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Bernardino Gomes TM, Vincent AE, Menger KE, Stewart JB, Nicholls TJ. Mechanisms and pathologies of human mitochondrial DNA replication and deletion formation. Biochem J 2024; 481:683-715. [PMID: 38804971 PMCID: PMC11346376 DOI: 10.1042/bcj20230262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 05/13/2024] [Accepted: 05/14/2024] [Indexed: 05/29/2024]
Abstract
Human mitochondria possess a multi-copy circular genome, mitochondrial DNA (mtDNA), that is essential for cellular energy metabolism. The number of copies of mtDNA per cell, and their integrity, are maintained by nuclear-encoded mtDNA replication and repair machineries. Aberrant mtDNA replication and mtDNA breakage are believed to cause deletions within mtDNA. The genomic location and breakpoint sequences of these deletions show similar patterns across various inherited and acquired diseases, and are also observed during normal ageing, suggesting a common mechanism of deletion formation. However, an ongoing debate over the mechanism by which mtDNA replicates has made it difficult to develop clear and testable models for how mtDNA rearrangements arise and propagate at a molecular and cellular level. These deletions may impair energy metabolism if present in a high proportion of the mtDNA copies within the cell, and can be seen in primary mitochondrial diseases, either in sporadic cases or caused by autosomal variants in nuclear-encoded mtDNA maintenance genes. These mitochondrial diseases have diverse genetic causes and multiple modes of inheritance, and show notoriously broad clinical heterogeneity with complex tissue specificities, which further makes establishing genotype-phenotype relationships challenging. In this review, we aim to cover our current understanding of how the human mitochondrial genome is replicated, the mechanisms by which mtDNA replication and repair can lead to mtDNA instability in the form of large-scale rearrangements, how rearranged mtDNAs subsequently accumulate within cells, and the pathological consequences when this occurs.
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Affiliation(s)
- Tiago M. Bernardino Gomes
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- NHS England Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, U.K
| | - Amy E. Vincent
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Katja E. Menger
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - James B. Stewart
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Thomas J. Nicholls
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
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2
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Gao K, Xu X, Wang C. FBXL4 mutation-caused mitochondrial DNA depletion syndrome is driven by BNIP3/BNIP3L-dependent excessive mitophagy. Trends Mol Med 2024; 30:113-116. [PMID: 38123379 DOI: 10.1016/j.molmed.2023.11.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Revised: 11/29/2023] [Accepted: 11/30/2023] [Indexed: 12/23/2023]
Abstract
Encephalomyopathic mitochondrial DNA (mtDNA) depletion syndrome 13 (MTDPS13) is an autosomal recessive disorder arising from biallelic F-box and leucine-rich repeat (LRR) protein 4 (FBXL4) gene mutations. Recent advances have shown that excessive BCL2 interacting protein 3 (BNIP3)/ BCL2 interacting protein 3 like (BNIP3L)-dependent mitophagy underlies the molecular pathogenesis of MTDPS13. Here, we provide an overview of these groundbreaking findings and discuss potential therapeutic strategies for this fatal disease.
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Affiliation(s)
- Kun Gao
- Department of Clinical Laboratory, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, China.
| | - Xiayun Xu
- State Key Laboratory of Genetic Engineering, MOE Engineering Research Center of Gene Technology, Shanghai Engineering Research Center of Industrial Microorganisms, School of Life Sciences, Fudan University, Shanghai, China
| | - Chenji Wang
- State Key Laboratory of Genetic Engineering, MOE Engineering Research Center of Gene Technology, Shanghai Engineering Research Center of Industrial Microorganisms, School of Life Sciences, Fudan University, Shanghai, China.
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3
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Cao Y, Zheng J, Wan H, Sun Y, Fu S, Liu S, He B, Cai G, Cao Y, Huang H, Li Q, Ma Y, Chen S, Wang F, Jiang H. A mitochondrial SCF-FBXL4 ubiquitin E3 ligase complex degrades BNIP3 and NIX to restrain mitophagy and prevent mitochondrial disease. EMBO J 2023; 42:e113033. [PMID: 36896912 PMCID: PMC10308365 DOI: 10.15252/embj.2022113033] [Citation(s) in RCA: 26] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 02/14/2023] [Accepted: 02/17/2023] [Indexed: 03/11/2023] Open
Abstract
Mitophagy is a fundamental quality control mechanism of mitochondria. Its regulatory mechanisms and pathological implications remain poorly understood. Here, via a mitochondria-targeted genetic screen, we found that knockout (KO) of FBXL4, a mitochondrial disease gene, hyperactivates mitophagy at basal conditions. Subsequent counter screen revealed that FBXL4-KO hyperactivates mitophagy via two mitophagy receptors BNIP3 and NIX. We determined that FBXL4 functions as an integral outer-membrane protein that forms an SCF-FBXL4 ubiquitin E3 ligase complex. SCF-FBXL4 ubiquitinates BNIP3 and NIX to target them for degradation. Pathogenic FBXL4 mutations disrupt SCF-FBXL4 assembly and impair substrate degradation. Fbxl4-/- mice exhibit elevated BNIP3 and NIX proteins, hyperactive mitophagy, and perinatal lethality. Importantly, knockout of either Bnip3 or Nix rescues metabolic derangements and viability of the Fbxl4-/- mice. Together, beyond identifying SCF-FBXL4 as a novel mitochondrial ubiquitin E3 ligase restraining basal mitophagy, our results reveal hyperactivated mitophagy as a cause of mitochondrial disease and suggest therapeutic strategies.
