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White-to-brite conversion in human adipocytes promotes metabolic reprogramming towards fatty acid anabolic and catabolic pathways.

Barquissau V, Beuzelin D, Pisani DF, Beranger GE, Mairal A, Montagner A, Roussel B, Tavernier G, Marques MA, Moro C, Guillou H, Amri EZ, Langin D - Mol Metab (2016)

Bottom Line: This conversion is associated with transcriptional changes leading to major metabolic adaptations.Conversion of human white fat cells into brite adipocytes results in a major metabolic reprogramming inducing fatty acid anabolic and catabolic pathways.PDK4 redirects glucose from oxidation towards triglyceride synthesis and favors the use of fatty acids as energy source for uncoupling mitochondria.

View Article: PubMed Central - PubMed

Affiliation: INSERM, UMR 1048, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, Paul Sabatier University, France.

ABSTRACT

Objective: Fat depots with thermogenic activity have been identified in humans. In mice, the appearance of thermogenic adipocytes within white adipose depots (so-called brown-in-white i.e., brite or beige adipocytes) protects from obesity and insulin resistance. Brite adipocytes may originate from direct conversion of white adipocytes. The purpose of this work was to characterize the metabolism of human brite adipocytes.

Methods: Human multipotent adipose-derived stem cells were differentiated into white adipocytes and then treated with peroxisome proliferator-activated receptor (PPAR)γ or PPARα agonists between day 14 and day 18. Gene expression profiling was determined using DNA microarrays and RT-qPCR. Variations of mRNA levels were confirmed in differentiated human preadipocytes from primary cultures. Fatty acid and glucose metabolism was investigated using radiolabelled tracers, Western blot analyses and assessment of oxygen consumption. Pyruvate dehydrogenase kinase 4 (PDK4) knockdown was achieved using siRNA. In vivo, wild type and PPARα- mice were treated with a β3-adrenergic receptor agonist (CL316,243) to induce appearance of brite adipocytes in white fat depot. Determination of mRNA and protein levels was performed on inguinal white adipose tissue.

Results: PPAR agonists promote a conversion of white adipocytes into cells displaying a brite molecular pattern. This conversion is associated with transcriptional changes leading to major metabolic adaptations. Fatty acid anabolism i.e., fatty acid esterification into triglycerides, and catabolism i.e., lipolysis and fatty acid oxidation, are increased. Glucose utilization is redirected from oxidation towards glycerol-3-phophate production for triglyceride synthesis. This metabolic shift is dependent on the activation of PDK4 through inactivation of the pyruvate dehydrogenase complex. In vivo, PDK4 expression is markedly induced in wild-type mice in response to CL316,243, while this increase is blunted in PPARα- mice displaying an impaired britening response.

Conclusions: Conversion of human white fat cells into brite adipocytes results in a major metabolic reprogramming inducing fatty acid anabolic and catabolic pathways. PDK4 redirects glucose from oxidation towards triglyceride synthesis and favors the use of fatty acids as energy source for uncoupling mitochondria.

No MeSH data available.


