Role Of Mitochondrial DNA Mutations Research Articles

Mitochondrial Dysfunction in Chronic Obstructive Pulmonary Disease: Unraveling the Molecular Nexus.

Chronic obstructive pulmonary disease (COPD) is a prevalent and debilitating respiratory disorder characterized by persistent airflow limitation and chronic inflammation. In recent years, the role of mitochondrial dysfunction in COPD pathogenesis has emerged as a focal point of investigation. This review endeavors to unravel the molecular nexus between mitochondrial dysfunction and COPD, delving into the intricate interplay of oxidative stress, bioenergetic impairment, mitochondrial genetics, and downstream cellular consequences. Oxidative stress, a consequence of mitochondrial dysfunction, is explored as a driving force behind inflammation, exacerbating the intricate cascade of events leading to COPD progression. Bioenergetic impairment sheds light on the systemic consequences of mitochondrial dysfunction, impacting cellular functions and contributing to the overall energy imbalance observed in COPD patients. This review navigates through the genetic landscape, elucidating the role of mitochondrial DNA mutations, variations, and haplogroups in COPD susceptibility and severity. Cellular consequences, including apoptosis, autophagy, and cellular senescence, are examined, providing insights into the intricate mechanisms by which mitochondrial dysfunction influences COPD pathology. Therapeutic implications, spanning antioxidant strategies, mitochondria-targeted compounds, and lifestyle modifications, are discussed in the context of translational research. Important future directions include identifying novel biomarkers, advancing mitochondria-targeted therapies, and embracing patient-centric approaches to redefine COPD management. This abstract provides a comprehensive overview of our review, offering a roadmap for understanding and addressing the molecular nexus between mitochondrial dysfunction and COPD, with potential implications for precision medicine and improved patient outcomes.

Mitochondrial DNA Mutations and Ageing.

Mitochondria are subcellular organelles present in most eukaryotic cells which play a significant role in numerous aspects of cell biology. These include carbohydrate and fatty acid metabolism to generate cellular energy through oxidative phosphorylation, apoptosis, cell signalling, haem biosynthesis and reactive oxygen species production. Mitochondrial dysfunction is a feature of many human ageing tissues, and since the discovery that mitochondrial DNA mutations were a major underlying cause of changes in oxidative phosphorylation capacity, it has been proposed that they have a role in human ageing. However, there is still much debate on whether mitochondrial DNA mutations play a causal role in ageing or are simply a consequence of the ageing process. This chapter describes the structure of mammalian mitochondria, and the unique features of mitochondrial genetics, and reviews the current evidence surrounding the role of mitochondrial DNA mutations in the ageing process. It then focusses on more recent discoveries regarding the role of mitochondrial dysfunction in stem cell ageing and age-related inflammation.

The Role of Mitochondrial DNA Mutations in Cardiovascular Diseases.

Cardiovascular diseases (CVD) are one of the leading causes of morbidity and mortality worldwide. mtDNA (mitochondrial DNA) mutations are known to participate in the development and progression of some CVD. Moreover, specific types of mitochondria-mediated CVD have been discovered, such as MIEH (maternally inherited essential hypertension) and maternally inherited CHD (coronary heart disease). Maternally inherited mitochondrial CVD is caused by certain mutations in the mtDNA, which encode structural mitochondrial proteins and mitochondrial tRNA. In this review, we focus on recently identified mtDNA mutations associated with CVD (coronary artery disease and hypertension). Additionally, new data suggest the role of mtDNA mutations in Brugada syndrome and ischemic stroke, which before were considered only as a result of mutations in nuclear genes. Moreover, we discuss the molecular mechanisms of mtDNA involvement in the development of the disease.