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Affiliation(s)
- Yu Cao
- College of Life SciencesBeijing Normal UniversityBeijingChina
- National Institute of Biological SciencesBeijingChina
- Beijing Key Laboratory of Cell Biology for Animal AgingBeijingChina
| | - Jing Zheng
- National Institute of Biological SciencesBeijingChina
- Beijing Key Laboratory of Cell Biology for Animal AgingBeijingChina
| | - Huayun Wan
- National Institute of Biological SciencesBeijingChina
- Beijing Key Laboratory of Cell Biology for Animal AgingBeijingChina
| | - Yuqiu Sun
- National Institute of Biological SciencesBeijingChina
- Beijing Key Laboratory of Cell Biology for Animal AgingBeijingChina
- Tsinghua Institute of Multidisciplinary Biomedical ResearchTsinghua UniversityBeijingChina
| | - Song Fu
- National Institute of Biological SciencesBeijingChina
- Beijing Key Laboratory of Cell Biology for Animal AgingBeijingChina
- Graduate School of Peking Union Medical CollegeBeijingChina
| | - Shanshan Liu
- National Institute of Biological SciencesBeijingChina
- Beijing Key Laboratory of Cell Biology for Animal AgingBeijingChina
| | - Baiyu He
- National Institute of Biological SciencesBeijingChina
- Beijing Key Laboratory of Cell Biology for Animal AgingBeijingChina
- College of Life SciencesChina Agriculture UniversityBeijingChina
| | - Gaihong Cai
- National Institute of Biological SciencesBeijingChina
| | - Yang Cao
- National Institute of Biological SciencesBeijingChina
| | - Huanwei Huang
- National Institute of Biological SciencesBeijingChina
| | - Qi Li
- National Institute of Biological SciencesBeijingChina
- Tsinghua Institute of Multidisciplinary Biomedical ResearchTsinghua UniversityBeijingChina
| | - Yan Ma
- National Institute of Biological SciencesBeijingChina
- Tsinghua Institute of Multidisciplinary Biomedical ResearchTsinghua UniversityBeijingChina
| | - She Chen
- National Institute of Biological SciencesBeijingChina
- Tsinghua Institute of Multidisciplinary Biomedical ResearchTsinghua UniversityBeijingChina
| | - Fengchao Wang
- National Institute of Biological SciencesBeijingChina
- Tsinghua Institute of Multidisciplinary Biomedical ResearchTsinghua UniversityBeijingChina
| | - Hui Jiang
- College of Life SciencesBeijing Normal UniversityBeijingChina
- National Institute of Biological SciencesBeijingChina
- Beijing Key Laboratory of Cell Biology for Animal AgingBeijingChina
- Tsinghua Institute of Multidisciplinary Biomedical ResearchTsinghua UniversityBeijingChina
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4
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Saini N, Vijayasree V, Nandury EC, Dalal A, Aggarwal S. Prenatal phenotype of FBXL4-associated encephalomyopathic mitochondrial DNA depletion syndrome-13. Prenat Diagn 2022; 42:1682-1685. [PMID: 36411461 DOI: 10.1002/pd.6272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/16/2022] [Accepted: 11/17/2022] [Indexed: 11/23/2022]
Abstract
FBXL4 -associated encephalomyopathic mitochondrial DNA depletion syndrome-13 (MTDPS13) is a rare genetic disorder characterized by early neonatal onset of encephalopathy, seizures, lactic acidosis, hypotonia, dysmorphism, and severe global developmental delay. Prenatal phenotype of molecularly confirmed MTDPS13 has not been well studied. This is the case report of a non-consanguineously conceived fetus ascertained first at 20 weeks of gestation with multiple soft markers. Follow-up fetal ultrasonogram at 26 weeks revealed periventricular cysts, periventricular echogenicity, ventriculomegaly, thin corpus callosum, mega cisterna magna, and large cavum. Fetal MRI confirmed these findings. Postnatally, the baby had clinical and biochemical findings indicative of a mitochondriopathy and died on neonatal day 3. Whole exome sequencing on stored amniotic fluid DNA confirmed the diagnosis of encephalomyopathic mitochondrial DNA depletion syndrome-13 (MTDPS13). This report presents the prenatal phenotype of this rare mitochondriopathy, which has been recognized primarily in postnatal patients. The brain imaging findings in the reported fetus indicate that MTDPS13 is associated with progressive neurological involvement and brain tissue destructive changes starting as early as the second trimester of pregnancy. The case also raises concerns regarding the association of so-called soft markers, which were the only initial finding in this case, with severe monogenic diseases.
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Affiliation(s)
- Neelam Saini
- Department of Medical Genetics, Nizam's Institute of Medical Sciences Hyderabad, Hyderabad, India
| | - Venkatapuram Vijayasree
- Department of Medical Genetics, Nizam's Institute of Medical Sciences Hyderabad, Hyderabad, India
| | | | - Ashwin Dalal
- Diagnostics Division, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
| | - Shagun Aggarwal
- Department of Medical Genetics, Nizam's Institute of Medical Sciences Hyderabad, Hyderabad, India.,Diagnostics Division, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
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Al Ojaimi M, Salah A, El-Hattab AW. Mitochondrial Fission and Fusion: Molecular Mechanisms, Biological Functions, and Related Disorders. MEMBRANES 2022; 12:membranes12090893. [PMID: 36135912 PMCID: PMC9502208 DOI: 10.3390/membranes12090893] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/04/2022] [Accepted: 09/11/2022] [Indexed: 05/13/2023]
Abstract
Mitochondria are dynamic organelles that undergo fusion and fission. These active processes occur continuously and simultaneously and are mediated by nuclear-DNA-encoded proteins that act on mitochondrial membranes. The balance between fusion and fission determines the mitochondrial morphology and adapts it to the metabolic needs of the cells. Therefore, these two processes are crucial to optimize mitochondrial function and its bioenergetics abilities. Defects in mitochondrial proteins involved in fission and fusion due to pathogenic variants in the genes encoding them result in disruption of the equilibrium between fission and fusion, leading to a group of mitochondrial diseases termed disorders of mitochondrial dynamics. In this review, the molecular mechanisms and biological functions of mitochondrial fusion and fission are first discussed. Then, mitochondrial disorders caused by defects in fission and fusion are summarized, including disorders related to MFN2, MSTO1, OPA1, YME1L1, FBXL4, DNM1L, and MFF genes.
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Affiliation(s)
- Mode Al Ojaimi
- College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates
- Pediatrics Department, University Hospital Sharjah, Sharjah 72772, United Arab Emirates
| | - Azza Salah
- Pediatrics Department, University Hospital Sharjah, Sharjah 72772, United Arab Emirates
| | - Ayman W. El-Hattab
- College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates
- Pediatrics Department, University Hospital Sharjah, Sharjah 72772, United Arab Emirates
- Genetics and Metabolic Department, KidsHeart Medical Center, Abu Dhabi 505193, United Arab Emirates
- Correspondence: ; Tel.: +971-508875123
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Comparative Proteomic Analysis of Liver Tissues and Serum in db/db Mice. Int J Mol Sci 2022; 23:ijms23179687. [PMID: 36077090 PMCID: PMC9455973 DOI: 10.3390/ijms23179687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 08/20/2022] [Accepted: 08/23/2022] [Indexed: 11/17/2022] Open
Abstract
Background and Aims: Non-alcoholic fatty liver disease (NAFLD) affects one-quarter of individuals worldwide. Liver biopsy, as the current reliable method for NAFLD evaluation, causes low patient acceptance because of the nature of invasive sampling. Therefore, sensitive non-invasive serum biomarkers are urgently needed. Results: The serum gene ontology (GO) classification and Kyoto encyclopedia of genes and genomes (KEGG) analysis revealed the DEPs enriched in pathways including JAK-STAT and FoxO. GO analysis indicated that serum DEPs were mainly involved in the cellular process, metabolic process, response to stimulus, and biological regulation. Hepatic proteomic KEGG analysis revealed the DEPs were mainly enriched in the PPAR signaling pathway, retinol metabolism, glycine, serine, and threonine metabolism, fatty acid elongation, biosynthesis of unsaturated fatty acids, glutathione metabolism, and steroid hormone biosynthesis. GO analysis revealed that DEPs predominantly participated in cellular, biological regulation, multicellular organismal, localization, signaling, multi-organism, and immune system processes. Protein-protein interaction (PPI) implied diverse clusters of the DEPs. Besides, the paralleled changes of the common upregulated and downregulated DEPs existed in both the liver and serum were validated in the mRNA expression of NRP1, MUP3, SERPINA1E, ALPL, and ALDOB as observed in our proteomic screening. Methods: We conducted hepatic and serum proteomic analysis based on the leptin-receptor-deficient mouse (db/db), a well-established diabetic mouse model with overt obesity and NAFLD. The results show differentially expressed proteins (DEPs) in hepatic and serum proteomic analysis. A parallel reaction monitor (PRM) confirmed the authenticity of the selected DEPs. Conclusion: These results are supposed to offer sensitive non-invasive serum biomarkers for diabetes and NAFLD.
