Evaluating the Bioenergetics Health Index Ratio in Leigh Syndrome Fibroblasts to Understand Disease Severity

Several pediatric mitochondrial disorders, including Leigh syndrome (LS), impact mitochondrial (mt) genetics, development, and metabolism, leading to complex pathologies and energy failure. The extent to which pathogenic mtDNA variants regulate disease severity in LS is currently not well understood. To better understand this relationship, we computed a glycolytic bioenergetics health index (BHI) for measuring mitochondrial dysfunction in LS patient fibroblast cells harboring varying percentages of pathogenic mutant mtDNA (T8993G, T9185C) exhibiting deficiency in complex V or complex I (T10158C, T12706C). A high percentage (>90%) of pathogenic mtDNA in cells affecting complex V and a low percentage (<39%) of pathogenic mtDNA in cells affecting complex I was quantified. Levels of defective enzyme activities of the electron transport chain correlated with the percentage of pathogenic mtDNA. Subsequent bioenergetics assays showed cell lines relied on both OXPHOS and glycolysis for meeting energy requirements. Results suggest that whereas the precise mechanism of LS has not been elucidated, a multi-pronged approach taking into consideration the specific pathogenic mtDNA variant, glycolytic BHI, and the composite BHI (average ratio of oxphos to glycolysis) can aid in better understanding the factors influencing disease severity in LS.

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Apoptosis inducing factor and mitochondrial NADH dehydrogenases: redox-controlled gear boxes to switch between mitochondrial biogenesis and cell death

Biological Chemistry ◽

10.1515/hsz-2020-0254 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Johannes M. Herrmann ◽

Jan Riemer

Keyword(s):

Cell Death ◽

Complex I ◽

Electron Transfer Reaction ◽

Apoptotic Protein ◽

Transport Chain ◽

Metabolic Conditions ◽

Nadh Dehydrogenases ◽

The One ◽

Apoptosis Inducing Factor ◽

Redox Switches

AbstractThe mitochondrial complex I serves as entry point for NADH into the electron transport chain. In animals, fungi and plants, additional NADH dehydrogenases carry out the same electron transfer reaction, however they do not pump protons. The apoptosis inducing factor (AIF, AIFM1 in humans) is a famous member of this group as it was the first pro-apoptotic protein identified that can induce caspase-independent cell death. Recent studies on AIFM1 and the NADH dehydrogenase Nde1 of baker’s yeast revealed two independent and experimentally separable activities of this class of enzymes: On the one hand, these proteins promote the functionality of mitochondrial respiration in different ways: They channel electrons into the respiratory chain and, at least in animals, promote the import of Mia40 (named MIA40 or CHCHD4 in humans) and the assembly of complex I. On the other hand, they can give rise to pro-apoptotic fragments that are released from the mitochondria to trigger cell death. Here we propose that AIFM1 and Nde1 serve as conserved redox switches which measure metabolic conditions on the mitochondrial surface and translate it into a binary life/death decision. This function is conserved among eukaryotic cells and apparently used to purge metabolically compromised cells from populations.

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Dysfunction in Mitochondrial Electron Transport Chain Complex I, Pyruvate Dehydrogenase Activity, and Mutations in ND1 and ND4 Gene in Autism Spectrum Disorder Subjects from Tamil Nadu Population, India

Molecular Neurobiology ◽

10.1007/s12035-021-02492-w ◽

2021 ◽

Author(s):

Iyer Mahalaxmi ◽

Mohana Devi Subramaniam ◽

Abilash Valsala Gopalakrishnan ◽

Balachandar Vellingiri

Keyword(s):

Autism Spectrum Disorder ◽

Electron Transport ◽

Pyruvate Dehydrogenase ◽

Complex I ◽

Electron Transport Chain ◽

Tamil Nadu ◽

Chain Complex ◽

Autism Spectrum ◽

Mitochondrial Electron Transport Chain ◽

Transport Chain

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TAT-Conjugated NDUFS8 Can Be Transduced into Mitochondria in a Membrane-Potential-Independent Manner and Rescue Complex I Deficiency

International Journal of Molecular Sciences ◽

10.3390/ijms22126524 ◽

2021 ◽

Vol 22 (12) ◽

pp. 6524

Author(s):

Bo-Yu Lin ◽

Gui-Teng Zheng ◽

Kai-Wen Teng ◽

Juan-Yu Chang ◽

Chao-Chang Lee ◽

...

