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Up-regulation of mitochondrial activity and acquirement of brown adipose tissue-like property in the white adipose tissue of fsp27 deficient mice.

Toh SY, Gong J, Du G, Li JZ, Yang S, Ye J, Yao H, Zhang Y, Xue B, Li Q, Yang H, Wen Z, Li P - PLoS ONE (2008)

Bottom Line: Fsp27, a member of the Cide family proteins, was shown to localize to lipid droplet and promote lipid storage in adipocytes.We further demonstrated that BAT-specific genes and key metabolic controlling factors such as FoxC2, PPAR and PGC1alpha were all markedly upregulated.Remarkably, Fsp27(-/-) MEFs differentiated in vitro show many brown adipocyte characteristics in the presence of the thyroid hormone triiodothyronine (T3).

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular and Cell Biology, Singapore.

ABSTRACT
Fsp27, a member of the Cide family proteins, was shown to localize to lipid droplet and promote lipid storage in adipocytes. We aimed to understand the biological role of Fsp27 in regulating adipose tissue differentiation, insulin sensitivity and energy balance. Fsp27(-/-) mice and Fsp27/lep double deficient mice were generated and we examined the adiposity, whole body metabolism, BAT and WAT morphology, insulin sensitivity, mitochondrial activity, and gene expression changes in these mouse strains. Furthermore, we isolated mouse embryonic fibroblasts (MEFs) from wildtype and Fsp27(-/-) mice, followed by their differentiation into adipocytes in vitro. We found that Fsp27 is expressed in both brown adipose tissue (BAT) and white adipose tissue (WAT) and its levels were significantly elevated in the WAT and liver of leptin-deficient ob/ob mice. Fsp27(-/-) mice had increased energy expenditure, lower levels of plasma triglycerides and free fatty acids. Furthermore, Fsp27(-/-)and Fsp27/lep double-deficient mice are resistant to diet-induced obesity and display increased insulin sensitivity. Moreover, white adipocytes in Fsp27(-/-) mice have reduced triglycerides accumulation and smaller lipid droplets, while levels of mitochondrial proteins, mitochondrial size and activity are dramatically increased. We further demonstrated that BAT-specific genes and key metabolic controlling factors such as FoxC2, PPAR and PGC1alpha were all markedly upregulated. In contrast, factors inhibiting BAT differentiation such as Rb, p107 and RIP140 were down-regulated in the WAT of Fsp27(-/-) mice. Remarkably, Fsp27(-/-) MEFs differentiated in vitro show many brown adipocyte characteristics in the presence of the thyroid hormone triiodothyronine (T3). Our data thus suggest that Fsp27 acts as a novel regulator in vivo to control WAT identity, mitochondrial activity and insulin sensitivity.

