Mitochondrial disorders are caused by defects in mitochondrial or nuclear DNA. Although the existence of large deletions in mitochondrial DNA (mtDNA) is well known, deletions affecting whole genes are not commonly described in patients with mitochondrial disorders. Based on the results of whole-genome analyses, copy number variations (CNVs) occur frequently in the human genome and may overlap with many genes associated with clinical phenotypes. We report the discovery of two large heterozygous CNVs on 22q13.33 in two patients with mitochondrial disorders. The first patient harboured a novel point mutation c.667G>A (p.D223N) in the SCO2 gene in combination with a paternally inherited 87-kb deletion. As hypertrophic cardiomyopathy (HCMP) was not documented in the patient, this observation prompted us to compare his clinical features with all 44 reported SCO2 patients in the literature. Surprisingly, the review shows that HCMP was present in only about 50% of the SCO2 patients with non-neonatal onset. In the second patient, who had mitochondrial neurogastrointestinal encephalopathy (MNGIE), a maternally inherited 175-kb deletion and the paternally inherited point mutation c.261G>T (p.E87D) in the TYMP gene were identified.
- MeSH
- bodová mutace * MeSH
- dítě MeSH
- familiární hypertrofická kardiomyopatie diagnóza genetika MeSH
- kojenec MeSH
- lidé MeSH
- lidské chromozomy, pár 22 genetika MeSH
- mitochondriální encefalomyopatie diagnóza genetika MeSH
- mitochondriální proteiny genetika MeSH
- střevní pseudoobstrukce diagnóza genetika MeSH
- thymidinfosforylasa genetika MeSH
- transportní proteiny genetika MeSH
- variabilita počtu kopií segmentů DNA * MeSH
- Check Tag
- dítě MeSH
- kojenec MeSH
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- kazuistiky MeSH
- práce podpořená grantem MeSH
We report the second known family with a very rare, maternally inherited missense m.8851T>C mutation in the mitochondrial MTATP6 gene. A failure to thrive, microcephaly, psychomotor retardation and hypotonia were present in a 3-year-old girl with a high mtDNA mutation load (87-97%). Ataxia and Leigh syndrome were subsequently documented in a neurological examination and brain MRI. A muscle biopsy demonstrated decreased ATP synthase and an accumulation of succinate dehydrogenase products, indicating mitochondrial myopathy. Her 36-year-old mother (68% blood heteroplasmy) developed peripheral neuropathy and muscle weakness at the age of 22 years. Our findings extend the clinical and laboratory phenotype associated with the m.8851T>C mutation.
- MeSH
- biopsie MeSH
- lidé MeSH
- mitochondriální protonové ATPasy genetika MeSH
- mitochondrie metabolismus MeSH
- mutace * MeSH
- předškolní dítě MeSH
- psi MeSH
- svaly patologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- předškolní dítě MeSH
- psi MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- kazuistiky MeSH
- práce podpořená grantem MeSH
Mitochondrial ATPases associated with diverse cellular activities (AAA) proteases are involved in the quality control and processing of inner-membrane proteins. Here we investigate the cellular activities of YME1L, the human orthologue of the Yme1 subunit of the yeast i-AAA complex, using stable short hairpin RNA knockdown and expression experiments. Human YME1L is shown to be an integral membrane protein that exposes its carboxy-terminus to the intermembrane space and exists in several complexes of 600-1100 kDa. The stable knockdown of YME1L in human embryonic kidney 293 cells led to impaired cell proliferation and apoptotic resistance, altered cristae morphology, diminished rotenone-sensitive respiration, and increased susceptibility to mitochondrial membrane protein carbonylation. Depletion of YME1L led to excessive accumulation of nonassembled respiratory chain subunits (Ndufb6, ND1, and Cox4) in the inner membrane. This was due to a lack of YME1L proteolytic activity, since the excessive accumulation of subunits was reversed by overexpression of wild-type YME1L but not a proteolytically inactive YME1L variant. Similarly, the expression of wild-type YME1L restored the lamellar cristae morphology of YME1L-deficient mitochondria. Our results demonstrate the importance of mitochondrial inner-membrane proteostasis to both mitochondrial and cellular function and integrity and reveal a novel role for YME1L in the proteolytic regulation of respiratory chain biogenesis.
