Dominantní atrofie optiku (dominant optic atrophy; DOA) je autozomálně dominantně děděné onemocnění manifestující se pomalou a nebolestivou bilaterální ztrátou zrakové ostrosti s různým stupněm závažnosti. DOA je podmíněna mutacemi v genech jaderné DNA kódující proteiny asociované s vnitřní membránou mitochondrií. Ve většině popsaných případů DOA se jedná o mutaci v OPA1 genu, jsou ale známy i další geny a lokusy podmiňující DOA. K manifestaci onemocnění obvykle dochází v prvních dvou dekádách života. Onemocnění se rozvíjí na podkladě neurodegenerativního postižení gangliových buněk sítnice vedoucího k atrofii zrakového nervu. Snížení zrakové ostrosti je doprovázeno poruchou barvocitu a centrálními nebo paracentrálními defekty v zorném poli. Při vyšetření očního pozadí lze pozorovat bledý terč zrakového nervu, případně i jeho exkavaci. U části pacientů jsou popisovány extraokulární příznaky, tzv. DOA plus syndrom. Nejčastěji se jedná o bilaterální senzorineurální poruchu sluchu; vzácněji je přítomna i chronická progresivní zevní oftalmoplegie, myopatie, periferní neuropatie, onemocnění podobné RS nebo spastická paraplegie dolních končetin. V současnosti není známa účinná terapie, která by zabránila rozvoji zrakového postižení. V Centru pro pacienty s mitochondriálními neuropatiemi optiku při VFN v Praze probíhá genetická diagnostika a dispenzarizace jedinců s DOA. Cílem přehledného článku je zvýšit povědomí o této nejčastější geneticky podmíněné neuropatii optiku.

Dominant optic atrophy (DOA) is an autosomal dominant disorder manifesting by slowly progressive painless bilateral visual acuity loss with variable degree of severity. DOA is caused by mutations in nuclear DNA encoding proteins associated with the inner mitochondrial membrane. Most individuals with DOA harbour a disease-causing mutation in the OPA1 gene; however, other genes and loci associated with DOA have also been identified. First symptoms usually manifest in the first two decades of life. The disease mechanism lies in neurodegenerative damage of retinal ganglion cells leading to optic nerve atrophy. Decrease of visual acuity is associated with colour vision alterations and central or paracentral visual field defects. On fundoscopic examination, optic head nerve pallor can be noticed, occasionally with excavation. Extraocular symptoms are present in some patients, causing so-called DOA plus syndrome. Bilateral sensorineural hearing loss, is the most common one; chronic progressive external ophthalmoplegia, myopathy, peripheral neuropathy, multiple sclerosis-like disorder, and spastic paraplegia of lower limbs are rare. Currently, there is no effective treatment available that would prevent the development of visual impairment. Genetic diagnostics and follow-up of patients with DOA are held in the Centre for Patients with Mitochondrial Optic Neuropathies, General University Hospital in Prague. The aim of this review is to increase awareness of the most common genetically determined optic neuropathy.

• MeSH
• autozomálně dominantně dědičná optická atrofie * diagnóza   patofyziologie   terapie   MeSH
• diferenciální diagnóza MeSH
• lidé MeSH
• mitochondriální nemoci genetika   MeSH
• mutace genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• práce podpořená grantem MeSH
• přehledy MeSH

PURPOSE: To determine the molecular genetic cause in previously unreported probands with optic atrophy from the United Kingdom, Czech Republic and Canada. METHODS: OPA1 coding regions and flanking intronic sequences were screened by direct sequencing in 82 probands referred with a diagnosis of bilateral optic atrophy. Detected rare variants were assessed for pathogenicity by in silico analysis. Segregation of the identified variants was performed in available first degree relatives. RESULTS: A total of 29 heterozygous mutations evaluated as pathogenic were identified in 42 probands, of these seven were novel. In two probands, only variants of unknown significance were found. 76% of pathogenic mutations observed in 30 (71%) of 42 probands were evaluated to lead to unstable transcripts resulting in haploinsufficiency. Three probands with the following disease-causing mutations c.1230+1G>A, c.1367G>A and c.2965dup were documented to suffer from hearing loss and/or neurological impairment. CONCLUSIONS: OPA1 gene screening in patients with bilateral optic atrophy is an important part of clinical evaluation as it may establish correct clinical diagnosis. Our study expands the spectrum of OPA1 mutations causing dominant optic atrophy and supports the fact that haploinsufficiency is the most common disease mechanism.