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A Maternally Inherited Rare Case with Chromoanagenesis-Related Complex Chromosomal Rearrangements and De Novo Microdeletions. Diagnostics (Basel) 2022; 12:diagnostics12081900. [PMID: 36010250 PMCID: PMC9406357 DOI: 10.3390/diagnostics12081900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 07/22/2022] [Accepted: 08/04/2022] [Indexed: 11/17/2022] Open
Abstract
Chromoanagenesis is a phenomenon of highly complex rearrangements involving the massive genomic shattering and reconstitution of chromosomes that has had a great impact on cancer biology and congenital anomalies. Complex chromosomal rearrangements (CCRs) are structural alterations involving three or more chromosomal breakpoints between at least two chromosomes. Here, we present a 3-year-old boy exhibiting multiple congenital malformations and developmental delay. The cytogenetic analysis found a highly complex CCR inherited from the mother involving four chromosomes and five breakpoints due to forming four derivative chromosomes (2, 3, 6 and 11). FISH analysis identified an ultrarare derivative chromosome 11 containing three parts that connected the 11q telomere to partial 6q and 3q fragments. We postulate that this derivative chromosome 11 is associated with chromoanagenesis-like phenomena by which DNA repair can result in a cooccurrence of inter-chromosomal translocations. Additionally, chromosome microarray studies revealed that the child has one subtle maternal-inherited deletion at 6p12.1 and two de novo deletions at 6q14.1 and 6q16.1~6q16.3. Here, we present a familial CCR case with rare rearranged chromosomal structures and the use of multiple molecular techniques to delineate these genomic alterations. We suggest that chromoanagenesis may be a possible mechanism involved in the repair and reconstitution of these rearrangements with evidence for increasing genomic imbalances such as additional deletions in this case.
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Clinical and genetic spectrum of Mitochondrial DNA depletion syndromes: a report of 6 cases with 4 novel variants. Mitochondrion 2022; 65:139-144. [PMID: 35750291 DOI: 10.1016/j.mito.2022.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 05/16/2022] [Accepted: 06/19/2022] [Indexed: 11/22/2022]
Abstract
Mitochondrial DNA (mtDNA) depletion syndromes (MDS) are a heterogeneous group of rare autosomal recessive genetic disorders characterized by a decrease in the number of mtDNA copies inside the organ involved. There are three distinct forms of MDS including the hepatocerebral, the myopathic and the encephalomyopathic forms. The diversity in the clinical and genetic spectrum of these disorders makes the diagnosis challenging. Here, we describe the clinical phenotype and the genetic spectrum of 6 patients with MDS including 4 novel variants and compare them with previously reported cases. Subject and Methods Six patients from six unrelated families were included in this study. All the patients were subjected to a detailed history, thorough general and neurologic examination, basic laboratory investigations including lactic acid and ammonia, amino acids, acylcarnitine profiles and brain MRI. Whole-exome sequencing was performed for all of them to confirm the suspicion of mitochondrial disorder. RESULTS: In our series, four patients presented with the hepatocerebral form of MDS with the major presenting manifestation of progressive liver cell failure with severe hypotonia and global developmental delay. Four variants in the DGUOK gene and the MPV17 have been identified including 2 novel variants. One patient was identified in the myopathic form presenting with myopathy associated with two novel variants in the TK2 gene. One patient was diagnosed with encephalomyopathic form presenting with persistent lactic acidosis and global delay due to a homozygous variant in the FBXL4 gene. CONCLUSION: MDS has a wide spectrum of heterogeneous clinical presentations and about nine different genes involved. Whole exome sequencing (WES) has resulted in faster diagnosis of these challenging cases as the phenotype overlap with many other disorders. This should be considered the first-tier diagnostic test obviating the need for more invasive testing like muscle biopsies.
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Roy A, Kandettu A, Ray S, Chakrabarty S. Mitochondrial DNA replication and repair defects: Clinical phenotypes and therapeutic interventions. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148554. [PMID: 35341749 DOI: 10.1016/j.bbabio.2022.148554] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 03/06/2022] [Accepted: 03/16/2022] [Indexed: 12/15/2022]
Abstract
Mitochondria is a unique cellular organelle involved in multiple cellular processes and is critical for maintaining cellular homeostasis. This semi-autonomous organelle contains its circular genome - mtDNA (mitochondrial DNA), that undergoes continuous cycles of replication and repair to maintain the mitochondrial genome integrity. The majority of the mitochondrial genes, including mitochondrial replisome and repair genes, are nuclear-encoded. Although the repair machinery of mitochondria is quite efficient, the mitochondrial genome is highly susceptible to oxidative damage and other types of exogenous and endogenous agent-induced DNA damage, due to the absence of protective histones and their proximity to the main ROS production sites. Mutations in replication and repair genes of mitochondria can result in mtDNA depletion and deletions subsequently leading to mitochondrial genome instability. The combined action of mutations and deletions can result in compromised mitochondrial genome maintenance and lead to various mitochondrial disorders. Here, we review the mechanism of mitochondrial DNA replication and repair process, key proteins involved, and their altered function in mitochondrial disorders. The focus of this review will be on the key genes of mitochondrial DNA replication and repair machinery and the clinical phenotypes associated with mutations in these genes.
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Affiliation(s)
- Abhipsa Roy
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | - Amoolya Kandettu
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | - Swagat Ray
- Department of Life Sciences, School of Life and Environmental Sciences, University of Lincoln, Lincoln LN6 7TS, United Kingdom
| | - Sanjiban Chakrabarty
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India.
