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Complex I dysfunction underlies the glycolytic switch in pulmonary hypertensive smooth muscle cells.

Rafikov R, Sun X, Rafikova O, Louise Meadows M, Desai AA, Khalpey Z, Yuan JX, Fineman JR, Black SM - Redox Biol (2015)

Bottom Line: In particular the role of the respiratory Complexes in the mitochondrial dysfunction associated with PH is unresolved and was the focus of our investigations.We further found that the defect in Complex I activity was due to a loss of Complex I assembly, although the assembly of Complexes II and III were both maintained.Thus, we conclude that loss of Complex I assembly may be involved in the switch of energy metabolism in smooth muscle cells to glycolysis and that maintaining Complex I activity may be a potential therapeutic target for the treatment of PH.

View Article: PubMed Central - PubMed

Affiliation: Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, AZ, USA; Department of Medicine, The University of Arizona, Tucson, AZ, USA. Electronic address: ruslanrafikov@deptofmed.arizona.edu.

No MeSH data available.


Related in: MedlinePlus

Complex I and Complex II dependent respiration is attenuated in pulmonary arterial smooth muscle cells isolated from rats with pulmonary hypertension. The Seahorse XF24 analyzer was used to take OCR measurements in PASMC (40,000/0.32 cm2) isolated from control (red) and PH (blue) rats to determine Complex I and II respiratory activity (A). Both Complex I (B) and Complex II (C) activities are attenuated in PH- compared to Control-PASMC. Values are means±SEM. *(p<0.05 vs. Control PH-PASMC, N=5–15 measurements from 3 independent SMC isolations). (For interpretation of the references to color in this figure legend,the reader is referred to the web version of this article.)
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f0015: Complex I and Complex II dependent respiration is attenuated in pulmonary arterial smooth muscle cells isolated from rats with pulmonary hypertension. The Seahorse XF24 analyzer was used to take OCR measurements in PASMC (40,000/0.32 cm2) isolated from control (red) and PH (blue) rats to determine Complex I and II respiratory activity (A). Both Complex I (B) and Complex II (C) activities are attenuated in PH- compared to Control-PASMC. Values are means±SEM. *(p<0.05 vs. Control PH-PASMC, N=5–15 measurements from 3 independent SMC isolations). (For interpretation of the references to color in this figure legend,the reader is referred to the web version of this article.)

Mentions: To understand the role of mitochondrial respiratory chain Complexes in mitochondrial dysfunction and glycolytic switch, we utilized a novel cell permeabilization protocol to allow us to measure individual Complex activity in cells. Our data indicate that the activities of both Complex I and Complex II are decreased by ∼50% in PH-PASMC (Fig. 3). Unfortunately, the Seahorse XF instrument is limited to 4 injections, so, we could not examine substrate utilization from all mitochondrial Complexes in a single experiment. Thus, in a separate set of experiments, we measured Complex I and Complex III activity. Our data indicate that Complex III activity is also inhibited by ∼50% in PH-PASMC (Fig. 4). Interestingly, this 50% reduction in Complex I–III activity correlates well with the ∼50% decrease in overall mitochondrial OCR (Fig. 1).


Complex I dysfunction underlies the glycolytic switch in pulmonary hypertensive smooth muscle cells.

Rafikov R, Sun X, Rafikova O, Louise Meadows M, Desai AA, Khalpey Z, Yuan JX, Fineman JR, Black SM - Redox Biol (2015)

Complex I and Complex II dependent respiration is attenuated in pulmonary arterial smooth muscle cells isolated from rats with pulmonary hypertension. The Seahorse XF24 analyzer was used to take OCR measurements in PASMC (40,000/0.32 cm2) isolated from control (red) and PH (blue) rats to determine Complex I and II respiratory activity (A). Both Complex I (B) and Complex II (C) activities are attenuated in PH- compared to Control-PASMC. Values are means±SEM. *(p<0.05 vs. Control PH-PASMC, N=5–15 measurements from 3 independent SMC isolations). (For interpretation of the references to color in this figure legend,the reader is referred to the web version of this article.)
© Copyright Policy - CC BY-NC-ND
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4556771&req=5

f0015: Complex I and Complex II dependent respiration is attenuated in pulmonary arterial smooth muscle cells isolated from rats with pulmonary hypertension. The Seahorse XF24 analyzer was used to take OCR measurements in PASMC (40,000/0.32 cm2) isolated from control (red) and PH (blue) rats to determine Complex I and II respiratory activity (A). Both Complex I (B) and Complex II (C) activities are attenuated in PH- compared to Control-PASMC. Values are means±SEM. *(p<0.05 vs. Control PH-PASMC, N=5–15 measurements from 3 independent SMC isolations). (For interpretation of the references to color in this figure legend,the reader is referred to the web version of this article.)
Mentions: To understand the role of mitochondrial respiratory chain Complexes in mitochondrial dysfunction and glycolytic switch, we utilized a novel cell permeabilization protocol to allow us to measure individual Complex activity in cells. Our data indicate that the activities of both Complex I and Complex II are decreased by ∼50% in PH-PASMC (Fig. 3). Unfortunately, the Seahorse XF instrument is limited to 4 injections, so, we could not examine substrate utilization from all mitochondrial Complexes in a single experiment. Thus, in a separate set of experiments, we measured Complex I and Complex III activity. Our data indicate that Complex III activity is also inhibited by ∼50% in PH-PASMC (Fig. 4). Interestingly, this 50% reduction in Complex I–III activity correlates well with the ∼50% decrease in overall mitochondrial OCR (Fig. 1).

Bottom Line: In particular the role of the respiratory Complexes in the mitochondrial dysfunction associated with PH is unresolved and was the focus of our investigations.We further found that the defect in Complex I activity was due to a loss of Complex I assembly, although the assembly of Complexes II and III were both maintained.Thus, we conclude that loss of Complex I assembly may be involved in the switch of energy metabolism in smooth muscle cells to glycolysis and that maintaining Complex I activity may be a potential therapeutic target for the treatment of PH.

View Article: PubMed Central - PubMed

Affiliation: Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, AZ, USA; Department of Medicine, The University of Arizona, Tucson, AZ, USA. Electronic address: ruslanrafikov@deptofmed.arizona.edu.

No MeSH data available.


Related in: MedlinePlus