Biochemical phenotypes associated with the mitochondrial ATP6 gene mutations at nt8993

Baracca, Alessandra; Sgarbi, Gianluca; Mattiazzi, Marina; Casalena, Gabriella; Pagnotta, Eleonora; Valentino, Maria Lucia; Moggio, Maurizio; Lenaz, Giorgio; Carelli, Valerio; Solaini, Giancarlo

doi:10.1016/j.bbabio.2007.05.005

Cited by 98 publications

(79 citation statements)

References 29 publications

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“…8 and 17) before a clear growth defect on respiratory medium can be observed in yeast. Even more significant is the fact that these observations also correlate with what is known about the relative severity of the corresponding atp6-NARP mutations in human (2,18,19), which likely reflects a high level of evolutionary conservation within the region of subunit a affected by these mutations. These observations constitute a preliminary validation of the use of yeast to model human inherited mitochondrial diseases affecting ATP synthase.…”

Section: Resultsmentioning

confidence: 71%

A yeast-based assay identifies drugs active against human mitochondrial disorders

Couplan

Aiyar

Kucharczyk

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Due to the lack of relevant animal models, development of effective treatments for human mitochondrial diseases has been limited. Here we establish a rapid, yeast-based assay to screen for drugs active against human inherited mitochondrial diseases affecting ATP synthase, in particular NARP (neuropathy, ataxia, and retinitis pigmentosa) syndrome. This method is based on the conservation of mitochondrial function from yeast to human, on the unique ability of yeast to survive without production of ATP by oxidative phosphorylation, and on the amenability of the yeast mitochondrial genome to site-directed mutagenesis. Our method identifies chlorhexidine by screening a chemical library and oleate through a candidate approach. We show that these molecules rescue a number of phenotypes resulting from mutations affecting ATP synthase in yeast. These compounds are also active on human cybrid cells derived from NARP patients. These results validate our method as an effective high-throughput screening approach to identify drugs active in the treatment of human ATP synthase disorders and suggest that this type of method could be applied to other mitochondrial diseases.budding yeast | drug screening | transcription profiling | NARP cybrid

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Section: Resultsmentioning

confidence: 71%

A yeast-based assay identifies drugs active against human mitochondrial disorders

Couplan

Aiyar

Kucharczyk

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…This conclusion is bolstered by our observation that cells severely deficient in ATP synthase reacquired almost normal morphology following treatment (Figure 2). Since mitochondrial membrane potential (⌬⌿ m ) is increased in cells with impaired ATP synthase, 8,26 these cells are expected to have an increased NADH:nicotinamide adenine dinucleotide (NAD ϩ ) ratio, which would inhibit the ␣-ketoglutarate dehydrogenase reaction and possibly render the addition of the substrates useless. However, in our system, the ␣-ketoglutarate dehydrogenase reaction can still proceed because its NADH product is used to reduce oxaloacetate (provided as its precursor aspartate) to malate, which, in turn, may leave the mitochondrial matrix through the oxoglutarate carrier that exchanges it for ␣-ketoglutarate (Figure 6).…”

Section: Commentmentioning

confidence: 99%

Human NARP Mitochondrial Mutation Metabolism Corrected With α-Ketoglutarate/Aspartate

Sgarbi

Casalena²,

Baracca³

et al. 2009

Arch Neurol

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To verify whether enhanced substrate-level phosphorylation increases viability and adenosine 5Јtriphosphate (ATP) content of cells with neuropathy, ataxia, and retinitis pigmentosa/maternally inherited Leigh syndrome (NARP/MILS) mitochondrial DNA mutations and ATP synthase dysfunction.Design: We used cell lines "poisoned" with oligomycin, the specific inhibitor of ATP synthase, and "natural" models, including transmitochondrial human cell lines (cybrids) harboring 2 different pathogenic mutations associated with the NARP/MILS phenotypes.Main Outcome Measures: Cell survival, morphology, and ATP content.Results: When normal human fibroblasts cultured in glucose-free medium were forced to increase energy consump-tion by exposure to the ionophore gramicidin or were energy challenged by oligomycin inhibition, their survival at 72 hours was 5%, but this increased to 70% when the medium was supplemented with ␣-ketoglutarate/aspartate to boost mitochondrial substrate-level phosphorylation. Homoplasmic cybrids harboring the 8993T→G NARP mutation were also protected from death (75% vs 15% survival at 72 hours) by the supplemented medium and their ATP content was similar to controls.Conclusions: These results show that ATP synthasedeficient cells can be rescued by increasing mitochondrial substrate-level phosphorylation and suggest potential dietary or pharmacological therapeutic approaches based on the supplementation of ␣-ketoglutarate/aspartate to patients with impaired ATP synthase activity.