- MeSH
- apoptóza MeSH
- genový knockdown MeSH
- GTP-fosfohydrolasy metabolismus MeSH
- lidé MeSH
- metaloendopeptidasy metabolismus MeSH
- mitochondriální membrány metabolismus MeSH
- mitochondrie metabolismus MeSH
- NADH, NADPH oxidoreduktasy metabolismus MeSH
- proliferace buněk MeSH
- proteasy závislé na ATP metabolismus MeSH
- proteasy metabolismus MeSH
- protein - isoformy metabolismus MeSH
- respirační komplex IV metabolismus MeSH
- Saccharomyces cerevisiae - proteiny metabolismus MeSH
- Saccharomyces cerevisiae cytologie metabolismus MeSH
- transport elektronů MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Tyrosine hydroxylase deficiency manifests mainly in early childhood and includes two clinical phenotypes: an infantile progressive hypokinetic-rigid syndrome with dystonia (type A) and a neonatal complex encephalopathy (type B). The biochemical diagnostics is exclusively based on the quantitative determination of the neurotransmitters or their metabolites in cerebrospinal fluid (CSF). The implementation of neurotransmitter analysis in clinical praxis is necessary for early diagnosis and adequate treatment. Neurotransmitter metabolites in CSF were analyzed in 82 children (at the age 1 month to 17 years) with clinical suspicion for neurometabolic disorders using high performance liquid chromatography (HPLC) with electrochemical detection. The CSF level of homovanillic acid (HVA) was markedly decreased in three children (64, 79 and 94 nmol/l) in comparison to
- MeSH
- analýza polymorfismu délky amplifikovaných restrikčních fragmentů metody využití MeSH
- diferenciální diagnóza MeSH
- dítě MeSH
- financování organizované MeSH
- karbidopa škodlivé účinky terapeutické užití MeSH
- klinický obraz nemoci MeSH
- levodopa aplikace a dávkování škodlivé účinky terapeutické užití MeSH
- lidé MeSH
- metabolické nemoci mozku diagnóza etiologie genetika MeSH
- mozkomíšní mok metabolismus MeSH
- mutační analýza DNA metody využití MeSH
- neurotransmiterové látky izolace a purifikace nedostatek MeSH
- tyrosin-3-monooxygenasa izolace a purifikace nedostatek MeSH
- vysokoúčinná kapalinová chromatografie metody využití MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- kazuistiky MeSH
The most common cause of pyruvate dehydrogenase complex (PDHc) deficiency is the deficit of the E1?-subunit. The aim of this study was to describe distinct course of the disease in two boys with mutations in PDHA1 gene and illustrate the possible obstacles in measurement of PDHc activity. Clinical data and metabolic profiles were collected and evaluated. PDHc and E1?-subunit activities were measured using radiometric assay. Subunits of PDHc were detected by Western blot. PDHA1 gene was analysed by direct sequencing. In patient 1, the initial hypotonia with psychomotor retardation was observed since early infancy. The child gradually showed symptoms of spasticity and arrest of psychomotor development. In patient 2, the disease manifested by seizures and hyporeflexia in the toddler age. The diagnosis was confirmed at the age of seven years after attacks of dystonia and clinical manifestation of myopathy with normal mental development. Brain MRI of both patients revealed lesions typical of Leigh syndrome. Enzymatic analyses revealed PDHc deficiency in isolated lymphocytes in the first but not in the second patient. The direct measurement of PDH E1-subunit revealed deficiency in this individual. In patient 1, a novel hemizigous mutation c.857C>T (Pro250Leu) was detected in the X-linked PDHA1 gene. Mutation c.367C>T (Arg88Cys) was found in patient 2. We present first two patients with PDHc deficit due to mutations in PDHA1 gene in the Czech Republic. We document the broad variability of clinical symptoms of this disease. We proved that normal PDHc activity may not exclude the disease.
- MeSH
- deficit pyruvátdehydrogenázového komplexu diagnóza genetika MeSH
- dítě MeSH
- financování organizované MeSH
- lidé MeSH
- mladiství MeSH
- mutace MeSH
- pyruvátdehydrogenasa (lipoamid) genetika MeSH
- sekvenční analýza DNA MeSH
- western blotting MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- Publikační typ
- kazuistiky MeSH
- Publikační typ
- abstrakt z konference MeSH
- Publikační typ
- abstrakt z konference MeSH
Mammalian CcO (cytochrome c oxidase) is a hetero-oligomeric protein complex composed of 13 structural subunits encoded by both the mitochondrial and nuclear genomes. To study the role of nuclear-encoded CcO subunits in the assembly and function of the human complex, we used stable RNA interference of COX4, COX5A and COX6A1, as well as expression of epitope-tagged Cox6a, Cox7a and Cox7b, in HEK (human embryonic kidney)-293 cells. Knockdown of Cox4, Cox5a and Cox6a resulted in reduced CcO activity, diminished affinity of the residual enzyme for oxygen, decreased holoCcO and CcO dimer levels, increased accumulation of CcO subcomplexes and gave rise to an altered pattern of respiratory supercomplexes. An analysis of the patterns of CcO subcomplexes found in both knockdown and overexpressing cells identified a novel CcO assembly intermediate, identified the entry points of three late-assembled subunits and demonstrated directly the essential character as well as the interdependence of the assembly of Cox4 and Cox5a. The ectopic expression of the heart/muscle-specific isoform of the Cox6 subunit (COX6A2) resulted in restoration of both CcO holoenzyme and activity in COX6A1-knockdown cells. This was in sharp contrast with the unaltered levels of COX6A2 mRNA in these cells, suggesting the existence of a fixed expression programme. The normal amount and function of respiratory complex I in all of our CcO-deficient knockdown cell lines suggest that, unlike non-human CcO-deficient models, even relatively small amounts of CcO can maintain the normal biogenesis of this respiratory complex in cultured human cells.