• MeSH
• autozomálně dominantně dědičná optická atrofie genetika   metabolismus   MeSH
• DNA genetika   MeSH
• fenotyp MeSH
• genetické techniky MeSH
• GTP-fosfohydrolasy genetika   metabolismus   MeSH
• heterozygot MeSH
• lidé MeSH
• mutace * MeSH
• mutační analýza DNA MeSH
• rodokmen MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH
• Kanada MeSH
• Spojené království MeSH

PURPOSE: To identify the underlying molecular genetic cause in a Czech family with optic atrophy, deafness, ptosis, ophthalmoplegia, polyneuropathy and ataxia transmitted as an autosomal dominant trait. METHODS: Ophthalmological and neurological examination followed by molecular genetic analyses. RESULTS: Seven family members were clinically affected. There was a variable but progressive visual, hearing and neurological disability across the family as a whole. The majority of subjects presented with impairment of visual function and a variable degree of ptosis and/or ophthalmoplegia from the first to the third decade of life. Deafness, neuropathy and ataxia appeared later, in the third and fourth decade. Migraine, tachycardia, intention tremor, nystagmus and cervical dystonia were observed in isolated individuals. A significant overall feature was the high level of neurological disability leading to 3 of 4 members being unable to walk or stand unaided before the age of 60 years. A novel missense mutation c.1345A>C (p.Thr449Pro) in OPA1 segregating with the disease phenotype over three generations was detected. In silico analysis supported pathogenicity of the identified sequence variant. CONCLUSION: Our work expands the spectrum of mutation in OPA1, which may lead to severe multisystem neurological disorder. The molecular genetic cause of dominant optic atrophy in the Czech population is reported for the first time. We propose that regular cardiac follow-up in patients diagnosed with dominant optic atrophy and widespread neurological disease should be considered.

• MeSH
• atrofie optického nervu diagnóza   genetika   MeSH
• blefaroptóza diagnóza   genetika   MeSH
• chronická progresivní externí oftalmoplegie diagnóza   genetika   MeSH
• dítě MeSH
• dospělí MeSH
• exony genetika   MeSH
• fenotyp MeSH
• genotyp MeSH
• GTP-fosfohydrolasy genetika   MeSH
• lidé středního věku MeSH
• lidé MeSH
• missense mutace * MeSH
• nedoslýchavost diagnóza   genetika   MeSH
• nemoci periferního nervového systému diagnóza   genetika   MeSH
• optická koherentní tomografie MeSH
• rodokmen MeSH
• senioři MeSH
• sluchové testy MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• Publikační typ
• abstrakt z konference MeSH

• Publikační typ
• abstrakt z konference MeSH

A single mitochondrial network in the cell undergoes constant fission and fusion primarily depending on the local GTP gradients and the mitochondrial energetics. Here we overview the main properties and regulation of pro-fusion and pro-fission mitodynamins, i.e. dynamins-related GTPases responsible for mitochondrial shape-forming, such as pro-fusion mitofusins MFN1, MFN2, and the inner membrane-residing long OPA1 isoforms, and pro-fission mitodynamins FIS1, MFF, and DRP1 multimers required for scission. Notably, the OPA1 cleavage into non-functional short isoforms at a diminished ATP level (collapsed membrane potential) and the DRP1 recruitment upon phosphorylation by various kinases are overviewed. Possible responses of mitodynamins to the oxidative stress, hypoxia, and concomitant mtDNA mutations are also discussed. We hypothesize that the increased GTP formation within the Krebs cycle followed by the GTP export via the ADP/ATP carrier shift the balance between fission and fusion towards fusion by activating the GTPase domain of OPA1 located in the peripheral intermembrane space (PIMS). Since the protein milieu of PIMS is kept at the prevailing oxidized redox potential by the TOM, MIA40 and ALR/Erv1 import-redox trapping system, redox regulations shift the protein environment of PIMS to a more reduced state due to the higher substrate load and increased respiration. A higher cytochrome c turnover rate may prevent electron transfer from ALR/Erv1 to cytochrome c. Nevertheless, the putative links between the mitodynamin responses, mitochondrial morphology and the changes in the mitochondrial bioenergetics, superoxide production, and hypoxia are yet to be elucidated, including the precise basis for signaling by the mitochondrion-derived vesicles.