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10
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Saini N, Venkatapuram VS, Vineeth VS, Kulkarni A, Tandon A, Koppolu G, Patil SJ, Dalal A, Aggarwal S. Fetal phenotypes of Mendelian disorders: A descriptive study from India. Prenat Diagn 2022; 42:911-926. [PMID: 35587316 DOI: 10.1002/pd.6172] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 05/12/2022] [Accepted: 05/14/2022] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Exome sequencing(ES) based diagnosis of Mendelian diseases in the fetus is limited by paucity of phenotypic information. This study reports the comprehensive phenotypes of some fetuses with Mendelian disorders. METHODS Next generation technology based sequencing of all coding regions of the genome(Exome sequencing) or targeted gene sequencing using Sanger or next generation platforms was performed in a cohort of deeply phenotyped, cytogenetically normal fetuses with morphological defects. Prenatal ultrasonographic phenotypes and Postmortem details including dysmorphology, histopathology, radiography were ascertained. Novel candidate genes, novel/ unusual findings and unusual genotypes in cases with confirmed Mendelian disorders are described. RESULTS Of the 102 fetuses sequenced, 45 (44%) achieved definitive diagnosis of a Mendelian disorder with 50 pathogenic/likely pathogenic variants. The majority (87%) were autosomal recessive, 69% families were consanguineous and 54% variants were novel. Dysmorphic syndromes, skeletal dysplasias and metabolic disorders were the commonest disease categories, ciliopathies and dystroglycanopathies commonest molecular categories. We describe the first fetal description of six monogenic diseases, and nine cases with novel histological findings. Nineteen cases had novel/ unusual findings. CONCLUSION This cohort demonstrates how deep fetal phenotypes of some Mendelian disorders can show novel/unusual findings which have important implications for prenatal diagnosis of these conditions. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Neelam Saini
- Department of Medical Genetics, Nizam's Institute of Medical Sciences, Hyderabad, India
| | | | | | | | - Ashwani Tandon
- Department of Pathology, All India Institute of Medical Sciences, Bhopal, India
| | | | - Siddaramappa Jagdish Patil
- Division of Medical Genetics, Mazumdar Shaw Medical Center, Narayana Hrudayalaya Hospitals, Bangalore, India
| | - Ashwin Dalal
- Diagnostics Division, Centre for DNA Fingerprinting & Diagnostics, Hyderabad, India
| | - Shagun Aggarwal
- Department of Medical Genetics, Nizam's Institute of Medical Sciences, Hyderabad, India.,Diagnostics Division, Centre for DNA Fingerprinting & Diagnostics, Hyderabad, India
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Yang W, Zhao P, Cao P, Miao C, Ji X, Gao Y, Li P, Cheng J. Global interpretation of novel alternative splicing events in human congenital pulmonary airway malformations: A pilot study. J Cell Biochem 2022; 123:736-745. [PMID: 35064685 DOI: 10.1002/jcb.30216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 01/04/2022] [Accepted: 01/06/2022] [Indexed: 11/08/2022]
Affiliation(s)
- Weili Yang
- Department of Pediatric Surgery The Second Affiliated Hospital of Xi'an Jiaotong University Xi'an Shaanxi China
| | - Pu Zhao
- Department of Neonatology Shaanxi Provincial People's Hospital Xi'an Shaanxi China
| | - Ping Cao
- Department of Pediatric Surgery The Second Affiliated Hospital of Xi'an Jiaotong University Xi'an Shaanxi China
| | - Chunlin Miao
- Department of Pediatric Surgery The Second Affiliated Hospital of Xi'an Jiaotong University Xi'an Shaanxi China
| | - Xiang Ji
- Department of Pediatric Surgery The Second Affiliated Hospital of Xi'an Jiaotong University Xi'an Shaanxi China
| | - Ya Gao
- Department of Pediatric Surgery The Second Affiliated Hospital of Xi'an Jiaotong University Xi'an Shaanxi China
| | - Peng Li
- Department of Pediatric Surgery The Second Affiliated Hospital of Xi'an Jiaotong University Xi'an Shaanxi China
| | - Jiwen Cheng
- Department of Pediatric Surgery The Second Affiliated Hospital of Xi'an Jiaotong University Xi'an Shaanxi China
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12
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Oncul U, Kose E, Eminoglu FT. A Mild Phenotype of Mitochondrial DNA Depletion Syndrome Type 13 with a Novel FBXL4 Variant. Mol Syndromol 2021; 12:294-299. [PMID: 34602956 PMCID: PMC8436661 DOI: 10.1159/000515928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Accepted: 03/16/2021] [Indexed: 11/19/2022] Open
Abstract
Mitochondrial DNA depletion syndromes (MDDS) are a group of rare genetic disorders caused by defects in multiple genes involved in mitochondrial DNA maintenance. Among these, FBXL4 gene variants result in encephalomyopathic mtDNA depletion syndrome 13 (MTDPS13), which commonly presents as a combination of failure to thrive, neurodevelopmental delays, encephalopathy, hypotonia, a pattern of mild facial dysmorphisms, and persistent lactic acidosis. To date, 53 pathogenic FBXL4 variants and 100 cases have been described in the literature. In the present case report, we report on a 4.5-year-old boy with MTDPS13 and a novel variant. The patient had a history of antenatal hydrocephalus, severe developmental delay and mental motor retardation with psychomotor delay, severe hypotonia, mild left ventricular hypertrophic cardiomyopathy, mild facial dysmorphism, and elevated lactate levels. Symptoms suggested mitochondrial myopathy; subsequently, whole-exome sequencing was performed and a novel homozygous variant FBXL4 (NM_012160.4): c.486T>G (p.Tyr162Ter) was identified. While most of the patients with FBLX4 gene mutation have severe clinical manifestation and die at a very young age, clinical progress of our case was milder than previously reported. MDDS are very rare and can present with many different clinical signs and symptoms. In this report, we identified a novel pathogenic variant in the FBXL4 gene. This report shows that patients with FBLX4 gene mutations may present with a milder clinical phenotype than previously reported.
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Affiliation(s)
- Ummuhan Oncul
- Department of Pediatric Metabolism, Faculty of Medicine, Ankara University, Ankara, Turkey
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13
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Zhang YM, Meng LB, Yu SJ, Ma DX. Identification of potential crucial genes in monocytes for atherosclerosis using bioinformatics analysis. J Int Med Res 2021; 48:300060520909277. [PMID: 32314637 PMCID: PMC7175059 DOI: 10.1177/0300060520909277] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Objective To use bioinformatics tools to screen for gene biomarkers from monocytes, which play an important role in the pathogenesis of atherosclerosis. Methods Two expression profiling datasets (GSE27034 and GSE10195) were obtained from the Gene Expression Omnibus dataset and the differentially expressed genes (DEGs) between atherosclerotic human peripheral blood mononuclear cells (PBMC) samples and control subjects were screened using GEO2R. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were conducted for the DEGs. STRING and MCODE plug-in of Cytoscape were used for constructing a protein–protein interaction network and analysing hub genes. Results The two datasets had 237 DEGs in common between non-atherosclerotic- and atherosclerotic PBMC samples. Functional annotation demonstrated that these DEGs were mainly enriched in protein binding, positive regulation of transcription from RNA polymerase II promoter, nucleus and viral carcinogenesis. Five hub genes, FBXL4, UBOX5, KBTBD6, FZR1 and FBXO2, were identified. Conclusion This present bioinformatics analysis identified that the FBXL4, UBOX5, KBTBD6 and FBXO21 genes might play vital roles in the pathogenesis of atherosclerosis. These four genes might represent new biomarkers for the diagnosis and treatment of atherosclerosis.
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Affiliation(s)
- Yuan-Meng Zhang
- Department of Internal Medicine, The Third Medical Centre of Chinese PLA General Hospital, The Training Site for Postgraduate of Jinzhou Medical University, Beijing, China
| | - Ling-Bing Meng
- Department of Neurology, Beijing Hospital, National Centre of Gerontology, Beijing, China
| | - Si-Jun Yu
- Department of Cardiology, The Third Medical Centre of Chinese PLA General Hospital, Beijing, China
| | - Dong-Xing Ma
- Department of Cardiology, The Third Medical Centre of Chinese PLA General Hospital, Beijing, China
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14
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Di Nottia M, Verrigni D, Torraco A, Rizza T, Bertini E, Carrozzo R. Mitochondrial Dynamics: Molecular Mechanisms, Related Primary Mitochondrial Disorders and Therapeutic Approaches. Genes (Basel) 2021; 12:247. [PMID: 33578638 PMCID: PMC7916359 DOI: 10.3390/genes12020247] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/02/2021] [Accepted: 02/04/2021] [Indexed: 02/06/2023] Open
Abstract
Mitochondria do not exist as individual entities in the cell-conversely, they constitute an interconnected community governed by the constant and opposite process of fission and fusion. The mitochondrial fission leads to the formation of smaller mitochondria, promoting the biogenesis of new organelles. On the other hand, following the fusion process, mitochondria appear as longer and interconnected tubules, which enhance the communication with other organelles. Both fission and fusion are carried out by a small number of highly conserved guanosine triphosphatase proteins and their interactors. Disruption of this equilibrium has been associated with several pathological conditions, ranging from cancer to neurodegeneration, and mutations in genes involved in mitochondrial fission and fusion have been reported to be the cause of a subset of neurogenetic disorders.
