scholarly journals The T414G mitochondrial DNA mutation: a biomarker of aging in human eye

Mutagenesis ◽  
2021 ◽  
Author(s):  
Anne-Sophie Gary ◽  
Marie M Dorr ◽  
Patrick J Rochette
Keyword(s):  
Mitochondrial Dna ◽  
Corneal Stroma ◽  
Human Cornea ◽  
Mitochondrial Dna Mutation ◽  
Posterior Portion ◽  
Mitochondrial Mutation ◽  
Human Eye ◽  
Mtdna Mutations ◽  
Solar Exposure ◽  
Uv Rays

Abstract The mitochondrial mutation T414G (mtDNA T414G) has been shown to accumulate in aged and sun-exposed skin. The human eye is also exposed to solar harmful rays. More precisely, the anterior structures of the eye (cornea, iris) filter UV rays and the posterior portion of the eye (retina) is exposed to visible light. These rays can catalyze mutations in mitochondrial DNA such as the mtDNA T414G, but the latter has never been investigated in the human ocular structures. In this study, we have developed a technique to precisely assess the occurrence of mtDNA T414G. Using this technique, we have quantified mtDNA T414G in different human ocular structures. We found an age-dependent accumulation of mtDNA T414G in the corneal stroma, the cellular layer conferring transparency and rigidity to the human cornea, and in the iris. Since cornea and iris are 2 anterior ocular structures exposed to solar UV rays, this suggests that the mtDNA T414G mutation is resulting from cumulative solar exposure and this could make the mtDNA T414G a good marker of solar exposure. We have previously shown that the mtDNA CD4977 and mtDNA 3895 deletions accumulate over time in photo-exposed ocular structures. With the addition of mtDNA T414G mutation, it becomes feasible to combine the levels of these different mtDNA mutations to obtain an accurate assessment of the solar exposure that an individual has accumulated during his/her lifetime.

Mitochondrial DNA Mutation, Diseases, and Nutrient-Regulated Mitophagy

2019 ◽  
Vol 39 (1) ◽  
pp. 201-226 ◽  
Author(s):  
Xuan Yang ◽  
Ruoyu Zhang ◽  
Kiichi Nakahira ◽  
Zhenglong Gu
Keyword(s):  
Mitochondrial Dna ◽  
Molecular Mechanisms ◽  
Genetic Manipulation ◽  
Wide Spectrum ◽  
Human Diseases ◽  
Nutrient Deficiencies ◽  
Mtdna Mutation ◽  
Mitochondrial Dna Mutation ◽  
Mtdna Mutations ◽  
Mitochondrial Homeostasis

A wide spectrum of human diseases, including cancer, neurodegenerative diseases, and metabolic disorders, have been shown to be associated with mitochondrial dysfunction through multiple molecular mechanisms. Mitochondria are particularly susceptible to nutrient deficiencies, and nutritional intervention is an essential way to maintain mitochondrial homeostasis. Recent advances in genetic manipulation and next-generation sequencing reveal the crucial roles of mitochondrial DNA (mtDNA) in various pathophysiological conditions. Mitophagy, a term coined to describe autophagy that targets dysfunctional mitochondria, has emerged as an important cellular process to maintain mitochondrial homeostasis and has been shown to be regulated by various nutrients and nutritional stresses. Given the high prevalence of mtDNA mutations in humans and their impact on mitochondrial function, it is important to investigate the mechanisms that regulate mtDNA mutation. Here, we discuss mitochondrial genetics and mtDNA mutations and their implications for human diseases. We also examine the role of mitophagy as a therapeutic target, highlighting how nutrients may eliminate mtDNA mutations through mitophagy.

scholarly journals Genetic mosaic analysis of a deleterious mitochondrial DNA mutation in Drosophila reveals novel aspects of mitochondrial regulation and function