• MeSH
• biologické modely MeSH
• hypoxie buňky fyziologie   MeSH
• lidé MeSH
• mitochondriální DNA fyziologie   genetika   MeSH
• mitochondrie metabolismus   MeSH
• oxidace-redukce MeSH
• oxidační stres fyziologie   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem MeSH
• přehledy MeSH

Mitochondrial protein quality control is crucial for the maintenance of correct mitochondrial homeostasis. It is ensured by several specific mitochondrial proteases located across the various mitochondrial subcompartments. Here, we focused on characterization of functional overlap and cooperativity of proteolytic subunits AFG3L2 (AFG3 Like Matrix AAA Peptidase Subunit 2) and YME1L (YME1 like ATPase) of mitochondrial inner membrane AAA (ATPases Associated with diverse cellular Activities) complexes in the maintenance of mitochondrial structure and respiratory chain integrity. We demonstrate that loss of AFG3L2 and YME1L, both alone and in combination, results in diminished cell proliferation, fragmentation of mitochondrial reticulum, altered cristae morphogenesis, and defective respiratory chain biogenesis. The double AFG3L2/YME1L knockdown cells showed marked upregulation of OPA1 protein forms, with the most prominent increase in short OPA1 (optic atrophy 1). Loss of either protease led to marked elevation in OMA1 (OMA1 zinc metallopeptidase) (60 kDa) and severe reduction in the SPG7 (paraplegin) subunit of the m-AAA complex. Loss of the YME1L subunit led to an increased Drp1 level in mitochondrial fractions. While loss of YME1L impaired biogenesis and function of complex I, knockdown of AFG3L2 mainly affected the assembly and function of complex IV. Our results suggest cooperative and partly redundant functions of AFG3L2 and YME1L in the maintenance of mitochondrial structure and respiratory chain biogenesis and stress the importance of correct proteostasis for mitochondrial integrity.

• MeSH
• ATPázy spojené s různými buněčnými aktivitami genetika   metabolismus   MeSH
• HEK293 buňky MeSH
• lidé MeSH
• metaloendopeptidasy genetika   metabolismus   MeSH
• mitochondriální membrány metabolismus   MeSH
• mitochondriální proteiny genetika   metabolismus   MeSH
• mitochondrie metabolismus   ultrastruktura   MeSH
• proliferace buněk genetika   fyziologie   MeSH
• proteasy závislé na ATP genetika   metabolismus   MeSH
• transmisní elektronová mikroskopie MeSH
• western blotting MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Significance: Mitochondrial (mt) reticulum network in the cell possesses amazing ultramorphology of parallel lamellar cristae, formed by the invaginated inner mitochondrial membrane. Its non-invaginated part, the inner boundary membrane (IBM) forms a cylindrical sandwich with the outer mitochondrial membrane (OMM). Crista membranes (CMs) meet IBM at crista junctions (CJs) of mt cristae organizing system (MICOS) complexes connected to OMM sorting and assembly machinery (SAM). Cristae dimensions, shape, and CJs have characteristic patterns for different metabolic regimes, physiological and pathological situations. Recent Advances: Cristae-shaping proteins were characterized, namely rows of ATP-synthase dimers forming the crista lamella edges, MICOS subunits, optic atrophy 1 (OPA1) isoforms and mitochondrial genome maintenance 1 (MGM1) filaments, prohibitins, and others. Detailed cristae ultramorphology changes were imaged by focused-ion beam/scanning electron microscopy. Dynamics of crista lamellae and mobile CJs were demonstrated by nanoscopy in living cells. With tBID-induced apoptosis a single entirely fused cristae reticulum was observed in a mitochondrial spheroid. Critical Issues: The mobility and composition of MICOS, OPA1, and ATP-synthase dimeric rows regulated by post-translational modifications might be exclusively responsible for cristae morphology changes, but ion fluxes across CM and resulting osmotic forces might be also involved. Inevitably, cristae ultramorphology should reflect also mitochondrial redox homeostasis, but details are unknown. Disordered cristae typically reflect higher superoxide formation. Future Directions: To link redox homeostasis to cristae ultramorphology and define markers, recent progress will help in uncovering mechanisms involved in proton-coupled electron transfer via the respiratory chain and in regulation of cristae architecture, leading to structural determination of superoxide formation sites and cristae ultramorphology changes in diseases. Antioxid. Redox Signal. 39, 635-683.

