Disorders of ATP synthase, the key enzyme in mitochondrial energy supply, belong to the most severe metabolic diseases, manifesting as early-onset mitochondrial encephalo-cardiomyopathies. Since ATP synthase subunits are encoded by both mitochondrial and nuclear DNA, pathogenic variants can be found in either genome. In addition, the biogenesis of ATP synthase requires several assembly factors, some of which are also hotspots for pathogenic variants. While variants of MT-ATP6 and TMEM70 represent the most common cases of mitochondrial and nuclear DNA mutations respectively, the advent of next-generation sequencing has revealed new pathogenic variants in a number of structural genes and TMEM70, sometimes with truly peculiar genetics. Here we present a systematic review of the reported cases and discuss biochemical mechanisms, through which they are affecting ATP synthase. We explore how the knowledge of pathophysiology can improve our understanding of enzyme biogenesis and function. Keywords: Mitochondrial diseases o ATP synthase o Nuclear DNA o Mitochondrial DNA o TMEM70.

• MeSH
• fenotyp * MeSH
• lidé MeSH
• membránové proteiny genetika   metabolismus   MeSH
• mitochondriální DNA genetika   MeSH
• mitochondriální nemoci genetika   enzymologie   MeSH
• mitochondriální proteiny genetika   metabolismus   MeSH
• mitochondriální protonové ATPasy * genetika   metabolismus   MeSH
• mitochondrie enzymologie   genetika   MeSH
• mutace MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• systematický přehled MeSH

Mutations of the TMEM70 gene disrupt the biogenesis of the ATP synthase and represent the most frequent cause of autosomal recessive encephalo-cardio-myopathy with neonatal onset. Patient tissues show isolated defects in the ATP synthase, leading to the impaired mitochondrial synthesis of ATP and insufficient energy provision. In the current study, we tested the efficiency of gene complementation by using a transgenic rescue approach in spontaneously hypertensive rats with the targeted Tmem70 gene (SHR-Tmem70ko/ko), which leads to embryonic lethality. We generated SHR-Tmem70ko/ko knockout rats expressing the Tmem70 wild-type transgene (SHR-Tmem70ko/ko,tg/tg) under the control of the EF-1α universal promoter. Transgenic rescue resulted in viable animals that showed the variable expression of the Tmem70 transgene across the range of tissues and only minor differences in terms of the growth parameters. The TMEM70 protein was restored to 16-49% of the controls in the liver and heart, which was sufficient for the full biochemical complementation of ATP synthase biogenesis as well as for mitochondrial energetic function in the liver. In the heart, we observed partial biochemical complementation, especially in SHR-Tmem70ko/ko,tg/0 hemizygotes. As a result, this led to a minor impairment in left ventricle function. Overall, the transgenic rescue of Tmem70 in SHR-Tmem70ko/ko knockout rats resulted in the efficient complementation of ATP synthase deficiency and thus in the successful genetic treatment of an otherwise fatal mitochondrial disorder.

