Kovalcikova 2017 MiP2017

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Kovalcikova Jana
Mitochondrial protein TMEM70: key role in the biogenesis of ATP synthase verified in a mouse knockout model.

Link: MiP2017

Kovalcikova J, Vrbacky M, Mracek T, Nuskova H, Tauchmannova K, Beck I, Sedlacek R, Kucera O, Cervinkova Z, Houstek J (2017)

Event: MiP2017

COST Action MITOEAGLE
TMEM70 is a transmembrane protein localized in the inner mitochondrial membrane and involved in the biogenesis of the eukaryotic ATP synthase, but its molecular role in this process is still unknown. TMEM70 mutations cause isolated deficiency of ATP synthase often resulting in a fatal neonatal mitochondrial encephalocardiomyopathy in patients. To understand molecular mechanism of TMEM70 action, we generated constitutive Tmem70 knockout mice, which led to embryonically lethal phenotype with disturbed ATP synthase biogenesis [1].

To obtain adult Tmem70-/- mice, we further generated tamoxifen (TAM) inducible knockout. Upon induction of Cre-mediated excision, the weight of mice progressively decreased and they died by the week 8 post-induction. Despite the similar knockout efficiency in liver and heart, blue native electrophoresis showed more pronounced decrease of the fully assembled F1Fo ATP synthase and accumulation of F1 subcomplex in liver than in heart. This is likely due to the slower turnover of ATP synthase in heart than in liver. Furthermore, using high-resolution native electrophoresis we demonstrated the presence of different profile of ATP synthase subcomplexes in liver of TAM treated mice than in other models of ATP synthase deficiency. We also quantified different OXPHOS proteins using SDS electrophoresis. It showed substantially decreased level of F1-alpha and changed levels of other complexes in liver. We also observed defective utilization of mitochondrial membrane potential for ATP phosphorylation measured by TPP+-selective electrode and poor inhibition of state 3 (ADP) respiration by oligomycin measured by high-resolution respirometry in the liver mitochondria of TAM treated mice in comparison to controls. Moreover, the oxygen consumption induced by addition of cytochrome c indicated damaged liver mitochondria of the treated mice. Liver damage was also confirmed by hyperammonemia and increased blood levels of its indicators alanine aminotransferase and aspartate aminotransferase. In addition, the oxidative stress and apoptosis were increased in liver.


Bioblast editor: Kandolf G O2k-Network Lab: CZ Prague Kalous M, CZ Prague Houstek J, CZ Hradec Kralove Cervinkova Z


Labels: MiParea: Respiration, Genetic knockout;overexpression 


Organism: Mouse  Tissue;cell: Heart, Liver 


Regulation: ATP production  Coupling state: LEAK, OXPHOS 

HRR: Oxygraph-2k 


Affiliations

Kovalčíková J(1), Vrbacký M(1), Mráček T(1), Nůsková H(1), Tauchmannová K(1), Beck I(2), Sedláček R(2), Kučera O(3), Červinková Z(3), Houštěk J(1)
  1. Inst Physiology, CAS
  2. Inst Molecular Genetics, CAS
  3. Fac Medicine Charles Univ, Hradec Králové; Prague, Czech Republic. - jana.kovalcikova@fgu.cas.cz

References and support

  1. Vrbacký M, Kovalčíková J, Chawengsaksophak K, Beck IM, Mráček T, Nůsková H, Sedmera D, Papoušek F, Kolář F, Sobol M, Hozák P, Sedlacek R, Houštěk J (2016) Knockout of Tmem70 alters biogenesis of ATP synthase and leads to embryonal lethality in mice. Human Mol Genet 25:4674-85.
Supported by grants 14-36804G and 16-33018A.