A Review on the Role of Mitochondrial DNA Mutations in Cancer

Mitochondria implement various cellular functions, including energy production through the electron transport chain by oxidative phosphorylation mechanism. These respiratory chains consist of several complexes and protein subunits which are encoded by nuclear and mitochondrial genes. Due to mutation susceptibility and repair limitation, more aberrations have occurred in mitochondrial DNA in comparison to nuclear DNA. Given the fact that mitochondrial DNA lacks introns, mutations almost occur in the coding sequence, which comprises a direct impact on its functions. Emerging evidence indicates that mutations in the mitochondrial DNA led to the production of reactive oxygen species, disrupted apoptosis, and tumor development. Studies reported various somatic and germline variants in mitochondrial DNA related to tumorigenesis. The D-loop region which is the starting point for replication and transcription of mitochondrial DNA is the most prevalent site of somatic mutations in solid tumors. The D-loop mutations also cause copy number variations which are gaining interest in studies of solid tumors including breast cancer, colon cancer, hepatocellular carcinomas, and prostate cancer. Most studies have reported a mitochondrial DNA reduction which subsequently prevents apoptosis and promotes metastasis. The mitochondrial DNA region-specific haplogroups are also involved in the sequence variations due to processes such as genetic drift and adaptive selection. This review article discusses the biology and function of mitochondria and related genes. By explanation of mitochondrial dysfunction caused by different kinds of alterations, we attempt to elucidate the role of mitochondria in tumorigenesis. Prominently published articles in this field were reviewed and the role of germline and somatic mutations of mitochondrial DNA have been investigated in common cancers. *Corresponding Author: Shirin Shahbazi; Email: sh.shahbazi@modares.ac.ir; ORCID iD: 0000-0002-7634-5350 Please cite this article as: Dahi F, Mortezanejad S, Nakhaee S, Geranpayeh L, Shahbazi S. A Review on the Role of Mitochondrial DNA Mutations in Cancer. Arch Med Lab Sci. 2021;7:1-12 (e18). https://doi.org/10.22037/amls.v7.34736

TBIO-12. THE SPECTRUM OF MITOCHONDRIAl DNA (mtDNA) MUTATIONS IN PEDIATRIC CENTRAL NERVOUS SYSTEM (CNS) TUMORS

To explore the role of mitochondrial DNA mutations in pediatric CNS tumors, we analyzed 749 tumor-normal paired whole genome sequencing data sets from the Children’s Brain Tumor Tissue Consortium (CBTTC). We detected 307 somatic mtDNA mutations in 222 CNS tumors (29.6%). Most frequently observed were missense mutations (38.1%). We also detected 34 loss-of-function mutations. Different pediatric CNS tumor subtypes have distinct mtDNA mutation profiles. For categorical comparisons, we analyzed subtypes with at least 15 samples. The highest number of mtDNA mutations per tumor sample was in meningiomas (0.85), while atypical teratoid rhabdoid tumors (ATRTs) had the lowest number per sample (0.18). High-grade gliomas had a higher number of mtDNA mutations per sample than low-grade gliomas (0.56 vs. 0.31) (p = 0.0011), with almost twice as many missense mtDNA mutations per sample (0.22 vs. 0.13) (p < 0.001), and higher average heteroplasmy levels (11% vs. 9%). The average heteroplasmy was 10.1%, ranging from 15.6% in medulloblastoma to 6.36% in schwannoma suggesting that these are clonal alterations and not artifacts. Intriguingly, the two chordoma patients in the CBTTC database had an identical heteroplasmic m.10971G>A MT-ND4 nonsense mutation. Similarly, our patient with recurrent gliofibroma harbored the same somatic MT-ND4 synonymous variant (m.10700A>G) detected at 53% heteroplasmy in the initial tumor, 79% in the first recurrence, and 97% in the second recurrence. Although the functional consequences of these alterations are not yet understood, our findings suggest that sequencing the mtDNA genome may be used to characterize CNS tumors at diagnosis and monitor disease progression.

Mitochondrion as a Selective Target for the Treatment of Atherosclerosis: Role of Mitochondrial DNA Mutations and Defective Mitophagy in the Pathogenesis of Atherosclerosis and Chronic Inflammation.