Related in: MedlinePlus

PPARα deficiency disrupts WAT britening-induced PDK4 expression in vivo. (A, C, E, G and I) WT and PPARα- male mice housed at thermoneutrality were treated with CL316,243 (CL, 0.1 mg/kg/d) or vehicle (DMSO) for 10 days. (B, D, F and H) WT and PPARα- male mice housed at standard temperature were treated with CL316,243 (CL, 1 mg/kg/d) or vehicle (DMSO) for 7 days. Analyses were performed on the inguinal white adipose tissue depot. (A, B) UCP1 mRNA and protein levels. (C–F) Gene expression levels of Cidea, Cpt1b, Cited1 and Tmem26. (G, H) PDK4 mRNA and protein levels. (I) Spearman correlation between UCP1 and PDK4 protein content (n = 23). Data represent mean ± SEM expressed as percentage of vehicle-treated WT mice (n = 7–9 mice per group). Open bars: wild-type mice, hatched bars: PPARα- mice. NA: not available. *: p < 0.05 for CL vs. DMSO; **: p < 0.01; ***: p < 0.001. $: p < 0.05 for PPARα- vs. wild type; $$: p < 0.01; $$$: p < 0.001.
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fig5: PPARα deficiency disrupts WAT britening-induced PDK4 expression in vivo. (A, C, E, G and I) WT and PPARα- male mice housed at thermoneutrality were treated with CL316,243 (CL, 0.1 mg/kg/d) or vehicle (DMSO) for 10 days. (B, D, F and H) WT and PPARα- male mice housed at standard temperature were treated with CL316,243 (CL, 1 mg/kg/d) or vehicle (DMSO) for 7 days. Analyses were performed on the inguinal white adipose tissue depot. (A, B) UCP1 mRNA and protein levels. (C–F) Gene expression levels of Cidea, Cpt1b, Cited1 and Tmem26. (G, H) PDK4 mRNA and protein levels. (I) Spearman correlation between UCP1 and PDK4 protein content (n = 23). Data represent mean ± SEM expressed as percentage of vehicle-treated WT mice (n = 7–9 mice per group). Open bars: wild-type mice, hatched bars: PPARα- mice. NA: not available. *: p < 0.05 for CL vs. DMSO; **: p < 0.01; ***: p < 0.001. $: p < 0.05 for PPARα- vs. wild type; $$: p < 0.01; $$$: p < 0.001.

Mentions: Two cohorts of mice were investigated. WT and PPARα- mice at 21 weeks of age acclimated at thermoneutrality were treated with the β3-adrenergic agonist CL316,243. Acclimation to thermoneutrality is essential to avoid the confounding effects due to activation of brown and brite fat depots at conventional housing temperature. Body weight and inguinal fat pad weight were higher in PPARα- mice compared to age-matched WT mice (Figure S6A). As the difference in adiposity between genotypes may influence britening in inguinal fat pad and obesity in PPARα- mice develops with aging [44], CL treatment was applied to younger mice housed at standard temperature. As expected, there was no difference in body and inguinal fat pad weights between 11 week-old WT and PPARα- mice (Figure S6B). Pparα mRNA was, respectively, undetectable and expressed at low level in inguinal WAT of vehicle-treated PPARα- and WT mice and was induced upon chronic β3-adrenergic stimulation only in WT mice (Figure S6C,D). UCP1 mRNA and protein were barely detectable in WAT of vehicle-treated WT and PPARα- mice. Upon CL316,243 treatment, UCP1 expression in WAT was sharply induced in WT mice while this increase was markedly blunted in PPARα- mice (Figure 5A,B). PPARα deficiency did not impair white adipogenesis as shown by similar expression of Pparγ and Dpt, a white adipocyte specific marker [35], in both WT and PPARα- mice (Figure S6E). Inguinal WAT mRNA levels of the classical markers of thermogenic cells, Cidea and Cpt1b, were barely detectable in vehicle-treated mice and sharply increased upon β3-adrenergic agonist treatment in WT mice, while this induction was impaired in PPARα- mice as thermogenic genes (Figure 5C,D). Classical brite adipocyte markers such as Cited1 and Tmem26 displayed the same pattern (Figure 5E,F). Noteworthy, the expression of these genes was induced by CL316,243 in interscapular BAT of both WT and PPARα- mice (Figure S6F), suggesting a specific role of PPARα in brite fat cells compared to brown fat cells upon chronic β3-adrenergic stimulation. PDK4 expression was upregulated in inguinal WAT at mRNA and protein levels during CL316,243 treatment in WT mice, while this induction was severely blunted in PPARα- mice (Figure 5G,H). Supporting the induction of PDK4 as a major feature of britening, PDK4 expression was strongly correlated with UCP1 expression at both protein and mRNA levels in inguinal WAT (Figure 5I and Figure S6G).


