Východisko. Mitochondriální neurogastrointestinální encefalomyopatie (MNGIE) je onemocnění, které je způsobeno poruchou jaderně kódované thymidinfosforylázy (TP) s autozomálně recesivním typem dědičnosti. Na biochemické úrovni se MNGIE projevuje poruchou mitochondriálního energetického metabolizmu a na molekulární úrovni mnohočetnými delecemi v mitochondriální DNA (mtDNA), které vznikají sekundárně jako důsledek nerovnováhy v množství mitochondriálních nukleotidů potřebných pro mtDNA replikaci. Klinicky se MNGIE projevuje jako multisystémové onemocnění charakterizované neprospíváním až dystrofií, gastrointestinální dysmotilitou s projevy pseudoobstrukce, ptózou, difuzní leukoencefalopatií, periferní neuropatií a myopatií. Předkládáme výsledky klinických, metabolických, histologických a molekulárních analýz u pacienta s MNGIE. Metody a výsledky. Třiatřicetiletý muž s výškou 168 cm a hmotností 34 kg, střevní dysmotilitou, externí oftalmoplegií, periferní neuropatií, leukoencefalopatií a hyperlaktacidemií byl doporučen k metabolickému vyšetření. Histochemické vyšetření svalové biopsie ukázalo subsarkolemální nahromadění zmnožených mitochondrií a „ragged-red fibers“. Plazmatické hladiny thymidinu (6,6 μmol/l, norma <0,05 μmol/l) a deoxyuridinu (15 μmol/l, norma <0,05 μmol/l) byly výrazně zvýšené a aktivita TP v izolovaných lymfocytech byla nízká (0,02 μmol/h/mg proteinu, referenční rozmezí 0,78±0,18). Molekulární analýzy ukázaly přítomnost mnohočetných delecí v mtDNA a v genu pro TP byla nalezena homozygotní mutace 1419G>A (Gly145Arg). Oba rodiče jsou zdraví heterozygoti. Závěry. Na diagnózu MNGIE je nutno pomýšlet především u pacientů s neprospíváním a poruchami střevní motility, u kterých se současně rozvíjí i neurologické příznaky. Metodou volby při diagnostice MNGIE je stanovení hladiny thymidinu v krvi, ale pro genetické poradenství v postižené rodině je nutná diagnostika na enzymatické a molekulární úrovni.
Background. Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a disorder with autosomal recessive inheritance caused by mutations in the gene encoding thymidine phosphorylase (TP). TP deficiency results in imbalance of mitochondrial pool of nucleotides leading secondary to multiple deletions and depletion of mitochondrial DNA (mtDNA) and impairment of oxidative phosphorylation system. The disease is clinically characterized by gastrointestinal dysmotility with symptoms of pseudo-obstruction, severe failure to thrive, ptosis, leukoencephalopathy, peripheral neuropathy and myopathy. We present results of the clinical, histochemical, biochemical and molecular analyses of the first Czech patient with MNGIE syndrome. Methods and Results. Man, 33-years old with twenty-year history of failure to thrive (height 168 cm, weight 34 kg) and progressive gastrointestinal dysmotility, external ophthalmoplegia, leucoencephalopathy and peripheral neuropathy was recommended to metabolic center. Histochemical analyses in muscle biopsy showed the presence of „ragged red fibers“ with focal decrease of cytochrome c oxidase activity, but spectrophotometric analyses in isolated muscle mitochondria revealed normal activities of all respiratory chain complexes. Metabolic investigation revealed markedly increased plasma level of thymidine (6.6 μmol/l, controls <0.05 μmol/l) and deoxyuridine (15 μmol/l, controls <0.05 μmol/l). The activity of TP in isolated lymphocytes was low (0.02 μmol/hour/mg protein, reference range 0.78±0.18). Molecular analyses in muscle biopsy revealed multiple mtDNA deletions and homozygous mutation 1419G>A (Gly145Arg) was found in gene for TP. Both parents are heterozygotes. Conclusions. MNGIE has to be considered in patients presenting with a combination of gastrointestinal and neurological symptoms. Plasma level of thymidine may serve as the best method for laboratory screening of MNGIE, but molecular analyses are necessary for genetic counselling and prenatal diagnosis in affected families.
Mitochondriální poruchy energetického metabolismu představují rozsáhlou skupinu metabolických onemocnění, která jsou pro své závažné klinické projevy, progredující charakter onemocnění s nepříznivou prognózou a genetický přenos s mendelovským i maternálním typem dědičnosti závažným zdravotnickým problémem. Mitochondrie byly objeveny v druhé polovině 19. století, ale ani na začátku 21. století není jejich role v organismu zcela objasněna.
Mitochondrial disorders of energetic metabolism represent an extensive group of metabolic illnesses which due to their serious clinical manifestations, the progressive character of the illness with unfavorable prognosis, and their genetic transfer via Mendel and maternal types of inheritance, present a grave health problem. Mitochondria were discovered in the second half of the 19th century, but even at the start of the 21st century their role in the organism is not fully understood.