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Lean phenotype of Fsp27 deficient and leptin/Fsp27 double deficient mice.A. Total lipid content of gonadal white fat pad from 3-month old wild-type (+/+) and Fsp27 mutant (−/−) mice, showing a decrease in lipid content in the WAT of Fsp27−/− mice. 5 pairs of mice were used for analysis. ***p<0.001. B. Body weight of wild type (WT), Fsp27 deficient (Fsp27−/−), leptin deficient (ob/ob) and leptin/Fsp27 double deficient (ob/ob/Fsp27−/−) mice. (wildtype: n = 12; Fsp−/−: n = 12, ob/ob, n = 10; ob/ob/ Fsp27−/−, n = 11, P<0.001)C. Adiposity index of 10 months old wild-type (+/+) and Fsp27 mutant mice (−/−) fed with a normal diet (ND) or high fat diet (HFD). Fsp27 mutant mice have significantly less adipose tissue. (ND: +/+ n = 13, −/− n = 14 , HFD: +/+ n = 12, −/− n = 15) (***p<0.001). D. Adiposity index of 3 months old ob/ob and ob/ob/Fsp27−/− mice. ob/ob: n = 8, ob/ob/ Fsp27−/−: n = 8) (***p<0.001). E. TAG content in gonadal white fat (GWAT) of wild type (WT), Fsp27 mutant (Fsp27−/−), ob/ob, and ob/ob/ Fsp27−/− mice fed with normal diet. 3 mice were used for each genotype. **p<0.01. F. Fasting serum leptin level in mice under normal diet (ND) or high-fat diet (HFD) feeding conditions. ND: +/+ n = 11, −/− n = 8; HFD: +/+ n = 14, −/− n = 11. *p<0.05, ***p<0.001. G. Increased food intake in Fsp27 mutant and ob/ob/Fsp27−/− mice. Wild type: n = 15, Fsp27−/−: n = 17; ob/ob: n = 6, ob/ob/Fsp27−/−: n = 6. **p<0.01. H. Whole body O2 consumption rate of wild-type or Fsp27 mutant mice fed with a ND or HFD. ND: +/+ n = 14, −/− n = 13, HFD: +/+ n = 16, −/− n = 18. **p<0.01, ***p<0.001. I. Lipolysis rate in GWAT of 3 months old wild type (+/+) and Fsp27 mutant (−/−) mice. Basal refers to no isoproterenol (Iso,1 µM) treatment.. N = 4 for each genotype. *p<0.05. J. Core Body temperature of wild-type (+/+) or Fsp27 mutant (−/−) mice after animals were exposed to cold ( 4°C). −1 refers to core body temperature 1 hr before transfer of mice to 4°C. Fsp27 mutant mice had lower core body temperature when exposed to cold. (+/+ n = 25, −/− n = 20, *p<0.05, **p<0.01, ***p<0.001).
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pone-0002890-g002: Lean phenotype of Fsp27 deficient and leptin/Fsp27 double deficient mice.A. Total lipid content of gonadal white fat pad from 3-month old wild-type (+/+) and Fsp27 mutant (−/−) mice, showing a decrease in lipid content in the WAT of Fsp27−/− mice. 5 pairs of mice were used for analysis. ***p<0.001. B. Body weight of wild type (WT), Fsp27 deficient (Fsp27−/−), leptin deficient (ob/ob) and leptin/Fsp27 double deficient (ob/ob/Fsp27−/−) mice. (wildtype: n = 12; Fsp−/−: n = 12, ob/ob, n = 10; ob/ob/ Fsp27−/−, n = 11, P<0.001)C. Adiposity index of 10 months old wild-type (+/+) and Fsp27 mutant mice (−/−) fed with a normal diet (ND) or high fat diet (HFD). Fsp27 mutant mice have significantly less adipose tissue. (ND: +/+ n = 13, −/− n = 14 , HFD: +/+ n = 12, −/− n = 15) (***p<0.001). D. Adiposity index of 3 months old ob/ob and ob/ob/Fsp27−/− mice. ob/ob: n = 8, ob/ob/ Fsp27−/−: n = 8) (***p<0.001). E. TAG content in gonadal white fat (GWAT) of wild type (WT), Fsp27 mutant (Fsp27−/−), ob/ob, and ob/ob/ Fsp27−/− mice fed with normal diet. 3 mice were used for each genotype. **p<0.01. F. Fasting serum leptin level in mice under normal diet (ND) or high-fat diet (HFD) feeding conditions. ND: +/+ n = 11, −/− n = 8; HFD: +/+ n = 14, −/− n = 11. *p<0.05, ***p<0.001. G. Increased food intake in Fsp27 mutant and ob/ob/Fsp27−/− mice. Wild type: n = 15, Fsp27−/−: n = 17; ob/ob: n = 6, ob/ob/Fsp27−/−: n = 6. **p<0.01. H. Whole body O2 consumption rate of wild-type or Fsp27 mutant mice fed with a ND or HFD. ND: +/+ n = 14, −/− n = 13, HFD: +/+ n = 16, −/− n = 18. **p<0.01, ***p<0.001. I. Lipolysis rate in GWAT of 3 months old wild type (+/+) and Fsp27 mutant (−/−) mice. Basal refers to no isoproterenol (Iso,1 µM) treatment.. N = 4 for each genotype. *p<0.05. J. Core Body temperature of wild-type (+/+) or Fsp27 mutant (−/−) mice after animals were exposed to cold ( 4°C). −1 refers to core body temperature 1 hr before transfer of mice to 4°C. Fsp27 mutant mice had lower core body temperature when exposed to cold. (+/+ n = 25, −/− n = 20, *p<0.05, **p<0.01, ***p<0.001).

