The role of Ndufb6 subunit of the electron transport system complex I in the regulation of mitochondrial energy metabolism and insulin sensitivity in C2C12 myotubes

2017 ◽  
Vol 12 (S 01) ◽  
pp. S1-S84
Author(s):  
T Jelenik ◽  
SW Görgens ◽  
N Krako Jakovljevic ◽  
I Rokitta ◽  
NM Lalic ◽  
...  
Keyword(s):  
Insulin Sensitivity ◽  
Energy Metabolism ◽  
Electron Transport ◽  
Transport System ◽  
Complex I ◽  
Electron Transport System ◽  
C2c12 Myotubes ◽  
Mitochondrial Energy Metabolism

scholarly journals RAPID COMMUNICATION: Differential skeletal muscle mitochondrial characteristics of weanling racing-bred horses1

2019 ◽  
Vol 97 (8) ◽  
pp. 3193-3198 ◽  
Author(s):  
Christine M Latham ◽  
Clara K Fenger ◽  
Sarah H White
Keyword(s):  
Skeletal Muscle ◽  
Electron Transport ◽  
Transport System ◽  
Complex I ◽  
Management Practices ◽  
Citrate Synthase ◽  
Fiber Type ◽  
Gluteus Medius ◽  
Electron Transport System ◽  
Mitochondrial Density

Abstract Responses of equine skeletal muscle characteristics to growth and training have been shown to differ between breeds. These differential responses may arise in part because muscle fiber type and mitochondrial density differ between breeds, even in untrained racing-bred horses. However, it is not known when these breed-specific differences manifest. To test the hypothesis that weanling Standardbreds (SB) and Thoroughbreds (TB) would have higher mitochondrial measures than Quarter Horses (QH), gluteus medius samples were collected from SB (mean ± SD; 6.2 ± 1.0 mo; n = 10), TB (6.1 ± 0.5 mo; n = 12), and QH (7.4 ± 0.6 mo; n = 10). Citrate synthase (CS) and cytochrome c oxidase (CCO) activities were assessed as markers of mitochondrial density and function, respectively. Mitochondrial oxidative (P) and electron transport system (E) capacities were assessed by high-resolution respirometry (HRR). Data for CCO and HRR are expressed as integrated (per mg protein and per mg tissue wet weight, respectively) and intrinsic (per unit CS). Data were analyzed using PROC MIXED in SAS v 9.4 with breed as a fixed effect. Mitochondrial density (CS) was higher for SB and TB than QH (P ≤ 0.0007). Mitochondrial function (integrated and intrinsic CCO) was higher in TB and QH than SB (P ≤ 0.01). Integrated CCO was also higher in TB than QH (P < 0.0001). However, SB had higher integrated maximum P (PCI+II) and E (ECI+II) than QH (P ≤ 0.02) and greater integrated and intrinsic complex II-supported E (ECII) than both QH and TB (P ≤ 0.02), whereas TB exhibited higher integrated P with complex I substrates (PCI) than SB and QH (P ≤ 0.003) and higher integrated PCI+II and ECI+II than QH (P ≤ 0.02). In agreement, TB and QH had higher contribution of complex I (CI) to max E than SB (P ≤ 0.001), whereas SB had higher contribution of CII than QH and TB (P ≤ 0.002). Despite having higher mitochondrial density than QH and TB, SB showed lower CCO activity and differences in contribution of complexes to oxidative and electron transport system capacities. Breed differences in mitochondrial parameters are present early in life and should be considered when developing feeding, training, medication, and management practices.

scholarly journals Human blood contains circulating cell-free mitochondria, but are they really functional?

2020 ◽  
Author(s):  
Antoine Stier
Keyword(s):  
Electron Transport ◽  
Transport System ◽  
Human Blood ◽  
Electron Transport System ◽  
Complex Iv ◽  
Mitochondrial Inhibitors ◽  
Functional Part ◽  
Positive Controls

AbstractDache et al. (2020, FASEB J. 15, e2002338–15) recently reported the presence of respiratory-competent cell-free mitochondria in human blood (up to 3.7 x 106 per mL of blood), providing exciting perspectives on the potential role of these extra-cellular mitochondria. While their evidence for the presence of cell-free mitochondria in human blood is compelling, their conclusion that these cell-free mitochondria are respiratory-competent or functional has to be re-evaluated. To this end, we evaluated the functionality of cell-free mitochondria in human blood using high-resolution respirometry and mitochondria extracted from platelets of the same blood samples as positive controls. While cell-free mitochondria were present in human plasma (i.e. significant complex IV activity), there was no evidence suggesting that their mitochondrial electron transport system (ETS) was functional (i.e. respiration rate not significantly different from 0; no significant responses to ADP, uncoupler or mitochondrial inhibitors oligomycin and antimycin A). Yet, in vitro complex IV activity was detectable and even slightly higher than levels found in mitochondria extracted from platelets, suggesting that cell-free mitochondria in human blood only retain a non-functional part of the electron transport system. Despite being unlikely to be fully functional in the narrow-sense (i.e. capable of oxidative phosphorylation), circulating cell-free mitochondria may have significant physiological roles that remain to be elucidated.

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