2015 ◽  
Vol 26 (4) ◽  
pp. 674-684 ◽  
Author(s):  
Zhe Chen ◽  
Yun Qi ◽  
Stephanie French ◽  
Guofeng Zhang ◽  
Raúl Covian Garcia ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Mtdna Mutation ◽  
Mitochondrial Dna Mutation ◽  
Tissue Specific ◽  
Dna Mutation ◽  
Mtdna Mutations ◽  
Genetic Mosaic ◽  
Age Related

Various human diseases are associated with mitochondrial DNA (mtDNA) mutations, but heteroplasmy—the coexistence of mutant and wild-type mtDNA—complicates their study. We previously isolated a temperature-lethal mtDNA mutation in Drosophila, mt:CoIT300I, which affects the cytochrome c oxidase subunit I (CoI) locus. In the present study, we found that the decrease in cytochrome c oxidase (COX) activity was ascribable to a temperature-dependent destabilization of cytochrome a heme. Consistently, the viability of homoplasmic flies at 29°C was fully restored by expressing an alternative oxidase, which specifically bypasses the cytochrome chains. Heteroplasmic flies are fully viable and were used to explore the age-related and tissue-specific phenotypes of mt:CoIT300I. The proportion of mt:CoIT300I genome remained constant in somatic tissues along the aging process, suggesting a lack of quality control mechanism to remove defective mitochondria containing a deleterious mtDNA mutation. Using a genetic scheme that expresses a mitochondrially targeted restriction enzyme to induce tissue-specific homoplasmy in heteroplasmic flies, we found that mt:CoIT300I homoplasmy in the eye caused severe neurodegeneration at 29°C. Degeneration was suppressed by improving mitochondrial Ca2+ uptake, suggesting that Ca2+ mishandling contributed to mt:CoIT300I pathogenesis. Our results demonstrate a novel approach for Drosophila mtDNA genetics and its application in modeling mtDNA diseases.

scholarly journals A Nonsense Mitochondrial DNA Mutation Associates with Dysfunction of HIF1α in a Von Hippel-Lindau Renal Oncocytoma

2019 ◽  
Vol 2019 ◽  
pp. 1-5 ◽  
Author(s):  
Monica De Luise ◽  
Vito Guarnieri ◽  
Claudio Ceccarelli ◽  
Leonardo D’Agruma ◽  
Anna Maria Porcelli ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Glucose Transporter ◽  
Krebs Cycle ◽  
Renal Oncocytoma ◽  
Mitochondrial Dna Mutation ◽  
Specific Staining ◽  
Dna Mutation ◽  
Von Hippel Lindau ◽  
Mtdna Mutations ◽  
Inactive Form

The Von Hippel-Lindau (VHL) syndrome has been rarely associated with renal oncocytomas, and tumors usually show HIF1α chronic stabilization. By contrast, oncocytomas mainly associated with respiratory chain (RC) defects due to severe mitochondrial DNA (mtDNA) mutations are incapable of stabilizing HIF1α, since oxygen consumption by the RC is dramatically diminished and prolylhydroxylase activity is increased by α-ketoglutarate accumulation following Krebs cycle slowdown. Here, we investigate the cooccurrence of a pseudohypoxic condition with oncocytic transformation in a case of VHL-associated renal oncocytoma. While HIF1α was abundant in nuclei concordantly with defects in VHL, negative staining of its targets carbonic anhydrase IX (CAIX) and glucose transporter GLUT1, usually overexpressed in VHL-associated neoplasms, suggested HIF1α to be present in its inactive (hydroxylated) form. MtDNA sequencing and immunohistochemistry analyses revealed a MT-CO1 stop-gain mutation and cytochrome c oxidase loss. We suggest that a mitochondrial respiration impairment may lead to hyperhydroxylation of the transcription factor, which we confirmed by specific staining of hydroxylated HIF1α. Such inactive form hence accumulated in the VHL-deficient tumor, where it may contribute to the benign nature of the neoplasm. We propose that the protumorigenic role of HIF1α in VHL cancers may be blunted through drugs inhibiting mitochondrial respiratory complexes, such as metformin.