Ochorenia s postihnutím nervového systému spôsobeným poruchou funkcie mitochondrií zahŕňajú pestrú paletu typov dedičnosti, poškodenia jednotlivých častí nervového systému v kombinácii s prejavmi dysfunkcie iných systémov s vysokými nárokmi na energetické zásobenie. Prístup k členeniu mitochondriálnych ochorení môže vychádzať primárne z klinického obrazu, z typu biochemického poškodenia alebo typu genetického poškodenia. V našej práci opisujeme syndrómové mitochondriálne ochorenia – ochorenia, ktorých fenotypická prezentácia tvorí ucelený syndróm. Diagnostika týchto ochorení, okrem zohľadnenia anamnézy a klinického obrazu, spočíva jednak v genetickom objasnení prítomného defektu, jednak v zistení zmien na mikroskopickej a biochemickej úrovni. V súčasnosti nie je v drvivej väčšine týchto ochorení možná účinná kauzálna liečba. Ich správna diagnostika však dáva predpoklad na uplatnenie účinnej liečby, ktorej perspektíva sa črtá v blízkej budúcnosti.
Diseases with nervous system involvement caused by impaired mitochondrial function include a wide range of types of inheritance, damage to individual parts of the nervous system in combination with manifestations of dysfunction of other systems with high demands for energy supply. The approach to classifying mitochondrial disease can be primarily based on the clinical presentation, the type of biochemical damage, or the type of genetic damage. The paper describes mitochondrial disease syndromes, i.e. diseases whose phenotypic presentation forms a coherent syndrome. Diagnosing these diseases, in addition to taking into account the history and clinical presentation, involves genetic elucidation of the present defect as well as identification of changes at a microscopic and biochemical level. Currently, no effective causal therapy is available in the vast majority of these conditions. Correct diagnosis, however, creates the precondition for the use of effective treatment the perspective of which is in sight in the near future.
- MeSH
- Acidosis, Lactic diagnosis physiopathology MeSH
- Diagnostic Techniques and Procedures MeSH
- Friedreich Ataxia physiopathology MeSH
- Kearns-Sayre Syndrome physiopathology MeSH
- Optic Atrophy, Hereditary, Leber physiopathology MeSH
- Leigh Disease physiopathology MeSH
- Humans MeSH
- Brain Diseases, Metabolic, Inborn * diagnosis metabolism physiopathology MeSH
- DNA, Mitochondrial genetics MeSH
- Mitochondrial Encephalomyopathies * diagnosis physiopathology therapy MeSH
- Mitochondrial Diseases * diagnosis physiopathology therapy MeSH
- Mitochondria genetics metabolism MeSH
- Brain metabolism physiopathology MeSH
- Spinal Cord Diseases diagnosis metabolism physiopathology MeSH
- Diffuse Cerebral Sclerosis of Schilder physiopathology MeSH
- MELAS Syndrome diagnosis physiopathology MeSH
- MERRF Syndrome diagnosis physiopathology MeSH
- Check Tag
- Humans MeSH
BACKGROUND: Although rapid changes in copy number and gene order are common within plant mitochondrial genomes, associated patterns of gene transcription are underinvestigated. Previous studies have shown that the gynodioecious plant species Silene vulgaris exhibits high mitochondrial diversity and occasional paternal inheritance of mitochondrial markers. Here we address whether variation in DNA molecular markers is correlated with variation in transcription of mitochondrial genes in S. vulgaris collected from natural populations. RESULTS: We analyzed RFLP variation in two mitochondrial genes, cox1 and atp1, in offspring of ten plants from a natural population of S. vulgaris in Central Europe. We also investigated transcription profiles of the atp1 and cox1 genes. Most DNA haplotypes and transcription profiles were maternally inherited; for these, transcription profiles were associated with specific mitochondrial DNA haplotypes. One individual exhibited a pattern consistent with paternal inheritance of mitochondrial DNA; this individual exhibited a transcription profile suggestive of paternal but inconsistent with maternal inheritance. We found no associations between gender and transcript profiles. CONCLUSIONS: Specific transcription profiles of mitochondrial genes were associated with specific mitochondrial DNA haplotypes in a natural population of a gynodioecious species S. vulgaris.Our findings suggest the potential for a causal association between rearrangements in the plant mt genome and transcription product variation.
