In recent years, the roles of mitochondrial RNA and its associated human diseases have been reported to increase significantly. Treatments based on mtRNA metabolic processes and nuclear gene mutations are thus discussed. The mitochondrial oxidative phosphorylation process is affected by mtRNA metabolism, including mtRNA production, maturation, stabilization, and degradation, which leads to a variety of inherited human mitochondrial diseases. Moreover, mitochondrial diseases are caused by mitochondrial messenger RNA, mitochondrial transfer RNA, and mitochondrial ribosomal RNA gene mutations. This review presents the molecular mechanisms of human mtRNA metabolism and pathological mutations in mtRNA metabolism-related nuclear-encoded/nonencoded genes and mitochondrial DNA mutations to highlight the importance of mitochondrial RNA-related diseases and treatments.
Humans ; Mitochondrial Diseases/therapy* ; RNA, Mitochondrial ; RNA/genetics* ; Mitochondria/genetics* ; Mutation/genetics* ; RNA, Transfer/genetics* ; DNA, Mitochondrial/genetics*

BACKGROUND: Mitochondria, which harbor their own genome (mtDNA), have attracted attention due to the potential of mtDNA copy number (mtDNA-CN) as an indicator of mitochondrial dysfunction. Although mtDNA-CN has been proposed as a simple and accessible biomarker for metabolic disorders such as metabolic dysfunction-associated steatotic liver disease, the underlying mechanisms and the causal relationship remain insufficiently elucidated. In this investigation, we combined longitudinal epidemiological data, animal studies, and in vitro assays to elucidate the potential causal relationship between reduced mtDNA-CN and the development of steatotic liver disease (SLD). METHODS: We conducted a longitudinal study using data from a health examination cohort initiated in 1981 in Yakumo, Hokkaido, Japan. Data from examinations performed in 2015 and 2022 were analyzed, focusing on 76 subjects without SLD at baseline (2015) to assess the association between baseline mtDNA-CN and subsequent risk of SLD development. In addition, 28-day-old SD rats were fed ad libitum on a 45% high-fat diet and dissected at 2 and 8 weeks of age. Blood and liver mtDNA-CN were measured and compared at each feeding period. Additionally, in vitro experiments were performed using HepG2 cells treated with mitochondrial function inhibitors to induce mtDNA-CN depletion and to examine its impact on intracellular lipid accumulation. RESULTS: Epidemiological analysis showed that the subjects with low mtDNA-CN had a significantly higher odds ratio for developing SLD compared to high (odds ratio [95% confidence interval]: 4.93 [1.08-22.50]). Analysis of the animal model showed that 8 weeks of high-fat diet led to the development of fatty liver and a significant decrease in mtDNA-CN. A further 2 weeks of high-fat diet consumption resulted in a significant decrease in hepatic mtDNA-CN, despite the absence of fatty liver development, and a similar trend was observed for blood. Complementary in vitro experiments revealed that pharmacologically induced mitochondrial dysfunction led to a significant reduction in mtDNA-CN and was associated with increases in intracellular lipid accumulation in HepG2 cells. CONCLUSIONS Our findings suggest that reduced mtDNA-CN may contribute causally to SLD development and could serve as a convenient, noninvasive biomarker for early detection and risk assessment.
Animals ; DNA, Mitochondrial/genetics* ; Humans ; Male ; DNA Copy Number Variations ; Female ; Fatty Liver/blood* ; Rats ; Middle Aged ; Longitudinal Studies ; Rats, Sprague-Dawley ; Adult ; Japan/epidemiology* ; Aged ; Biomarkers/blood* ; Hep G2 Cells ; Diet, High-Fat/adverse effects*