Do mitochondrial DNA mutations play the key role in chronification of sterile inflammation? Special focus on atherosclerosis

2020 ◽  
Vol 26 ◽  
Author(s):  
Alexander N. Orekhov ◽  
Elena V. Gerasimova ◽  
Vasily N. Sukhorukov ◽  
Anastasia V. Poznyak ◽  
Nikita G. Nikiforov
Keyword(s):  
Innate Immunity ◽  
Mitochondrial Dna ◽  
Low Density Lipoprotein ◽  
Atherosclerotic Lesion ◽  
Density Lipoprotein ◽  
Sterile Inflammation ◽  
Special Focus ◽  
Mitochondrial Dysfunctions ◽  
Mtdna Mutations ◽  
Dna Mutations

Background: The elucidation of mechanisms implicated in the chronification of inflammation is able to shed the light on the pathogenesis of disorders that are responsible for the majority of the incidence of disease and deaths, and also causes of ageing. Atherosclerosis is an example of the most significant inflammatory pathology. The inflammatory response of innate immunity is implicated in the development of atherosclerosis arising locally or focally. Modified low-density lipoprotein (LDL) was regarded as the trigger for this response. No atherosclerotic changes in the arterial wall occur due to the quick decrease in inflammation rate. Nonetheless, the atherosclerotic lesion formation can be a result of the chronification of local inflammation, which, in turn, is caused by alteration of the response of innate immunity. Objective: In this review, we discussed potential mechanisms of the altered response of the immunity in atherosclerosis with a particular emphasis on mitochondrial dysfunctions. Conclusion: A few mitochondrial dysfunctions can be caused by the mitochondrial DNA (mtDNA) mutations. Moreover, mtDNA mutations were found to affect the development of defective mitophagy. Modern investigations have demonstrated the controlling mitophagy function in the response of the immune system. Therefore, we hypothesized that impaired mitophagy, as a consequence of mutations in mtDNA, can raise a disturbed innate immunity response resulting in the chronification of inflammation in atherosclerosis.

scholarly journals The mitochondrial DNA mutation T12297C affects a highly conserved nucleotide of tRNALeu(CUN) and is associated with dilated cardiomyopathy

2001 ◽  
Vol 9 (4) ◽  
pp. 311-315 ◽  
Author(s):  
Maurizia Grasso ◽  
Marta Diegoli ◽  
Agnese Brega ◽  
Carlo Campana ◽  
Luigi Tavazzi ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Dilated Cardiomyopathy ◽  
Mitochondrial Dna Mutation ◽  
Dna Mutation

scholarly journals Intramyocellular lipid excess in the mitochondrial disorder MELAS

2017 ◽  
Vol 3 (3) ◽  
pp. e160 ◽  
Author(s):  
Sailaja Golla ◽  
Jimin Ren ◽  
Craig R. Malloy ◽  
Juan M. Pascual
Keyword(s):  
Mitochondrial Dna ◽  
Fat Metabolism ◽  
Mitochondrial Disorder ◽  
Scientific Investigation ◽  
Resonance Spectroscopy ◽  
Lipid Deposition ◽  
Metabolic Dysfunction ◽  
Intramyocellular Lipid ◽  
Mitochondrial Dna Mutation ◽  
Dna Mutation

Objective:There is a paucity of objective, quantifiable indicators of mitochondrial disease available for clinical and scientific investigation.Methods:To this end, we explore intramyocellular lipid (IMCL) accumulation noninvasively by 7T magnetic resonance spectroscopy (MRS) as a reporter of metabolic dysfunction in MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes). We reasoned that mitochondrial dysfunction may impair muscle fat metabolism, resulting in lipid deposition (as is sometimes observed in biopsies), and that MRS is well suited to quantify these lipids.Results:In 10 MELAS participants and relatives, IMCL abundance correlates with percent mitochondrial DNA mutation abundance and with disease severity.Conclusions:These results indicate that IMCL accumulation is a novel potential disease hallmark in MELAS.

The A1555G mitochondrial DNA mutation in Greek patients with non-syndromic, sensorineural hearing loss

2009 ◽  
Vol 390 (3) ◽  
pp. 755-757 ◽  
Author(s):  
Haris Kokotas ◽  
Maria Grigoriadou ◽  
George S. Korres ◽  
Elisabeth Ferekidou ◽  
Eleftheria Papadopoulou ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Mitochondrial Dna ◽  
Sensorineural Hearing Loss ◽  
Sensorineural Hearing ◽  
Mitochondrial Dna Mutation ◽  
Dna Mutation

Abstract 17097: Non-Synonymous Mitochondrial DNA Variants Are Common in Myocardial Tissue of Heart Failure Patients

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Pappu Ananya ◽  
Michael Binder ◽  
Yang Wanjun ◽  
Rebecca McClellan ◽  
Brittney Murray ◽  
...  
Keyword(s):  
Heart Failure ◽  
Mitochondrial Dna ◽  
Nuclear Dna ◽  
Left Ventricular ◽  
Individual Risk ◽  
Myocardial Tissue ◽  
Mtdna Mutation ◽  
Mtdna Mutations ◽  
Ventricular Tissue ◽  
Mtdna Variants

Introduction: Mitochondrial heart disease due to pathogenic mitochondrial DNA (mtDNA) mutations can present as hypertrophic or dilated cardiomyopathy, ventricular arrhythmias and conduction disease. It is estimated that the mutation rate of mtDNA is 10 to 20-fold higher than that of nuclear DNA genes due to damage from reactive oxygen species released as byproducts during oxidative phosphorylation. When a new mtDNA mutation arises, it creates an intracellular heteroplasmic mixture of mutant and normal mtDNAs, called heteroplasmy. Heteroplasmy levels can vary in various tissues and examining mtDNA variants in blood may not be representative for the heart. The frequency of pathogenic mtDNA variants in myocardial tissues in unknown. Hypothesis: Human ventricular tissue may contain mtDNA mutations which can lead to alterations in mitochondrial function and increase individual risk for heart failure. Methods: Mitochondrial DNA was isolated from 61 left ventricular myocardial samples obtained from failing human hearts at the time of transplantation. mtDNA was sequenced with 23 primer pairs. In silico prediction of non-conservative missense variants was performed via PolyPhen-2. Heteroplasmy levels of variants predicted to be pathogenic were quantified using allele-specific ARMS-PCR. Results: We identified 21 mtDNA non-synonymous variants predicted to be pathogenic in 17 hearts. Notably, one heart contained four pathogenic mtDNA variants (ATP6: p.M104; ND5: p.P265S; ND4: p.N390S and p.L445F). Heteroplasmy levels exceeded 90% for all four variants in myocardial tissue and were significantly lower in blood. No pathogenic mtDNA variants were identified in 44 hearts. Hearts with mtDNA mutations had higher levels of myocardial GDF-15 (growth differentiation factor-15; 6.2±2.3 vs. 1.3±0.18, p=0.045), an established serum biomarker in various mitochondrial diseases. Conclusions: Non-synonymous mtDNA variants predicted to be pathogenic are common in human left ventricular tissue and may be an important modifier of the heart failure phenotype. Future studies are necessary to correlate myocardial mtDNA mutations with cardiovascular outcomes and to assess whether serum GDF-15 allows identifying patients with myocardial mtDNA mutations.