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Affiliation(s)
| | | | | | | | | | - Rosalba Carrozzo
- Laboratory of Molecular Medicine, Unit of Muscular and Neurodegenerative Disorders, Bambino Gesù Children’s Hospital, IRCCS, 00146 Rome, Italy; (M.D.N.); (D.V.); (A.T.); (T.R.); (E.B.)
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15
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Blondelle J, Biju A, Lange S. The Role of Cullin-RING Ligases in Striated Muscle Development, Function, and Disease. Int J Mol Sci 2020; 21:E7936. [PMID: 33114658 PMCID: PMC7672578 DOI: 10.3390/ijms21217936] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 10/11/2020] [Accepted: 10/13/2020] [Indexed: 02/07/2023] Open
Abstract
The well-orchestrated turnover of proteins in cross-striated muscles is one of the fundamental processes required for muscle cell function and survival. Dysfunction of the intricate protein degradation machinery is often associated with development of cardiac and skeletal muscle myopathies. Most muscle proteins are degraded by the ubiquitin-proteasome system (UPS). The UPS involves a number of enzymes, including E3-ligases, which tightly control which protein substrates are marked for degradation by the proteasome. Recent data reveal that E3-ligases of the cullin family play more diverse and crucial roles in cross striated muscles than previously anticipated. This review highlights some of the findings on the multifaceted functions of cullin-RING E3-ligases, their substrate adapters, muscle protein substrates, and regulatory proteins, such as the Cop9 signalosome, for the development of cross striated muscles, and their roles in the etiology of myopathies.
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Affiliation(s)
- Jordan Blondelle
- Department of Medicine, University of California, La Jolla, CA 92093, USA
| | - Andrea Biju
- Department of Medicine, University of California, La Jolla, CA 92093, USA
| | - Stephan Lange
- Department of Medicine, University of California, La Jolla, CA 92093, USA
- Department of Molecular and Clinical Medicine, University of Gothenburg, 41345 Gothenburg, Sweden
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16
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Wang S, Lin L, Wang Y, Wang A, Liu Z, Wu S, Lan X, Jia J, Zhang Y, Yuan F, Wang C, Luo X, Sun X, Avula SK, Tolaymat A, Liu C, Ren Y, Chen Y. Novel homozygous mutation in the FBXL4 gene is associated with mitochondria DNA depletion syndrome-13. J Neurol Sci 2020; 416:116948. [PMID: 32559514 DOI: 10.1016/j.jns.2020.116948] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 05/24/2020] [Accepted: 05/25/2020] [Indexed: 10/24/2022]
Abstract
BACKGROUND Mitochondrial DNA depletion syndrome-13 (MTDPS13) is caused by mutations in FBXL4 (F-box and leucine-rich repeat protein 4), a nuclear gene encoding an F-box protein that plays a role in maintaining mtDNA integrity and stability. METHODS We identified a novel homozygous FBXL4 gene mutation, c.993dupA (p.L332Tfs*3), in a 1-year-old girl of Han Chinese descent. We performed three-dimensional protein structural analysis and targeted mtDNA next-generation sequencing. We analysed FBXL4 expression and mitochondrial DNA level, and reviewed mutations reported in FBXL4-related literature. RESULTS This mutation resulted in premature termination of translation and loss of 288 amino acids from C-terminus. A three-dimensional structural analysis revealed that conserved LRR domains were lost in mutant FBXL4 protein, which likely affected its ability to form protein-protein interactions. There were no differences in FBXL4 mRNA expression levels between the patient and her parents. There were no mtDNA mutations in either the patient or her parents. However, ND1/GAPDH ratio in lymphocytes and urine, which represents mtDNA/nuclear DNA ratio, showed that the number of mitochondrial genomes was significantly lower in the patient than in her parents or wild-type subjects. CONCLUSION Homozygous FBXL4 gene mutation, c.993dupA, can cause mitochondrial dysfunction, and LRR region is especially important for FBXL4 protein function.
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Affiliation(s)
- Simei Wang
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai 200062, China; Division of Pediatric Neurology, Department of Pediatrics, University of Illinois and Children's Hospital of Illinois, Peoria, IL 61637, USA
| | - Longlong Lin
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai 200062, China
| | - Yilin Wang
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai 200062, China
| | - Anqi Wang
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai 200062, China
| | - Zhao Liu
- Division of Pediatric Neurology, Department of Pediatrics, University of Illinois and Children's Hospital of Illinois, Peoria, IL 61637, USA
| | - Shengnan Wu
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai 200062, China
| | - Xiaoping Lan
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai 200062, China
| | - Jia Jia
- Shanghai Center for Bioinformation Technology, Shanghai 201202, China
| | - Yuanfeng Zhang
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai 200062, China
| | - Fang Yuan
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai 200062, China
| | - Chunmei Wang
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai 200062, China
| | - Xiaona Luo
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai 200062, China
| | - Xiaomin Sun
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai 200062, China
| | - Sreenivas K Avula
- Division of Pediatric Neurology, Department of Pediatrics, University of Illinois and Children's Hospital of Illinois, Peoria, IL 61637, USA
| | - Abdullah Tolaymat
- Division of Pediatric Neurology, Department of Pediatrics, University of Illinois and Children's Hospital of Illinois, Peoria, IL 61637, USA
| | | | - Yun Ren
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai 200062, China
| | - Yucai Chen
- Department of Neurology, Shanghai Children's Hospital, Shanghai JiaoTong University, Shanghai 200062, China.
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17
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Re CJ, Batterman AI, Gerstner JR, Buono RJ, Ferraro TN. The Molecular Genetic Interaction Between Circadian Rhythms and Susceptibility to Seizures and Epilepsy. Front Neurol 2020; 11:520. [PMID: 32714261 PMCID: PMC7344275 DOI: 10.3389/fneur.2020.00520] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 05/12/2020] [Indexed: 12/19/2022] Open
Abstract
Seizure patterns observed in patients with epilepsy suggest that circadian rhythms and sleep/wake mechanisms play some role in the disease. This review addresses key topics in the relationship between circadian rhythms and seizures in epilepsy. We present basic information on circadian biology, but focus on research studying the influence of both the time of day and the sleep/wake cycle as independent but related factors on the expression of seizures in epilepsy. We review studies investigating how seizures and epilepsy disrupt expression of core clock genes, and how disruption of clock mechanisms impacts seizures and the development of epilepsy. We focus on the overlap between mechanisms of circadian-associated changes in SCN neuronal excitability and mechanisms of epileptogenesis as a means of identifying key pathways and molecules that could represent new targets or strategies for epilepsy therapy. Finally, we review the concept of chronotherapy and provide a perspective regarding its application to patients with epilepsy based on their individual characteristics (i.e., being a “morning person” or a “night owl”). We conclude that better understanding of the relationship between circadian rhythms, neuronal excitability, and seizures will allow both the identification of new therapeutic targets for treating epilepsy as well as more effective treatment regimens using currently available pharmacological and non-pharmacological strategies.