- MeSH
- DNA, Plant genetics MeSH
- Haplotypes MeSH
- DNA, Mitochondrial genetics MeSH
- Genes, Mitochondrial MeSH
- Polymorphism, Restriction Fragment Length MeSH
- Genetics, Population MeSH
- Sequence Analysis, DNA MeSH
- Silene genetics MeSH
- Gene Expression Profiling MeSH
- Inheritance Patterns MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
BACKGROUND: The presence of mitochondria is a distinguishing feature between prokaryotic and eukaryotic cells. It is currently accepted that the evolutionary origin of mitochondria coincided with the formation of eukaryotes and from that point control of mitochondrial inheritance was required. Yet, the way the mitochondrial presence has been maintained throughout the eukaryotic cell cycle remains a matter of study. Eukaryotes control mitochondrial inheritance mainly due to the presence of the genetic component; still only little is known about the segregation of mitochondria to daughter cells during cell division. Additionally, anaerobic eukaryotic microbes evolved a variety of genomeless mitochondria-related organelles (MROs), which could be theoretically assembled de novo, providing a distinct mechanistic basis for maintenance of stable mitochondrial numbers. Here, we approach this problem by studying the structure and inheritance of the protist Giardia intestinalis MROs known as mitosomes. RESULTS: We combined 2D stimulated emission depletion (STED) microscopy and focused ion beam scanning electron microscopy (FIB/SEM) to show that mitosomes exhibit internal segmentation and conserved asymmetric structure. From a total of about forty mitosomes, a small, privileged population is harnessed to the flagellar apparatus, and their life cycle is coordinated with the maturation cycle of G. intestinalis flagella. The orchestration of mitosomal inheritance with the flagellar maturation cycle is mediated by a microtubular connecting fiber, which physically links the privileged mitosomes to both axonemes of the oldest flagella pair and guarantees faithful segregation of the mitosomes into the daughter cells. CONCLUSION: Inheritance of privileged Giardia mitosomes is coupled to the flagellar maturation cycle. We propose that the flagellar system controls segregation of mitochondrial organelles also in other members of this supergroup (Metamonada) of eukaryotes and perhaps reflects the original strategy of early eukaryotic cells to maintain this key organelle before mitochondrial fusion-fission dynamics cycle as observed in Metazoa was established.
Mutations in DNA polymerase gamma (POLG) are known as the predominant cause of inherited mitochondrial disorders. But how these POLG mutations disturb mitochondrial function remains to be determined. Furthermore, no effective therapy, to date, has been reported for POLG diseases. Using differentiated SH-SY5Y cells, a human neuronal model cell line, the current study investigated whether the novel POLG variant p.A962T impairs mitochondrial function. This involved quantifying mitochondrial DNA (mtDNA) content using PCR and assessing the expression levels of the subunits of complex IV (COXI-IV), a complex I subunit NDUFV1 and Cytochrome C (Cyto C) release using Western blotting. Activities of mitochondrial complex I, II, and IV were measured using colorimetric assays. Mitochondrial membrane potential (delta Psim) and ATP were evaluated using fluorescence assays and luminescent assays, respectively. In addition, we investigated whether mitochondrial transplantation (MT) using Pep-1-conjugated mitochondria could compensate for mitochondrial defects caused by the variant in cells carrying mutant POLG. The results of this study showed that POLG p.A962T mutation resulted in mitochondrial defects, including mitochondrial DNA (mtDNA) depletion, membrane potential (delta Psim) depolarization and adenosine triphosphate (ATP) reduction. Mechanistically, POLG mutation-caused mtDNA depletion led to the loss of mtDNA-encoded subunits of complex I and IV and thus compromised their activities. POLG p.A962T mutation is a pathogenic mutation leading to mitochondrial malfunction and mtDNA depletion in neurons. Cell-penetrating peptide Pep-1-mediated MT treatment compensated for mitochondrial defects induced by these POLG variants, suggesting the therapeutic application of this method in POLG diseases.
- MeSH
- DNA Polymerase gamma * genetics metabolism MeSH
- DNA-Directed DNA Polymerase genetics metabolism MeSH
- Humans MeSH
- Membrane Potential, Mitochondrial MeSH
- DNA, Mitochondrial genetics MeSH
- Mitochondrial Diseases genetics metabolism MeSH
- Mitochondria * metabolism MeSH
- Mutation * MeSH
- Cell Line, Tumor MeSH
- Neurons * metabolism MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
Dysfunctions of the F(1)F(o)-ATPase complex cause severe mitochondrial diseases affecting primarily the paediatric population. While in the maternally inherited ATPase defects due to mtDNA mutations in the ATP6 gene the enzyme is structurally and functionally modified, in ATPase defects of nuclear origin mitochondria contain a decreased amount of otherwise normal enzyme. In this case biosynthesis of ATPase is down-regulated due to a block at the early stage of enzyme assembly-formation of the F(1) catalytic part. The pathogenetic mechanism implicates dysfunction of Atp12 or other F(1)-specific assembly factors. For cellular energetics, however, the negative consequences may be quite similar irrespective of whether the ATPase dysfunction is of mitochondrial or nuclear origin.
- MeSH
- Adenosine Triphosphatases genetics MeSH
- Cell Nucleus enzymology metabolism MeSH
- Fibroblasts metabolism MeSH
- Humans MeSH
- DNA, Mitochondrial genetics metabolism MeSH
- Mitochondrial Diseases enzymology genetics MeSH
- Mitochondrial Proton-Translocating ATPases biosynthesis genetics deficiency MeSH
- Mitochondria enzymology MeSH
- Mutation MeSH
- Reactive Oxygen Species analysis metabolism MeSH
- Vacuolar Proton-Translocating ATPases * genetics metabolism MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
- Comparative Study MeSH
The mitogenome of the Orthotrichum speciousum (GenBank accession number KM288416) has a total length of 104,747 bp and consist of 40 protein-coding genes, 3 ribosomal RNA (rRNA) and 24 transfer RNA. The gene order is identical to other known moss mitogenomes.
