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

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

As conserved enzymes with important functions, aminoacyl-tRNA synthetase are expressed ubiquitously in cells. These include cytoplasmic aminoacyl-tRNA synthetase, mitochondrial aminoacyl-tRNA synthetase and bifunctional aminoacyl-tRNA synthetase. Mitochondrial aminoacyl-tRNA synthetases catalyze the binding of amino acids with its corresponding tRNA in the mitochondria and participate in the translation of 13 subunits of oxidative phosphorylation enzyme complexes encoded by the mitochondrial genome. Mutations in genes encoding mitochondrial aminoacyl-tRNA synthase may cause a variety of genetic disorders. This review has summarized the clinical characteristics, molecular pathogenesis and treatment of genetic diseases caused by mutations of such genes.
Humans ; RNA, Transfer, Amino Acyl ; Genes, Mitochondrial ; Amino Acyl-tRNA Synthetases/genetics* ; Genome, Mitochondrial ; Mitochondria/genetics*

OBJECTIVE: To explore the characteristics of mutations of four common pathogenic genes (GJB2, SLC26A4, GJB3 and 12S rRNA) among patients with nonsyndromic hearing loss (NSHL) from eastern Shandong. METHODS: Peripheral blood samples of 420 NSHL patients were collected, and a hereditary-deafness-gene microarray was used to detect GJB2 c.235delC, c.299-300delAT, c.35delG and c.176del16 mutations, GJB3 c.538C>T mutation, SLC26A4 c.2168A>G and c.IVS7-2A>G mutations, and 12S rRNA c.1555A>C and c.1494C>T mutations. For patients carrying single heterozygous mutations, the coding regions of the above genes were analyzed with Sanger sequencing. RESULTS: The results of the microarray assay and Sanger sequencing showed that 84 patients (20.00%) carried GJB2 mutations, with c.235delC (16.43%) and c.299-300delAT (7.86%) being most common. Seventy-five patients (17.86%) carried SLC26A4 mutations, for which c.IVS7-2A>G accounted for 15.71%. In addition, 5.95% of patients carried 12S rRNA mutations. Only one patient was found to carried GJB3 mutation (c.538C>T). CONCLUSION Common pathogenic mutations for NSHL in eastern Shandong included GJB2 c.235delC and SLC26A4 c.IVS7-2A>G. Of note, 5.95% of patients were due to 12S rRNA m.1555A>G mutation, which gave a frequency greater than other regions of China.
China ; Connexin 26 ; Connexins ; DNA Mutational Analysis ; DNA, Mitochondrial ; Deafness ; Genes, rRNA ; Hearing Loss ; Humans ; Mutation ; RNA, Ribosomal ; Sulfate Transporters

OBJECTIVE: To explore the genetic basis for a child with Leigh syndrome. METHODS: Clinical features and laboratory test of the patient were analyzed. Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA) of the mitochondrial genome were carried out. Next generation sequencing (NGS) was used to capture and sequence nuclear genes related to mitochondrial structure and function. RESULTS: The child presented with developmental delay, unsteady gait, falling episodes, bilateral upper extremity tremor, muscle hypertonia, convulsions, and mouth angle asymmetry. Serum lactic acid was significantly increased. Cranial MRI showed abnormal signal in bilateral cerebellar hemispheres, bilateral basal ganglia, left thalamus, and corona radiata. Her mother and brother did not show any anomalies. Sanger sequencing revealed the child, her mother and brother all carried the MT-ND3 m.10191 T>C mutation, with heterogeneous rates respectively being 74.34%, 9.73%, and 6.28%. MLPA revealed heterogeneity of (MT-ND6, MTCYB-390nt)] deletion in all three individuals. No significant mutation was found by NGS sequencing of the children, their parents and brother. CONCLUSION Leigh syndrome can be caused by the simultaneous existence of multiple mitochondrial genes, and multiple mutations may play a synergic role in the occurrence of the disease.
Child ; DNA, Mitochondrial ; Female ; Genes, Mitochondrial ; High-Throughput Nucleotide Sequencing ; Humans ; Leigh Disease ; genetics ; Male ; Mutation