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Affiliation(s)
- Christopher J Re
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, NJ, United States
| | - Alexander I Batterman
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, NJ, United States
| | - Jason R Gerstner
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA, United States
| | - Russell J Buono
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, NJ, United States
| | - Thomas N Ferraro
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, NJ, United States
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18
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Alsina D, Lytovchenko O, Schab A, Atanassov I, Schober FA, Jiang M, Koolmeister C, Wedell A, Taylor RW, Wredenberg A, Larsson NG. FBXL4 deficiency increases mitochondrial removal by autophagy. EMBO Mol Med 2020; 12:e11659. [PMID: 32525278 PMCID: PMC7338799 DOI: 10.15252/emmm.201911659] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 05/11/2020] [Accepted: 05/14/2020] [Indexed: 01/29/2023] Open
Abstract
Pathogenic variants in FBXL4 cause a severe encephalopathic syndrome associated with mtDNA depletion and deficient oxidative phosphorylation. To gain further insight into the enigmatic pathophysiology caused by FBXL4 deficiency, we generated homozygous Fbxl4 knockout mice and found that they display a predominant perinatal lethality. Surprisingly, the few surviving animals are apparently normal until the age of 8–12 months when they gradually develop signs of mitochondrial dysfunction and weight loss. One‐year‐old Fbxl4 knockouts show a global reduction in a variety of mitochondrial proteins and mtDNA depletion, whereas lysosomal proteins are upregulated. Fibroblasts from patients with FBXL4 deficiency and human FBXL4 knockout cells also have reduced steady‐state levels of mitochondrial proteins that can be attributed to increased mitochondrial turnover. Inhibition of lysosomal function in these cells reverses the mitochondrial phenotype, whereas proteasomal inhibition has no effect. Taken together, the results we present here show that FBXL4 prevents mitochondrial removal via autophagy and that loss of FBXL4 leads to decreased mitochondrial content and mitochondrial disease.
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Affiliation(s)
- David Alsina
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.,Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - Oleksandr Lytovchenko
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.,Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - Aleksandra Schab
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Ilian Atanassov
- Proteomics Core Facility, Max Planck Institute for Biology of Ageing, Cologne, Germnay
| | - Florian A Schober
- Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden.,Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Min Jiang
- Key Laboratory of Growth Regulation and Translation Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, China
| | - Camilla Koolmeister
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.,Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - Anna Wedell
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.,Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Anna Wredenberg
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.,Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden.,Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Nils-Göran Larsson
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.,Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden.,Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden
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19
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Wang X, Kadarmideen HN. Metabolite Genome-Wide Association Study (mGWAS) and Gene-Metabolite Interaction Network Analysis Reveal Potential Biomarkers for Feed Efficiency in Pigs. Metabolites 2020; 10:E201. [PMID: 32429265 PMCID: PMC7281523 DOI: 10.3390/metabo10050201] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 05/10/2020] [Accepted: 05/11/2020] [Indexed: 12/21/2022] Open
Abstract
Metabolites represent the ultimate response of biological systems, so metabolomics is considered the link between genotypes and phenotypes. Feed efficiency is one of the most important phenotypes in sustainable pig production and is the main breeding goal trait. We utilized metabolic and genomic datasets from a total of 108 pigs from our own previously published studies that involved 59 Duroc and 49 Landrace pigs with data on feed efficiency (residual feed intake (RFI)), genotype (PorcineSNP80 BeadChip) data, and metabolomic data (45 final metabolite datasets derived from LC-MS system). Utilizing these datasets, our main aim was to identify genetic variants (single-nucleotide polymorphisms (SNPs)) that affect 45 different metabolite concentrations in plasma collected at the start and end of the performance testing of pigs categorized as high or low in their feed efficiency (based on RFI values). Genome-wide significant genetic variants could be then used as potential genetic or biomarkers in breeding programs for feed efficiency. The other objective was to reveal the biochemical mechanisms underlying genetic variation for pigs' feed efficiency. In order to achieve these objectives, we firstly conducted a metabolite genome-wide association study (mGWAS) based on mixed linear models and found 152 genome-wide significant SNPs (p-value < 1.06 × 10-6) in association with 17 metabolites that included 90 significant SNPs annotated to 52 genes. On chromosome one alone, 51 significant SNPs associated with isovalerylcarnitine and propionylcarnitine were found to be in strong linkage disequilibrium (LD). SNPs in strong LD annotated to FBXL4, and CCNC consisted of two haplotype blocks where three SNPs (ALGA0004000, ALGA0004041, and ALGA0004042) were in the intron regions of FBXL4 and CCNC. The interaction network revealed that CCNC and FBXL4 were linked by the hub gene N6AMT1 that was associated with isovalerylcarnitine and propionylcarnitine. Moreover, three metabolites (i.e., isovalerylcarnitine, propionylcarnitine, and pyruvic acid) were clustered in one group based on the low-high RFI pigs. This study performed a comprehensive metabolite-based genome-wide association study (GWAS) analysis for pigs with differences in feed efficiency and provided significant metabolites for which there is significant genetic variation as well as biological interaction networks. The identified metabolite genetic variants, genes, and networks in high versus low feed efficient pigs could be considered as potential genetic or biomarkers for feed efficiency.
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Affiliation(s)
| | - Haja N. Kadarmideen
- Quantitative Genomics, Bioinformatics and Computational Biology Group, Department of Applied Mathematics and Computer Science, Technical University of Denmark, Richard Petersens Plads, Building 324, 2800 Kongens Lyngby, Denmark;
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20
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Wilton KM, Morales‐Rosado JA, Selcen D, Muthusamy K, Ewing S, Agre K, Nickels K, Klee EW, Ho M, Morava E. Developmental brain abnormalities and acute encephalopathy in a patient with myopathy with extrapyramidal signs secondary to pathogenic variants in MICU1. JIMD Rep 2020; 53:22-28. [PMID: 32395406 PMCID: PMC7203647 DOI: 10.1002/jmd2.12114] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Revised: 02/09/2020] [Accepted: 03/03/2020] [Indexed: 01/01/2023] Open
Abstract
Mitochondria play a variety of roles in the cell, far beyond their widely recognized role in ATP generation. One such role is the regulation and sequestration of calcium, which is done with the help of the mitochondrial calcium uniporter (MCU) and its regulators, MICU1 and MICU2. Genetic variations in MICU1 and MICU2 have been reported to cause myopathy, developmental disability and neurological symptoms typical of mitochondrial disorders. The symptoms of MICU1/2 deficiency have generally been attributed to calcium regulation in the metabolic and biochemical roles of mitochondria. Here, we report a female child with heterozygous MICU1 variants and multiple congenital brain malformations on MRI. Specifically, she shows anterior perisylvian polymicrogyria, dysmorphic basal ganglia, and cerebellar dysplasia in addition to white matter abnormalities. These novel findings suggest that MICU1 is necessary for proper neurodevelopment through a variety of potential mechanisms, including calcium-mediated regulation of the neuronal cytoskeleton, Miro1-MCU complex-mediated mitochondrial movement, or enhancing ATP production. This case provides new insight into the molecular pathogenesis of MCU dysfunction and may represent a novel diagnostic feature of calcium-based mitochondrial disease.
