Mitochondrial diseases caused by mtDNA mutations: a mini-review Anastasia I Ryzhkova,1,2 Margarita A Sazonova,1,3 Vasily V Sinyov,1 Elena V Galitsyna,4 Mariya M Chicheva,4 Alexandra A Melnichenko,4 Andrey V Grechko,5 Anton Yu Postnov,1 Alexander N Orekhov,3,6 Tatiana P Shkurat4 1Laboratory of Medical Genetics, National Medical Research Center of Cardiology, Moscow, Russian Federation; 2Department of Virology, K.I. Skryabin Moscow State Academy of Veterinary Medicine and Biotechnology-MVA, Moscow, Russian Federation; 3Laboratory of Angiopathology, Institute of General Pathology and Pathophysiology, Moscow, Russian Federation; 4Department of Genetics, Southern Federal University, Rostov-on-Don, Russian Federation; 5Federal Research and Clinical Center of Reanimatology and Rehabilitology, Moscow, Russian Federation; 6Institute for Atherosclerosis Research, Skolkovo Innovative Centre, Moscow Region, Russian Federation There are several types of mitochondrial cytopathies, which cause a set of disorders, arise as a result of mitochondria’s failure. Mitochondria’s functional disruption leads to development of physical, growing and cognitive disabilities and includes multiple organ pathologies, essentially disturbing the nervous and muscular systems. The origins of mitochondrial cytopathies are mutations in genes of nuclear DNA encoding mitochondrial proteins or in mitochondrial DNA. Nowadays, numerous mtDNA mutations significant to the appearance and progress of pathologies in humans are detected. In this mini-review, we accent on the mitochondrial cytopathies related to mutations of mtDNA. As well known, there are definite set of symptoms of mitochondrial cytopathies distinguishing or similar for different syndromes. The present article contains data about mutations linked with cytopathies that facilitate diagnosis of different syndromes by using genetic analysis methods. In addition, for every individual, more effective therapeutic approach could be developed after wide-range mutant background analysis of mitochondrial genome. Keywords: mitochondrial cytopathy, mitochondrial dysfunction, mtDNA mutation, mitochondrial gene mutation

Mutations of mtDNA, due to their higher frequency of occurrence compared to nuclear DNA mutations, are the most promising biomarkers for assessing predisposition of the occurrence and development of atherogenesis. The aim of the present article was an analysis of correlation of several mitochondrial genome mutations with carotid atherosclerosis. Leukocytes from blood of study participants from Moscow polyclinics were used as research material. The sample size was 700 people. The sample members were diagnosed with “atherosclerosis” on the basis of ultrasonographic examination and biochemical and molecular cell tests. DNA was isolated from blood leukocyte samples of the study participants. PCR fragments of DNA, containing the region of 11 investigated mutations, were pyrosequenced. The heteroplasmy level of these mutations was detected. Statistical analysis of the obtained results was performed using the software package SPSS 22.0. According to the obtained results, an association of mutations m.652delG, m.3336C>T, m.12315G>A, m.14459G>A m.15059G>A with carotid atherosclerosis was found. These mutations can be biomarkers for assessing predisposition to this disease. Additionally, two single nucleotide substitutions (m.13513G>A and m.14846G>A), negatively correlating with atherosclerotic lesions, were detected. These mutations may be potential candidates for gene therapy of atherosclerosis and its risk factors.

Objective.The aim of the present study was an analysis of heteroplasmy level in mitochondrial mutations 652delG, A1555G, C3256T, T3336C, 652insG, C5178A, G12315A, G13513A, G14459A, G14846A, and G15059A in normal and affected by atherosclerosis segments of morphologically mapped aortic walls.Methods.We investigated the 265 normal and atherosclerotic tissue sections of 5 human aortas. Intima of every aorta was divided according to morphological characteristics into segments with different types of atherosclerotic lesions: fibrous plaque, lipofibrous plaque, primary atherosclerotic lesion (fatty streak and fatty infiltration), and normal intima from human aorta. PCR-fragments were analyzed by a new original method developed in our laboratory on the basis of pyrosequence technology.Results.According to the obtained data, mutations G12315A and G14459A are significantly associated with total and primary atherosclerotic lesions of intimal segments and lipofibrous plaques (P≤0.01andP≤0.05, accordingly). Mutation C5178A is significantly associated with fibrous plaques and total atherosclerotic lesions(P≤0.01). A1555G mutation shows an antiatherosclerotic effect in primary lesion in lipofibrous plaques(P≤0.05). Meanwhile, G14846A mutation is antiatherogenic for lipofibrous plaques(P≤0.05).Conclusion.Therefore, mutations C5178A, G14459A, G12315A, A1555G, and G14846A were found to be associated with atherosclerotic lesions.