Background Atherosclerosis is a chronic inflammatory condition that affects different arteries in the human body and often leads to severe neurological complications, such as stroke and its sequelae. Affected blood vessels develop atherosclerotic lesions in the form of focal thickening of the intimal layer, so called atherosclerotic plaques.Objectives Despite the high priority of atherosclerosis research for global health and the numerous preclinical and clinical studies conducted, currently, there is no effective pharmacological treatment that directly impacts atherosclerotic plaques. Many knowledge gaps exist in our understanding of the mechanisms of plaque formation. In this review, we discuss the role of mitochondria in different cell types involved in atherogenesis and provide information about mtDNA mutations associated with the disease.Results Mitochondria of blood and arterial wall cells appear to be one of the important factors in disease initiation and development. Significant experimental evidence connects oxidative stress associated with mitochondrial dysfunction and vascular disease. Moreover, mitochondrial DNA (mtDNA) deletions and mutations are being considered as potential disease markers. Further study of mtDNA damage and associated dysfunction may open new perspectives for atherosclerosis treatment.Conclusion Mitochondria can be considered as important disease-modifying factors in several chronic pathologies. Deletions and mutations of mtDNA may be used as potential disease markers. Mitochondria-targeting antioxidant therapies appear to be promising for the development of treatment of atherosclerosis and other diseases associated with oxidative stress and chronic inflammation.

The role of mitochondrial DNA mutations in coronary heart disease.

Coronary heart disease (CHD) is a leading cause of death worldwide. It is a multifactorial disorder resulting from harmful interactions between genetic and environmental factors. Due to the central role of mitochondria in cellular energy homeostasis, there is growing evidence supporting the role of damage to mitochondrial components such as mitochondrial DNA (mtDNA) in the pathogenesis and progression of CHD. However, the molecular mechanisms linking mtDNA and CHD remains unknown. In terms of mutations, we found that mitochondrial transfer RNA (mt-tRNA) genes are hot spots for pathogenic mutations associated with CHD. These mutations cause structural and functional changes in tRNA; specifically, failure of tRNA metabolism may impair mitochondrial protein synthesis and lead to mitochondrial dysfunction responsible for CHD. This review provides a detailed summary of the mtDNA mutations that have been reported to be associated with CHD and further discusses the possible molecular mechanisms behind the involvement of these mtDNA mutations in CHD.

Possible Role of Mitochondrial DNA Mutations in Chronification of Inflammation: Focus on Atherosclerosis.

Chronification of inflammation is the process that lies at the basis of several human diseases that make up to 80% of morbidity and mortality worldwide. It can also explain a great deal of processes related to aging. Atherosclerosis is an example of the most important chronic inflammatory pathology in terms of public health impact. Atherogenesis is based on the inflammatory response of the innate immunity arising locally or focally. The main trigger for this response appears to be modified low-density lipoprotein (LDL), although other factors may also play a role. With the quick resolution of inflammation, atherosclerotic changes in the arterial wall do not occur. However, a violation of the innate immunity response can lead to chronification of local inflammation and, as a result, to atherosclerotic lesion formation. In this review, we discuss possible mechanisms of the impaired immune response with a special focus on mitochondrial dysfunction. Some mitochondrial dysfunctions may be due to mutations in mitochondrial DNA. Several mitochondrial DNA mutations leading to defective mitophagy have been identified. The regulatory role of mitophagy in the immune response has been shown in recent studies. We suggest that defective mitophagy promoted by mutations in mitochondrial DNA can cause innate immunity disorders leading to chronification of inflammation.

Mutations of Nuclear and Mitochondrial Genomes as Potential Targets for the Treatment of Metabolic Syndrome.

