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Inhibition of oxidative stress by coenzyme Q10 increases mitochondrial mass and improves bioenergetic function in optic nerve head astrocytes.

Noh YH, Kim KY, Shim MS, Choi SH, Choi S, Ellisman MH, Weinreb RN, Perkins GA, Ju WK - Cell Death Dis (2013)

Bottom Line: In contrast, CoQ10 not only prevented activation of ONH astrocytes but also significantly decreased SOD2 and HO-1 protein expression in the ONH astrocytes against oxidative stress.Finally, oxidative stress triggered the upregulation of OXPHOS Cx protein expression, as well as reduction of cellular adeonsine triphosphate (ATP) production and increase of ROS generation in the ONH astocytes.However, CoQ10 preserved OXPHOS protein expression and cellular ATP production, as well as decreased ROS generation in the ONH astrocytes.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Optic Nerve Biology, Hamilton Glaucoma Center and Department of Ophthalmology, University of California, San Diego, La Jolla, CA, USA.

ABSTRACT
Oxidative stress contributes to dysfunction of glial cells in the optic nerve head (ONH). However, the biological basis of the precise functional role of mitochondria in this dysfunction is not fully understood. Coenzyme Q10 (CoQ10), an essential cofactor of the electron transport chain and a potent antioxidant, acts by scavenging reactive oxygen species (ROS) for protecting neuronal cells against oxidative stress in many neurodegenerative diseases. Here, we tested whether hydrogen peroxide (100 μM H2O2)-induced oxidative stress alters the mitochondrial network, oxidative phosphorylation (OXPHOS) complex (Cx) expression and bioenergetics, as well as whether CoQ10 can ameliorate oxidative stress-mediated alterations in mitochondria of the ONH astrocytes in vitro. Oxidative stress triggered the activation of ONH astrocytes and the upregulation of superoxide dismutase 2 (SOD2) and heme oxygenase-1 (HO-1) protein expression in the ONH astrocytes. In contrast, CoQ10 not only prevented activation of ONH astrocytes but also significantly decreased SOD2 and HO-1 protein expression in the ONH astrocytes against oxidative stress. Further, CoQ10 prevented a significant loss of mitochondrial mass by increasing mitochondrial number and volume density and by preserving mitochondrial cristae structure, as well as promoted mitofilin and peroxisome-proliferator-activated receptor-γ coactivator-1 protein expression in the ONH astrocyte, suggesting an induction of mitochondrial biogenesis. Finally, oxidative stress triggered the upregulation of OXPHOS Cx protein expression, as well as reduction of cellular adeonsine triphosphate (ATP) production and increase of ROS generation in the ONH astocytes. However, CoQ10 preserved OXPHOS protein expression and cellular ATP production, as well as decreased ROS generation in the ONH astrocytes. On the basis of these observations, we suggest that oxidative stress-mediated mitochondrial dysfunction or alteration may be an important pathophysiological mechanism in the dysfunction of ONH astrocytes. CoQ10 may provide new therapeutic potentials and strategies for protecting ONH astrocytes against oxidative stress-mediated mitochondrial dysfunction or alteration in glaucoma and other optic neuropathies.