• Publikační typ
• časopisecké články MeSH

Dědičná deficience ATP syntázy, klíčového enzymu buněčné energetiky, patří mezi nejzávažnější metabolická onemocnění. Její nejčastější příčinou jsou mutace v genu asemblačního faktoru TMEM70. Možnosti terapeutického ovlivnění mitochondriálních onemocnění jsou v současnosti velmi omezené, kausální léčba zcela chybí. TMEM70 defekty jsou vhodnými kandidáty pro hledání nových terapií, neboť TMEM70 není absolutně nezbytný pro biogenezi ATP syntázy a lze očekávat, že k plnému obnovení ATP produkce dojde již po částečném zvýšení množství nově tvořeného enzymu. Cílem projektu je (i) identifikovat farmakologické aktivátory ATP syntázy na modelu buněk s delecí TMEM70 genu a následně validovat kandidátní látky na unikátním souboru linií fibroblastů od pacientů s TMEM70 mutací pro ověření jejich možné terapeutické využitelnosti, dále (ii) testovat možnost genetické komplementace defektu ATP syntázy u potkanů s knockoutem TMEM70 genu pomocí transgenní overexprese TMEM70 pod nepřirozeným promotorem. Zaměříme se na studium odpovědi pomocí komplexní fenotypizace od enzymu po celý organismus.; Inborn deficiency of ATP synthase, the key enzyme of cellular energy provision, belongs to the most severe metabolic diseases. The prevailing cause of this disease are mutation in the gene for specific assembly factor TMEM70. Present therapy for mitochondrial diseases is rather limited and causal treatment is missing. However, TMEM70 defects represent promising target for establishing of new therapy as it is not absolutely essential for ATP synthase biogenesis and sufficient recovery of ATP production can be expected even after partial increase of ATP synthase content. Our aim is to (i) identify pharmacological activators of ATP synthesis on a model of TMEM70 knockout cells and subsequently test candidate compounds on our unique collection of patients’ fibroblasts cell lines harbouring mutations in TMEM70 as a proof of principle for their utility. (ii) We will test the possibility to complement TMEM70 knockout in rats by transgenic overexpression of TMEM70 and perform complex phenotyping study of enzyme to organismal responses to the TMEM70 expression under non-natural promotor.

• MeSH
• krysa rodu rattus MeSH
• lidé MeSH
• mitochondriální nemoci farmakoterapie   genetika   MeSH
• mitochondriální protonové ATPasy genetika   nedostatek   MeSH
• modely nemocí na zvířatech MeSH
• mutace genetika   MeSH
• vzácné nemoci genetika   terapie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• lidé MeSH
• zvířata MeSH

• Konspekt
• Patologie. Klinická medicína
• NLK Obory
• genetika, lékařská genetika
• farmacie a farmakologie
• NLK Publikační typ
• závěrečné zprávy o řešení grantu AZV MZ ČR

Biogenesis of F1Fo ATP synthase, the key enzyme of mitochondrial energy provision, depends on transmembrane protein 70 (TMEM70), localized in the inner mitochondrial membrane of higher eukaryotes. TMEM70 absence causes severe ATP-synthase deficiency and leads to a neonatal mitochondrial encephalocardiomyopathy in humans. However, the exact biochemical function of TMEM70 remains unknown. Using TMEM70 conditional knockout in mice, we show that absence of TMEM70 impairs the early stage of enzyme biogenesis by preventing incorporation of hydrophobic subunit c into rotor structure of the enzyme. This results in the formation of an incomplete, pathologic enzyme complex consisting of F1 domain and peripheral stalk but lacking Fo proton channel composed of subunits c and a. We demonstrated direct interaction between TMEM70 and subunit c and showed that overexpression of subunit c in TMEM70-/- cells partially rescued TMEM70 defect. Accordingly, TMEM70 knockdown prevented subunit c accumulation otherwise observed in F1-deficient cells. Altogether, we identified TMEM70 as specific ancillary factor for subunit c. The biologic role of TMEM70 is to increase the low efficacy of spontaneous assembly of subunit c oligomer, the key and rate-limiting step of ATP-synthase biogenesis, and thus to reach an adequately high physiologic level of ATP synthase in mammalian tissues.-Kovalčíková, J., Vrbacký, M., Pecina, P., Tauchmannová, K., Nůsková, H., Kaplanová, V., Brázdová, A., Alán, L., Eliáš, J., Čunátová, K., Kořínek, V., Sedlacek, R., Mráček, T., Houštěk, J. TMEM70 facilitates biogenesis of mammalian ATP synthase by promoting subunit c incorporation into the rotor structure of the enzyme.