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Affiliation(s)
- Katelynn M. Wilton
- Medical Scientist Training Program, Mayo Clinic Alix College of MedicineMayo ClinicRochesterMinnesotaUSA
| | - Joel A. Morales‐Rosado
- Center for Individualized MedicineMayo ClinicRochesterMinnesotaUSA
- Department of Health Science Research, Division of Biomedical Statistics and InformaticsMayo ClinicRochesterMinnesotaUSA
| | - Duygu Selcen
- Department of NeurologyMayo ClinicRochesterMinnesotaUSA
| | | | - Sarah Ewing
- Department of Clinical GenomicsMayo ClinicRochesterMinnesotaUSA
| | - Katherine Agre
- Department of Clinical GenomicsMayo ClinicRochesterMinnesotaUSA
| | | | - Eric W. Klee
- Center for Individualized MedicineMayo ClinicRochesterMinnesotaUSA
- Department of Health Science Research, Division of Biomedical Statistics and InformaticsMayo ClinicRochesterMinnesotaUSA
- Department of Clinical GenomicsMayo ClinicRochesterMinnesotaUSA
| | - Mai‐Lan Ho
- Department of RadiologyNationwide Children's HospitalColumbusOhioUSA
| | - Eva Morava
- Center for Individualized MedicineMayo ClinicRochesterMinnesotaUSA
- Department of Clinical GenomicsMayo ClinicRochesterMinnesotaUSA
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21
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Devyatkin VA, Muraleva NA, Kolosova NG. Identification of Single-Nucleotide Polymorphisms in Mitochondria-Associated Genes Capable of Affecting the Development of Hypertrophic Cardiomyopathy in Senescence-Accelerated OXYS Rats. ADVANCES IN GERONTOLOGY 2020. [DOI: 10.1134/s2079057020020058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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22
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Emperador S, Garrido-Pérez N, Amezcua-Gil J, Gaudó P, Andrés-Sanz JA, Yubero D, Fernández-Marmiesse A, O'Callaghan MM, Ortigoza-Escobar JD, Iriondo M, Ruiz-Pesini E, García-Cazorla A, Gil-Campos M, Artuch R, Montoya J, Bayona-Bafaluy MP. Molecular Characterization of New FBXL4 Mutations in Patients With mtDNA Depletion Syndrome. Front Genet 2020; 10:1300. [PMID: 31969900 PMCID: PMC6960396 DOI: 10.3389/fgene.2019.01300] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Accepted: 11/26/2019] [Indexed: 12/17/2022] Open
Abstract
Encephalomyopathic mitochondrial DNA (mtDNA) depletion syndrome 13 (MTDPS13) is a rare genetic disorder caused by defects in F-box leucine-rich repeat protein 4 (FBXL4). Although FBXL4 is essential for the bioenergetic homeostasis of the cell, the precise role of the protein remains unknown. In this study, we report two cases of unrelated patients presenting in the neonatal period with hyperlactacidemia and generalized hypotonia. Severe mtDNA depletion was detected in muscle biopsy in both patients. Genetic analysis showed one patient as having in compound heterozygosis a splice site variant c.858+5G>C and a missense variant c.1510T>C (p.Cys504Arg) in FBXL4. The second patient harbored a frameshift novel variant c.851delC (p.Pro284LeufsTer7) in homozygosis. To validate the pathogenicity of these variants, molecular and biochemical analyses were performed using skin-derived fibroblasts. We observed that the mtDNA depletion was less severe in fibroblasts than in muscle. Interestingly, the cells harboring a nonsense variant in homozygosis showed normal mtDNA copy number. Both patient fibroblasts, however, demonstrated reduced mitochondrial transcript quantity leading to diminished steady state levels of respiratory complex subunits, decreased respiratory complex IV (CIV) activity, and finally, low mitochondrial ATP levels. Both patients also revealed citrate synthase deficiency. Genetic complementation assays established that the deficient phenotype was rescued by the canonical version of FBXL4, confirming the pathological nature of the variants. Further analysis of fibroblasts allowed to establish that increased mitochondrial mass, mitochondrial fragmentation, and augmented autophagy are associated with FBXL4 deficiency in cells, but are probably secondary to a primary metabolic defect affecting oxidative phosphorylation.
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Affiliation(s)
- Sonia Emperador
- Departamento de Bioquímica, Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain.,Instituto de Investigación Sanitaria de Aragón (IIS-Aragón), Zaragoza, Spain.,Fundación ARAID, Universidad de Zaragoza, Zaragoza, Spain
| | - Nuria Garrido-Pérez
- Departamento de Bioquímica, Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain.,Instituto de Investigación Sanitaria de Aragón (IIS-Aragón), Zaragoza, Spain.,Fundación ARAID, Universidad de Zaragoza, Zaragoza, Spain
| | - Javier Amezcua-Gil
- Departamento de Bioquímica, Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain
| | - Paula Gaudó
- Departamento de Bioquímica, Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain
| | | | - Delia Yubero
- Clinical Biochemistry, Genetics, Pediatric Neurology and Neonatalogy Departments, Institut de Recerca Sant Joan de Déu, Barcelona, Spain.,Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Ana Fernández-Marmiesse
- Genomes&Disease Group, Molecular Medicine and Chronic Diseases Research Centre (CiMUS), Santiago de Compostela University-IDIS, Santiago de Compostela, Spain
| | - Maria M O'Callaghan
- Clinical Biochemistry, Genetics, Pediatric Neurology and Neonatalogy Departments, Institut de Recerca Sant Joan de Déu, Barcelona, Spain.,Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Juan D Ortigoza-Escobar
- Clinical Biochemistry, Genetics, Pediatric Neurology and Neonatalogy Departments, Institut de Recerca Sant Joan de Déu, Barcelona, Spain.,Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Marti Iriondo
- Clinical Biochemistry, Genetics, Pediatric Neurology and Neonatalogy Departments, Institut de Recerca Sant Joan de Déu, Barcelona, Spain.,Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Eduardo Ruiz-Pesini
- Departamento de Bioquímica, Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain.,Instituto de Investigación Sanitaria de Aragón (IIS-Aragón), Zaragoza, Spain.,Fundación ARAID, Universidad de Zaragoza, Zaragoza, Spain.,Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Angels García-Cazorla
- Clinical Biochemistry, Genetics, Pediatric Neurology and Neonatalogy Departments, Institut de Recerca Sant Joan de Déu, Barcelona, Spain.,Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Mercedes Gil-Campos
- Metabolism Unit, Reina Sofia University Clinical Hospital, Institute Maimónides of Biomedicine Investigation of Córdoba (IMIBIC), University of Córdoba, Córdoba, Spain.,CIBEROBN (Physiopathology of Obesity and Nutrition CB12/03/30038), Madrid, Spain
| | - Rafael Artuch
- Clinical Biochemistry, Genetics, Pediatric Neurology and Neonatalogy Departments, Institut de Recerca Sant Joan de Déu, Barcelona, Spain.,Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Julio Montoya
- Departamento de Bioquímica, Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain.,Instituto de Investigación Sanitaria de Aragón (IIS-Aragón), Zaragoza, Spain.,Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - María Pilar Bayona-Bafaluy
- Departamento de Bioquímica, Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain.,Instituto de Investigación Sanitaria de Aragón (IIS-Aragón), Zaragoza, Spain.,Centro de Investigaciones Biomédicas en Red de Enfermedades Raras (CIBERER), Madrid, Spain
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23
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Nardi N, Proulx F, Brunel-Guiton C, Oligny LL, Piché N, Mitchell GA, Joyal JS. Fulminant Necrotizing Enterocolitis and Multiple Organ Dysfunction in a Toddler with Mitochondrial DNA Depletion Syndrome-13. J Pediatr Intensive Care 2019; 9:54-59. [PMID: 31984159 DOI: 10.1055/s-0039-1697620] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Accepted: 08/15/2019] [Indexed: 12/13/2022] Open
Abstract
Necrotizing enterocolitis (NEC) is exceptional after the neonatal period. A toddler with encephalopathy, mitochondrial myopathy, and hypertrophic cardiomyopathy developed fatal NEC and multiple organ dysfunction within 48 hours of the introduction of enteral feeding. She was subsequently found to have pathogenic mutations in FBXL4 , a cause of mitochondrial DNA depletion syndrome-13. Intestinal dysmotility in the context of deficient mitochondrial respiration may have contributed to the development of NEC. Current paradigms call for early introduction of enteral nutrition to reinstate energy homeostasis. Enteral feeding should be administered with caution during metabolic crises of patients with mitochondrial DNA depletion syndromes.
