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Gonzalez CD, Nissanka N, Van Booven D, Griswold AJ, Moraes CT. Absence of both MGME1 and POLG EXO abolishes mtDNA whereas absence of either creates unique mtDNA duplications. J Biol Chem 2024; 300:107128. [PMID: 38432635 PMCID: PMC11002302 DOI: 10.1016/j.jbc.2024.107128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 02/21/2024] [Accepted: 02/23/2024] [Indexed: 03/05/2024] Open
Abstract
Both POLG and MGME1 are needed for mitochondrial DNA (mtDNA) maintenance in animal cells. POLG, the primary replicative polymerase of the mitochondria, has an exonuclease activity (3'→5') that corrects for the misincorporation of bases. MGME1 serves as an exonuclease (5'→3'), producing ligatable DNA ends. Although both have a critical role in mtDNA replication and elimination of linear fragments, these mechanisms are still not fully understood. Using digital PCR to evaluate and compare mtDNA integrity, we show that Mgme1 knock out (Mgme1 KK) tissue mtDNA is more fragmented than POLG exonuclease-deficient "Mutator" (Polg MM) or WT tissue. In addition, next generation sequencing of mutant hearts showed abundant duplications in/nearby the D-loop region and unique 100 bp duplications evenly spaced throughout the genome only in Mgme1 KK hearts. However, despite these unique mtDNA features at steady-state, we observed a similar delay in the degradation of mtDNA after an induced double strand DNA break in both Mgme1 KK and Polg MM models. Lastly, we characterized double mutant (Polg MM/Mgme1 KK) cells and show that mtDNA cannot be maintained without at least one of these enzymatic activities. We propose a model for the generation of these genomic abnormalities which suggests a role for MGME1 outside of nascent mtDNA end ligation. Our results highlight the role of MGME1 in and outside of the D-loop region during replication, support the involvement of MGME1 in dsDNA degradation, and demonstrate that POLG EXO and MGME1 can partially compensate for each other in maintaining mtDNA.
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Affiliation(s)
- Christian D Gonzalez
- MSTP and MCDB Programs, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Nadee Nissanka
- Department of Neurology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Derek Van Booven
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Anthony J Griswold
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Carlos T Moraes
- Department of Neurology, University of Miami Miller School of Medicine, Miami, Florida, USA.
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Liu C, Zhang N, Xu Z, Wang X, Yang Y, Bu J, Cao H, Xiao J, Xie Y. Nuclear mitochondria-related genes-based molecular classification and prognostic signature reveal immune landscape, somatic mutation, and prognosis for glioma. Heliyon 2023; 9:e19856. [PMID: 37809472 PMCID: PMC10559255 DOI: 10.1016/j.heliyon.2023.e19856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 08/22/2023] [Accepted: 09/04/2023] [Indexed: 10/10/2023] Open
Abstract
Background Glioma is the most frequent malignant primary brain tumor, and mitochondria may influence the progression of glioma. The aim of this study was to analyze the role of nuclear mitochondria related genes (MTRGs) in glioma, identify subtypes and construct a prognostic model based on nuclear MTRGs and machine learning algorithms. Methods Samples containing both gene expression profiles and clinical information were retrieved from the TCGA database, CGGA database, and GEO database. We selected 16 nuclear MTRGs and identified two clusters of glioma. Prognostic features, microenvironment, mutation landscape, and drug sensitivity were compared between the clusters. A prognostic model based on multiple machine learning algorithms was then constructed and validated by multiple datasets. Results We observed significant discrepancies between the two clusters. Cluster One had higher nuclear MTRG expression, a lower survival rate, and higher immune infiltration than Cluster Two. For the two clusters, we found distinct predictive drug sensitivities and responses to immune therapy, and the infiltration of immune cells was significantly different. Among the 22 combinations of machine learning algorithms we tested, LASSO was the most effective in constructing the prognostic model. The model's accuracy was further verified in three independent glioma datasets. We identified MGME1 as a vital gene associated with infiltrating immune cells in multiple types of tumors. Conclusion In short, our research identified two clusters of glioma and developed a dependable prognostic model based on machine learning methods. MGME1 was identified as a potential biomarker for multiple tumors. Our results will contribute to precise medicine and glioma management.