• MeSH
• genotyp MeSH
• genový knockout metody   MeSH
• HEK293 buňky MeSH
• kultivované buňky MeSH
• lidé MeSH
• mitochondriální proteiny genetika   metabolismus   MeSH
• mitochondriální protonové ATPasy genetika   metabolismus   MeSH
• myši knockoutované MeSH
• myši MeSH
• proteolipidy metabolismus   MeSH
• regulace genové exprese MeSH
• tamoxifen farmakologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

TMEM70, a 21-kDa protein localized in the inner mitochondrial membrane, has been shown to facilitate the biogenesis of mammalian F1Fo ATP synthase. Mutations of the TMEM70 gene represent the most frequent cause of isolated ATP synthase deficiency resulting in a severe mitochondrial disease presenting as neonatal encephalo-cardiomyopathy (OMIM 604273). To better understand the biological role of this factor, we generated Tmem70-deficient mice and found that the homozygous Tmem70-/- knockouts exhibited profound growth retardation and embryonic lethality at ∼9.5 days post coitum. Blue-Native electrophoresis demonstrated an isolated deficiency in fully assembled ATP synthase in the Tmem70-/- embryos (80% decrease) and a marked accumulation of F1 complexes indicative of impairment in ATP synthase biogenesis that was stalled at the early stage, following the formation of F1 oligomer. Consequently, a decrease in ADP-stimulated State 3 respiration, respiratory control ratio and ATP/ADP ratios, indicated compromised mitochondrial ATP production. Tmem70-/- embryos exhibited delayed development of the cardiovascular system and a disturbed heart mitochondrial ultrastructure, with concentric or irregular cristae structures. Tmem70+/- heterozygous mice were fully viable and displayed normal postnatal growth and development of the mitochondrial oxidative phosphorylation system. Nevertheless, they presented with mild deterioration of heart function. Our results demonstrated that Tmem70 knockout in the mouse results in embryonic lethality due to the lack of ATP synthase and impairment of mitochondrial energy provision. This is analogous to TMEM70 dysfunction in humans and verifies the crucial role of this factor in the biosynthesis and assembly of mammalian ATP synthase.

• MeSH
• adenosintrifosfát metabolismus   MeSH
• homozygot MeSH
• kardiomyopatie metabolismus   MeSH
• membránové proteiny nedostatek   genetika   metabolismus   MeSH
• mitochondriální membrány metabolismus   MeSH
• mitochondriální nemoci genetika   metabolismus   MeSH
• mitochondriální proteiny nedostatek   genetika   metabolismus   MeSH
• mitochondriální protonové ATPasy biosyntéza   genetika   metabolismus   MeSH
• mitochondrie metabolismus   MeSH
• mutace MeSH
• myši knockoutované MeSH
• myši MeSH
• oxidativní fosforylace MeSH
• těhotenství MeSH
• vrozené poruchy metabolismu metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Disorders of ATP synthase, the key enzyme of mitochondrial energy provision belong to the most severe metabolic diseases presenting as early-onset mitochondrial encephalo-cardiomyopathies. Up to now, mutations in four nuclear genes were associated with isolated deficiency of ATP synthase. Two of them, ATP5A1 and ATP5E encode enzyme's structural subunits alpha and epsilon, respectively, while the other two ATPAF2 and TMEM70 encode specific ancillary factors that facilitate the biogenesis of ATP synthase. All these defects share a similar biochemical phenotype with pronounced decrease in the content of fully assembled and functional ATP synthase complex. However, substantial differences can be found in their frequency, molecular mechanism of pathogenesis, clinical manifestation as well as the course of the disease progression. While for TMEM70 the number of reported patients as well as spectrum of the mutations is steadily increasing, mutations in ATP5A1, ATP5E and ATPAF2 genes are very rare. Apparently, TMEM70 gene is highly prone to mutagenesis and this type of a rare mitochondrial disease has a rather frequent incidence. Here we present overview of individual reported cases of nuclear mutations in ATP synthase and discuss, how their analysis can improve our understanding of the enzyme biogenesis.