OBJECTIVES: To explore the mechanism by which Wiskott-Aldrich syndrome protein family verprolin-homologous protein 1 (WAVE1) regulates lipopolysaccharide (LPS)-induced mitochondrial metabolic abnormalities and inflammatory responses in macrophages. METHODS: Macrophage cell lines with overexpressed WAVE1 (mouse BMDM and human THP1 cells) were prepared. The macrophages were treated with LPS (500 ng/mL) to simulate sepsis-induced inflammatory responses. The experiment consisted of two parts. The first part included control, LPS, vector (LPS+oe-NC), WAVE1 overexpression (LPS+oe-WAVE1) groups. The second part included LPS, LPS+oe-NC, LPS+oe-WAVE1 and exogenous high mobility group box-1 (HMGB1) intervention (LPS+oe-WAVE1+HMGB1) groups. RT-PCR was used to measure mitochondrial DNA content, and RT-qPCR was used to detect the mRNA expression levels of WAVE1, tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6. Western blot was performed to measure the protein expression of WAVE1, hexokinase 2, and pyruvate kinase M2. ELISA was utilized to detect the levels of TNF-α, IL-1β, IL-6, and HMGB1. JC-1 staining was used to assess mitochondrial membrane potential. Seahorse XP96 was used to evaluate oxygen consumption rate and extracellular acidification rate. MitoSOX probe was employed to measure mitochondrial reactive oxygen species levels, and 2-NBDG method was used to assess glucose uptake. Kits were used to measure pyruvate kinase activity, lactate, adenosine triphosphate (ATP), and HMGB1 levels. RESULTS: Compared with the control group, the LPS group showed lower levels of WAVE1 protein and mRNA expression, mitochondrial membrane potential, oxygen consumption rate, and mitochondrial DNA content (P<0.05), while TNF-α, IL-1β, IL-6 levels and mRNA expression, mitochondrial reactive oxygen species, glucose uptake, lactate, ATP, hexokinase 2, and pyruvate kinase M2 protein expression levels as well as extracellular acidification rate, pyruvate kinase activity, and HMGB1 release were significantly increased (P<0.05). Compared with the LPS+oe-NC group, the LPS+oe-WAVE1 group showed increased WAVE1 protein and mRNA expression, mitochondrial membrane potential, oxygen consumption rate, and mitochondrial DNA content (P<0.05), while TNF-α, IL-1β, IL-6 levels and mRNA expression, mitochondrial reactive oxygen species, glucose uptake, lactate, ATP, hexokinase 2, and pyruvate kinase M2 protein expressions, as well as extracellular acidification rate, pyruvate kinase activity, and HMGB1 release were decreased (P<0.05). Compared with the LPS+oe-WAVE1 group, the LPS+oe-WAVE1+HMGB1 group exhibited increased glucose uptake, lactate, ATP levels, and extracellular acidification rate (P<0.05). CONCLUSIONS WAVE1 participates in the regulation of LPS-induced inflammatory responses in macrophages by modulating the release of inflammatory factors, mitochondrial metabolism, and HMGB1 release.
Lipopolysaccharides ; Humans ; Mitochondria/metabolism* ; Animals ; Macrophages/metabolism* ; Mice ; Hexokinase/genetics* ; Wiskott-Aldrich Syndrome Protein Family/metabolism* ; HMGB1 Protein/physiology* ; Inflammation/metabolism* ; DNA, Mitochondrial ; Pyruvate Kinase/metabolism*

