Structural and functional consequences of mitochondrial biogenesis in human adipocytes in vitro.
BACKGROUND
Mitochondrial biogenesis is a complex process, and several factors and signaling pathways regulate this process in muscle or brown adipocytes. The aim of the study was to explore pathways affecting mitochondrial biogenesis and fatty acid oxidation (FAO) in human white adipocytes.


METHODS
Human preadipocytes obtained from liposuction samples were differentiated in vitro. On the 10th day of differentiation, 4 microM forskolin and 1 microM peroxisome proliferator-activated receptor-gamma (PPARgamma) agonist (pioglitazone, rosiglitazone, or GW 929) or 10 microM PPARalpha agonist (WY-14,643) were added to the media for 96 h. Quantitative real-time PCR was used to determine gene expression/mitochondrial copy number and 14C-labeled palmitate to measure direct energy dissipation.


RESULTS
The treatment of adipocytes with forskolin increased mitochondrial copy number and the expression of genes involved in mitochondrial biogenesis (PPARgamma coactivator 1alpha and transcriptional factor A) and fatty acid oxidation (PPARalpha and medium-chain acyl-coenzyme A dehydrogenase). The end (CO2) and intermediate products (14C-labeled acid-soluble products) of FAO were also increased after forskolin treatment. PPARgamma and PPARalpha agonists increased mitochondrial copy number, uncoupling protein 1, medium-chain acyl-coenzyme A dehydrogenase, and carnitine palmitoyltransferase 1, but did not change PPARalpha, PPARgamma coactivator 1alpha, or transcriptional factor A mRNA levels. FAO was higher after rosiglitazone, GW 929, and WY-14,643 but not after pioglitazone treatment.


CONCLUSIONS
Pharmacological activation of the cAMP or PPARgamma pathway pushes the white adipocyte down the oxidative continuum. The direct energy-dissipating effects could be significant tools to treat obesity and to improve insulin resistance in type 2 diabetic patients by reduction of fat accumulation in adipocytes or by reprogramming fatty acid metabolism.
Bogacka
Iwona
I
Pennington Biomedical Research Center, Department of Molecular Endocrinology, 6400 Perkins Road, Baton Rouge, Louisiana 70808, USA. iwonab@uwm.edu.pl
Ukropcova
Barbara
B
McNeil
Michele
M
Gimble
Jeffrey M
JM
Smith
Steven R
SR
D017667:Adipocytes / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure*; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D004272:DNA, Mitochondrial; D005227:Fatty Acids / Q000378:metabolism; D018628:Gene Dosage / Q000187:drug effects; D015870:Gene Expression; D005990:Glycerol / Q000378:metabolism; D006801:Humans; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure*; D009994:Osmolar Concentration; D010084:Oxidation-Reduction; D047493:PPAR alpha / Q000819:agonists; D047495:PPAR gamma / Q000819:agonists / Q000037:antagonists & inhibitors
D004272:DNA, Mitochondrial; D005227:Fatty Acids; D047493:PPAR alpha; D047495:PPAR gamma; D005576:Colforsin; D005990:Glycerol