Complex I-Associated Hydrogen Peroxide Production Is Decreased and Electron Transport Chain Enzyme Activities Are Altered in n-3 Enriched fat-1 Mice

Abstract

The polyunsaturated nature of n-3 fatty acids makes them prone to oxidative damage. However, it is not clear if n-3 fatty acids are simply a passive site for oxidative attack or if they also modulate mitochondrial reactive oxygen species (ROS) production. The present study used fat-1 transgenic mice, that are capable of synthesizing n-3 fatty acids, to investigate the influence of increases in n-3 fatty acids and resultant decreases in the n-6∶n-3 ratio on liver mitochondrial H2O2 production and electron transport chain (ETC) activity. There was an increase in n-3 fatty acids and a decrease in the n-6∶n-3 ratio in liver mitochondria from the fat-1 compared to control mice. This change was largely due to alterations in the fatty acid composition of phosphatidylcholine and phosphatidylethanolamine, with only a small percentage of fatty acids in cardiolipin being altered in the fat-1 animals. The lipid changes in the fat-1 mice were associated with a decrease (p<0.05) in the activity of ETC complex I and increases (p<0.05) in the activities of complexes III and IV. Mitochondrial H2O2 production with either succinate or succinate/glutamate/malate substrates was also decreased (p<0.05) in the fat-1 mice. This change in H2O2 production was due to a decrease in ROS production from ETC complex I in the fat-1 animals. These results indicate that the fatty acid changes in fat-1 liver mitochondria may at least partially oppose oxidative stress by limiting ROS production from ETC complex I.

Molecular interplay between Δ5/Δ6 desaturases and long-chain fatty acids in the pathogenesis of non-alcoholic steatohepatitis

“…These findings are in agreement with the existence of a higher antioxidant potential in fat-1 mice 31. Since CYP2E1, a member of the oxido-reductase cytochrome family that oxidises a variety of substrates including fatty acids,32 remained unchanged in fat-1 mice, our findings support the concept that fat-1 mice may at least partially oppose oxidative stress by the existence of an impaired mitochondrial electron transport chain 33. In any event, the observed individual peculiarities of supplying ω-3 from either endogenous or exogenous sources were not the consequence of ineffective enrichment of hepatic tissues with EPA/DHA because the total ω-3 content and the ω-3 index were significantly higher in the ω-3 diet group than in fat-1 mice.…”

Perspectives on the membrane fatty acid unsaturation/pacemaker hypotheses of metabolism and aging

“…Differences in unsaturation index and DHA concentration in the muscle mitochondria of rats, toads, and lizards were also correlated with differences in their mitochondrial oxidative capacities (Guderley et al, 2005). Furthermore, dietary manipulations in trout and genetic manipulations in mammals that increased the amount of PUFA in membranes increased mitochondrial activity or increased the activities of individual complexes in the electron transport chain (Guderley et al, 2008;Hagopian et al, 2010;Jaureguiberry et al, 2014). Experiments where Na+/K+ ATPase from rats and cattle was put into the less unsaturated membranes of toads and crocodiles exhibited a decrease in Na+/K+ ATPase activity.…”

“…Fat-1 transgenic mice, which express a desaturase allowing the synthesis of n-3 fatty acids from n-6 fatty acids, had significant increases in the DHA content of phosphatidylethanolamine and phosphatidylcholine, but not in cardiolipin or phosphatidylserine, in comparison with control mice (Hagopian et al, 2010). It is reasonable to assume that, had the acyl composition of different phospholipid classes been separated out in more studies, other differences in the way phospholipid class acyl composition react to experimental treatments would have been found, potentially explaining why differences in PUFA composition of phospholipids do not always correlate with changes in metabolic rate and longevity.…”

“…The use of primary cell cultures has multiple advantages including the ability to culture cells from relatively harmless biopsies, elimination of the effects of diet by culturing in a common environment, and the ability to measure several physiological parameters in the same primary cell lines, such as metabolic rate of whole cells, phospholipid composition, and in situ measures of lipid peroxidizability (Calhoon et al, 2014(Calhoon et al, , 2013Jimenez et al, 2014bJimenez et al, , 2014c. Furthermore, genetic manipulations, such as CRISPR-Cas, could be done in cultures from a variety of species, not just in the model species that have been used so far to test these hypotheses (Hagopian et al, 2010;Sander and Joung, 2014;Shmookler Reis et al, 2011). Use of cell culture would also help eliminate problems with conflicting effects of experimental treatments on different organs (Price and Guglielmo, 2009;Stroud et al, 2009;Wone et al, 2013), as well as the confounding factor of relative internal organ size (Brzęk et al, 2007).…”

The influence of dietary fat source on liver and skeletal muscle mitochondrial modifications and lifespan changes in calorie-restricted mice

“…In addition, mitochondrial phospholipid fatty acids could also influence aging by altering the activity of membrane proteins (Innis and Clandinin 1981; Daum 1985; Dowhan et al 2004; Lee 2004; Marsh 2008), membrane permeability (Brand et al 1994; Brookes et al 1998), ROS production (Ramsey et al 2005; Hagopian et al 2010) or other membrane-linked processes. Membrane n-6 and n-3 fatty acids of 20 carbons in length may also serve as precursors for the formation of eicosanoids, which modulate inflammatory responses (Calder 2004; 2007; Schmitz and Ecker 2008; Deckelbaum and Torrejon 2012).…”