Objective:By conducting genetic testing of hereditary hearing loss in pregnant women within 17 weeks of gestation in Dali areas, the importance of genetic testing and genetic counseling during pregnancy was emphasized. Methods:Twenty-one mutation sites of 4 hearing loss genes, including GJB2, GJB3, SLC26A4 and mtDNA, were detected by PCR amplification technology. The positive ratio, mutation ratio and ethnic distribution of positive samples were statistically described. Results:The positive ratios of GJB2 and SLC26A4 genes were 1.24% and 1.43%, respectively, with mutation rates of 40.62% and 46.88% in the positive samples, respectively. The positive ratio of GJB3gene was 0.19%, and mtDNA mutation genes accounted for 0.14%, and all of them were mtDNA（Heterozygous）. There was only one case of GJB2/SLC26A4 double positive multi-gene mutation, with a positive ratio of 0.05%. The frequency of GJB2 c. 235delC site was the highest, accounting for 65.38% of GJB2 mutation genes and 26.56% of mutation gene samples. Conclusion:GJB2 and SLC26A4 are the most common genes of hearing loss, and GJB2 c. 235delC site is the most common mutation site. Identifying the hearing loss mutation site is of great importance to prevent the birth of hereditary hearing loss children, and genetic diagnosis, genetic counseling, and appropriate intervention are crucial to alleviate congenital problems.
Humans ; Female ; Pregnancy ; Sulfate Transporters/genetics* ; Connexin 26 ; Genetic Testing/methods* ; Connexins/genetics* ; Mutation ; Hearing Loss/diagnosis* ; DNA, Mitochondrial/genetics* ; Adult ; Membrane Transport Proteins/genetics* ; Genetic Counseling

Mitochondrial DNA (mtDNA) mutations result in a variety of genetic diseases. As an emerging therapeutic method, mtDNA editing technology recognizes targets more based on the protein and less on the nucleic acid. Although the protein recognition type mtDNA editing technology represented by zinc finger nuclease technology, transcription activator like effector nuclease technology and base editing technology has made some progress, the disadvantages of complex recognition sequence design hinder further popularization. Gene editing based on nucleic acid recognition by the CRISPR system shows superiority due to the simple structure, easy design and modification. However, the lack of effective means to deliver nucleic acids into mitochondria limits application in the field of mtDNA editing. With the advances in the study of endogenous and exogenous import pathways and the deepening understanding of DNA repair mechanisms, growing evidence shows the feasibility of nucleic acid delivery and the broad application prospects of nucleic acid recognition type mtDNA editing technology. Based on the classification of recognition elements, this article summarizes the current principles and development of mitochondrial gene editing technology, and discusses its application prospects.
Genes, Mitochondrial ; Gene Editing ; Mitochondria/genetics* ; DNA, Mitochondrial/genetics* ; Nucleic Acids ; Technology

Humans ; Mitochondrial Diseases/therapy* ; DNA, Mitochondrial/genetics*

Humans ; Mitochondrial Diseases/prevention & control* ; DNA, Mitochondrial/genetics*

OBJECTIVE: The study aimed to estimate the benchmark dose (BMD) of coke oven emissions (COEs) exposure based on mitochondrial damage with the mitochondrial DNA copy number (mtDNAcn) as a biomarker. METHODS: A total of 782 subjects were recruited, including 238 controls and 544 exposed workers. The mtDNAcn of peripheral leukocytes was detected through the real-time fluorescence-based quantitative polymerase chain reaction. Three BMD approaches were used to calculate the BMD of COEs exposure based on the mitochondrial damage and its 95% confidence lower limit (BMDL). RESULTS: The mtDNAcn of the exposure group was lower than that of the control group (0.60 ± 0.29 vs. 1.03 ± 0.31; P < 0.001). A dose-response relationship was shown between the mtDNAcn damage and COEs. Using the Benchmark Dose Software, the occupational exposure limits (OELs) for COEs exposure in males was 0.00190 mg/m ³. The OELs for COEs exposure using the BBMD were 0.00170 mg/m ³ for the total population, 0.00158 mg/m ³ for males, and 0.00174 mg/m ³ for females. In possible risk obtained from animal studies (PROAST), the OELs of the total population, males, and females were 0.00184, 0.00178, and 0.00192 mg/m ³, respectively. CONCLUSION Based on our conservative estimate, the BMDL of mitochondrial damage caused by COEs is 0.002 mg/m ³. This value will provide a benchmark for determining possible OELs.
Male ; Female ; Animals ; Coke ; Polycyclic Aromatic Hydrocarbons ; DNA Copy Number Variations ; Benchmarking ; Occupational Exposure/analysis* ; DNA, Mitochondrial/genetics* ; DNA Damage