White-to-brite conversion in human adipocytes promotes metabolic reprogramming towards fatty acid anabolic and catabolic pathways.

Barquissau V, Beuzelin D, Pisani DF, Beranger GE, Mairal A, Montagner A, Roussel B, Tavernier G, Marques MA, Moro C, Guillou H, Amri EZ, Langin D - Mol Metab (2016)

PPARα deficiency disrupts WAT britening-induced PDK4 expression in vivo. (A, C, E, G and I) WT and PPARα- male mice housed at thermoneutrality were treated with CL316,243 (CL, 0.1 mg/kg/d) or vehicle (DMSO) for 10 days. (B, D, F and H) WT and PPARα- male mice housed at standard temperature were treated with CL316,243 (CL, 1 mg/kg/d) or vehicle (DMSO) for 7 days. Analyses were performed on the inguinal white adipose tissue depot. (A, B) UCP1 mRNA and protein levels. (C–F) Gene expression levels of Cidea, Cpt1b, Cited1 and Tmem26. (G, H) PDK4 mRNA and protein levels. (I) Spearman correlation between UCP1 and PDK4 protein content (n = 23). Data represent mean ± SEM expressed as percentage of vehicle-treated WT mice (n = 7–9 mice per group). Open bars: wild-type mice, hatched bars: PPARα- mice. NA: not available. *: p < 0.05 for CL vs. DMSO; **: p < 0.01; ***: p < 0.001. $: p < 0.05 for PPARα- vs. wild type; $$: p < 0.01; $$$: p < 0.001.
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fig5: PPARα deficiency disrupts WAT britening-induced PDK4 expression in vivo. (A, C, E, G and I) WT and PPARα- male mice housed at thermoneutrality were treated with CL316,243 (CL, 0.1 mg/kg/d) or vehicle (DMSO) for 10 days. (B, D, F and H) WT and PPARα- male mice housed at standard temperature were treated with CL316,243 (CL, 1 mg/kg/d) or vehicle (DMSO) for 7 days. Analyses were performed on the inguinal white adipose tissue depot. (A, B) UCP1 mRNA and protein levels. (C–F) Gene expression levels of Cidea, Cpt1b, Cited1 and Tmem26. (G, H) PDK4 mRNA and protein levels. (I) Spearman correlation between UCP1 and PDK4 protein content (n = 23). Data represent mean ± SEM expressed as percentage of vehicle-treated WT mice (n = 7–9 mice per group). Open bars: wild-type mice, hatched bars: PPARα- mice. NA: not available. *: p < 0.05 for CL vs. DMSO; **: p < 0.01; ***: p < 0.001. $: p < 0.05 for PPARα- vs. wild type; $$: p < 0.01; $$$: p < 0.001.
Mentions: Two cohorts of mice were investigated. WT and PPARα- mice at 21 weeks of age acclimated at thermoneutrality were treated with the β3-adrenergic agonist CL316,243. Acclimation to thermoneutrality is essential to avoid the confounding effects due to activation of brown and brite fat depots at conventional housing temperature. Body weight and inguinal fat pad weight were higher in PPARα- mice compared to age-matched WT mice (Figure S6A). As the difference in adiposity between genotypes may influence britening in inguinal fat pad and obesity in PPARα- mice develops with aging [44], CL treatment was applied to younger mice housed at standard temperature. As expected, there was no difference in body and inguinal fat pad weights between 11 week-old WT and PPARα- mice (Figure S6B). Pparα mRNA was, respectively, undetectable and expressed at low level in inguinal WAT of vehicle-treated PPARα- and WT mice and was induced upon chronic β3-adrenergic stimulation only in WT mice (Figure S6C,D). UCP1 mRNA and protein were barely detectable in WAT of vehicle-treated WT and PPARα- mice. Upon CL316,243 treatment, UCP1 expression in WAT was sharply induced in WT mice while this increase was markedly blunted in PPARα- mice (Figure 5A,B). PPARα deficiency did not impair white adipogenesis as shown by similar expression of Pparγ and Dpt, a white adipocyte specific marker [35], in both WT and PPARα- mice (Figure S6E). Inguinal WAT mRNA levels of the classical markers of thermogenic cells, Cidea and Cpt1b, were barely detectable in vehicle-treated mice and sharply increased upon β3-adrenergic agonist treatment in WT mice, while this induction was impaired in PPARα- mice as thermogenic genes (Figure 5C,D). Classical brite adipocyte markers such as Cited1 and Tmem26 displayed the same pattern (Figure 5E,F). Noteworthy, the expression of these genes was induced by CL316,243 in interscapular BAT of both WT and PPARα- mice (Figure S6F), suggesting a specific role of PPARα in brite fat cells compared to brown fat cells upon chronic β3-adrenergic stimulation. PDK4 expression was upregulated in inguinal WAT at mRNA and protein levels during CL316,243 treatment in WT mice, while this induction was severely blunted in PPARα- mice (Figure 5G,H). Supporting the induction of PDK4 as a major feature of britening, PDK4 expression was strongly correlated with UCP1 expression at both protein and mRNA levels in inguinal WAT (Figure 5I and Figure S6G).

Bottom Line: This conversion is associated with transcriptional changes leading to major metabolic adaptations.Conversion of human white fat cells into brite adipocytes results in a major metabolic reprogramming inducing fatty acid anabolic and catabolic pathways.PDK4 redirects glucose from oxidation towards triglyceride synthesis and favors the use of fatty acids as energy source for uncoupling mitochondria.

View Article: PubMed Central - PubMed

Affiliation: INSERM, UMR 1048, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France; University of Toulouse, Paul Sabatier University, France.

ABSTRACT

Objective: Fat depots with thermogenic activity have been identified in humans. In mice, the appearance of thermogenic adipocytes within white adipose depots (so-called brown-in-white i.e., brite or beige adipocytes) protects from obesity and insulin resistance. Brite adipocytes may originate from direct conversion of white adipocytes. The purpose of this work was to characterize the metabolism of human brite adipocytes.

Methods: Human multipotent adipose-derived stem cells were differentiated into white adipocytes and then treated with peroxisome proliferator-activated receptor (PPAR)γ or PPARα agonists between day 14 and day 18. Gene expression profiling was determined using DNA microarrays and RT-qPCR. Variations of mRNA levels were confirmed in differentiated human preadipocytes from primary cultures. Fatty acid and glucose metabolism was investigated using radiolabelled tracers, Western blot analyses and assessment of oxygen consumption. Pyruvate dehydrogenase kinase 4 (PDK4) knockdown was achieved using siRNA. In vivo, wild type and PPARα- mice were treated with a β3-adrenergic receptor agonist (CL316,243) to induce appearance of brite adipocytes in white fat depot. Determination of mRNA and protein levels was performed on inguinal white adipose tissue.

Results: PPAR agonists promote a conversion of white adipocytes into cells displaying a brite molecular pattern. This conversion is associated with transcriptional changes leading to major metabolic adaptations. Fatty acid anabolism i.e., fatty acid esterification into triglycerides, and catabolism i.e., lipolysis and fatty acid oxidation, are increased. Glucose utilization is redirected from oxidation towards glycerol-3-phophate production for triglyceride synthesis. This metabolic shift is dependent on the activation of PDK4 through inactivation of the pyruvate dehydrogenase complex. In vivo, PDK4 expression is markedly induced in wild-type mice in response to CL316,243, while this increase is blunted in PPARα- mice displaying an impaired britening response.

Conclusions: Conversion of human white fat cells into brite adipocytes results in a major metabolic reprogramming inducing fatty acid anabolic and catabolic pathways. PDK4 redirects glucose from oxidation towards triglyceride synthesis and favors the use of fatty acids as energy source for uncoupling mitochondria.

No MeSH data available.


Related in: MedlinePlus