Mentions: The drastic reduction of lipid droplet size in WAT prompted us to investigate if the atrophy of WAT was due to its loss of lipid content by measuring the total amount of lipid in gonadal WAT. We found that total lipid in gonadal white fat (GWAT) pad was reduced by almost 6 fold (from 0.8995±0.1436 g in wild type to 0.1512±0.0079 g in Fsp27−/− mice, P<0.001, Fig. 2A), which strongly suggests that the reduction in fat pad size observed in WAT of Fsp27−/− mice is a result of decreased lipid content in the adipocytes. The total amount of protein and DNA content within this fat pad was similar between wild-type and Fsp27 mice (data not shown). We then investigated the potential role of Fsp27 in regulating overall body weight and adiposity. Under normal diet (ND) conditions, the body weight of wild type and Fsp27−/− mice were similar (Fig. 2B), while the average body weight of ob/ob mice was dramatically higher than that of wild type or Fsp27−/− mice. However, the body weight of leptin/Fsp27 double deficient (ob/ob/Fsp27−/−) mice was significantly lower than that of ob/ob mice (Fig. 2B, P<0.001), suggesting that Fsp27-deficiency could counteract with weight gain in ob/ob mice. When fed with a ND, the adiposity index of Fsp27−/− mice (0.0611±0.0021) was approximately 45% lower than that of wild type mice (0.1101±0.0008, P<0.0001). We also observed no difference in overall size with a slightly increased weight of some individual organs such as liver and heart in Fsp27−/− mice compared to control animals (data not shown). When mice were fed with a high fat diet (HFD), there was a 54% reduction in adiposity index in Fsp27 mice (0.0772±0.0042) compared to that of wild type mice (0.1695±0.0052, P<0.0001, Fig. 2C). While the adiposity index of ob/ob mice is approximately 30%, the adiposity index for ob/ob/Fsp27−/− mice (10%) was markedly lower (P<0.001), representing a 70% reduction in total body fat (Fig. 2D). Consistent with the decreased adiposity index, the weight of fat pads from different anatomical locations in Fsp27−/− as well as WAT and BAT in ob/ob/Fsp27−/− mice was significantly reduced (Table 1 & 2). Levels of TAG in the WAT of Fsp27−/− mice (25.3±2.6 µmol/mg protein) were much lower than that of wild type mice (213.2±62.5 µmol/mg protein), representing a 90% reduction (P<0.01, Fig. 2E). Furthermore, TAG levels in the WAT of ob/ob/Fsp27−/− mice were much lower (27.7±3.9 vs 586.9±100.7 µmol/mg protein, P<0.01, Fig. 2E) compared with that of ob/ob mice. In addition to a reduced amount of TAG in WAT, the amount of TAG in the liver and skeletal muscle of Fsp27−/− mice was also significantly reduced (Fig. S1B). Therefore, the reduced TAG levels in WAT were not due to alternative lipid storage in other tissues such as liver and SM.


Up-regulation of mitochondrial activity and acquirement of brown adipose tissue-like property in the white adipose tissue of fsp27 deficient mice.

Toh SY, Gong J, Du G, Li JZ, Yang S, Ye J, Yao H, Zhang Y, Xue B, Li Q, Yang H, Wen Z, Li P - PLoS ONE (2008)