Schizothorax argentatus that only distributes in the Ili River basin in Xinjiang is one of the rare and endangered species of schizothorax in China, thus has high scientific and economic values. In this study, the complete mitochondrial genome sequence of S. argenteus with a length of 16 580 bp was obtained by high-throughput sequencing. The gene compositions and arrangement were similar to those of typical vertebrates. It contained 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and a non-coding region (D-loop). The nucleotide compositions were A (30.25%), G (17.28%), C (27.20%), and T (25.27%), respectively, showing obvious AT bias and anti-G bias. Among the tRNA genes, only tRNA-Ser^(GCU) could not form a typical cloverleaf structure due to the lack of dihydrouracil arm. The AT-skew and GC-skew values of the ND6 gene were fluctuating the most, suggesting that the gene may experience different selection and mutation pressures from other genes. The mitochondrial control region of S. argenteus contained three different domains, i.e., termination sequence region (ETAS), central conserved region (CSB-F, CSB-E, CSB-D, and CSB-B), and conserved sequence region (CSB1, CSB2, and CSB3). The conserved sequence fragment TT (AT) nGTG, which was ubiquitous in Cypriniformes, was identified at about 50 bp downstream CSB3. Phylogenetic relationships based on the complete mitochondrial genome sequence of 28 Schizothorax species showed that S. argenteus had differentiated earlier and had a distant relationship with other species, which may be closely related to the geographical location and the hydrological environment where it lives.
Animals ; Genome, Mitochondrial/genetics* ; Phylogeny ; Sequence Analysis, DNA ; Cyprinidae/genetics* ; RNA, Transfer/genetics* ; DNA, Mitochondrial/genetics* ; Genes, Mitochondrial

OBJECTIVE: To explore the correlation of mitochondrial DNA (mtDNA) variants and coronary heart disease (CHD) in a Chinese pedigree and the possible molecular mechanisms. METHODS: A Chinese pedigree featuring matrilineal inheritance of CHD who visited Hangzhou First People's Hospital in May 2022 was selected as the study subject. Clinical data of the proband and her affected relatives was collected. By sequencing the mtDNA of the proband and her pedigree members, candidate variants were identified through comparison with wild type mitochondrial genes. Conservative analysis among various species was conducted, and bioinformatics software was used to predict the impact of variants on the secondary structure of tRNA. Real-time PCR was carried out to determine the copy number of mtDNA, and a transmitochondrial cell line was established for analyzing the mitochondrial functions, including membrane potential and ATP level. RESULTS: This pedigree had contained thirty-two members from four generations. Among ten maternal members, four had CHD, which yielded a penetrance rate of 40%. Sequence analysis of proband and her matrilineal relatives revealed the presence of a novel m.4420A>T variant and a m.10463T>C variant, both of which were highly conserved among various species. Structurally, the m.4420A>T variant had occurred at position 22 in the D-arm of tRNAMet, which disrupted the 13T-22A base-pairing, while the m.10463T>C variant was located at position 67 in the acceptor arm of tRNAArg, a position critical for steady-state level of the tRNA. Functional analysis revealed that patients with the m.4420A>T and m.10463T>C variants exhibited much fewer copy number of mtDNA and lower mitochondrial membrane potential (MMP) and ATP contents (P < 0.05), which were decreased by approximately 50.47%, 39.6% and 47.4%, respectively. CONCLUSION Mitochondrial tRNAMet 4420A>T and tRNAArg 10463T>C variants may underlay the maternally transmitted CHD in this pedigree, which had shown variation in mtDNA homogeneity, age of onset, clinical phenotype and other differences, suggesting that nuclear genes, environmental factors and mitochondrial genetic background have certain influence on the pathogenesis of CHD.
Humans ; Female ; Mutation ; Pedigree ; RNA, Transfer, Met ; East Asian People ; RNA, Transfer, Arg ; DNA, Mitochondrial/genetics* ; Coronary Disease/genetics* ; Adenosine Triphosphate