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CoQ10 triggers mitochondrial biogenesis in ONH astrocytes that counters oxidative stress. (a) The representative 2D images from TEM analysis showed that control ONH astrocytes exposed to vehicle contained classic elongated tubular mitochondria. However, ONH astrocytes exposed to H2O2 contained fewer mitochondria in the ONH astrocytes. Interestingly, ONH astrocytes pretreated with CoQ10 showed a greater number compared with the ONH astrocytes exposed to H2O2. (b) Quantitative analysis showed that mitochondrial number per area and volume density were significantly decreased in the ONH astrocytes exposed to H2O2. However, ONH astrocytes pretreated with CoQ10 had a significant increase in mitochondrial number and volume density compared with the ONH astrocytes exposed to H2O2. There was no difference in mitochondrial length among control, H2O2 and CoQ10/H2O2-treated ONH astrocytes. Values are mean±S.E.M. *P<0.05, **P<0.01 and ***P<0.001 compared with vehicle-treated control ONH astrocytes or H2O2-treated ONH astrocytes. Scale bar, 500 nm. (c) Mitofilin protein expression was significantly increased in the ONH astrocytes exposed to H2O2 compared with vehicle-treated control ONH astrocytes. In contrast, CoQ10 significantly increased mitofilin protein expression compared with ONH astrocytes exposed to H2O2. PGC-1α protein expression was significantly increased in the ONH astrocytes exposed to H2O2 compared with vehicle-treated control ONH astrocytes. Of interest, pretreatment of CoQ10 showed greater increase of PGC-1α protein expression in the ONH astrocytes exposed to H2O2. Relative intensity of chemiluminescence for each protein band was normalized using actin. Values are mean±S.D. (n=3). CoQ10, coenzyme Q10; H2O2, hydrogen peroxide
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fig4: CoQ10 triggers mitochondrial biogenesis in ONH astrocytes that counters oxidative stress. (a) The representative 2D images from TEM analysis showed that control ONH astrocytes exposed to vehicle contained classic elongated tubular mitochondria. However, ONH astrocytes exposed to H2O2 contained fewer mitochondria in the ONH astrocytes. Interestingly, ONH astrocytes pretreated with CoQ10 showed a greater number compared with the ONH astrocytes exposed to H2O2. (b) Quantitative analysis showed that mitochondrial number per area and volume density were significantly decreased in the ONH astrocytes exposed to H2O2. However, ONH astrocytes pretreated with CoQ10 had a significant increase in mitochondrial number and volume density compared with the ONH astrocytes exposed to H2O2. There was no difference in mitochondrial length among control, H2O2 and CoQ10/H2O2-treated ONH astrocytes. Values are mean±S.E.M. *P<0.05, **P<0.01 and ***P<0.001 compared with vehicle-treated control ONH astrocytes or H2O2-treated ONH astrocytes. Scale bar, 500 nm. (c) Mitofilin protein expression was significantly increased in the ONH astrocytes exposed to H2O2 compared with vehicle-treated control ONH astrocytes. In contrast, CoQ10 significantly increased mitofilin protein expression compared with ONH astrocytes exposed to H2O2. PGC-1α protein expression was significantly increased in the ONH astrocytes exposed to H2O2 compared with vehicle-treated control ONH astrocytes. Of interest, pretreatment of CoQ10 showed greater increase of PGC-1α protein expression in the ONH astrocytes exposed to H2O2. Relative intensity of chemiluminescence for each protein band was normalized using actin. Values are mean±S.D. (n=3). CoQ10, coenzyme Q10; H2O2, hydrogen peroxide

Mentions: To determine whether oxidative stress triggers alteration of the intracellular mitochondrial network in ONH astrocytes and whether CoQ10 treatment inhibits this alteration in mitochondria against oxidative stress, the mitochondrial morphology of ONH astrocytes were assessed by MitoTracker Red (Invitrogen-Molecular Probes, Eugene, OR, USA) staining, a marker for mitochondria. Further, we quantified the aterations of mitochondrial number, length and volume density following exposure of H2O2 using transmission electron microscopy (TEM) analysis. Our results showed that control ONH astrocytes contained classic elongated tubular mitochondria. However, ONH astrocytes exposed to H2O2 contained small rounded mitochondria. Interestingly, ONH astrocytes pretreated with CoQ10 and exposed to H2O2 showed a partial preservation of mitochondrial morphology compared with the ONH astrocytes exposed to H2O2 (Figure 3). Of note, representative 2D images from TEM showed that ONH astrocytes exposed to oxidative stress produced fewer mitochondria. In good agreement with this result, quantitative analyses importantly showed that the number of mitochondria, normalized to the total area occupied by somas in each image, was significantly decreased in the ONH astrocytes exposed to H2O2 (0.15±0.01 μm2) compared with control ONH astrocytes (0.52±0.07 μm2; P<0.001; Figures 4a and b). In contrast, pretreatment of CoQ10 increased mitochondrial numbers to a lesser extent (0.26±0.03) compared with ONH astrocytes exposed to H2O2 (P<0.05; Figure 4b). In addition, mitochondrial volume density, defined as the volume occupied by mitochondria divided by the volume occupied by the cytoplasm in terms of a percentage, was decreased in the ONH astrocytes exposed to H2O2 (3.58±0.38%) compared with control ONH astrocytes (6.36±0.87% P<0.01; Figures 4a and b). In contrast, pretreatment of CoQ10 significantly increased the mitochondrial volume density (5.84±0.75%) compared with ONH astrocytes exposed to H2O2 (P<0.05; Figure 4b). Interestingly, however, there was no difference in mitochondrial length among control, H2O2- and CoQ10/H2O2-treated ONH astrocytes (Figures 4a and b), indicating that mitochondrial biogenesis by CoQ10 did not come from increased mitochondrial fusion but rather by nascent mitochondria.