In addition to external factors, such as exercise, food and the environment, genetic predisposition makes great contribution to the development of metabolic disorders and cardiovascular disease. This review is aimed to examine the genetic basis of complex metabolic disorders conventionally described as "metabolic syndrome" (MetS), with the special focus on currently known mutations in the nuclear and mitochondrial genomes, which are associated with both the individual components of MetS and combinations thereof, and also on the studies of the relationship of MetS phenotype as a binary trait. The defects in the mitochondrial genome should be considered as one of the possible genetic reasons leading to MetS. It is known that mitochondrial dysfunction is closely associated with metabolic disorders, as mitochondria are the center of energy metabolism. Consequently, the changes in mitochondrial genes and their functions affect regulation of metabolism. Until now, the role of mitochondrial DNA damage in the development of cardiovascular diseases, age-related and metabolic disorders is still poorly understood. The results of performed studies would help assessing the role of mitochondrial DNA mutations in susceptibility to metabolic syndrome and related metabolic diseases.

Cardiac Response to Oxidative Stress Induced by Mitochondrial Dysfunction.

The heart works without resting, requiring enormous amounts of energy to continuously pump blood throughout the body. Because of its considerable energy requirements, the heart is vulnerable to oxidative stress caused by the generation of endogenous reactive oxygen species (ROS). Therefore, the heart has effective regulatory and adaptive mechanisms to protect against oxidative stress. Inherited or acquired mitochondrial respiratory chain dysfunction disrupts energy metabolism and causes excessive ROS production and oxidative stress. The physiological cardiac response to oxidative stress can strengthen the heart, but pathological cardiac responses or altered regulatory mechanisms can cause heart disease. Therefore, mitochondria-targeted antioxidants have been tested and some are used clinically. In this review, we briefly discuss the role of mitochondrial DNA mutations, mitochondrial dysfunction, and ROS generation in the development of heart disease and recent developments in mitochondria-targeted antioxidants for the treatment of heart disease.

A genetic component of extinction risk in mammals

Genetic factors may play an important role in species extinction but their actual effect remains poorly understood, particularly because of a strong and potentially masking effect expected from ecological traits. We investigated the role of genetics in mammal extinction taking both ecological and genetic factors into account. As a proxy for the role of genetics we used the ratio of the rates of nonsynonymous (amino acid changing) to synonymous (leaving the amino acid unchanged) nucleotide substitutions, Ka / Ks. Because most nonsynonymous substitutions are likely to be slightly deleterious and thus selected against, this ratio is a measure of the inefficiency of selection: if large (but less than 1), it implies a low efficiency of selection against nonsynonymous mutations. As a result, nonsynonymous mutations may accumulate and thus contribute to extinction. As a proxy for the role of ecology we used body mass W, with which most extinction-related ecological traits strongly correlate. As a measure of extinction risk we used species’ affiliation with the five levels of extinction threat according to the IUCN Red List of Threatened Species. We calculated Ka / Ks for mitochondrial protein-coding genes of 211 mammalian species, each of which was characterized by body mass and the level of threat. Using logistic regression analysis, we then constructed a set of logistic regression models of extinction risk on ln(Ka / Ks) and lnW. We found that Ka / Ks and body mass are responsible for a 38% and a 62% increase in extinction risk, respectively. Given that the standard error of these values is 13%, the contribution of genetic factors to extinction risk in mammals is estimated to be one-quarter to one-half of the total of ecological and genetic effects. We conclude that the effect of genetics on extinction is significant, though it is almost certainly smaller than the effect of ecological traits. Synthesis Mutation provides the material for evolution. However, most mutations that play a role in evolution are slightly deleterious and thus may contribute to extinction. We assess the role of mitochondrial DNA mutations in mammalian extinction risk and find it to be one-quarter to one-half of the total of mutation and body mass effects, where body mass represents an integral measure of extinction-related ecological traits. Genetic factors may be all the more important, because ecological traits associated with large body mass would both promote and protect from extinction, while mutation accumulation caused by low effective population size seems to have no counterbalance.

Role of mitochondrial DNA mutations in brain tumors: A mini-review.