BACKGROUND: Chronic hyperglycemia has deleterious effects on pancreatic β-cell function and turnover. Recent studies support the view that cyclin-dependent kinase 5 (CDK5) plays a role in β-cell failure under hyperglycemic conditions. However, little is known about how CDK5 impair β-cell function. Myricetin, a natural flavonoid, has therapeutic potential for the treatment of type 2 diabetes mellitus. In this study, we examined the effect of myricetin on high glucose (HG)-induced β-cell apoptosis and explored the relationship between myricetin and CDK5. METHODS: To address this question, we subjected INS-1 cells and isolated rat islets to HG conditions (30 mM) in the presence or absence of myricetin. Docking studies were conducted to validate the interaction between myricetin and CDK5. Gene expression and protein levels of endoplasmic reticulum (ER) stress markers were measured by real-time reverse transcription polymerase chain reaction and Western blot analysis. RESULTS: Activation of CDK5 in response to HG coupled with the induction of ER stress via the down regulation of sarcoendoplasmic reticulum calcium ATPase 2b (SERCA2b) gene expression and reduced the nuclear accumulation of pancreatic duodenal homeobox 1 (PDX1) leads to β-cell apoptosis. Docking study predicts that myricetin inhibit CDK5 activation by direct binding in the ATP-binding pocket. Myricetin counteracted the decrease in the levels of PDX1 and SERCA2b by HG. Moreover, myricetin attenuated HG-induced apoptosis in INS-1 cells and rat islets and reduce the mitochondrial dysfunction by decreasing reactive oxygen species production and mitochondrial membrane potential (Δψm) loss. CONCLUSION: Myricetin protects the β-cells against HG-induced apoptosis by inhibiting ER stress, possibly through inactivation of CDK5 and consequent upregulation of PDX1 and SERCA2b.
Animals ; Apoptosis ; Blotting, Western ; Calcium-Transporting ATPases ; Cyclin-Dependent Kinase 5 ; Diabetes Mellitus, Type 2 ; Down-Regulation ; Endoplasmic Reticulum Stress ; Endoplasmic Reticulum ; Gene Expression ; Genes, Homeobox ; Glucose ; Hyperglycemia ; Insulin-Secreting Cells ; Membrane Potential, Mitochondrial ; Polymerase Chain Reaction ; Rats ; Reactive Oxygen Species ; Reticulum ; Reverse Transcription ; Up-Regulation

This study was undertaken to determine the complete mitochondrial DNA sequence and structure of the mitochondrial genome of Spirometra ranarum, and to compare it with those of S. erinaceieuropaei and S. decipiens. The aim of this study was to provide information of the species level taxonomy of Spirometra spp. using the mitochondrial genomes of 3 Spirometra tapeworms. The S. ranarum isolate originated from Myanmar. The mitochondrial genome sequence of S. ranarum was compared with that of S. erinaceieuropaei (GenBank no. KJ599680) and S. decipiens (Gen-Bank no. KJ599679). The complete mtDNA sequence of S. ranarum comprised 13,644 bp. The S. ranarum mt genome contained 36 genes comprising 12 protein-coding genes, 22 tRNAs and 2 rRNAs. The mt genome lacked the atp8 gene, as found for other cestodes. All genes in the S. ranarum mitochondrial genome are transcribed in the same direction and arranged in the same relative position with respect to gene loci as found for S. erinaceieuropaei and S. decipiens mt genomes. The overall nucleotide sequence divergence of 12 protein-coding genes between S. ranarum and S. decipiens differed by 1.5%, and 100% sequence similarity was found in the cox2 and nad6 genes, while the DNA sequence divergence of the cox1, nad1, and nad4 genes of S. ranarum and S. decipiens was 2.2%, 2.1%, and 2.6%, respectively.
Base Sequence ; Cestoda ; Classification ; DNA, Mitochondrial ; Genes, vif ; Genome ; Genome, Mitochondrial ; Myanmar ; RNA, Transfer ; Spirometra