Keyword(s):

Membrane Potential ◽

Fusion Proteins ◽

Complex I ◽

Nadh Dehydrogenase ◽

Leigh Syndrome ◽

Protein Transduction ◽

Independent Manner ◽

Complex I Deficiency ◽

Transactivator Of Transcription ◽

Hiv 1

NADH dehydrogenase (ubiquinone) Fe-S protein 8 (NDUFS8) is a nuclear-encoded core subunit of human mitochondrial complex I. Defects in NDUFS8 are associated with Leigh syndrome and encephalomyopathy. Cell-penetrating peptide derived from the HIV-1 transactivator of transcription protein (TAT) has been successfully applied as a carrier to bring fusion proteins into cells without compromising the biological function of the cargoes. In this study, we developed a TAT-mediated protein transduction system to rescue complex I deficiency caused by NDUFS8 defects. Two fusion proteins (TAT-NDUFS8 and NDUFS8-TAT) were exogenously expressed and purified from Escherichia coli for transduction of human cells. In addition, similar constructs were generated and used in transfection studies for comparison. The results showed that both exogenous TAT-NDUFS8 and NDUFS8-TAT were delivered into mitochondria and correctly processed. Interestingly, the mitochondrial import of TAT-containing NDUFS8 was independent of mitochondrial membrane potential. Treatment with TAT-NDUFS8 not only significantly improved the assembly of complex I in an NDUFS8-deficient cell line, but also partially rescued complex I functions both in the in-gel activity assay and the oxygen consumption assay. Our current findings suggest the considerable potential of applying the TAT-mediated protein transduction system for treatment of complex I deficiency.

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New inhibitors of Complex I of the mitochondrial electron transport chain with activity as pesticides

Biochemical Society Transactions ◽

10.1042/bst0220230 ◽

1994 ◽

Vol 22 (1) ◽

pp. 230-233 ◽

Cited By ~ 90

Author(s):

Robert M. Hollingworth ◽

Kabeer I. Ahammadsahib ◽

G. Gadelhak ◽

J. L. McLaughlin

Keyword(s):

Electron Transport ◽

Complex I ◽

Electron Transport Chain ◽

Mitochondrial Electron Transport Chain ◽

Transport Chain

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P311 Defective Complex I assembly due to C20orf7 mutations as a new cause of Leigh syndrome

European Journal of Paediatric Neurology ◽

10.1016/s1090-3798(09)70369-1 ◽

2009 ◽

Vol 13 ◽

pp. S118

Author(s):

I.F.M. de Coo ◽

M. Gerards ◽

W. Sluiter ◽

B.J.C. van den Bosch ◽

M. Frentzen ◽

...

Keyword(s):

Complex I ◽

Leigh Syndrome ◽

Complex I Assembly

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Complex I-Associated Hydrogen Peroxide Production Is Decreased and Electron Transport Chain Enzyme Activities Are Altered in n-3 Enriched fat-1 Mice

PLoS ONE ◽

10.1371/journal.pone.0012696 ◽

2010 ◽

Vol 5 (9) ◽

pp. e12696 ◽

Cited By ~ 45

Author(s):

Kevork Hagopian ◽

Kristina L. Weber ◽

Darren T. Hwee ◽

Alison L. Van Eenennaam ◽

Guillermo López-Lluch ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Electron Transport ◽

Enzyme Activities ◽

Complex I ◽

Electron Transport Chain ◽

Hydrogen Peroxide Production ◽

Transport Chain

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A novel mitochondrial m.14430A>G (MT-ND6, p.W82R) variant causes complex I deficiency and mitochondrial Leigh syndrome

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm-2020-0150 ◽

2020 ◽

Vol 58 (11) ◽

pp. 1809-1817

Author(s):

Miaomiao Du ◽

Xiujuan Wei ◽

Pu Xu ◽

Anran Xie ◽

Xiyue Zhou ◽

...