Brain tumor is molecularly a heterogeneous group of diseases, and genetic factors seem to play a crucial role in its genesis. Even though multiple alterations in the nuclear-encoded genes such as tumor suppressor and oncogenes are believed to play a key role in brain tumorigenesis, the involvement of the mitochondrial genome to this event remains controversial to date. Mitochondrial DNA (mtDNA) has been suspected to be associated with the carcinogenesis because of its high sensitivity to mutations and inefficient repair mechanisms in comparison to nuclear DNA. Thus, defects in mtDNA could also lead to the development of brain tumor. By virtue of their clonal nature and high copy number, mtDNA mutations may provide a new effective molecular biomarker for the cancer detection. It has been suggested that establishing mtDNA defective pattern might be useful in cancer diagnostics and detection, the prognosis of cancer outcome, and/or the response to certain treatments. This mini-review gives a brief overview on the several aspects of mtDNA, with a particular focus on its role in tumorigenesis and progression of brain tumor. Understanding the role of mitochondria and brain tumor development could potentially translate into therapeutic strategies for patients with these tumors.

The Role of Mitochondrial DNA Mutations in Hearing Loss

Mutations in mitochondrial DNA (mtDNA) are one of the most important causes of hearing loss. Of these, the homoplasmic A1555G and C1494T mutations at the highly conserved decoding site of the 12S rRNA gene are well documented as being associated with either aminoglycoside-induced or nonsyndromic hearing loss in many families worldwide. Moreover, five mutations associated with nonsyndromic hearing loss have been identified in the tRNA(Ser(UCN)) gene: A7445G, 7472insC, T7505C, T7510C, and T7511C. Other mtDNA mutations associated with deafness are mainly located in tRNA and protein-coding genes. Failures in mitochondrial tRNA metabolism or protein synthesis were observed from cybrid cells harboring these primary mutations, thereby causing the mitochondrial dysfunctions responsible for deafness. This review article provides a detailed summary of mtDNA mutations that have been reported in deafness and further discusses the molecular mechanisms of these mtDNA mutations in deafness expression.

234 Role of mitochondrial DNA mutations in childhood MDS

234 Role of mitochondrial DNA mutations in childhood MDS

Reassessing the role of mitochondrial DNA mutations in autism spectrum disorder

BackgroundThere is increasing evidence that impairment of mitochondrial energy metabolism plays an important role in the pathophysiology of autism spectrum disorders (ASD; OMIM number: 209850). A significant proportion of ASD cases display biochemical alterations suggestive of mitochondrial dysfunction and several studies have reported that mutations in the mitochondrial DNA (mtDNA) molecule could be involved in the disease phenotype.MethodsWe analysed a cohort of 148 patients with idiopathic ASD for a number of mutations proposed in the literature as pathogenic in ASD. We also carried out a case control association study for the most common European haplogroups (hgs) and their diagnostic single nucleotide polymorphisms (SNPs) by comparing cases with 753 healthy and ethnically matched controls.ResultsWe did not find statistical support for an association between mtDNA mutations or polymorphisms and ASD.ConclusionsOur results are compatible with the idea that mtDNA mutations are not a relevant cause of ASD and the frequent observation of concomitant mitochondrial dysfunction and ASD could be due to nuclear factors influencing mitochondrion functions or to a more complex interplay between the nucleus and the mitochondrion/mtDNA.

Age-dependent cardiomyopathy in mitochondrial mutator mice is attenuated by overexpression of catalase targeted to mitochondria.