PURPOSE: To evaluate the classification, diagnosis, and natural course of ophthalmoplegia associated with mitochondrial disease. MATERIALS AND METHODS: Among 372 patients with mitochondrial disease who visited our hospital between January 2006 and January 2016, 21 patients with ophthalmoplegia were retrospectively identified. Inclusion criteria included onset before 20 years of age, pigmentary retinopathy, and cardiac involvement. The 16 patients who were finally included in the study were divided into three groups according to disease type: Kearns-Sayre syndrome (KSS), KSS-like, and chronic progressive external ophthalmoplegia (CPEO). RESULTS: The prevalences of clinical findings were as follows: ptosis and retinopathy, both over 80%; myopathy, including extraocular muscles, 75%; lactic acidosis, 71%; and elevated levels of serum creatine kinase, 47%. Half of the patients had normal magnetic resonance imaging findings. A biochemical enzyme assay revealed mitochondrial respiratory chain complex I defect as the most common (50%). The prevalence of abnormal muscle findings in light or electron microscopic examinations was 50% each, while that of large-scale mitochondrial DNA (mtDNA) deletions in a gene study was 25%. We compared the KSS and KSS-like groups with the CPEO patient group, which showed pigmentary retinopathy (p < 0.001), cardiac conduction disease (p=0.013), and large-scale mtDNA deletions (p=0.038). KSS and KSS-like groups also had gastrointestinal tract disorders such as abnormal gastrointestinal motility (p=0.013) unlike the CPEO group. CONCLUSION: Patients with KSS had gastrointestinal symptoms, which may indicate another aspect of systemic involvement. The presence of large-scale mtDNA deletions was an objective diagnostic factor for KSS and a gene study may be helpful for evaluating patients with KSS.
Acidosis, Lactic ; Classification ; Creatine Kinase ; Diagnosis ; DNA, Mitochondrial ; Electron Transport ; Enzyme Assays ; Gastrointestinal Motility ; Gastrointestinal Tract ; Genes, vif ; Humans ; Kearns-Sayre Syndrome ; Magnetic Resonance Imaging ; Mitochondrial Diseases* ; Muscles ; Muscular Diseases ; Ophthalmoplegia* ; Ophthalmoplegia, Chronic Progressive External ; Prevalence ; Retinitis Pigmentosa ; Retrospective Studies

Triatoma rubrofasciata is a wide-spread vector of Chagas disease in Americas. In this study, we completed the mitochondrial genome sequencing of T. rubrofasciata. The total length of T. rubrofasciata mitochondrial genome was 17,150 bp with the base composition of 40.4% A, 11.6% G, 29.4% T and 18.6% C. It included 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and one control region. We constructed a phylogenetic tree on the 13 protein-coding genes of T. rubrofasciata and other 13 closely related species to show their phylogenic relationship. The determination of T. rubrofasciata mitogenome would play an important role in understanding the genetic diversity and evolution of triatomine bugs.
Americas ; Base Composition ; Chagas Disease ; Genes, rRNA ; Genetic Variation ; Genome, Mitochondrial ; Phylogeny ; RNA, Transfer ; Trees ; Triatoma

Hymenolepis nana and Hymenolepis diminuta are globally widespread zoonotic cestodes. Rodents are the main reservoir host of these cestodes. Brown rats (Rattus norvegicus) are the best known and most common rats, and usually live wherever humans live, especially in less than desirable hygiene conditions. Due to the little information of the 2 hymenolepidid species in brown rats in China, the aim of this study was to understand the prevalence and genetic characterization of H. nana and H. diminuta in brown rats in Heilongjiang Province, China. Total 114 fecal samples were collected from brown rats in Heilongjiang Province. All the samples were subjected to morphological examinations by microscopy and genetic analysis by PCR amplification of the mitochondrial cytochrome c oxidase subunit 1 (COX1) gene and the internal transcribed spacer 2 (ITS2) region of the nuclear ribosomal RNA gene. In total, 6.1% (7/114) and 14.9% (17/114) of samples were positive for H. nana and H. diminuta, respectively. Among them, 7 and 3 H. nana isolates were successfully amplified and sequenced at the COX1 and ITS2 loci, respectively. No nucleotide variations were found among H. nana isolates at either of the 2 loci. Seventeen H. diminuta isolates produced 2 different COX1 sequences while 7 ITS2 sequences obtained were identical to each other. The present results of H. nana and H. diminuta infections in brown rats implied the risk of zoonotic transmission of hymenolepiasis in China. These molecular data will be helpful to deeply study intra-specific variations within Hymenolepis cestodes in the future.
Animals ; Cestoda ; China* ; Electron Transport Complex IV ; Genes, Mitochondrial ; Genes, rRNA ; Humans ; Hygiene ; Hymenolepiasis ; Hymenolepis diminuta ; Hymenolepis nana* ; Hymenolepis* ; Microscopy ; Polymerase Chain Reaction ; Prevalence* ; Rats* ; Rodentia