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“…The majority of frequently reported mutations of ATPase 6 gene were heteroplasmic transversion T8993C and T8993G, which were associated with Leigh and NARP syndrome. Symptom severity was proportional to the heteroplasmy load (35)(36)(37)(38).…”

Section: Discussionmentioning

confidence: 99%

A novel heteroplasmic mitochondrial DNA mutation, A8890G, in a patient with juvenile-onset metabolic syndrome: A case report

Chen

Jin

et al. 2013

Molecular Medicine Reports

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Abstract. Metabolic syndrome (MS) is a complex disorder characterized by a group of metabolic abnormalities. In the present study, the case of an 18-year-old male who presented with MS characteristics with central obesity (overweight and a waist circumference of 95 cm) and dyslipidemia (high TG, low HDL levels and low apoA-I/apoB-100) was reported. The patient's family has maternally inherited diabetes and a number of the patient's maternal relatives present MS features. For the investigation of the mitochondrial DNA variants in the patient and the patient's family, genomic DNA of all the family members were extracted from peripheral blood using routine methods. Amplification of mitochondrial DNA in 24 overlapping fragments by PCR, direct sequencing and denaturing high-performance liquid chromatography was utilized for genetic analysis. Sequences were compared to the reference sequence to identify variants. Bioinformatic methods and databases were used to analyze conservation of the variants and to predict the protein secondary structure. With the exception of the patient, five relatives were diagnosed with MS. Moreover, 5 of the 8 family members had been diagnosed with diabetes, hearing loss and mild kidney impairment according to serum biochemical analysis. Further molecular genetic analysis indicated that the MS-associated variant T16189C was detected in this family. Notably, a heteroplasmic mutation A8890G was detected in the patient in the mitochondrial ATP6 gene, which codes the ATP synthase subunit 6 (ATPase6). A8890G changed the highly conserved ATPase6 Lys 122 into Glu 122 in the mitochondrial inner membrane. However, this mutation was not detected in other family members. In conclusion, the mutation A8890G may affect the function of ATPase 6 and the production of ATP, thus contributing to juvenile-onset MS. It was not detected in other family members possibly due to the mitochondrial genetic segregation or production of a new germline mutation in the juvenile-onset patient. IntroductionMetabolic syndrome (1) is a complex disorder, characterized by a group of metabolic disorders, including hyperglycemia, hypertension, hyperlipaemia and central obesity, which are the risk factors of cardiovascular disease and diabetes. There is a high prevalence of MS in developed countries. According to the national health statistic reports issued in 2009 from the National Health and Nutrition Examination Survey 2003Survey -2006, the prevalence of metabolic syndrome in the USA, is 34% in the population of 20 years of age. The prevalence of metabolic syndrome increased in different age groups for the two genders (2). However, in recent years, the prevalence of MS has increased at an alarming rate in developing countries and districts of Asia An unhealthy lifestyle, including lack of physical exercise, bad nutritional habits, hormone changes and aging factors are associated with the onset of MS (6). However the two important risk factors for MS are central obesity and insulin resistance (7). Individuals with excess abdom...

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Biochemical phenotypes associated with the mitochondrial ATP6 gene mutations at nt8993

Cited by 98 publications

References 29 publications

A yeast-based assay identifies drugs active against human mitochondrial disorders

A yeast-based assay identifies drugs active against human mitochondrial disorders

Human NARP Mitochondrial Mutation Metabolism Corrected With α-Ketoglutarate/Aspartate

A novel heteroplasmic mitochondrial DNA mutation, A8890G, in a patient with juvenile-onset metabolic syndrome: A case report

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