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: SURF1 knockout

• O2k-Network Lab: CZ Prague Houstek J

Labels: MiParea: Respiration, nDNA;cell genetics, Genetic knockout;overexpression, mt-Medicine  Pathology: Inherited  Stress:Mitochondrial disease  Organism: Mouse  Tissue;cell: Endothelial;epithelial;mesothelial cell, Fibroblast  Preparation: Intact cells, Isolated mitochondria  Enzyme: Complex IV;cytochrome c oxidase  Regulation: ADP, mt-Membrane potential, Oxygen kinetics  Coupling state: OXPHOS 

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