• MeSH
• genetická predispozice k nemoci genetika   MeSH
• jednonukleotidový polymorfismus genetika   MeSH
• lidé MeSH
• mitochondriální nemoci enzymologie   genetika   MeSH
• mitochondriální protonové ATPasy genetika   MeSH
• mitochondrie enzymologie   genetika   patologie   MeSH
• modely genetické MeSH
• mutace genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

Early onset mitochondrial encephalo-cardiomyopathy due to isolated deficiency of ATP synthase is frequently caused by mutations in TMEM70 gene encoding enzyme-specific ancillary factor. Diminished ATP synthase results in low ATP production, elevated mitochondrial membrane potential and increased ROS production. To test whether the patient cells may react to metabolic disbalance by changes in oxidative phosphorylation system, we performed a quantitative analysis of respiratory chain complexes and intramitochondrial proteases involved in their turnover. SDS- and BN-PAGE Western blot analysis of fibroblasts from 10 patients with TMEM70 317-2A>G homozygous mutation showed a significant 82-89% decrease of ATP synthase and 50-162% increase of respiratory chain complex IV and 22-53% increase of complex III. The content of Lon protease, paraplegin and prohibitins 1 and 2 was not significantly changed. Whole genome expression profiling revealed a generalized upregulation of transcriptional activity, but did not show any consistent changes in mRNA levels of structural subunits, specific assembly factors of respiratory chain complexes, or in regulatory genes of mitochondrial biogenesis which would parallel the protein data. The mtDNA content in patient cells was also not changed. The results indicate involvement of posttranscriptional events in the adaptive regulation of mitochondrial biogenesis that allows for the compensatory increase of respiratory chain complexes III and IV in response to deficiency of ATP synthase.

• MeSH
• fibroblasty metabolismus   patologie   MeSH
• lidé MeSH
• membránové proteiny genetika   MeSH
• messenger RNA genetika   metabolismus   MeSH
• mitochondriální DNA metabolismus   MeSH
• mitochondriální proteiny genetika   MeSH
• mitochondriální protonové ATPasy nedostatek   metabolismus   MeSH
• mitochondrie enzymologie   genetika   MeSH
• mutace genetika   MeSH
• oxidativní fosforylace MeSH
• proteasy metabolismus   MeSH
• respirační komplex III metabolismus   MeSH
• respirační komplex IV metabolismus   MeSH
• stanovení celkové genové exprese MeSH
• transport elektronů genetika   MeSH
• upregulace * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

TMEM70 protein represents a novel ancillary factor of mammalian ATP synthase. We have investigated import and processing of this factor in human cells using GFP- and FLAG-tagged forms of TMEM70 and specific antibodies. TMEM70 is synthesized as a 29kDa precursor protein that is processed to a 21kDa mature form. Immunocytochemical detection of TMEM70 showed mitochondrial colocalization with MitoTracker Red and ATP synthase. Western blot of subcellular fractions revealed the highest signal of TMEM70 in isolated mitochondria and mitochondrial location was confirmed by mass spectrometry analysis. Based on analysis of submitochondrial fractions, TMEM70 appears to be located in the inner mitochondrial membrane, in accordance with predicated transmembrane regions in the central part of the TMEM70 sequence. Two-dimensional electrophoretic analysis did not show direct interaction of TMEM70 with assembled ATP synthase but indicated the presence of dimeric form of TMEM70. No TMEM70 protein could be found in cells and isolated mitochondria from patients with ATP synthase deficiency due to TMEM70 c.317-2A>G mutation thus confirming that TMEM70 biosynthesis is prevented in these patients.

