A metabolic role for mitochondria in palmitate-induced cardiac myocyte apoptosis

Sparagna, Genevieve C.; Hickson-Bick, Diane L.; Buja, L. Maximilian; McMillin, Jeanie B.

doi:10.1152/ajpheart.2000.279.5.h2124

Cited by 203 publications

(152 citation statements)

References 53 publications

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“…However, because these inhibitors did not block apoptosis, we conclude that ceramide accumulation is not involved in palmitate-induced apoptosis. Recent data obtained with CHO cells and cardiomyocytes also support a non-essential role for de novo ceramide synthesis in palmitate-induced apoptosis (13,44). Excess palmitate may also lead to increased mitochondrial ␤-oxidation pathway generating ROS in excess of endogenous antioxidant.…”

Section: Discussionmentioning

confidence: 85%

Saturated Fatty Acid-induced Apoptosis in MDA-MB-231 Breast Cancer Cells

Hardy

El-Assaad

Przybytkowski

et al. 2003

Journal of Biological Chemistry

248

243

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Little is known about the biochemical basis of the action of free fatty acids (FFA) on breast cancer cell proliferation and apoptosis. Here we report that unsaturated FFAs stimulated the proliferation of human MDA-MB-231 breast cancer cells, whereas saturated FFAs inhibited it and caused apoptosis. Saturated FFA palmitate decreased the mitochondrial membrane potential and caused cytochrome c release. Palmitate-induced apoptosis was enhanced by the fat oxidation inhibitor etomoxir, whereas it was reduced by fatty-acyl CoA synthase inhibitor triacsin C. The non-metabolizable analog 2-bromopalmitate was not cytotoxic. This indicates that palmitate must be metabolized to exert its toxic effect but that its action does not involve fat oxidation. Pharmacological studies showed that the action of palmitate is not mediated via ceramides, reactive oxygen species, or changes in phosphatidylinositol 3-kinase activity. Palmitate caused early enhancement of cardiolipin turnover and decreased the levels of this mitochondrial phospholipid, which is necessary for cytochrome c retention. Cosupplementation of oleate, or increasing ␤-oxidation with the AMP-activated protein kinase activator, 5-aminoimidazole-4-carboxamide-1-␤-D-ribonucleoside, both restored cardiolipin levels and blocked palmitate-induced apoptosis. Oleate was preferentially metabolized to triglycerides, and oleate cosupplementation channeled palmitate esterification processes to triglycerides. Overexpression of Bcl-2 family members blocked palmitateinduced apoptosis. The results provide evidence that a decrease in cardiolipin levels and altered mitochondrial function are involved in palmitate-induced breast cancer cell death. They also suggest that the antiapoptotic action of oleate on palmitate-induced cell death involves both restoration of cardiolipin levels and redirection of palmitate esterification processes to triglycerides.

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Section: Discussionmentioning

confidence: 85%

Saturated Fatty Acid-induced Apoptosis in MDA-MB-231 Breast Cancer Cells

Hardy

El-Assaad

Przybytkowski

et al. 2003

Journal of Biological Chemistry

248

243

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“…The membrane-permeable dye DCFH-DA enters cardiomyocytes and produces a fluorescent signal after intracellular oxidation by ROS such as hydrogen peroxide and the hydroxyl radical (29). Neonatal cardiomyocytes were incubated in palmitate or the control fatty acid oleate for 4 or 20 h. We have previously shown that exposure of these cells to palmitate for 4 h is sufficient to induce mitochondrial cytochrome c release, whereas after 20 h, palmitate causes caspase-3-like activation, increased ceramide production, and DNA laddering (8,26). With the use of video microscopy of live cells and examination of multiple fields of cells, we were unable to detect any increase in fluorescence in palmitate-treated cells over control oleate-treated cells at either time.…”

Section: Resultsmentioning

confidence: 99%

“…We have previously shown that this apoptosis is characterized by an early mitochondrial release of cytochrome c and a loss of mitochondrial membrane potential (26). Later events include an increase in ceramide synthesis, inhibition of mitochondrial electron transport complex III, activa- Values are means of caspasase-3-like activity (in fluorescence units ⅐ min Ϫ1 ⅐ mg protein Ϫ1 ) Ϯ SE.…”

