Nuskova 2011 Abstract IOC61

Nuskova H, Pecina P, Kovarova N, Dell’Agnello C, Zeviani M, Houstek J (2011) Cytochrome c oxidase with decreased H+/e− ratio in SURF1 knockout mice. MiPNet16.01.

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Nuskova H, Pecina P, Kovarova N, Dell’Agnello C, Zeviani M, Houstek J (2011)

Event: IOC61

Leigh syndrome is most frequently caused by mutations in SURF1 gene which encodes cytochrome c oxidase (COX) specific assembly factor. Our previous studies focused on fibroblasts from patients harbouring SURF1 mutations (1, 2). To further characterize the mitochondrial energetics affected by SURF1 mutation, we used immortalised fibroblasts originated from SURF1 knockout (KO) mice (3).

The COX content was decreased to 58 % of the control, which was in accordance with 38% decline of COX activity measured spectrophotometrically. However, there was no change in the rate of endogenous respiration or in the rate of ascorbate+TMPD-dependent respiration of permeabilised cells. In contrast, mitochondrial membrane potential generated by COX achieved 92 % of maximal membrane potential in the control cells, but only 73 % in the KO cells. Furthermore using ascorbate and TMPD, the decrease of membrane potential at state 3 (ADP) compared to state 4 (oligomycin) was more profound in the KO fibroblasts. Therefore, the proton-pumping activity of COX was partially impaired unlike the electron-transporting activity, suggesting a decrease in the H+/e− ratio. Since the p50 value of the KO cells was approximately 2-fold increased in all metabolic states measured, the oxygen affinity of COX was also decreased.

Taken together, the KO cells from mice showed similar but milder functional manifestations of COX impairment than the cells of Surf1-deficient patients, which indicates that the Surf1 protein is not as essential for mouse as for human.

(1) Pecina P, Capkova M, Chowdhury SKR, Drahota Z, Dubot A, Vojtiskova A, Hansikova H, Houstkova H, Zeman J, Godinot C, Houstek J (2003) Functional alteration of cytochrome c oxidase by SURF1 mutations in Leigh syndrome. BBA 1639: 53-63.

(2) Pecina P, Gnaiger E, Zeman J, Pronicka E, Houstek J (2004) Decreased affinity for oxygen of cytochrome-c oxidase in Leigh syndrome caused by SURF1 mutations. Am. J. Physiol. Cell. Physiol. 287: C1384-C1388.

(3) Dell’Agnello C, Leo S, Agostino A, Szabadkai G, Tiveron C, Zulian A, Prelle A, Roubertoux P, Rizzuto R, Zeviani M (2007) Increased longevity and refractoriness to Ca2+-dependent neurodegeneration in Surf1 knockout mice. Hum. Mol. Gen. 16: 431-444.

• Keywords: cytochrome c oxidase; SURF1 knockout; respiratory capacity; membrane potential

Labels:

Stress:Mitochondrial Disease; Degenerative Disease and Defect"Mitochondrial Disease; Degenerative Disease and Defect" is not in the list (Cell death, Cryopreservation, Ischemia-reperfusion, Permeability transition, Oxidative stress;RONS, Temperature, Hypoxia, Mitochondrial disease) of allowed values for the "Stress" property., Genetic Defect; Knockdown; Overexpression"Genetic Defect; Knockdown; Overexpression" is not in the list (Cell death, Cryopreservation, Ischemia-reperfusion, Permeability transition, Oxidative stress;RONS, Temperature, Hypoxia, Mitochondrial disease) of allowed values for the "Stress" property.  Organism: Mouse  Tissue;cell: Skeletal Muscle"Skeletal Muscle" is not in the list (Heart, Skeletal muscle, Nervous system, Liver, Kidney, Lung;gill, Islet cell;pancreas;thymus, Endothelial;epithelial;mesothelial cell, Blood cells, Fat, ...) of allowed values for the "Tissue and cell" property., Endothelial; Epithelial; Mesothelial Cell"Endothelial; Epithelial; Mesothelial Cell" is not in the list (Heart, Skeletal muscle, Nervous system, Liver, Kidney, Lung;gill, Islet cell;pancreas;thymus, Endothelial;epithelial;mesothelial cell, Blood cells, Fat, ...) of allowed values for the "Tissue and cell" property.  Preparation: Intact Cell; Cultured; Primary"Intact Cell; Cultured; Primary" is not in the list (Intact organism, Intact organ, Permeabilized cells, Permeabilized tissue, Homogenate, Isolated mitochondria, SMP, Chloroplasts, Enzyme, Oxidase;biochemical oxidation, ...) of allowed values for the "Preparation" property., Isolated Mitochondria"Isolated Mitochondria" is not in the list (Intact organism, Intact organ, Permeabilized cells, Permeabilized tissue, Homogenate, Isolated mitochondria, SMP, Chloroplasts, Enzyme, Oxidase;biochemical oxidation, ...) of allowed values for the "Preparation" property., Permeabilized Cell or Tissue; Homogenate"Permeabilized Cell or Tissue; Homogenate" is not in the list (Intact organism, Intact organ, Permeabilized cells, Permeabilized tissue, Homogenate, Isolated mitochondria, SMP, Chloroplasts, Enzyme, Oxidase;biochemical oxidation, ...) of allowed values for the "Preparation" property.  Enzyme: Complex IV; Cytochrome c Oxidase"Complex IV; Cytochrome c Oxidase" is not in the list (Adenine nucleotide translocase, Complex I, Complex II;succinate dehydrogenase, Complex III, Complex IV;cytochrome c oxidase, Complex V;ATP synthase, Inner mt-membrane transporter, Marker enzyme, Supercomplex, TCA cycle and matrix dehydrogenases, ...) of allowed values for the "Enzyme" property.  Regulation: Respiration; OXPHOS; ETS Capacity"Respiration; OXPHOS; ETS Capacity" is not in the list (Aerobic glycolysis, ADP, ATP, ATP production, AMP, Calcium, Coupling efficiency;uncoupling, Cyt c, Flux control, Inhibitor, ...) of allowed values for the "Respiration and regulation" property., Coupling; Membrane Potential"Coupling; Membrane Potential" is not in the list (Aerobic glycolysis, ADP, ATP, ATP production, AMP, Calcium, Coupling efficiency;uncoupling, Cyt c, Flux control, Inhibitor, ...) of allowed values for the "Respiration and regulation" property. 

HRR: Oxygraph-2k 

Nuskova Hana (1), Pecina P (1), Kovarova N (1), Dell’Agnello C (2), Zeviani M (2), Houstek J (1)

(1) Department of Bioenergetics, Institute of Physiology, Academy of Sciences of the Czech Republic, v.v.i., Prague, Czech Republic

(2) Unit of Molecular Neurogenetics, Pierfranco and Luisa Mariani Center for the Study of Children’s Mitochondrial Disorders, National Neurological Institute ‘C. Besta’, Milano, Italy

hana.nuskova@gmail.com