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Affiliation(s)
- Chang Liu
- College of Life Sciences, Anhui Medical University, Hefei, 230032, Anhui, China
- School of Basic Medical Sciences, Anhui Medical University, Hefei, 230032, Anhui, China
- Second School of Clinical Medicine, Anhui Medical University, Hefei, 230032, Anhui, China
| | - Ning Zhang
- School of Basic Medical Sciences, Anhui Medical University, Hefei, 230032, Anhui, China
- First School of Clinical Medicine, Anhui Medical University, Hefei, 230032, Anhui, China
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
| | - Zhihao Xu
- School of Basic Medical Sciences, Anhui Medical University, Hefei, 230032, Anhui, China
- First School of Clinical Medicine, Anhui Medical University, Hefei, 230032, Anhui, China
- Department of Neurosurgery, First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
| | - Xiaofeng Wang
- School of Basic Medical Sciences, Anhui Medical University, Hefei, 230032, Anhui, China
| | - Yang Yang
- School of Basic Medical Sciences, Anhui Medical University, Hefei, 230032, Anhui, China
- First School of Clinical Medicine, Anhui Medical University, Hefei, 230032, Anhui, China
| | - Junming Bu
- School of Basic Medical Sciences, Anhui Medical University, Hefei, 230032, Anhui, China
- Second School of Clinical Medicine, Anhui Medical University, Hefei, 230032, Anhui, China
| | - Huake Cao
- School of Basic Medical Sciences, Anhui Medical University, Hefei, 230032, Anhui, China
- First School of Clinical Medicine, Anhui Medical University, Hefei, 230032, Anhui, China
| | - Jin Xiao
- Department of Neurosurgery, First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
| | - Yinyin Xie
- College of Life Sciences, Anhui Medical University, Hefei, 230032, Anhui, China
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da Silva Rocha EB, de Lima Rodrigues K, Montouro LAM, Coelho ÉN, Kouyoumdjian JA, Kok F, Nóbrega PR, Graca CR, Morita MDPA, Estephan EDP. A case of mitochondrial DNA depletion syndrome type 11 - expanding the genotype and phenotype. Neuromuscul Disord 2023; 33:692-696. [PMID: 37429773 DOI: 10.1016/j.nmd.2023.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 05/26/2023] [Accepted: 06/13/2023] [Indexed: 07/12/2023]
Abstract
Mitochondrial DNA depletion syndrome type 11 (MTDPS11) is caused by pathogenic variants in MGME1 gene. We report a woman, 40-year-old, who presented slow progressive drop eyelid at 11-year-old with, learning difficulty and frequent falls. Phisical examination revealed: mild scoliosis, elbow hyperextensibility, flat feet, chronic progressive external ophthalmoplegia with upper eyelid ptosis, diffuse hypotonia, and weakness of arm abduction and neck flexion. Investigation evidenced mild serum creatine kinase increase and glucose intolerance; second-degree atrioventricular block; mild mixed-type respiratory disorder and atrophy and granular appearance of the retinal pigment epithelium. Brain magnetic resonance showed cerebellar atrophy. Muscle biopsy was compatible with mitochondrial myopathy. Genetic panel revealed a homozygous pathogenic variant in the MGME1 gene, consistent with MTDPS11 (c.862C>T; p.Gln288*). This case of MTDPS11 can contribute to the phenotypic characterization of this ultra-rare mitochondrial disorder, presenting milder respiratory and nutritional involvement than the previously reported cases, with possible additional features.
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Affiliation(s)
- Emanuelle Bianchi da Silva Rocha
- Department of Neurological Sciences, Psychiatry and Medical Psychology, Faculdade Estadual de Medicina de São José do Rio Preto (FAMERP), Brigadeiro Faria Lima Avenue, 5416, 15090-000 São José do Rio Preto, São Paulo, Brazil
| | - Ketteny de Lima Rodrigues
- Department of Neurological Sciences, Psychiatry and Medical Psychology, Faculdade Estadual de Medicina de São José do Rio Preto (FAMERP), Brigadeiro Faria Lima Avenue, 5416, 15090-000 São José do Rio Preto, São Paulo, Brazil
| | - Laura Alonso Matheus Montouro