Lean phenotype of Fsp27 deficient and leptin/Fsp27 double deficient mice.A. Total lipid content of gonadal white fat pad from 3-month old wild-type (+/+) and Fsp27 mutant (−/−) mice, showing a decrease in lipid content in the WAT of Fsp27−/− mice. 5 pairs of mice were used for analysis. ***p<0.001. B. Body weight of wild type (WT), Fsp27 deficient (Fsp27−/−), leptin deficient (ob/ob) and leptin/Fsp27 double deficient (ob/ob/Fsp27−/−) mice. (wildtype: n = 12; Fsp−/−: n = 12, ob/ob, n = 10; ob/ob/ Fsp27−/−, n = 11, P<0.001)C. Adiposity index of 10 months old wild-type (+/+) and Fsp27 mutant mice (−/−) fed with a normal diet (ND) or high fat diet (HFD). Fsp27 mutant mice have significantly less adipose tissue. (ND: +/+ n = 13, −/− n = 14 , HFD: +/+ n = 12, −/− n = 15) (***p<0.001). D. Adiposity index of 3 months old ob/ob and ob/ob/Fsp27−/− mice. ob/ob: n = 8, ob/ob/ Fsp27−/−: n = 8) (***p<0.001). E. TAG content in gonadal white fat (GWAT) of wild type (WT), Fsp27 mutant (Fsp27−/−), ob/ob, and ob/ob/ Fsp27−/− mice fed with normal diet. 3 mice were used for each genotype. **p<0.01. F. Fasting serum leptin level in mice under normal diet (ND) or high-fat diet (HFD) feeding conditions. ND: +/+ n = 11, −/− n = 8; HFD: +/+ n = 14, −/− n = 11. *p<0.05, ***p<0.001. G. Increased food intake in Fsp27 mutant and ob/ob/Fsp27−/− mice. Wild type: n = 15, Fsp27−/−: n = 17; ob/ob: n = 6, ob/ob/Fsp27−/−: n = 6. **p<0.01. H. Whole body O2 consumption rate of wild-type or Fsp27 mutant mice fed with a ND or HFD. ND: +/+ n = 14, −/− n = 13, HFD: +/+ n = 16, −/− n = 18. **p<0.01, ***p<0.001. I. Lipolysis rate in GWAT of 3 months old wild type (+/+) and Fsp27 mutant (−/−) mice. Basal refers to no isoproterenol (Iso,1 µM) treatment.. N = 4 for each genotype. *p<0.05. J. Core Body temperature of wild-type (+/+) or Fsp27 mutant (−/−) mice after animals were exposed to cold ( 4°C). −1 refers to core body temperature 1 hr before transfer of mice to 4°C. Fsp27 mutant mice had lower core body temperature when exposed to cold. (+/+ n = 25, −/− n = 20, *p<0.05, **p<0.01, ***p<0.001).
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pone-0002890-g002: Lean phenotype of Fsp27 deficient and leptin/Fsp27 double deficient mice.A. Total lipid content of gonadal white fat pad from 3-month old wild-type (+/+) and Fsp27 mutant (−/−) mice, showing a decrease in lipid content in the WAT of Fsp27−/− mice. 5 pairs of mice were used for analysis. ***p<0.001. B. Body weight of wild type (WT), Fsp27 deficient (Fsp27−/−), leptin deficient (ob/ob) and leptin/Fsp27 double deficient (ob/ob/Fsp27−/−) mice. (wildtype: n = 12; Fsp−/−: n = 12, ob/ob, n = 10; ob/ob/ Fsp27−/−, n = 11, P<0.001)C. Adiposity index of 10 months old wild-type (+/+) and Fsp27 mutant mice (−/−) fed with a normal diet (ND) or high fat diet (HFD). Fsp27 mutant mice have significantly less adipose tissue. (ND: +/+ n = 13, −/− n = 14 , HFD: +/+ n = 12, −/− n = 15) (***p<0.001). D. Adiposity index of 3 months old ob/ob and ob/ob/Fsp27−/− mice. ob/ob: n = 8, ob/ob/ Fsp27−/−: n = 8) (***p<0.001). E. TAG content in gonadal white fat (GWAT) of wild type (WT), Fsp27 mutant (Fsp27−/−), ob/ob, and ob/ob/ Fsp27−/− mice fed with normal diet. 3 mice were used for each genotype. **p<0.01. F. Fasting serum leptin level in mice under normal diet (ND) or high-fat diet (HFD) feeding conditions. ND: +/+ n = 11, −/− n = 8; HFD: +/+ n = 14, −/− n = 11. *p<0.05, ***p<0.001. G. Increased food intake in Fsp27 mutant and ob/ob/Fsp27−/− mice. Wild type: n = 15, Fsp27−/−: n = 17; ob/ob: n = 6, ob/ob/Fsp27−/−: n = 6. **p<0.01. H. Whole body O2 consumption rate of wild-type or Fsp27 mutant mice fed with a ND or HFD. ND: +/+ n = 14, −/− n = 13, HFD: +/+ n = 16, −/− n = 18. **p<0.01, ***p<0.001. I. Lipolysis rate in GWAT of 3 months old wild type (+/+) and Fsp27 mutant (−/−) mice. Basal refers to no isoproterenol (Iso,1 µM) treatment.. N = 4 for each genotype. *p<0.05. J. Core Body temperature of wild-type (+/+) or Fsp27 mutant (−/−) mice after animals were exposed to cold ( 4°C). −1 refers to core body temperature 1 hr before transfer of mice to 4°C. Fsp27 mutant mice had lower core body temperature when exposed to cold. (+/+ n = 25, −/− n = 20, *p<0.05, **p<0.01, ***p<0.001).
Mentions: The drastic reduction of lipid droplet size in WAT prompted us to investigate if the atrophy of WAT was due to its loss of lipid content by measuring the total amount of lipid in gonadal WAT. We found that total lipid in gonadal white fat (GWAT) pad was reduced by almost 6 fold (from 0.8995±0.1436 g in wild type to 0.1512±0.0079 g in Fsp27−/− mice, P<0.001, Fig. 2A), which strongly suggests that the reduction in fat pad size observed in WAT of Fsp27−/− mice is a result of decreased lipid content in the adipocytes. The total amount of protein and DNA content within this fat pad was similar between wild-type and Fsp27 mice (data not shown). We then investigated the potential role of Fsp27 in regulating overall body weight and adiposity. Under normal diet (ND) conditions, the body weight of wild type and Fsp27−/− mice were similar (Fig. 2B), while the average body weight of ob/ob mice was dramatically higher than that of wild type or Fsp27−/− mice. However, the body weight of leptin/Fsp27 double deficient (ob/ob/Fsp27−/−) mice was significantly lower than that of ob/ob mice (Fig. 2B, P<0.001), suggesting that Fsp27-deficiency could counteract with weight gain in ob/ob mice. When fed with a ND, the adiposity index of Fsp27−/− mice (0.0611±0.0021) was approximately 45% lower than that of wild type mice (0.1101±0.0008, P<0.0001). We also observed no difference in overall size with a slightly increased weight of some individual organs such as liver and heart in Fsp27−/− mice compared to control animals (data not shown). When mice were fed with a high fat diet (HFD), there was a 54% reduction in adiposity index in Fsp27 mice (0.0772±0.0042) compared to that of wild type mice (0.1695±0.0052, P<0.0001, Fig. 2C). While the adiposity index of ob/ob mice is approximately 30%, the adiposity index for ob/ob/Fsp27−/− mice (10%) was markedly lower (P<0.001), representing a 70% reduction in total body fat (Fig. 2D). Consistent with the decreased adiposity index, the weight of fat pads from different anatomical locations in Fsp27−/− as well as WAT and BAT in ob/ob/Fsp27−/− mice was significantly reduced (Table 1 & 2). Levels of TAG in the WAT of Fsp27−/− mice (25.3±2.6 µmol/mg protein) were much lower than that of wild type mice (213.2±62.5 µmol/mg protein), representing a 90% reduction (P<0.01, Fig. 2E). Furthermore, TAG levels in the WAT of ob/ob/Fsp27−/− mice were much lower (27.7±3.9 vs 586.9±100.7 µmol/mg protein, P<0.01, Fig. 2E) compared with that of ob/ob mice. In addition to a reduced amount of TAG in WAT, the amount of TAG in the liver and skeletal muscle of Fsp27−/− mice was also significantly reduced (Fig. S1B). Therefore, the reduced TAG levels in WAT were not due to alternative lipid storage in other tissues such as liver and SM.