• MeSH
• adenosintrifosfát metabolismus   MeSH
• homeostáza MeSH
• mitochondriální membrány * metabolismus   MeSH
• mitochondriální proteiny metabolismus   MeSH
• oxidace-redukce MeSH
• superoxidy * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

The relationship of the inner mitochondrial membrane (IMM) cristae structure and intracristal space (ICS) to oxidative phosphorylation (oxphos) is not well understood. Mitofilin (subunit Mic60) of the mitochondrial contact site and cristae organizing system (MICOS) IMM complex is attached to the outer membrane (OMM) via the sorting and assembly machinery/topogenesis of mitochondrial outer membrane β-barrel proteins (SAM/TOB) complex and controls the shape of the cristae. ATP synthase dimers determine sharp cristae edges, whereas trimeric OPA1 tightens ICS outlets. Metabolism is altered during hypoxia, and we therefore studied cristae morphology in HepG2 cells adapted to 5% oxygen for 72 h. Three dimensional (3D), super-resolution biplane fluorescence photoactivation localization microscopy with Eos-conjugated, ICS-located lactamase-β indicated hypoxic ICS expansion with an unchanged OMM (visualized by Eos-mitochondrial fission protein-1). 3D direct stochastic optical reconstruction microscopy immunocytochemistry revealed foci of clustered mitofilin (but not MICOS subunit Mic19) in contrast to its even normoxic distribution. Mitofilin mRNA and protein decreased by ∼20%. ATP synthase dimers vs monomers and state-3/state-4 respiration ratios were lower during hypoxia. Electron microscopy confirmed ICS expansion (maximum in glycolytic cells), which was absent in reduced or OMM-detached cristae of OPA1- and mitofilin-silenced cells, respectively. Hypoxic adaptation is reported as rounding sharp cristae edges and expanding cristae width (ICS) by partial mitofilin/Mic60 down-regulation. Mitofilin-depleted MICOS detaches from SAM while remaining MICOS with mitofilin redistributes toward higher interdistances. This phenomenon causes partial oxphos dormancy in glycolytic cells via disruption of ATP synthase dimers.-Plecitá-Hlavatá, L., Engstová, H., Alán, L., Špaček, T., Dlasková, A., Smolková, K., Špačková, J., Tauber, J., Strádalová, V., Malínský, J., Lessard, M., Bewersdorf, J., Ježek, P. Hypoxic HepG2 cell adaptation decreases ATP synthase dimers and ATP production in inflated cristae by mitofilin down-regulation concomitant to MICOS clustering.

• MeSH
• adenosintrifosfát biosyntéza   MeSH
• ATP-synthetasa (komplexy) metabolismus   MeSH
• buňky Hep G2 MeSH
• down regulace MeSH
• fyziologická adaptace fyziologie   MeSH
• interakční proteinové domény a motivy MeSH
• kyslík * MeSH
• lidé MeSH
• mitochondriální dynamika fyziologie   MeSH
• mitochondriální proteiny genetika   metabolismus   MeSH
• mitochondrie fyziologie   MeSH
• multiproteinové komplexy fyziologie   MeSH
• podjednotky proteinů MeSH
• regulace genové exprese fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Purpose: Retinal ischemia (RI) and progressive neuronal death are sight-threatening conditions. Mitochondrial (mt) dysfunction and fusion/fission processes have been suggested to play a role in the pathophysiology of RI. This study focuses on changes in the mt parameters of the neuroretina, retinal pigment epithelium (RPE) and choroid in a porcine high intraocular pressure (IOP)-induced RI minipig model. Methods: In one eye, an acute IOP elevation was induced in minipigs and compared to the other control eye. Activity and amount of respiratory chain complexes (RCC) were analyzed by spectrophotometry and Western blot, respectively. The coenzyme Q10 (CoQ10) content was measured using HPLC, and the ultrastructure of the mt was studied via transmission electron microscopy. The expression of selected mt-pathway genes was determined by RT-PCR. Results: At a functional level, increased RCC I activity and decreased total CoQ10 content were found in RPE cells. At a protein level, CORE2, a subunit of RCC III, and DRP1, was significantly decreased in the neuroretina. Drp1 and Opa1, protein-encoding genes responsible for mt quality control, were decreased in most of the samples from the RPE and neuroretina. Conclusions: The eyes of the minipig can be considered a potential RI model to study mt dysfunction in this disease. Strategies targeting mt protection may provide a promising way to delay the acute damage and onset of RI.

• MeSH
• glaukom * metabolismus   MeSH
• ischemie metabolismus   MeSH
• karcinom z renálních buněk * metabolismus   MeSH
• miniaturní prasata MeSH
• mitochondrie metabolismus   MeSH
• nádory ledvin * metabolismus   MeSH
• nitrooční tlak MeSH
• prasata MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH