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 Detecting respiratory chain deficiency in osteoblasts of older patients

2021 ◽  
Author(s):  
Daniel Hipps ◽  
Philip Dobson ◽  
Charlotte Warren ◽  
David McDonald ◽  
Andrew Fuller ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Mouse Model ◽  
Respiratory Chain ◽  
Nuclear Genome ◽  
Mitochondrial Dna Mutation ◽  
Human Osteoblasts ◽  
Dna Mutation ◽  
Respiratory Chain Deficiency ◽  
Age Related ◽  
Cellular Dysfunction

Mitochondria contain their own genome which encodes 13 essential mitochondrial proteins and accumulates somatic variants at up to 10 times the rate of the nuclear genome. These mitochondrial genome variants lead to respiratory chain deficiency and cellular dysfunction. Work with the PolgAmut/PolgAmut mouse model, which has a high mitochondrial DNA mutation rate, showed enhanced levels of age related osteoporosis in affected mice along with respiratory chain deficiency in osteoblasts. To explore whether respiratory chain deficiency is also seen in human osteoblasts with age, we developed a protocol and analysis framework for imaging mass cytometry (IMC) in bone tissue sections to analyse osteoblasts in situ. We have demonstrated significant increases in complex I deficiency with age in human osteoblasts. This work is consistent with findings from the PolgAmut/PolgAmut mouse model and suggests that respiratory chain deficiency, as a consequence of the accumulation of age related mitochondrial DNA mutations, may have a significant role to play in the pathogenesis of human age related osteoporosis.

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 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.

Decreased Cytochrome-c Oxidase Activity and Lack of Age-Related Accumulation of Mitochondrial DNA Deletions in the Brains of Schizophrenics

Genomics ◽  
1995 ◽  
Vol 29 (1) ◽  
pp. 217-224 ◽  
Author(s):  
Lucia Cavelier ◽  
Elena E. Jazin ◽  
Inger Eriksson ◽  
Jonathan Prince ◽  
Ullvi Båve ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Oxidase Activity ◽  
Age Related ◽  
Dna Deletions

scholarly journals Age-related decrease in expression of mitochondrial DNA encoded subunits of cytochrome c oxidase in Drosophila melanogaster

2008 ◽  
Vol 129 (9) ◽  
pp. 558-561 ◽  
Author(s):  
Rajindar S. Sohal ◽  
Dikran Toroser ◽  
Catherine Brégère ◽  
Robin J. Mockett ◽  
William C. Orr
Keyword(s):  
Mitochondrial Dna ◽  
Drosophila Melanogaster ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Age Related

scholarly journals Quantitative Mitochondrial DNA Mutation Analysis by Denaturing HPLC

2007 ◽  
Vol 53 (6) ◽  
pp. 1046-1052 ◽  
Author(s):  
Kok Seong Lim ◽  
Robert K Naviaux ◽  
Richard H Haas
Keyword(s):  
Mitochondrial Dna ◽  
Gene Segment ◽  
Simultaneous Detection ◽  
Mtdna Mutation ◽  
Mitochondrial Dna Mutation ◽  
Dna Mutation ◽  
Dna Mutations ◽  
Peak Areas ◽  
Kinetics Of ◽  
Heteroduplex Formation

Abstract Background: In recent years, denaturing HPLC (DHPLC) has been widely used to screen the whole mitochondrial genome or specific regions of the genome for DNA mutations. The quantification and mathematical modeling of DHPLC results is, however, underexplored. Methods: We generated site-directed mutants containing some common mutations in the mitochondrial DNA (mtDNA) tRNA(leu) region with different mutation loads and used PCR to amplify the gene segment of interest in these mutants. We then performed restriction digestion followed by slow reannealing to induce heteroduplex formation and analyzed the samples by use of DHPLC. Results: We observed a quadratic relationship between the heteroduplex peak areas and mutant loads, consistent with the kinetics of heteroduplex formation reported by others. This was modeled mathematically and used to quantify mtDNA mutation load. The method was able to detect a mutation present in a concentration as low as 1% and gave reproducible measurements of the mutations in the range of 2.5%–97.5%. Conclusion: The quantitative DHPLC assay is well suited for simultaneous detection and quantification of DNA mutations.

Arsenic Trioxide Induces Mitochondrial DNA Mutation on D-Loop Region in Patients with Acute Myeloid Leukemia.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 4356-4356
Author(s):  
Jin Zhou ◽  
Ran Meng
Keyword(s):  
Acute Myeloid Leukemia ◽  
Mitochondrial Dna ◽  
Myeloid Leukemia ◽  
Mtdna Mutation ◽  
Mitochondrial Dna Mutation ◽  
Dna Mutation ◽  
D Loop ◽  
Acute Myeloid

Abstract Objective:To investigate the effect of arsenic trioxide (As2O3) on mitochondrial DNA (mtDNA) in acute myeloid leukemia cells. Methods: NB4 cell line and primary leucocytes, isolated from peripheral blood of eight cases with newly diagnosed acute myeloid leukemia (the ratio of the blast cell was more than 80%), were incubated in RPMI-1640 medium supplemented with 10% heat-inactivated FCS, and treated with 0.1, 1.0, 2.0 micromol/L of As2O3 for 48hrs respectively in vitro. Blood samples in eight cases above were collected before and 14 days after As2O3 treatment with the dosage of 0.16mg/kg.d in vivo. Genome DNA was isolated from the cells and blood samples by salt fractionation, and the D-loop fragment of mtDNA was isolated from the genome DNA and amplified by polymerase chain reaction, and the sequencing techniques were applied to identify positive clones. MTT assay, electrophoresis of genomic DNA, and protein/DNA dual parameter flow cytometry were used to examine the effect of As2O3 on cell proliferation and apoptosis. Results: mtDNA mutations were found on D-loop fragment of mtDNA in both NB4 cells and primary leucocytes, the number of single nucleotide polymorphism (SNP) or mutation were increased remarkably after 1.0, 2.0 micromol/L of As2O3 treatment both in vitro and in vivo than non-As2O3 treated baseline. The types of mutation were included the base transversion, transition, depletion and insertion. The 1.0 and 2.0 micromol/L of As2O3-treated samples revealed apoptosis, reduced proliferation and mtDNA mutation, while in the 0.1 micromol/L of As2O3-treated samples, showed reduced proliferation, differentiation and mtDNA mutation, but no apoptosis was appeared. Conclusions: As2O3 promoted leucocytes’ mtDNA mutation on D-loop fragment both in NB4 cell line and in primary leucocytes isolated from patients with acute myeloid leukemia. Mitochondrial DNA might be one of the targets of As2O3 act on leukemia cells. Mitochondrial DNA mutation as well as nuclear DNA might participate the process of As2O3 inducing differentiation and reducing proliferation.

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