Bottom Line: Fsp27, a member of the Cide family proteins, was shown to localize to lipid droplet and promote lipid storage in adipocytes.We further demonstrated that BAT-specific genes and key metabolic controlling factors such as FoxC2, PPAR and PGC1alpha were all markedly upregulated.Remarkably, Fsp27(-/-) MEFs differentiated in vitro show many brown adipocyte characteristics in the presence of the thyroid hormone triiodothyronine (T3).

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular and Cell Biology, Singapore.

ABSTRACT
Fsp27, a member of the Cide family proteins, was shown to localize to lipid droplet and promote lipid storage in adipocytes. We aimed to understand the biological role of Fsp27 in regulating adipose tissue differentiation, insulin sensitivity and energy balance. Fsp27(-/-) mice and Fsp27/lep double deficient mice were generated and we examined the adiposity, whole body metabolism, BAT and WAT morphology, insulin sensitivity, mitochondrial activity, and gene expression changes in these mouse strains. Furthermore, we isolated mouse embryonic fibroblasts (MEFs) from wildtype and Fsp27(-/-) mice, followed by their differentiation into adipocytes in vitro. We found that Fsp27 is expressed in both brown adipose tissue (BAT) and white adipose tissue (WAT) and its levels were significantly elevated in the WAT and liver of leptin-deficient ob/ob mice. Fsp27(-/-) mice had increased energy expenditure, lower levels of plasma triglycerides and free fatty acids. Furthermore, Fsp27(-/-)and Fsp27/lep double-deficient mice are resistant to diet-induced obesity and display increased insulin sensitivity. Moreover, white adipocytes in Fsp27(-/-) mice have reduced triglycerides accumulation and smaller lipid droplets, while levels of mitochondrial proteins, mitochondrial size and activity are dramatically increased. We further demonstrated that BAT-specific genes and key metabolic controlling factors such as FoxC2, PPAR and PGC1alpha were all markedly upregulated. In contrast, factors inhibiting BAT differentiation such as Rb, p107 and RIP140 were down-regulated in the WAT of Fsp27(-/-) mice. Remarkably, Fsp27(-/-) MEFs differentiated in vitro show many brown adipocyte characteristics in the presence of the thyroid hormone triiodothyronine (T3). Our data thus suggest that Fsp27 acts as a novel regulator in vivo to control WAT identity, mitochondrial activity and insulin sensitivity.

Show MeSH
Related in: MedlinePlus