RESUMO
OBJECTIVES: The specific purpose of this study was the assessment of A5935G, G5949A, G6081A, G6267A mutations in MT-CO1 and T9540C in MT-CO3, and alterations detected during the analysis of MT-CO gene fragments in subject and control groups. A secondary aim was to assess the relationship between MT-CO1 and MT-CO3 gene alterations and endometrial cancer incidence and evaluation of the prognostic value of MT-CO1 and MT-CO3 gene alterations. MATERIAL AND METHODS: In this study, we investigated A5935G, G5949A, G6081A, G6267A mutations in MT-CO1 and T9540C in MT-CO3, and alterations detected during the analysis of MT-CO gene fragments in formalin-fixed, paraffin-embedded endometrial and benign endometrial hyperplasia of a cohort of 125 subjects. RESULTS: The T9540C mutation in MT-CO3 was detected in one patient from the subject group. None of the remaining muta-tions were detected. The research showed that the presence of alterations in MT-CO1 and MT-CO3 typical of other types of cancer is not a risk factor for endometrial cancer. Analysis of MT-CO1 and MT-CO3 gene fragments revealed 10 alterations (6 and 4 respectively). The alterations detected were identified in 10% of the tested group and 8% of the control group. CONCLUSIONS: The research showed that the presence of alterations in MT-CO1 (A5935G, G5949A, G6081A, G6267A) typical of other types of cancer is not a risk factor for endometrial cancer. Three new alterations detected in this study (A6052G, A9545G, G9575A) were described for the first time.
Assuntos
Complexo IV da Cadeia de Transporte de Elétrons/genética , Neoplasias do Endométrio/genética , Mutação , Estudos de Casos e Controles , DNA Mitocondrial/genética , Feminino , HumanosRESUMO
The geographic origins of populations can be identified by their maternally inherited mitochondrial DNA (mtDNA) haplogroups. This study compared human cybrids (cytoplasmic hybrids), which are cell lines with identical nuclei but mitochondria from different individuals with mtDNA from either the H haplogroup or L haplogroup backgrounds. The most common European haplogroup is H while individuals of maternal African origin are of the L haplogroup. Despite lower mtDNA copy numbers, L cybrids had higher expression levels for nine mtDNA-encoded respiratory complex genes, decreased ATP (adenosine triphosphate) turnover rates and lower levels of reactive oxygen species production, parameters which are consistent with more efficient oxidative phosphorylation. Surprisingly, GeneChip arrays showed that the L and H cybrids had major differences in expression of genes of the canonical complement system (5 genes), dermatan/chondroitin sulfate biosynthesis (5 genes) and CCR3 (chemokine, CC motif, receptor 3) signaling (9 genes). Quantitative nuclear gene expression studies confirmed that L cybrids had (a) lower expression levels of complement pathway and innate immunity genes and (b) increased levels of inflammation-related signaling genes, which are critical in human diseases. Our data support the hypothesis that mtDNA haplogroups representing populations from different geographic origins may play a role in differential susceptibilities to diseases.
Assuntos
População Negra/genética , DNA Mitocondrial/genética , Metabolismo Energético/genética , Haplótipos/genética , População Branca/genética , Trifosfato de Adenosina/metabolismo , Adulto , Linhagem Celular , Proliferação de Células , Dosagem de Genes , Perfilação da Expressão Gênica , Genes Mitocondriais/genética , Predisposição Genética para Doença/etnologia , Predisposição Genética para Doença/genética , Humanos , Células Híbridas/citologia , Células Híbridas/metabolismo , Lactatos/metabolismo , Pessoa de Meia-Idade , Análise de Sequência com Séries de Oligonucleotídeos , Polimorfismo de Nucleotídeo Único , Espécies Reativas de Oxigênio/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Leber hereditary optic neuropathy (LHON) is a rare maternally inherited mitochondrial disorder that typically affects young male adults in their second and third decades of life. It usually manifests as painless, subacute, progressive, bilateral vision loss, with more than 90% of affected individuals losing their vision before age 50. Compared with other diseases that cause optic neuritis (multiple sclerosis or neuromyelitis optica spectrum disorders), LHON has worsening visual function in the first 6-12 months of disease progression, is predominantly male, the optic nerve is affected bilaterally from onset, there is no gadolinium enhancement on MRI, no response to disease-modifying therapy, and there is a family history of mutation in mitochondrial DNA. In this article, we describe an interesting and challenging case of LHON due to a homoplasmic variant in the MT -CO3 gene that was initially misdiagnosed as a monophasic demyelinating disorder (clinically isolated syndrome vs acute disseminated encephalomyelitis vs neuromyelitis optica spectrum disorders).
