Docosahexaenoic acid lowers cardiac mitochondrial enzyme activity by replacing linoleic acid in the phospholipidome

Abstract

Cardiac mitochondrial phospholipid acyl chains regulate respiratory enzymatic activity. In several diseases, the rodent cardiac phospholipidome is extensively rearranged; however, whether specific acyl chains impair respiratory enzyme function is unknown. One unique remodeling event in the myocardium of obese and diabetic rodents is an increase in docosahexaenoic acid (DHA) levels. Here, we first confirmed that cardiac DHA levels are elevated in diabetic humans relative to controls. We then used dietary supplementation of a Western diet with DHA as a tool to promote cardiac acyl chain remodeling and to study its influence on respiratory enzyme function. DHA extensively remodeled the acyl chains of cardiolipin (CL), mono-lyso CL, phosphatidylcholine, and phosphatidylethanolamine. Moreover, DHA lowered enzyme activities of respiratory complexes I, IV, V, and I+III. Mechanistically, the reduction in enzymatic activities were not driven by a dramatic reduction in the abundance of supercomplexes. Instead, replacement of tetralinoleoyl-CL with tetradocosahexaenoyl-CL in biomimetic membranes prevented formation of phospholipid domains that regulate enzyme activity. Tetradocosahexaenoyl-CL inhibited domain organization due to favorable Gibbs free energy of phospholipid mixing. Furthermore, in vitro substitution of tetralinoleoyl-CL with tetradocosahexaenoyl-CL blocked complex-IV binding. Finally, reintroduction of linoleic acid, via fusion of phospholipid vesicles to mitochondria isolated from DHA-fed mice, rescued the major losses in the mitochondrial phospholipidome and complexes I, IV, and V activities. Altogether, our results show that replacing linoleic acid with DHA lowers select cardiac enzyme activities by potentially targeting domain organization and phospholipid-protein binding, which has implications for the ongoing debate about polyunsaturated fatty acids and cardiac health.

ATP-binding cassette A1 deficiency causes cardiolipin-driven mitochondrial dysfunction in podocytes

“…We found that peroxidized cardiolipin species were increased in db/db vehicle-treated mice while A30 treatment prevented this increase ( Figure 6, A and B, Supplemental Figure 10). These data suggest that renoprotection of ABCA1 inducers may be linked to modulation of DHA-rich cardiolipin species that have been previously reported to enhance oxidative stress and to be upregulated in diabetes (35)(36)(37), which may further reduce the oxidation of cardiolipin. Elamipretide treatment ameliorates podocyte loss and DKD.…”

Mitochondrial PE potentiates respiratory enzymes to amplify skeletal muscle aerobic capacity

“…The specific activity of each complex was measured at 37°C using reagents and substrates specified previously. 48 For experiments involving C2C12 cells, Complexes I and V activities were measured in isolated mitochondria, whereas activities of other Complexes were measured in whole cells. Citrate synthase activity was measured on a 96-well plate using a commercially available kit (Sigma Aldrich, CS0720).…”

Proteolipid domains form in biomimetic and cardiac mitochondrial vesicles and are regulated by cardiolipin concentration but not monolyso-cardiolipin

“…It is important to point out that in some cases of extreme CL remodeling, the acyl chains may be major drivers of changes in mitochondrial bioenergetics. We previously demonstrated that dietary docosahexaenoic acid promoted robust CL remodeling, which lowered cardiac respiratory enzyme activities through changes in protein-CL binding and formation of membrane microdomains (68).…”

“…For select experiments, the addition of cyt c (3.8 -17 M final concentration), as well as other proteins, to GUVs and GMVs occurred immediately prior to imaging. Samples were drawn into a rectangular capillary tube (VitroTubes) and mounted onto a glass microscope slide as previously shown (68,74).…”

“…Pressure-area isotherms were analyzed at physiologically relevant surface pressures (i.e. 30 mN/m) as previously described (26,68). Raw isotherms were used to calculate the surface elasticity modulus (C s…”