- Department of Neurological Sciences, Psychiatry and Medical Psychology, Faculdade Estadual de Medicina de São José do Rio Preto (FAMERP), Brigadeiro Faria Lima Avenue, 5416, 15090-000 São José do Rio Preto, São Paulo, Brazil
| | - Érica Nogueira Coelho
- Department of Neurological Sciences, Psychiatry and Medical Psychology, Fundação Faculdade Regional de Medicina São José do Rio Preto (FUNFARME), Brigadeiro Faria Lima Avenue, 5416, 15090-000 São José do Rio Preto, São Paulo, Brazil
| | - João Aris Kouyoumdjian
- Department of Neurological Sciences, Psychiatry and Medical Psychology, Faculdade Estadual de Medicina de São José do Rio Preto (FAMERP), Brigadeiro Faria Lima Avenue, 5416, 15090-000 São José do Rio Preto, São Paulo, Brazil
| | - Fernando Kok
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Ovídio Pires de Campos Street, 225, 05403-010 São Paulo, Brazil
| | - Paulo Ribeiro Nóbrega
- Department of Neurology, Faculdade de Medicina da Universidade Federal do Ceará (UFC), Alexandre Baraúna, 949, 60430-160 Fortaleza, Ceará, Brazil
| | - Carla Renata Graca
- Department of Neurological Sciences, Psychiatry and Medical Psychology, Faculdade Estadual de Medicina de São José do Rio Preto (FAMERP), Brigadeiro Faria Lima Avenue, 5416, 15090-000 São José do Rio Preto, São Paulo, Brazil
| | - Maria da Penha Ananias Morita
- Department of Neurological Sciences, Psychiatry and Medical Psychology, Faculdade Estadual de Medicina de São José do Rio Preto (FAMERP), Brigadeiro Faria Lima Avenue, 5416, 15090-000 São José do Rio Preto, São Paulo, Brazil
| | - Eduardo de Paula Estephan
- Department of Neurological Sciences, Psychiatry and Medical Psychology, Fundação Faculdade Regional de Medicina São José do Rio Preto (FUNFARME), Brigadeiro Faria Lima Avenue, 5416, 15090-000 São José do Rio Preto, São Paulo, Brazil; Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Ovídio Pires de Campos Street, 225, 05403-010 São Paulo, Brazil; Hospital Santa Marcelina, Department of Neurology, São Paulo, Brazil; Faculdade de Medicina Santa Marcelina (FASM), Department of Medical Clinic, São Paulo, Brazil.
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Xiao F, Zeng J, Wang H, Zhu H, Guo Y, Zhang Z, Xiao Y, Hu G, Huang K, Yang Q, Guo H. MGME1 associates with poor prognosis and is vital for cell proliferation in lower-grade glioma. Aging (Albany NY) 2023; 15:3690-3714. [PMID: 37166417 PMCID: PMC10449294 DOI: 10.18632/aging.204705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 04/18/2023] [Indexed: 05/12/2023]
Abstract
OBJECTIVE Mitochondrial genome maintenance exonuclease 1 (MGME1) is associated with DNA depletion, deletion, duplication, and rearrangement. However, the function of MGME1 in tumors, especially lower-grade gliomas (LGGs), has not been established. METHODS Pan-cancer analysis was used to define the expression patterns and prognostic value of MGME1 in various cancers. Subsequently, we systematically determined the associations between MGME1 expression and clinicopathological characteristics, prognosis, biological functions, immune characteristics, genomic mutations, and therapeutic responses of LGGs based on their expression patterns. The expression level and specific functions of MGME1 in LGGs was detected by conducting in vitro experiments. RESULTS Abnormally enhanced and high MGME1 expressions were associated with poor prognoses of various tumors, including LGG. Multivariate and univariate Cox regression analyses manifested that MGME1 expression was an independent prognostic biomarker for LGG. The immune-related signatures, infiltration of immune cells, immune checkpoint genes (ICPGs), copy number alteration (CNA), tumor mutation burden (TMB), and treatment responses of LGG patients were associated with the expression of MGME1. The in vitro experiments affirmed that MGME1 was elevated and tightly connected with the cell proliferation and cell cycle in LGG. CONCLUSIONS MGME1 is an independent prognostic biomarker and closely related to the cell proliferation in LGG.
