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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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Differentiated Fsp27−/− MEFs display many brown adipocyte characteristics.A. Smaller lipid droplets in differentiated Fsp27 mutant mouse embryonic fibroblasts (MEFs). Lipid droplets were stained with BODIPY493/503, and nuclei were stained with Hochest 366243. Fields shown were visualized under fluorescence microscope at appropriate wavelengths for GFP (green) and Hoechst (blue). B. Lower TAG accumulation in differentiated Fsp27−/− MEFs (−/−) than in wildtype (+/+) cells. (n = 4) (**p<0.01; ***p<0.001). C. Increased basal lipolysis rate in differentiated Fsp27−/− MEFs in the absence or presence of T3 (10 nM) in the differentiation medium. (n = 3) (*p<0.05; **p<0.01). D. Western blot analysis showing levels of various proteins in differentiated MEF cells in the absence or presence of T3 (10 nM). β-tubulin was used as a loading control. E. Relative mRNA levels of various genes in differentiated wildtype (+/+) and Fsp27−/−(−/−)MEFs. mRNA levels for Rb were measured using MEFs that were differentiated for 3 days. (n = 4) (*p<0.05). F. Higher levels of fatty acid β-oxidation rate in differentiated Fsp27−/− (−/−) MEFs as compared to wildtype (+/+) MEFs in the presence of T3 (10nM). (n = 4) (**p<0.01). Results of relative amount of 3H2O released into the medium after four (4h) or six (6h) hours chase of pre-labelled MEFs with cold palmitate. Wildtype oxidation rate at 4h is set to 100. G. Regulatory and metabolic pathways that are altered in the WAT of Fsp27−/− mutant mice, leading to anti-obesity and insulin sensitive phenotype.
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pone-0002890-g006: Differentiated Fsp27−/− MEFs display many brown adipocyte characteristics.A. Smaller lipid droplets in differentiated Fsp27 mutant mouse embryonic fibroblasts (MEFs). Lipid droplets were stained with BODIPY493/503, and nuclei were stained with Hochest 366243. Fields shown were visualized under fluorescence microscope at appropriate wavelengths for GFP (green) and Hoechst (blue). B. Lower TAG accumulation in differentiated Fsp27−/− MEFs (−/−) than in wildtype (+/+) cells. (n = 4) (**p<0.01; ***p<0.001). C. Increased basal lipolysis rate in differentiated Fsp27−/− MEFs in the absence or presence of T3 (10 nM) in the differentiation medium. (n = 3) (*p<0.05; **p<0.01). D. Western blot analysis showing levels of various proteins in differentiated MEF cells in the absence or presence of T3 (10 nM). β-tubulin was used as a loading control. E. Relative mRNA levels of various genes in differentiated wildtype (+/+) and Fsp27−/−(−/−)MEFs. mRNA levels for Rb were measured using MEFs that were differentiated for 3 days. (n = 4) (*p<0.05). F. Higher levels of fatty acid β-oxidation rate in differentiated Fsp27−/− (−/−) MEFs as compared to wildtype (+/+) MEFs in the presence of T3 (10nM). (n = 4) (**p<0.01). Results of relative amount of 3H2O released into the medium after four (4h) or six (6h) hours chase of pre-labelled MEFs with cold palmitate. Wildtype oxidation rate at 4h is set to 100. G. Regulatory and metabolic pathways that are altered in the WAT of Fsp27−/− mutant mice, leading to anti-obesity and insulin sensitive phenotype.

Mentions: To check whether the conversion of WAT to BAT in Fsp27−/− mice is cell autonomous or requires exogenous signals, we isolated mouse embryonic fibroblasts (MEFs) from wild type and Fsp27−/− mice and induced them to differentiate into adipocytes in vitro. The morphologies of differentiated MEFs from wildtype and Fsp27−/− mice are very different. Wildtype adipocytes have fewer but larger lipid droplets while differentiated Fsp27−/− MEFs possesses more but smaller lipid droplets (Fig. 6A). The small lipid droplets in Fsp27−/− adipocytes tend to cluster together, fully resembling the morphology seen in WAT from Fsp27−/− mice. Furthermore, levels of TAG from differentiated Fsp27−/− MEFs were significantly lower than that of differentiated wild type MEFs (Fig. 6B). The lower amount of TAG and smaller lipid droplets in Fsp27−/− adipocytes was not due to their defect in differentiation as the levels of adipocyte-specific markers such as Fabp and Perilipin-A were in fact slightly higher in Fsp27−/− adipocytes (data not shown). Furthermore, the lower amount of TAG in differentiated Fsp27−/− MEFs was not due to a decrease in FFA uptake as the rate of fatty acid uptake was similar between differentiated wildtype and Fsp27−/− MEFs (data not shown). Consistent with data observed with WAT of Fsp27−/− mice, rates of basal lipolysis were all significantly increased in differentiated Fsp27−/− MEFs compared with that of wild type cells (Fig. 6C, P<0.05). These data suggest that Fsp27 deficiency in differentiated MEFs leads to lower TAG accumulation, increased basal lipolysis and smaller lipid droplets.