Abstract 206: Accumulation of Mitochondrial DNA Mutations Impairs Survival, Proliferation, and Differentiation of Cardiac Progenitor Cells

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Amabel M Orogo ◽  
Dieter A Kubli ◽  
Anne N Murphy ◽  
Åsa B Gustafsson
Keyword(s):  
Mitochondrial Dna ◽  
Progenitor Cells ◽  
Mitochondrial Biogenesis ◽  
Nuclear Dna ◽  
Critical Role ◽  
Chemotherapeutic Agents ◽  
Cardiac Progenitor Cells ◽  
Mtdna Mutations ◽  
Differentiation Medium ◽  
Proliferation And Differentiation

Activation and participation of cardiac progenitor cells (CPCs) in regeneration are critical for effective repair in the wake of pathologic injury. Stem cell activation and commitment involve increased energy demand and mitochondrial biogenesis. To date, little attention has been paid to the importance of mitochondria in CPC survival, proliferation and differentiation. CPC function is reduced with age but the underlying mechanism is still unclear. Mitochondrial DNA (mtDNA) is more susceptible to oxidative attacks than nuclear DNA due to its proximity to the mitochondrial respiratory chain and lack of protective histone-like proteins. With age, mtDNA accumulates mutations that can impair mitochondrial respiration and increase ROS production. In this study, we examined the effects of accumulating mtDNA mutations on CPC proliferation and survival. We have found that incubation of uncommitted c-kit+ CPCs in differentiation medium increased mitochondrial mass and expansion of the mitochondrial network, which correlated with increased cell size and expression of cardiac lineage commitment markers. Differentiation activated mitochondrial biogenesis, increased mtDNA copy number, and enhanced oxidative capacity and cellular ATP levels in CPCs. To investigate the effect of mtDNA mutations and aging on CPC survival and function, we utilized a mouse model in which a mutation in the mtDNA polymerase γ (POLG m/m ) leads to accumulation of mtDNA mutations, mitochondrial dysfunction, and accelerated aging. Isolated CPCs from hearts of 2-month old POLG m/m mice had reduced proliferation and were more susceptible to oxidative stress and chemotherapeutic agents compared to WT CPCs. The majority of POLG m/m CPCs contained fragmented mitochondria as shown by immunostaining. Incubation in differentiation medium resulted in fewer GATA-4 positive POLG m/m CPCs compared to WT CPCs. The reduced differentiation in these POLG m/m CPCs correlated with reduced PGC-1α expression and OXPHOS protein levels, suggesting that mitochondrial biogenesis is impaired. These data demonstrate that mitochondria play a critical role in CPC function, and accumulation of mtDNA mutations impairs CPC function and reduces their repair potential.

scholarly journals Mitochondrial nucleoids maintain genetic autonomy but allow for functional complementation

2008 ◽  
Vol 181 (7) ◽  
pp. 1117-1128 ◽  
Author(s):  
Robert W. Gilkerson ◽  
Eric A. Schon ◽  
Evelyn Hernandez ◽  
Mercy M. Davidson
Keyword(s):  
Mitochondrial Dna ◽  
Protein Synthesis ◽  
Molecular Mechanism ◽  
Cell Lines ◽  
Mitochondrial Protein ◽  
Functional Complementation ◽  
Mitochondrial Protein Synthesis ◽  
Protein Assemblies ◽  
Mtdna Mutations ◽  
Mitochondrial Nucleoids

Mitochondrial DNA (mtDNA) is packaged into DNA-protein assemblies called nucleoids, but the mode of mtDNA propagation via the nucleoid remains controversial. Two mechanisms have been proposed: nucleoids may consistently maintain their mtDNA content faithfully, or nucleoids may exchange mtDNAs dynamically. To test these models directly, two cell lines were fused, each homoplasmic for a partially deleted mtDNA in which the deletions were nonoverlapping and each deficient in mitochondrial protein synthesis, thus allowing the first unequivocal visualization of two mtDNAs at the nucleoid level. The two mtDNAs transcomplemented to restore mitochondrial protein synthesis but were consistently maintained in discrete nucleoids that did not intermix stably. These results indicate that mitochondrial nucleoids tightly regulate their genetic content rather than freely exchanging mtDNAs. This genetic autonomy provides a molecular mechanism to explain patterns of mitochondrial genetic inheritance, in addition to facilitating therapeutic methods to eliminate deleterious mtDNA mutations.

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