Section: Discussionmentioning

confidence: 99%

“…tion of caspase-3-like enzymes, and DNA laddering (8,26). Increased production of ROS have been implicated in stress induction of apoptosis in cardiac myocytes and reported to be involved in palmitate-induced apoptosis of CHO cells (14).…”

Section: Discussionmentioning

confidence: 99%

“…We have previously shown that palmitate causes apoptosis in rat neonatal cardiac myocytes manifested by cytochrome c release, mitochondrial membrane potential loss, mitochondrial swelling, inhibition of carnitine palmitoyltransferase I-␤, inhibition of complex III, caspase-3-like activation, poly(ADP-ribose) polymerase (PARP) cleavage, and DNA laddering (8,26). In this study, we examined the role of ROS in palmitate-induced apoptosis by employing several techniques including ROS-sensitive fluorescent dyes, antioxidants, nitric oxide (NO) measurement, nuclear factor (NF)-B translocation, and protein carbonylation to detect evidence of oxidative stress during palmitate-induced apoptosis.…”

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confidence: 99%

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Palmitate-induced apoptosis in neonatal cardiomyocytes is not dependent on the generation of ROS

Hickson-Bick¹,

Sparagna²,

Buja³

et al. 2002

American Journal of Physiology-Heart and Circulatory Physiology

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The saturated fatty acid palmitate induces apoptosis in neonatal rat cardiomyocytes. This apoptosis is associated with early mitochondrial release of cytochrome c and a subsequent loss of mitochondrial membrane potential. Recent reports implicate a role for reactive oxygen species (ROS) in palmitate-induced apoptosis. We studied the role of ROS in palmitate-induced apoptosis in the neonatal rat cardiomyocyte and report no evidence of ROS involvement. ROS production, nitric oxide production, and nuclear factor-B activation were not increased above those observed using the nonapoptotic fatty acid oleate. Indeed, the production of ROS was significantly higher in cells treated with oleate. Furthermore, the presence of antioxidants and ROS scavengers did not attenuate the induction of apoptosis by palmitate. Variations in the fatty acid-to-albumin ratio from 2:1 to 7:1 had no effect on the absence of ROS production or on the extent of apoptosis. No evidence was found for an increase in oxidative protein modification in palmitate-treated cells. Our results lead us to conclude that oxidative stress does not play a role in palmitate-induced apoptosis.antioxidants; nitric oxide; mitochondria; nuclear factor-B

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Determination of the cardiolipin content of individual mitochondria by capillary electrophoresis with laser-induced fluorescence detection

2002

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We report the application of capillary electrophoresis (CE) with postcolumn laser-induced fluorescence (LIF) detection to measure the cardiolipin content of individual mitochondria from cultured NS1 cells. Mitochondria were isolated by differential centrifugation and stained with the fluorescent dye 10-N-nonyl acridine orange which stoichiometrically binds to cardiolipin in a 1:1 or 2:1 ratio depending on the dye concentration. The green fluorescence resulting from the 1:1 complex was chosen for analysis because it is substantially more intense than the red fluorescence resulting from the 2:1 complex. Two dye concentrations that resulted in maximal and submaximal formation of the 1:1 10-N-nonyl acridine orange-cardiolipin complex were identified by spectrofluorometry. Individual mitochondria stained with both dye concentrations were separated and detected by CE with LIF detection. The data from mitochondria dosed with the lower dye concentration, where it is assumed that all the dye added to the mitochondrial sample was bound to cardiolipin, were used to derive a sensitivity factor relating fluorescence intensity of a mitochondrial event to its cardiolipin content. Using this factor, the cardiolipin contents of individual mitochondria stained with the higher dye concentration were determined, and ranged from 1.2 to 920 amol, with a median value of 4 amol. These results suggest a new strategy for estimating the organellar content of compounds that can be fluorescently tagged.

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A metabolic role for mitochondria in palmitate-induced cardiac myocyte apoptosis

Cited by 203 publications

References 53 publications

Saturated Fatty Acid-induced Apoptosis in MDA-MB-231 Breast Cancer Cells

Saturated Fatty Acid-induced Apoptosis in MDA-MB-231 Breast Cancer Cells

Palmitate-induced apoptosis in neonatal cardiomyocytes is not dependent on the generation of ROS

Determination of the cardiolipin content of individual mitochondria by capillary electrophoresis with laser-induced fluorescence detection

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