• MeSH
• buněčné linie MeSH
• Escherichia coli enzymologie   MeSH
• fibroblasty enzymologie   MeSH
• hmotnostní spektrometrie metody   MeSH
• klonování DNA MeSH
• komplementární DNA genetika   MeSH
• ledviny enzymologie   MeSH
• lidé MeSH
• membránové proteiny chemie   genetika   metabolismus   MeSH
• mitochondriální proteiny chemie   genetika   metabolismus   MeSH
• mitochondriální protonové ATPasy nedostatek   MeSH
• mitochondrie enzymologie   MeSH
• molekulární sekvence - údaje MeSH
• myši MeSH
• sekvence aminokyselin MeSH
• sekvenční homologie aminokyselin MeSH
• sekvenční seřazení MeSH
• skot MeSH
• submitochondriální částice enzymologie   MeSH
• western blotting MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• skot MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

F1Fo-ATP synthase is a key enzyme of mitochondrial energy provision producing most of cellular ATP. So far, mitochondrial diseases caused by isolated disorders of the ATP synthase have been shown to result from mutations in mtDNA genes for the subunits ATP6 and ATP8 or in nuclear genes encoding the biogenesis factors TMEM70 and ATPAF2. Here, we describe a patient with a homozygous p.Tyr12Cys mutation in the epsilon subunit encoded by the nuclear gene ATP5E. The 22-year-old woman presented with neonatal onset, lactic acidosis, 3-methylglutaconic aciduria, mild mental retardation and developed peripheral neuropathy. Patient fibroblasts showed 60-70% decrease in both oligomycin-sensitive ATPase activity and mitochondrial ATP synthesis. The mitochondrial content of the ATP synthase complex was equally reduced, but its size was normal and it contained the mutated epsilon subunit. A similar reduction was found in all investigated F1 and Fo subunits with the exception of Fo subunit c, which was found to accumulate in a detergent-insoluble form. This is the first case of a mitochondrial disease due to a mutation in a nuclear encoded structural subunit of the ATP synthase. Our results indicate an essential role of the epsilon subunit in the biosynthesis and assembly of the F1 part of the ATP synthase. Furthermore, the epsilon subunit seems to be involved in the incorporation of subunit c to the rotor structure of the mammalian enzyme.

• MeSH
• fibroblasty enzymologie   chemie   MeSH
• kultivované buňky MeSH
• lidé MeSH
• missense mutace * MeSH
• mitochondriální nemoci * enzymologie   genetika   MeSH
• mitochondriální protonové ATPasy * genetika   nedostatek   MeSH
• mladý dospělý MeSH
• molekulární sekvence - údaje MeSH
• proteiny genetika   chemie   metabolismus   MeSH
• sekvence aminokyselin MeSH
• sekvence nukleotidů MeSH
• sekvenční seřazení MeSH
• Check Tag
• lidé MeSH
• mladý dospělý MeSH
• ženské pohlaví MeSH
• Publikační typ
• kazuistiky MeSH
• práce podpořená grantem MeSH

An increasing number of patients with nuclear genetic defects of mitochondrial ATP synthase have been identified in recent years. They are characterized by early onset, lactic acidosis, 3-methylglutaconic aciduria, hypertrophic cardiomyopathy and encephalopathy and most cases have a fatal outcome. Patient tissues show isolated defect of the ATP synthase complex and its content decreases to > or =30% of normal due to altered enzyme biosynthesis and assembly. Gene mapping and complementation studies have identified mutations in TMEM70 gene encoding a 30kD mitochondrial protein of unknown function as the cause of the disease. An altered synthesis of this new ancillary factor in ATP synthase biogenesis was found in most of the known patients with decreased ATP synthase content. As revealed by phylogenetic analysis, TMEM70 is specific for higher eukaryotes.

• MeSH
• buněčné jádro genetika   patologie   MeSH
• druhová specificita MeSH
• familiární hypertrofická kardiomyopatie genetika   metabolismus   MeSH
• fylogeneze MeSH
• lidé MeSH
• membránové proteiny * genetika   MeSH
• mitochondriální proteiny * genetika   MeSH
• mitochondriální protonové ATPasy genetika   metabolismus   MeSH
• mitochondrie genetika   metabolismus   MeSH
• mutace MeSH
• nemoci mozku genetika   metabolismus   MeSH
• oxidativní fosforylace MeSH
• respirační komplex IV genetika   metabolismus   MeSH
• savci MeSH
• testy genetické komplementace MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem MeSH