Keyword(s):

Mitochondrial Respiration ◽

Complex I ◽

Clinical Symptoms ◽

Lactate Production ◽

Mitochondrial Diseases ◽

Leigh Syndrome ◽

Extracellular Lactate ◽

Next Generation Sequencing Ngs ◽

Mutant Cells ◽

Generation Sequencing

AbstractObjectivesLeigh syndrome (LS) is one of the most common mitochondrial diseases and has variable clinical symptoms. However, the genetic variant spectrum of this disease is incomplete.MethodsNext-generation sequencing (NGS) was used to identify the m.14430A > G (p.W82R) variant in a patient with LS. The pathogenesis of this novel complex I (CI) variant was verified by determining the mitochondrial respiration, assembly of CI, ATP, MMP and lactate production, and cell growth rate in cybrids with and without this variant.ResultsA novel m.14430A > G (p.W82R) variant in the NADH dehydrogenase 6 (ND6) gene was identified in the patient; the mutant loads of m.14430A > G (p.W82R) in the patient were much higher than those in his mother. Although the transmitochondrial cybrid-based study showed that mitochondrial CI assembly remains unaffected in cells with the m.14430G variant, control cells had significantly higher endogenous and CI-dependent mitochondrial respiration than mutant cells. Accordingly, mutant cells had a lower ATP, MMP and higher extracellular lactate production than control cells. Notably, mutant cells had impaired growth in a galactose-containing medium when compared to wild-type cells.ConclusionsA novel m.14430A > G (p.W82R) variant in the ND6 gene was identified from a patient suspected to have LS, and this variant impaired mitochondrial respiration by decreasing the activity of mitochondrial CI.

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Pleurotus albidus Modulates Mitochondrial Metabolism Disrupted by Hyperglycaemia in EA.hy926 Endothelial Cells

BioMed Research International ◽

10.1155/2018/2859787 ◽

2018 ◽

Vol 2018 ◽

pp. 1-10 ◽

Cited By ~ 5

Author(s):

Gabriela Gambato ◽

Elisa Maria Pavão ◽

Gabriela Chilanti ◽

Roselei Claudete Fontana ◽

Mirian Salvador ◽

...

Keyword(s):

Nitric Oxide ◽

Endothelial Cells ◽

Mitochondrial Dysfunction ◽

Complex I ◽

Electron Transport Chain ◽

Mitochondrial Disorder ◽

Antioxidant Enzyme Activities ◽

Ros Production ◽

Oxygen Species ◽

Transport Chain

Hyperglycaemia exacerbates the production of reactive oxygen species (ROS), contributing to the multiple complications associated with diabetes. Mitochondrial dysfunction is also known to be associated with diabetes. Therefore, the aim of this work was to study the effect of Pleurotus albidus extract on the mitochondrial dysfunction induced by hyperglycaemia in EA.hy926 endothelial cells. The results showed that P. albidus treatment prevented the increase in the activity of complex I of the electron transport chain and minimized the ROS production induced by hyperglycaemia. In addition, the extract minimized oxidative damage to lipids and proteins, caused an imbalance in the antioxidant enzyme activities of superoxide dismutase and catalase, and decreased the nitric oxide levels induced by hyperglycaemia. These data contribute to our understanding of the mitochondrial disorder induced by hyperglycaemia as well as establishing the conditions required to minimize these alterations.

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