RESUMO
Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) is a maternally inherited mitochondrial disease. Most cases of MELAS are caused by the m.3243A > G variant in the MT-TL1 gene encoding tRNALeu(UUR). However, the genetic cause in 10% of patients with MELAS is unknown. We investigated the pathogenicity of the novel mtDNA variant m.9396G > A/MT-CO3 (p.E64K), which affects an extremely conserved amino acid in the CO3 subunit of mitochondrial respiratory chain (MRC) complex IV (CIV) in a patient with MELAS. Biochemical assays of a muscle biopsy confirmed remarkable CIV deficiency, and pathological examination showed ragged red fibers and generalized COX non-reactive muscle fibers. Transfer of the mutant mtDNA into cybrids impaired CIV assembly, followed by remarkable mitochondrial dysfunction and ROS production. Our findings highlight the pathogenicity of a novel m.9396G > A variant and extend the spectrum of pathogenic mtDNA variants.
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MicroRNAs (miRNAs) have been recently found in the mitochondria, and were named "mitomiRs", but their function has remained elusive. Here, we aimed to assess the presence and function(s) of mitomiRs in tongue squamous cell carcinoma (TSCC). Methods: miRNA microarray was performed in paired TSCC cell lines, Cal27 and its chemoresistant counterpart, Cal27-re. Decreased expression of mitomiRs in chemoresistant cells was characterized. The functions of mitomiRs were investigated by a series of in vitro and in vivo experiments. Results: Differential microarray analysis identified downregulation of mitomiR-5787 in Cal27-re cells. We knocked down mitomiR-5787 in parental cells and upregulated its expression in cisplatin-resistant cells. The sensitivity of TSCC cells to cisplatin was regulated by miR-5787. The glucose metabolism assay suggested that reduced expression of miR-5787 changed the balance of glucose metabolism by shifting it from oxidative phosphorylation to aerobic glycolysis. Xenograft experiments in BALB/c-nu mice further verified the in vitro results. Reduced expression of miR-5787 contributes to chemoresistance in TSCC cells by inhibiting the translation of mitochondrial cytochrome c oxidase subunit 3 (MT-CO3). The prognostic analysis of 126 TSCC patients showed that the patients with low expression of miR-5787 and/or MT-CO3 had poor cisplatin sensitivity and prognosis. Conclusions: Mitochondrial miR-5787 could regulate cisplatin resistance of TSCC cells and affect oxidative phosphorylation and aerobic glycolysis. Downregulation of miR-5787 inhibited the translation of MT-CO3 to regulate cisplatin resistance of TSCC. Mitochondrial miR-5787 and MT-CO3 can be used as predictive biomarkers or therapeutic targets for cisplatin chemotherapy resistance.
Assuntos
Carcinoma de Células Escamosas/genética , Grupo dos Citocromos c/metabolismo , MicroRNAs/metabolismo , Mitocôndrias/metabolismo , Neoplasias da Língua/genética , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Carcinoma de Células Escamosas/tratamento farmacológico , Carcinoma de Células Escamosas/metabolismo , Linhagem Celular Tumoral , Cisplatino/uso terapêutico , Resistencia a Medicamentos Antineoplásicos/genética , Feminino , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/genética , Glucose/metabolismo , Glicólise/efeitos dos fármacos , Glicólise/genética , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , MicroRNAs/genética , Fosforilação Oxidativa , Neoplasias da Língua/tratamento farmacológico , Neoplasias da Língua/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Genetic mutation in cytochrome c oxidase subunit III gene (MT-CO3) could influence the kinetics of cytochrome c oxidase (COX), which catalyzes oxygen transport capacity in oxidative phosphorylation. However, the potential relationship between MT-CO3 variants and high-altitude adaptation remains poorly understood in Tibetan chicken. Here, we sequenced MT-CO3 gene of 125 Tibetan chickens and 144 Chinese domestic chickens in areas at a low elevation (below 1,000 m). Eight single nucleotide polymorphisms (SNPs) were detected; and five of them (m.10081A>G, m.10115G>A, m.10270G>A, m.10336A>G and m.10447C>T) shared by Tibetan chicken and lowland chicken with the significant difference in their respective allele frequencies. Nine haplotypes (H1-H9) were finally defined. Among them, haplotype H4 was positively associated with high-altitude adaptation whereas haplotypes H6, H7 and H8 had negative association with high-altitude adaptation. The Median-joining profile suggested that haplotype H5 had the ancestral position to the other haplotypes but had no significant relationship with high-altitude adaptation. However, there was only m.10081A>G mutation differed from haplotype H4 and H5. Results also suggested that chickens with A allele at m.10081A>G, had over 2.6 times than those with G allele in the probability of the ability to adapt hypoxia. It suggests that the synonymous mutation m.10081A>G may be a prerequisite for shaping high-altitude adaptation-specific haplotypes.