Mitochondrial defects have been found in aging and several age-related diseases. Mice with a homozygous mutation in the exonuclease encoding domain of mitochondrial DNA polymerase gamma (Polg(m/m)) are prone to age-dependent accumulation of mitochondrial DNA mutations and have shown a broad spectrum of aging-like phenotypes. However, the mechanism of cardiac phenotypes in relation to the role of mitochondrial DNA mutations and oxidative stress in this mouse model has not been fully addressed. We demonstrate age-dependent cardiomyopathy in Polg(m/m) mice, which by 13-14 months of age displays marked cardiac hypertrophy and dilatation, impairment of systolic and diastolic function, and increased cardiac fibrosis. This age-dependent cardiomyopathy is associated with increases in mitochondrial DNA (mtDNA) deletions and protein oxidative damage, increased expression of apoptotic and senescence markers, as well as a decline in signaling for mitochondrial biogenesis. The relationship of these changes to mitochondrial reactive oxygen species (ROS) was tested by crossing Polg(m/m) mice with mice that overexpress mitochondrial targeted catalase (mCAT). All of the above phenotypes were partially rescued in Polg(m/m)/mCAT mice. These data indicate that accumulation of mitochondrial DNA damage with age can lead to cardiomyopathy and that this phenotype is partly mediated by mitochondrial oxidative stress.

Mitochondrial protein import in aging muscle: can Tom still do it? Focus on “Biogenesis of the mitochondrial Tom40 channel in skeletal muscle from aged animals and its adaptability to chronic contractile activity”

mitochondria are vital to the function of all nucleated mammalian cells and are particularly important in skeletal muscle for provision of the ATP necessary to fuel muscle contraction. The mitochondrial content of skeletal muscle is not static and can respond rapidly to increases ([6][1]) and

Mitochondrial DNA Mutations in Disease, Aging, and Neurodegeneration

Patients with disorders from mutations in the mitochondrial genome have variable phenotypes, but common to many of these disorders are underlying changes in postmitotic cells, particularly neurons and muscle fibers. The mitochondrial dysfunction caused by these mutations has been shown to be associated with signs of apoptosis and to cause cell loss. Mutations of the mitochondrial genome have also been shown to accumulate with age and in common neurodegenerative diseases, such as Parkinson's disease. This review presents recent data to show that the information gained from studying patients with mitochondrial disorders can help our understanding of the role of mitochondrial DNA mutations in brain aging and neurodegeneration.

Evolving insight into the role of mitochondrial DNA mutations in aging

Mitochondria have occupied a central place in theories on the underlying cellular mechanisms of eukaryotic aging for several decades and much debate has ensued regarding the role of oxidative stress and mitochondrial genomic damage in these processes. Mouse models with greatly enhanced mitochondrial mutagenesis have produced dramatic aging-like phenotypes but recent results have led some to reassess whether such models are relevant to naturally occurring aging mechanisms. Here, we discuss the evolving insight that may be gained from these models regarding the contribution of mitochondrial DNA mutations to aging.

The role of mitochondrial DNA mutations in aging and sarcopenia: Implications for the mitochondrial vicious cycle theory of aging

Aging is associated with a progressive loss of skeletal muscle mass and strength and the mechanisms mediating these effects likely involve mitochondrial DNA (mtDNA) mutations, mitochondrial dysfunction and the activation of mitochondrial-mediated apoptosis. Because the mitochondrial genome is densely packed and close to the main generator of reactive oxygen species (ROS) in the cell, the electron transport chain (ETC), an important role for mtDNA mutations in aging has been proposed. Point mutations and deletions in mtDNA accumulate with age in a wide variety of tissues in mammals, including humans, and often coincide with significant tissue dysfunction. Here, we examine the evidence supporting a causative role for mtDNA mutations in aging and sarcopenia. We review experimental outcomes showing that mtDNA mutations, leading to mitochondrial dysfunction and possibly apoptosis, are causal to the process of sarcopenia. Moreover, we critically discuss and dispute an important part of the mitochondrial ‘vicious cycle’ theory of aging which proposes that accumulation of mtDNA mutations may lead to an enhanced mitochondrial ROS production and ever increasing oxidative stress which ultimately leads to tissue deterioration and aging. Potential mechanism(s) by which mtDNA mutations may mediate their pathological consequences in skeletal muscle are also discussed.