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Peroxisome proliferator-activated receptor-gamma coactivator-1alpha overexpression increases lipid oxidation in myocytes from extremely obese individuals.

Consitt LA, Bell JA, Koves TR, Muoio DM, Hulver MW, Haynie KR, Dohm GL, Houmard JA - Diabetes (2010)

Bottom Line: To determine whether the obesity-related decrement in fatty acid oxidation (FAO) in primary human skeletal muscle cells (HSkMC) is linked with lower mitochondrial content and whether this deficit could be corrected via overexpression of peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha).Obesity was associated with a 30% decrease (P < 0.05) in complete FAO, which was accompanied by higher relative rates of incomplete FAO ([(14)C]ASM production/(14)CO(2)), increased partitioning of fatty acid toward storage, and lower (P < 0.05) mtDNA (-27%), COXIV (-35%), and mitochondrial transcription factor (mtTFA) (-43%) protein levels.Increasing PGC-1alpha protein levels did not correct the obesity-related absolute reduction in FAO or mtDNA content, implicating mechanisms other than PGC-1alpha abundance.

View Article: PubMed Central - PubMed

Affiliation: Department of Exercise and Sport Science, East Carolina University, Greenville, North Carolina, USA. consittl@ecu.edu

ABSTRACT

Objective: To determine whether the obesity-related decrement in fatty acid oxidation (FAO) in primary human skeletal muscle cells (HSkMC) is linked with lower mitochondrial content and whether this deficit could be corrected via overexpression of peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha).

Research design and methods: FAO was studied in HSkMC from lean (BMI 22.4 +/- 0.9 kg/m(2); N = 12) and extremely obese (45.3 +/- 1.4 kg/m(2); N = 9) subjects. Recombinant adenovirus was used to increase HSkMC PGC-1alpha expression (3.5- and 8.0-fold), followed by assessment of mitochondrial content (mtDNA and cytochrome C oxidase IV [COXIV]), complete ((14)CO(2) production from labeled oleate), and incomplete (acid soluble metabolites [ASM]) FAO, and glycerolipid synthesis.

Results: Obesity was associated with a 30% decrease (P < 0.05) in complete FAO, which was accompanied by higher relative rates of incomplete FAO ([(14)C]ASM production/(14)CO(2)), increased partitioning of fatty acid toward storage, and lower (P < 0.05) mtDNA (-27%), COXIV (-35%), and mitochondrial transcription factor (mtTFA) (-43%) protein levels. PGC-1alpha overexpression increased (P < 0.05) FAO, mtDNA, COXIV, mtTFA, and fatty acid incorporation into triacylglycerol in both lean and obese groups. Perturbations in FAO, triacylglycerol synthesis, mtDNA, COXIV, and mtTFA in obese compared with lean HSkMC persisted despite PGC-1alpha overexpression. When adjusted for mtDNA and COXIV content, FAO was equivalent between lean and obese groups.

Conclusion: Reduced mitochondrial content is related to impaired FAO in HSkMC derived from obese individuals. Increasing PGC-1alpha protein levels did not correct the obesity-related absolute reduction in FAO or mtDNA content, implicating mechanisms other than PGC-1alpha abundance.

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Ad-PGC-1α overexpression in cultured myotubes (HSkMC) from lean and obese donors. A: PGC-1α protein content in no-virus controls (NVC), Ad-β-gal controls, and Ad-PGC-1α–treated HSkMC. PGC-1α protein content increased dose dependently in HSkMC from lean and obese donors. B: mtTFA and COXIV protein content increased dose dependently with increasing PGC-1α viral titer in HSkMC.
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Figure 1: Ad-PGC-1α overexpression in cultured myotubes (HSkMC) from lean and obese donors. A: PGC-1α protein content in no-virus controls (NVC), Ad-β-gal controls, and Ad-PGC-1α–treated HSkMC. PGC-1α protein content increased dose dependently in HSkMC from lean and obese donors. B: mtTFA and COXIV protein content increased dose dependently with increasing PGC-1α viral titer in HSkMC.

Mentions: Myoblasts were subcultured onto 6- and 24-well type I collagen-coated plates at densities of 80 and 20 × 103 cells per well, respectively. Upon reaching 70–80% confluence, differentiation to myotubes was induced by switching the growth media to differentiation media (Dulbecco's Modified Eeagle's Medium supplemented with 2% horse serum, 0.5 mg/ml BSA, 0.5 mg/ml fetuin, and 50 μg/ml gentamicin/amphotericin B). On day five, myotubes were given fresh differentiation media (no-virus control) or transfected with either Ad-PGC-1α or Ad-β-gal (control virus). To determine the appropriate adenoviral titer to use for metabolic experiments, we initially performed a protein (Fig. 1) and mRNA (not shown) dose-response curve.