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Affiliation(s)
- Feng Xiao
- Departments of Neurosurgery, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, Jiangxi, China
- Jiangxi Key Laboratory of Neurological Tumors and Cerebrovascular Diseases, Nanchang 330006, Jiangxi, China
- Jiangxi Health Commission Key Laboratory of Neurological Medicine, Nanchang 330006, Jiangxi, China
- Institute of Neuroscience, Nanchang University, Nanchang 330006, Jiangxi, China
| | - Jie Zeng
- Departments of Neurosurgery, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, Jiangxi, China
- Jiangxi Key Laboratory of Neurological Tumors and Cerebrovascular Diseases, Nanchang 330006, Jiangxi, China
- Jiangxi Health Commission Key Laboratory of Neurological Medicine, Nanchang 330006, Jiangxi, China
- Institute of Neuroscience, Nanchang University, Nanchang 330006, Jiangxi, China
| | - Haiyan Wang
- Department of Operation, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, Jiangxi, China
| | - Hong Zhu
- Departments of Neurosurgery, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, Jiangxi, China
- Jiangxi Key Laboratory of Neurological Tumors and Cerebrovascular Diseases, Nanchang 330006, Jiangxi, China
- Jiangxi Health Commission Key Laboratory of Neurological Medicine, Nanchang 330006, Jiangxi, China
- Institute of Neuroscience, Nanchang University, Nanchang 330006, Jiangxi, China
| | - Yun Guo
- Departments of Neurosurgery, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, Jiangxi, China
- Jiangxi Key Laboratory of Neurological Tumors and Cerebrovascular Diseases, Nanchang 330006, Jiangxi, China
- Jiangxi Health Commission Key Laboratory of Neurological Medicine, Nanchang 330006, Jiangxi, China
- Institute of Neuroscience, Nanchang University, Nanchang 330006, Jiangxi, China
| | - Zhe Zhang
- Departments of Neurosurgery, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, Jiangxi, China
- Jiangxi Key Laboratory of Neurological Tumors and Cerebrovascular Diseases, Nanchang 330006, Jiangxi, China
- Jiangxi Health Commission Key Laboratory of Neurological Medicine, Nanchang 330006, Jiangxi, China
- Institute of Neuroscience, Nanchang University, Nanchang 330006, Jiangxi, China
| | - Yao Xiao
- Departments of Neurosurgery, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, Jiangxi, China
- Jiangxi Key Laboratory of Neurological Tumors and Cerebrovascular Diseases, Nanchang 330006, Jiangxi, China
- Jiangxi Health Commission Key Laboratory of Neurological Medicine, Nanchang 330006, Jiangxi, China
- Institute of Neuroscience, Nanchang University, Nanchang 330006, Jiangxi, China
| | - Guowen Hu
- Departments of Neurosurgery, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, Jiangxi, China
| | - Kai Huang
- Departments of Neurosurgery, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, Jiangxi, China
- Jiangxi Key Laboratory of Neurological Tumors and Cerebrovascular Diseases, Nanchang 330006, Jiangxi, China
- Jiangxi Health Commission Key Laboratory of Neurological Medicine, Nanchang 330006, Jiangxi, China
- Institute of Neuroscience, Nanchang University, Nanchang 330006, Jiangxi, China
| | - Qing Yang
- Department of Respiratory Medicine, The Second Affiliated Hospital of Nanchang University, Nanchang 330030, Jiangxi, China
| | - Hua Guo
- Departments of Neurosurgery, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, Jiangxi, China
- Jiangxi Key Laboratory of Neurological Tumors and Cerebrovascular Diseases, Nanchang 330006, Jiangxi, China
- Jiangxi Health Commission Key Laboratory of Neurological Medicine, Nanchang 330006, Jiangxi, China
- Institute of Neuroscience, Nanchang University, Nanchang 330006, Jiangxi, China
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Hebbar M, Girisha KM, Srivastava A, Bielas S, Shukla A. Homozygous c.359del variant in MGME1 is associated with early onset cerebellar ataxia. Eur J Med Genet 2017; 60:533-535. [PMID: 28711739 DOI: 10.1016/j.ejmg.2017.07.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 07/04/2017] [Accepted: 07/11/2017] [Indexed: 11/25/2022]
Abstract
We ascertained a child with early onset cerebellar ataxia and identified a novel frameshift deletion, c.359del [p. (Pro120Leufs*2), NM_052865.2] in exon 2 of MGME1 (mitochondrial genome maintenance exonuclease 1) by exome sequencing. Variations in MGME1 have been reported to cause mitochondrial DNA (mtDNA) depletion syndrome 11 (MIM #615084) in an earlier work. The phenotype included progressive external ophthalmoplegia, emaciation, respiratory failure and late onset progressive ataxia. However, the child presented here has early onset progressive ataxia, speech delay, microcephaly, cerebellar atrophy and fundus albipunctatus. This is the second report of a mutation in MGME1 and describes a more severe phenotype.
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Affiliation(s)
- Malavika Hebbar
- Department of Medical Genetics, Kasturba Medical College, Manipal University, Manipal, India
| | - Katta M Girisha
- Department of Medical Genetics, Kasturba Medical College, Manipal University, Manipal, India
| | - Anshika Srivastava
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Stephanie Bielas
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Anju Shukla
- Department of Medical Genetics, Kasturba Medical College, Manipal University, Manipal, India.
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Abstract
The small circular mitochondrial genome in mammalian cells is replicated by a dedicated replisome, defects in which can cause mitochondrial disease in humans. A fundamental step in mitochondrial DNA (mtDNA) replication and maintenance is the removal of the RNA primers needed for replication initiation. The nucleases RNase H1, FEN1, DNA2, and MGME1 have been implicated in this process. Here we review the role of these nucleases in the light of primer removal pathways in mitochondria, highlight associations with disease, as well as consider the implications for mtDNA replication initiation.
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