Modelling of pathological processes in cells is one of the most sought‐after technologies of the 21st century. Using models of such processes may help to study the pathogenetic mechanisms of various diseases. The aim of the present study was to analyse the literature, dedicated to obtaining and investigating cybrid models. Besides, the possibility of modeling pathological processes in cells and treatment of different diseases using the models was evaluated. Methods of obtaining Rho0 cell cultures showed that, during their creation, mainly a standard technique, based on the use of mtDNA replication inhibitors (ethidium bromide), was applied. Cybrid lines were usually obtained by PEG fusion. Most frequently, platelets acted as donors of mitochondria. According to the analysis of the literature data, cybrid cell cultures can be modeled to study the dysfunction of the mitochondrial genome and molecular cellular pathological processes. Such models can be very promising for the development of therapeutic approaches to the treatment of various human diseases.

Chronic stress is a combination of nonspecific adaptive reactions of the body to the influence of various adverse stress factors which disrupt its homeostasis, and it is also a corresponding state of the organism’s nervous system (or the body in general). We hypothesized that chronic stress may be one of the causes occurence of several molecular and cellular types of stress. We analyzed literary sources and considered most of these types of stress in our review article. We examined genes and mutations of nuclear and mitochondrial genomes and also molecular variants which lead to various types of stress. The end result of chronic stress can be metabolic disturbance in humans and animals, leading to accumulation of reactive oxygen species (ROS), oxidative stress, energy deficiency in cells (due to a decrease in ATP synthesis) and mitochondrial dysfunction. These changes can last for the lifetime and lead to severe pathologies, including neurodegenerative diseases and atherosclerosis. The analysis of literature allowed us to conclude that under the influence of chronic stress, metabolism in the human body can be disrupted, mutations of the mitochondrial and nuclear genome and dysfunction of cells and their compartments can occur. As a result of these processes, oxidative, genotoxic, and cellular stress can occur. Therefore, chronic stress can be one of the causes forthe occurrence and development of neurodegenerative diseases and atherosclerosis. In particular, chronic stress can play a large role in the occurrence and development of oxidative, genotoxic, and cellular types of stress.

Myocardial infarction is one of the clinical manifestations of coronary heart disease. In some cases, the cause of myocardial infarction may be atherosclerotic plaques which occurred in the human aorta. The association of mtDNA mutations with atherosclerotic lesions in human arteries was previously detected by our research group. In this study, we used samples of white blood cells collected from 225 patients with myocardial infarction and 239 control persons with no health complaints. DNA was isolated from the blood leukocyte samples. Then, PCR fragments of DNA were obtained. They contained the investigated regions of 11 mitochondrial genome mutations (m.5178C>A, m.3336T>C, m.652delG, m.12315G>A, m.14459G>A, m.652insG, m.14846G>A, m.13513G>A, m.1555A>G, m.15059G>A, m.3256C>T). According to the obtained results, three mutations of the human mitochondrial genome correlated with myocardial infarction. A positive correlation was observed for mutation m.5178C>A. At the same time, a highly significant negative correlation with myocardial infarction was observed for mutation m.14846G>A. One single-nucleotide substitution of m.12315G>A had a trend towards negative correlation. These mutations can potentially be useful for creating molecular/cellular models for studying the mechanisms of myocardial infarction and designing novel therapies. Moreover, these mutations can possibly be used for diagnostic purposes.