Peroxisome proliferator-activated receptor-gamma coactivator-1alpha overexpression increases lipid oxidation in myocytes from extremely obese individuals.

Consitt LA, Bell JA, Koves TR, Muoio DM, Hulver MW, Haynie KR, Dohm GL, Houmard JA - Diabetes (2010)

Ad-PGC-1α overexpression in cultured myotubes (HSkMC) from lean and obese donors. A: PGC-1α protein content in no-virus controls (NVC), Ad-β-gal controls, and Ad-PGC-1α–treated HSkMC. PGC-1α protein content increased dose dependently in HSkMC from lean and obese donors. B: mtTFA and COXIV protein content increased dose dependently with increasing PGC-1α viral titer in HSkMC.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2874701&req=5

Figure 1: Ad-PGC-1α overexpression in cultured myotubes (HSkMC) from lean and obese donors. A: PGC-1α protein content in no-virus controls (NVC), Ad-β-gal controls, and Ad-PGC-1α–treated HSkMC. PGC-1α protein content increased dose dependently in HSkMC from lean and obese donors. B: mtTFA and COXIV protein content increased dose dependently with increasing PGC-1α viral titer in HSkMC.
Mentions: Myoblasts were subcultured onto 6- and 24-well type I collagen-coated plates at densities of 80 and 20 × 103 cells per well, respectively. Upon reaching 70–80% confluence, differentiation to myotubes was induced by switching the growth media to differentiation media (Dulbecco's Modified Eeagle's Medium supplemented with 2% horse serum, 0.5 mg/ml BSA, 0.5 mg/ml fetuin, and 50 μg/ml gentamicin/amphotericin B). On day five, myotubes were given fresh differentiation media (no-virus control) or transfected with either Ad-PGC-1α or Ad-β-gal (control virus). To determine the appropriate adenoviral titer to use for metabolic experiments, we initially performed a protein (Fig. 1) and mRNA (not shown) dose-response curve.

Bottom Line: To determine whether the obesity-related decrement in fatty acid oxidation (FAO) in primary human skeletal muscle cells (HSkMC) is linked with lower mitochondrial content and whether this deficit could be corrected via overexpression of peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha).Obesity was associated with a 30% decrease (P < 0.05) in complete FAO, which was accompanied by higher relative rates of incomplete FAO ([(14)C]ASM production/(14)CO(2)), increased partitioning of fatty acid toward storage, and lower (P < 0.05) mtDNA (-27%), COXIV (-35%), and mitochondrial transcription factor (mtTFA) (-43%) protein levels.Increasing PGC-1alpha protein levels did not correct the obesity-related absolute reduction in FAO or mtDNA content, implicating mechanisms other than PGC-1alpha abundance.

View Article: PubMed Central - PubMed

Affiliation: Department of Exercise and Sport Science, East Carolina University, Greenville, North Carolina, USA. consittl@ecu.edu

ABSTRACT

Objective: To determine whether the obesity-related decrement in fatty acid oxidation (FAO) in primary human skeletal muscle cells (HSkMC) is linked with lower mitochondrial content and whether this deficit could be corrected via overexpression of peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha).

Research design and methods: FAO was studied in HSkMC from lean (BMI 22.4 +/- 0.9 kg/m(2); N = 12) and extremely obese (45.3 +/- 1.4 kg/m(2); N = 9) subjects. Recombinant adenovirus was used to increase HSkMC PGC-1alpha expression (3.5- and 8.0-fold), followed by assessment of mitochondrial content (mtDNA and cytochrome C oxidase IV [COXIV]), complete ((14)CO(2) production from labeled oleate), and incomplete (acid soluble metabolites [ASM]) FAO, and glycerolipid synthesis.

Results: Obesity was associated with a 30% decrease (P < 0.05) in complete FAO, which was accompanied by higher relative rates of incomplete FAO ([(14)C]ASM production/(14)CO(2)), increased partitioning of fatty acid toward storage, and lower (P < 0.05) mtDNA (-27%), COXIV (-35%), and mitochondrial transcription factor (mtTFA) (-43%) protein levels. PGC-1alpha overexpression increased (P < 0.05) FAO, mtDNA, COXIV, mtTFA, and fatty acid incorporation into triacylglycerol in both lean and obese groups. Perturbations in FAO, triacylglycerol synthesis, mtDNA, COXIV, and mtTFA in obese compared with lean HSkMC persisted despite PGC-1alpha overexpression. When adjusted for mtDNA and COXIV content, FAO was equivalent between lean and obese groups.

Conclusion: Reduced mitochondrial content is related to impaired FAO in HSkMC derived from obese individuals. Increasing PGC-1alpha protein levels did not correct the obesity-related absolute reduction in FAO or mtDNA content, implicating mechanisms other than PGC-1alpha abundance.

Show MeSH
Related in: MedlinePlus