tissue mitochondrial dysfunction are not clear. The aim of present study was to test the hypothesis that nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase sirtuin-3 (SIRT3) in adipocytes plays a critical role in adipose tissue mitochondrial biology and obesity. We first measured adipose tissue SIRT3 expression in obese and lean mice. Next, adipocyte-specific mitochondrial Sirt3 knockout (AMiSKO) mice were generated and metabolically characterized. We evaluated glucose and lipid metabolism in adult mice fed either a regular-chow diet or high-fat diet (HFD) and in aged mice. We also determined the effects of Sirt3 deletion on adipose tissue metabolism and mitochondrial biology. Supporting our hypothesis, obese mice had decreased SIRT3 gene and protein expression in adipose tissue. However, despite successful knockout of SIRT3, AMiSKO mice had normal glucose and lipid metabolism and did not change metabolic responses to HFD-feeding and aging. In addition, loss of SIRT3 had no major impact on putative SIRT3 targets, key metabolic pathways, and mitochondrial function in white and brown adipose tissue. Collectively, these findings suggest that adipocyte SIRT3 is dispensable for maintaining normal adipose tissue mitochondrial function and whole body metabolism. Contrary to our hypothesis, loss of SIRT3 function in adipocytes is unlikely to contribute to the pathophysiology of obesity-induced metabolic complications.

Keywords: NAD+; SIRT3; adipocyte; adipose tissue; glucose metabolism; mitochondria; obesity.

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Figures

Fig. 1.
Fig. 1.
Adipose tissue sirtuin 3 (SIRT3) expression in obese mice. A: gene expression of Sirt3, peroxisome proliferator-activated receptor-γ coactivator 1α(Pgc1α) and adiponectin (Adipoq), was determined in visceral adipose tissue (VAT) obtained from genetically obese (db/db) and high-fat diet (HFD)-induced obese mice and their lean controls (db/+ mice and regular-chow diet [RCD]-fed mice, respectively; n = 5 per group). B: VAT mitochondrial DNA (mtDNA) contents were normalized to nuclear DNA (nucDNA) contents (n = 3–5 per group). C: Western blot analysis of SIRT3 in VAT (n = 4–5 per group). Densitometric analysis of SIRT3 protein normalized to tubulin is shown. *Value significantly different from control value (Student’s t-test, P < 0.05). Values are means ± SE.
Fig. 2.
Fig. 2.
Generation of adipocyte-specific mitochondrial Sirt3 knockout (AMiSKO) mice. AMiSKO mice were generated by using Adipoq-Cre transgenic mice and floxed-Sirt3 (flox/flox) mice. A: Western blot analysis of SIRT3 in VAT, subcutaneous adipose tissue (SAT), brown adipose tissue (BAT), liver, skeletal muscle, and heart. B: gene expression of mitochondrial sirtuins (Sirt3, Sirt4, Sirt5) in VAT adipocytes and BAT (n = 3–5 per group). C: Western blot analysis of SIRT3, acetylated lysine (Ac-K), and cytochrome c oxidase (COX) IV. Mitochondrial proteins isolated from VAT adipocytes and BAT were separated on Any-kD gels (Bio-Rad). Densitometric analysis of acetylated mitochondrial protein bands (between 20 and 50 kDa) is shown. *Value significantly different from control value (Student’s t-test, P < 0.05). Values are means ± SE.
Fig. 3.
Fig. 3.
Metabolic phenotype of AMiSKO mice under RCD and HFD conditions. Characterization of male AMiSKO and flox/flox mice fed either a RCD (A–D) or HFD (E–H). For HFD study, mice were placed on a HFD starting from 3 to 7 wk of age. Body weight and body composition were measured in 3- to 6-mo-old RCD-fed mice (A) and in mice after 6 mo of HFD feeding (E) (n = 5–9 per group). Blood glucose concentrations during the intraperitoneal glucose tolerance tests (IPGTTs) in 9- to 12-mo-old RCD-fed mice (B) and in mice after 4 mo of HFD feeding (F) (n = 9–10 per group). Area under the curve (AUC) for glucose is shown next to each curve. Blood glucose concentrations during insulin tolerance tests (ITTs) in 9- to 12-mo-old RCD-fed mice (C) and in mice after 4 mo of HFD feeding (G) (n = 9–10 per group). AUC for glucose is shown next to each curve. Plasma concentrations of triglyceride (TG), total cholesterol (TC), and free fatty acids (FFA) were determined in 9- to 12-mo-old RCD- fed mice (D) and in mice after 6 mo of HFD feeding (H) (n = 5–10 per group). There was a significant time effect (P < 0.05) but no group × time interaction in body weight, IPGTT, and ITT data (ANOVA). Values are means ± SE.
Fig. 4.
Fig. 4.
Adipose tissue metabolism and mitochondrial biology in AMiSKO mice. SIRT3 targets and mitochondrial metabolic pathways in VAT of AMiSKO and flox/flox mice. Adipocyte size (n = 4 per group; A), plasma adiponectin and leptin concentrations (n = 5 per group; B), gene expression of SIRT3 targets and proteins involved in adipose tissue metabolism, inflammation, mitochondrial function, and oxidative stress defense (n = 5 per group; C), mtDNA contents (n = 5 per group; D), GSH and GSSG concentrations and their ratios (n = 3–5 per group; E), and NAD+ and NADH concentrations (n = 4 per group; F) in VAT obtained from 3- to 5-mo-old male mice. G: Western blot analysis of subunits of electron transport chain (ETC) complex (C) in VAT obtained from 3- to 4-mo-old female mice. Densitometric analysis of each protein normalized to tubulin is shown. H: ex vivo respiratory function was evaluated in VAT obtained from 3- to 5-mo-old male mice by using the Seahorse system (n = 6–9 per group). Oxygen consumption rate (OCR) was measured during the basal conditions and in responses to oligomycin (Oligo), carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), and rotenone-antimycin (R-A). Values are means ± SE.
Fig. 5.
Fig. 5.
Brown adipose tissue (BAT) function and energy metabolism in AMiSKO mice. BAT function and energy metabolism were evaluated in AMiSKO and flox/flox mice. A: whole body oxygen consumption (V̇o2), respiratory exchange rate (RER), and energy expenditure (EE) were determined in 4- to 5-mo-old male mice (n = 4 per group). B: rectal body temperature was monitored during cold exposure in 4- to 5-mo-old male mice (n = 5 per group). There was a significant time effect (P < 0.05) but no group × time interaction (ANOVA). Gene expression of SIRT3 targets and proteins involved in regulating thermogenesis, mitochondrial function, and oxidative stress defense (n = 5 per group; C), mtDNA contents (n = 4 per group; D), GSH and GSSG concentrations and their ratios (n = 3–5 per group; E), and NAD+ and NADH concentrations (n = 4 per group; F), in BAT obtained from 3- to 5-mo-old male mice. G: Western blot analysis of subunits of ETC complex (C) in BAT obtained from 3- to 4-mo-old female mice. Densitometric analysis of each protein normalized to tubulin is shown. Values are means ± SE.
Fig. 6.
Fig. 6.
Metabolic phenotype of aged AMiSKO mice. Characterization of aged male AMiSKO and flox/flox mice. A: body composition in 20- to 23-mo-old mice (n = 5–7 per group). Blood glucose concentrations during the IPGTTs (B) and ITTs (C) were determined in 18- to 21-mo-old mice (n = 8–9 per group). AUC for glucose is shown next to each curve. D: plasma lipid profile was determined in 18- to 21-mo-old mice (n = 7–9 per group). E: whole body V̇o2, RER, and EE were determined in 21- to 23-mo-old mice (n = 4 per group). There was a significant time effect (P < 0.05) but no group × time interaction in IPGTTs and ITTs data (ANOVA). Values are means ± SE.
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References

    1. Anderson KA, Hirschey MD. Mitochondrial protein acetylation regulates metabolism. Essays Biochem 52: 23–35, 2012. doi:10.1042/bse0520023. - DOI - PMC - PubMed
    1. Bogacka I, Xie H, Bray GA, Smith SR. Pioglitazone induces mitochondrial biogenesis in human subcutaneous adipose tissue in vivo. Diabetes 54: 1392–1399, 2005. doi:10.2337/diabetes.54.5.1392. - DOI - PubMed
    1. Bugge A, Dib L, Collins S. Measuring respiratory activity of adipocytes and adipose tissues in real time. Methods Enzymol 538: 233–247, 2014. doi:10.1016/B978-0-12-800280-3.00013-X. - DOI - PubMed
    1. Chalkiadaki A, Guarente L. High-fat diet triggers inflammation-induced cleavage of SIRT1 in adipose tissue to promote metabolic dysfunction. Cell Metab 16: 180–188, 2012. doi:10.1016/j.cmet.2012.07.003. - DOI - PMC - PubMed
    1. Cheng A, Yang Y, Zhou Y, Maharana C, Lu D, Peng W, Liu Y, Wan R, Marosi K, Misiak M, Bohr VA, Mattson MP. Mitochondrial SIRT3 mediates adaptive responses of neurons to exercise and metabolic and excitatory challenges. Cell Metab 23: 128–142, 2016. doi:10.1016/j.cmet.2015.10.013. - DOI - PMC - PubMed

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