Exp Mol Med.  2004 Oct;36(5):476-485.

Extracellular ATP is generated by ATP synthase complex in adipocyte lipid rafts

Affiliations
  • 1Graduate School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea. ygko@korea.ac.kr

Abstract

Mitochondrial biogenesis is known to accompany adipogenesis to complement ATP and acetyl-CoA required for lipogenesis. Here, we demonstrated that mitochondrial proteins such as ATP synthase alpha and beta, and cytochrome c were highly expressed during the 3T3-L1 differentiation into adipocytes. Fully-differentiated adipocytes showed a significant increase of mitochondria under electron microscopy. Analysis by immunofluorescence, cellular fractionation, and surface biotinylation demonstrated the elevated levels of ATP synthase complex found not only in the mitochondria but also on the cell surface (particularly lipid rafts) of adipocytes. High rate of ATP (more than 30 micrometer) synthesis from the added ADP and Pi in the adipocyte media suggests the involvement of the surface ATP synthase complex for the exracellular ATP synthesis. In addition, this ATP synthesis was significantly inhibited in the presence of oligomycin, an ATP synthase inhibitor, and carbonyl cyanide m-chlorophenylhydrazone (CCCP), an ATP synthase uncoupler. Decrease of extracellular ATP synthesis in acidic but not in basic media further indicates that the surface ATP synthase may also be regulated by proton gradient through the plasma membrane.

Keyword

adipocytes; ATP synthase complex; membrane microdomains; mitochondria

MeSH Terms

Adenosine Triphosphate/analysis/*biosynthesis
Adipocytes/*enzymology/ultrastructure
Animals
Cell Differentiation/physiology
Cell Membrane/chemistry
Cells, Cultured
Humans
Membrane Microdomains/chemistry/*enzymology
Mice
Mitochondria/metabolism/ultrastructure
Mitochondrial Proton-Translocating ATPases/analysis/*physiology
Research Support, Non-U.S. Gov't
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