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)

Differentiated Fsp27−/− MEFs display many brown adipocyte characteristics.A. Smaller lipid droplets in differentiated Fsp27 mutant mouse embryonic fibroblasts (MEFs). Lipid droplets were stained with BODIPY493/503, and nuclei were stained with Hochest 366243. Fields shown were visualized under fluorescence microscope at appropriate wavelengths for GFP (green) and Hoechst (blue). B. Lower TAG accumulation in differentiated Fsp27−/− MEFs (−/−) than in wildtype (+/+) cells. (n = 4) (**p<0.01; ***p<0.001). C. Increased basal lipolysis rate in differentiated Fsp27−/− MEFs in the absence or presence of T3 (10 nM) in the differentiation medium. (n = 3) (*p<0.05; **p<0.01). D. Western blot analysis showing levels of various proteins in differentiated MEF cells in the absence or presence of T3 (10 nM). β-tubulin was used as a loading control. E. Relative mRNA levels of various genes in differentiated wildtype (+/+) and Fsp27−/−(−/−)MEFs. mRNA levels for Rb were measured using MEFs that were differentiated for 3 days. (n = 4) (*p<0.05). F. Higher levels of fatty acid β-oxidation rate in differentiated Fsp27−/− (−/−) MEFs as compared to wildtype (+/+) MEFs in the presence of T3 (10nM). (n = 4) (**p<0.01). Results of relative amount of 3H2O released into the medium after four (4h) or six (6h) hours chase of pre-labelled MEFs with cold palmitate. Wildtype oxidation rate at 4h is set to 100. G. Regulatory and metabolic pathways that are altered in the WAT of Fsp27−/− mutant mice, leading to anti-obesity and insulin sensitive phenotype.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2483355&req=5

pone-0002890-g006: Differentiated Fsp27−/− MEFs display many brown adipocyte characteristics.A. Smaller lipid droplets in differentiated Fsp27 mutant mouse embryonic fibroblasts (MEFs). Lipid droplets were stained with BODIPY493/503, and nuclei were stained with Hochest 366243. Fields shown were visualized under fluorescence microscope at appropriate wavelengths for GFP (green) and Hoechst (blue). B. Lower TAG accumulation in differentiated Fsp27−/− MEFs (−/−) than in wildtype (+/+) cells. (n = 4) (**p<0.01; ***p<0.001). C. Increased basal lipolysis rate in differentiated Fsp27−/− MEFs in the absence or presence of T3 (10 nM) in the differentiation medium. (n = 3) (*p<0.05; **p<0.01). D. Western blot analysis showing levels of various proteins in differentiated MEF cells in the absence or presence of T3 (10 nM). β-tubulin was used as a loading control. E. Relative mRNA levels of various genes in differentiated wildtype (+/+) and Fsp27−/−(−/−)MEFs. mRNA levels for Rb were measured using MEFs that were differentiated for 3 days. (n = 4) (*p<0.05). F. Higher levels of fatty acid β-oxidation rate in differentiated Fsp27−/− (−/−) MEFs as compared to wildtype (+/+) MEFs in the presence of T3 (10nM). (n = 4) (**p<0.01). Results of relative amount of 3H2O released into the medium after four (4h) or six (6h) hours chase of pre-labelled MEFs with cold palmitate. Wildtype oxidation rate at 4h is set to 100. G. Regulatory and metabolic pathways that are altered in the WAT of Fsp27−/− mutant mice, leading to anti-obesity and insulin sensitive phenotype.
Mentions: To check whether the conversion of WAT to BAT in Fsp27−/− mice is cell autonomous or requires exogenous signals, we isolated mouse embryonic fibroblasts (MEFs) from wild type and Fsp27−/− mice and induced them to differentiate into adipocytes in vitro. The morphologies of differentiated MEFs from wildtype and Fsp27−/− mice are very different. Wildtype adipocytes have fewer but larger lipid droplets while differentiated Fsp27−/− MEFs possesses more but smaller lipid droplets (Fig. 6A). The small lipid droplets in Fsp27−/− adipocytes tend to cluster together, fully resembling the morphology seen in WAT from Fsp27−/− mice. Furthermore, levels of TAG from differentiated Fsp27−/− MEFs were significantly lower than that of differentiated wild type MEFs (Fig. 6B). The lower amount of TAG and smaller lipid droplets in Fsp27−/− adipocytes was not due to their defect in differentiation as the levels of adipocyte-specific markers such as Fabp and Perilipin-A were in fact slightly higher in Fsp27−/− adipocytes (data not shown). Furthermore, the lower amount of TAG in differentiated Fsp27−/− MEFs was not due to a decrease in FFA uptake as the rate of fatty acid uptake was similar between differentiated wildtype and Fsp27−/− MEFs (data not shown). Consistent with data observed with WAT of Fsp27−/− mice, rates of basal lipolysis were all significantly increased in differentiated Fsp27−/− MEFs compared with that of wild type cells (Fig. 6C, P<0.05). These data suggest that Fsp27 deficiency in differentiated MEFs leads to lower TAG accumulation, increased basal lipolysis and smaller lipid droplets.

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