Inhibition of oxidative stress by coenzyme Q10 increases mitochondrial mass and improves bioenergetic function in optic nerve head astrocytes.

Noh YH, Kim KY, Shim MS, Choi SH, Choi S, Ellisman MH, Weinreb RN, Perkins GA, Ju WK - Cell Death Dis (2013)

CoQ10 triggers mitochondrial biogenesis in ONH astrocytes that counters oxidative stress. (a) The representative 2D images from TEM analysis showed that control ONH astrocytes exposed to vehicle contained classic elongated tubular mitochondria. However, ONH astrocytes exposed to H2O2 contained fewer mitochondria in the ONH astrocytes. Interestingly, ONH astrocytes pretreated with CoQ10 showed a greater number compared with the ONH astrocytes exposed to H2O2. (b) Quantitative analysis showed that mitochondrial number per area and volume density were significantly decreased in the ONH astrocytes exposed to H2O2. However, ONH astrocytes pretreated with CoQ10 had a significant increase in mitochondrial number and volume density compared with the ONH astrocytes exposed to H2O2. There was no difference in mitochondrial length among control, H2O2 and CoQ10/H2O2-treated ONH astrocytes. Values are mean±S.E.M. *P<0.05, **P<0.01 and ***P<0.001 compared with vehicle-treated control ONH astrocytes or H2O2-treated ONH astrocytes. Scale bar, 500 nm. (c) Mitofilin protein expression was significantly increased in the ONH astrocytes exposed to H2O2 compared with vehicle-treated control ONH astrocytes. In contrast, CoQ10 significantly increased mitofilin protein expression compared with ONH astrocytes exposed to H2O2. PGC-1α protein expression was significantly increased in the ONH astrocytes exposed to H2O2 compared with vehicle-treated control ONH astrocytes. Of interest, pretreatment of CoQ10 showed greater increase of PGC-1α protein expression in the ONH astrocytes exposed to H2O2. Relative intensity of chemiluminescence for each protein band was normalized using actin. Values are mean±S.D. (n=3). CoQ10, coenzyme Q10; H2O2, hydrogen peroxide
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fig4: CoQ10 triggers mitochondrial biogenesis in ONH astrocytes that counters oxidative stress. (a) The representative 2D images from TEM analysis showed that control ONH astrocytes exposed to vehicle contained classic elongated tubular mitochondria. However, ONH astrocytes exposed to H2O2 contained fewer mitochondria in the ONH astrocytes. Interestingly, ONH astrocytes pretreated with CoQ10 showed a greater number compared with the ONH astrocytes exposed to H2O2. (b) Quantitative analysis showed that mitochondrial number per area and volume density were significantly decreased in the ONH astrocytes exposed to H2O2. However, ONH astrocytes pretreated with CoQ10 had a significant increase in mitochondrial number and volume density compared with the ONH astrocytes exposed to H2O2. There was no difference in mitochondrial length among control, H2O2 and CoQ10/H2O2-treated ONH astrocytes. Values are mean±S.E.M. *P<0.05, **P<0.01 and ***P<0.001 compared with vehicle-treated control ONH astrocytes or H2O2-treated ONH astrocytes. Scale bar, 500 nm. (c) Mitofilin protein expression was significantly increased in the ONH astrocytes exposed to H2O2 compared with vehicle-treated control ONH astrocytes. In contrast, CoQ10 significantly increased mitofilin protein expression compared with ONH astrocytes exposed to H2O2. PGC-1α protein expression was significantly increased in the ONH astrocytes exposed to H2O2 compared with vehicle-treated control ONH astrocytes. Of interest, pretreatment of CoQ10 showed greater increase of PGC-1α protein expression in the ONH astrocytes exposed to H2O2. Relative intensity of chemiluminescence for each protein band was normalized using actin. Values are mean±S.D. (n=3). CoQ10, coenzyme Q10; H2O2, hydrogen peroxide
Mentions: To determine whether oxidative stress triggers alteration of the intracellular mitochondrial network in ONH astrocytes and whether CoQ10 treatment inhibits this alteration in mitochondria against oxidative stress, the mitochondrial morphology of ONH astrocytes were assessed by MitoTracker Red (Invitrogen-Molecular Probes, Eugene, OR, USA) staining, a marker for mitochondria. Further, we quantified the aterations of mitochondrial number, length and volume density following exposure of H2O2 using transmission electron microscopy (TEM) analysis. Our results showed that control ONH astrocytes contained classic elongated tubular mitochondria. However, ONH astrocytes exposed to H2O2 contained small rounded mitochondria. Interestingly, ONH astrocytes pretreated with CoQ10 and exposed to H2O2 showed a partial preservation of mitochondrial morphology compared with the ONH astrocytes exposed to H2O2 (Figure 3). Of note, representative 2D images from TEM showed that ONH astrocytes exposed to oxidative stress produced fewer mitochondria. In good agreement with this result, quantitative analyses importantly showed that the number of mitochondria, normalized to the total area occupied by somas in each image, was significantly decreased in the ONH astrocytes exposed to H2O2 (0.15±0.01 μm2) compared with control ONH astrocytes (0.52±0.07 μm2; P<0.001; Figures 4a and b). In contrast, pretreatment of CoQ10 increased mitochondrial numbers to a lesser extent (0.26±0.03) compared with ONH astrocytes exposed to H2O2 (P<0.05; Figure 4b). In addition, mitochondrial volume density, defined as the volume occupied by mitochondria divided by the volume occupied by the cytoplasm in terms of a percentage, was decreased in the ONH astrocytes exposed to H2O2 (3.58±0.38%) compared with control ONH astrocytes (6.36±0.87% P<0.01; Figures 4a and b). In contrast, pretreatment of CoQ10 significantly increased the mitochondrial volume density (5.84±0.75%) compared with ONH astrocytes exposed to H2O2 (P<0.05; Figure 4b). Interestingly, however, there was no difference in mitochondrial length among control, H2O2- and CoQ10/H2O2-treated ONH astrocytes (Figures 4a and b), indicating that mitochondrial biogenesis by CoQ10 did not come from increased mitochondrial fusion but rather by nascent mitochondria.

