Abstract
The objective of this study was to investigate membrane fatty acids for their effects on mitochondrial function in live cells. Mitochondrial potential and oxidant production were measured in human colonic adenocarcinoma (HT-29) cells with membranes enhanced in either oleic acid, linoleic acid, arachidonic acid, eicosapentaenoic acid, or docosahexaenoic acid. Docosahexaenoic acid-enriched cells had increased mitochondrial potential and produced 5-fold more cellular oxidants than did cells enriched with any other fatty acid. Oxidant production in fatty acid-enriched HT-29 cells did not correlate with the degree of unsaturation for total membrane fatty acids. However, there was a strong correlation between the degree of fatty acid unsaturation of cardiolipin, a critical inner-mitochondrial membrane phospholipid, and oxidant production. Cardiolipin acyl composition is known to influence the activity of electron transport complexes, an effect that can increase mitochondrial oxidant production. Docosahexaenoic acid was enriched to 48 mol% of the fatty acids present in HT-29 cell cardiolipin.▪ These results demonstrate the importance of membrane acyl composition to mitochondrial potential and oxidant production in live cells. Additionally, results suggest that docosahexaenoic acid increases cell oxidant production by accumulating in cardiolipin, where its presence alters electron transport efficiency.—Watkins, S. M., L. C. Carter, and J. B. German. Docosahexaenoic acid accumulates in cardiolipin and enhances HT-29 cell oxidant production.
Highlights
The objective of this study was to investigate membrane fatty acids for their effects on mitochondrial function in live cells
Mitochondrial potential and cellular reactive oxygen species (ROS) production were measured in live HT-29 cells that had been enriched with specific fatty acids
Cardiolipin from fatty acid-enriched HT-29 cells contained 26, 41, 6, 9, or 48 mol% oleic acid (OA), linoleic acid (LA), arachidonic acid (AA), eicosapentaenoic acid (EPA), or docosahexaenoic acid (DHA), respectively, in cells enriched with those fatty acids (Table 1)
Summary
The objective of this study was to investigate membrane fatty acids for their effects on mitochondrial function in live cells. Docosahexaenoic acid was enriched to 48 mol% of the fatty acids present in HT-29 cell cardiolipin These results demonstrate the importance of membrane acyl composition to mitochondrial potential and oxidant production in live cells. Despite the known effects of CL and CL acyl composition on the in vitro activities of electron transport complexes, membrane fatty acid composition has not been investigated for its role in changing mitochondrial potential or ROS production. The extensive incorporation of DHA into HT-29 cell CL and the increased mitochondrial potential and oxidant production in DHA-enriched cells suggest a Abbreviations: AA, arachidonic acid; CL, cardiolipin; DHR123, dihydrorhodamine 123; DHA, docosahexaenoic acid; EPA, eicosapentaenoic acid; IMM, inner-mitochondrial membrane; LA, linoleic acid; OA, oleic acid; PUFA, polyunsaturated fatty acid; R123, rhodamine 123; ROS, reactive oxygen species
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