Bottom Line: In contrast, CoQ10 not only prevented activation of ONH astrocytes but also significantly decreased SOD2 and HO-1 protein expression in the ONH astrocytes against oxidative stress.Finally, oxidative stress triggered the upregulation of OXPHOS Cx protein expression, as well as reduction of cellular adeonsine triphosphate (ATP) production and increase of ROS generation in the ONH astocytes.However, CoQ10 preserved OXPHOS protein expression and cellular ATP production, as well as decreased ROS generation in the ONH astrocytes.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Optic Nerve Biology, Hamilton Glaucoma Center and Department of Ophthalmology, University of California, San Diego, La Jolla, CA, USA.

ABSTRACT
Oxidative stress contributes to dysfunction of glial cells in the optic nerve head (ONH). However, the biological basis of the precise functional role of mitochondria in this dysfunction is not fully understood. Coenzyme Q10 (CoQ10), an essential cofactor of the electron transport chain and a potent antioxidant, acts by scavenging reactive oxygen species (ROS) for protecting neuronal cells against oxidative stress in many neurodegenerative diseases. Here, we tested whether hydrogen peroxide (100 μM H2O2)-induced oxidative stress alters the mitochondrial network, oxidative phosphorylation (OXPHOS) complex (Cx) expression and bioenergetics, as well as whether CoQ10 can ameliorate oxidative stress-mediated alterations in mitochondria of the ONH astrocytes in vitro. Oxidative stress triggered the activation of ONH astrocytes and the upregulation of superoxide dismutase 2 (SOD2) and heme oxygenase-1 (HO-1) protein expression in the ONH astrocytes. In contrast, CoQ10 not only prevented activation of ONH astrocytes but also significantly decreased SOD2 and HO-1 protein expression in the ONH astrocytes against oxidative stress. Further, CoQ10 prevented a significant loss of mitochondrial mass by increasing mitochondrial number and volume density and by preserving mitochondrial cristae structure, as well as promoted mitofilin and peroxisome-proliferator-activated receptor-γ coactivator-1 protein expression in the ONH astrocyte, suggesting an induction of mitochondrial biogenesis. Finally, oxidative stress triggered the upregulation of OXPHOS Cx protein expression, as well as reduction of cellular adeonsine triphosphate (ATP) production and increase of ROS generation in the ONH astocytes. However, CoQ10 preserved OXPHOS protein expression and cellular ATP production, as well as decreased ROS generation in the ONH astrocytes. On the basis of these observations, we suggest that oxidative stress-mediated mitochondrial dysfunction or alteration may be an important pathophysiological mechanism in the dysfunction of ONH astrocytes. CoQ10 may provide new therapeutic potentials and strategies for protecting ONH astrocytes against oxidative stress-mediated mitochondrial dysfunction or alteration in glaucoma and other optic neuropathies.

Show MeSH
Related in: MedlinePlus