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Affiliation(s)
- Nicolas Nardi
- Department of Pediatrics, Sainte-Justine Hospital, University of Montreal, Montreal, Canada
| | - François Proulx
- Department of Pediatrics, Sainte-Justine Hospital, University of Montreal, Montreal, Canada
| | | | - Luc L Oligny
- Department of Pediatric Pathology, Sainte-Justine Hospital, University of Montreal, Montreal, Canada
| | - Nelson Piché
- Department of Pediatric Surgery, Sainte-Justine Hospital, University of Montreal, Montreal, Canada
| | - Grant A Mitchell
- Department of Pediatrics, Sainte-Justine Hospital, University of Montreal, Montreal, Canada
| | - Jean Sébastien Joyal
- Department of Pediatrics, Sainte-Justine Hospital, University of Montreal, Montreal, Canada
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24
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Matsushima N, Takatsuka S, Miyashita H, Kretsinger RH. Leucine Rich Repeat Proteins: Sequences, Mutations, Structures and Diseases. Protein Pept Lett 2019; 26:108-131. [PMID: 30526451 DOI: 10.2174/0929866526666181208170027] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 11/26/2018] [Accepted: 11/26/2018] [Indexed: 12/18/2022]
Abstract
Mutations in the genes encoding Leucine Rich Repeat (LRR) containing proteins are associated with over sixty human diseases; these include high myopia, mitochondrial encephalomyopathy, and Crohn's disease. These mutations occur frequently within the LRR domains and within the regions that shield the hydrophobic core of the LRR domain. The amino acid sequences of fifty-five LRR proteins have been published. They include Nod-Like Receptors (NLRs) such as NLRP1, NLRP3, NLRP14, and Nod-2, Small Leucine Rich Repeat Proteoglycans (SLRPs) such as keratocan, lumican, fibromodulin, PRELP, biglycan, and nyctalopin, and F-box/LRR-repeat proteins such as FBXL2, FBXL4, and FBXL12. For example, 363 missense mutations have been identified. Replacement of arginine, proline, or cysteine by another amino acid, or the reverse, is frequently observed. The diverse effects of the mutations are discussed based on the known structures of LRR proteins. These mutations influence protein folding, aggregation, oligomerization, stability, protein-ligand interactions, disulfide bond formation, and glycosylation. Most of the mutations cause loss of function and a few, gain of function.
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Affiliation(s)
- Norio Matsushima
- Center for Medical Education, Sapporo Medical University, Sapporo 060-8556, Japan.,Institute of Tandem Repeats, Noboribetsu 059-0464, Japan
| | - Shintaro Takatsuka
- Center for Medical Education, Sapporo Medical University, Sapporo 060-8556, Japan
| | - Hiroki Miyashita
- Institute of Tandem Repeats, Noboribetsu 059-0464, Japan.,Hokubu Rinsho Co., Ltd, Sapporo 060-0061, Japan
| | - Robert H Kretsinger
- Department of Biology, University of Virginia, Charlottesville, VA 22904, United States
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25
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Holt RJ, Young RM, Crespo B, Ceroni F, Curry CJ, Bellacchio E, Bax DA, Ciolfi A, Simon M, Fagerberg CR, van Binsbergen E, De Luca A, Memo L, Dobyns WB, Mohammed AA, Clokie SJ, Zazo Seco C, Jiang YH, Sørensen KP, Andersen H, Sullivan J, Powis Z, Chassevent A, Smith-Hicks C, Petrovski S, Antoniadi T, Shashi V, Gelb BD, Wilson SW, Gerrelli D, Tartaglia M, Chassaing N, Calvas P, Ragge NK. De Novo Missense Variants in FBXW11 Cause Diverse Developmental Phenotypes Including Brain, Eye, and Digit Anomalies. Am J Hum Genet 2019; 105:640-657. [PMID: 31402090 PMCID: PMC6731360 DOI: 10.1016/j.ajhg.2019.07.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 07/09/2019] [Indexed: 12/20/2022] Open
Abstract
The identification of genetic variants implicated in human developmental disorders has been revolutionized by second-generation sequencing combined with international pooling of cases. Here, we describe seven individuals who have diverse yet overlapping developmental anomalies, and who all have de novo missense FBXW11 variants identified by whole exome or whole genome sequencing and not reported in the gnomAD database. Their phenotypes include striking neurodevelopmental, digital, jaw, and eye anomalies, and in one individual, features resembling Noonan syndrome, a condition caused by dysregulated RAS signaling. FBXW11 encodes an F-box protein, part of the Skp1-cullin-F-box (SCF) ubiquitin ligase complex, involved in ubiquitination and proteasomal degradation and thus fundamental to many protein regulatory processes. FBXW11 targets include β-catenin and GLI transcription factors, key mediators of Wnt and Hh signaling, respectively, critical to digital, neurological, and eye development. Structural analyses indicate affected residues cluster at the surface of the loops of the substrate-binding domain of FBXW11, and the variants are predicted to destabilize the protein and/or its interactions. In situ hybridization studies on human and zebrafish embryonic tissues demonstrate FBXW11 is expressed in the developing eye, brain, mandibular processes, and limb buds or pectoral fins. Knockdown of the zebrafish FBXW11 orthologs fbxw11a and fbxw11b resulted in embryos with smaller, misshapen, and underdeveloped eyes and abnormal jaw and pectoral fin development. Our findings support the role of FBXW11 in multiple developmental processes, including those involving the brain, eye, digits, and jaw.
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26
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Sabouny R, Wong R, Lee-Glover L, Greenway SC, Sinasac DS, Khan A, Shutt TE. Characterization of the C584R variant in the mtDNA depletion syndrome gene FBXL4, reveals a novel role for FBXL4 as a regulator of mitochondrial fusion. Biochim Biophys Acta Mol Basis Dis 2019; 1865:165536. [PMID: 31442532 DOI: 10.1016/j.bbadis.2019.165536] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 07/16/2019] [Accepted: 08/18/2019] [Indexed: 12/16/2022]
Abstract
Mutations in FBXL4 (F-Box and Leucine rich repeat protein 4), a nuclear-encoded mitochondrial protein with an unknown function, cause mitochondrial DNA depletion syndrome. We report two siblings, from consanguineous parents, harbouring a previously uncharacterized homozygous variant in FBXL4 (c.1750 T > C; p.Cys584Arg). Both patients presented with encephalomyopathy, lactic acidosis and cardiac hypertrophy, which are reported features of FBXL4 impairment. Remarkably, dichloroacetate (DCA) administration to the younger sibling improved metabolic acidosis and reversed cardiac hypertrophy. Characterization of FBXL4 patient fibroblasts revealed severe bioenergetic defects, mtDNA depletion, fragmentation of mitochondrial networks, and abnormalities in mtDNA nucleoids. These phenotypes, observed with other pathogenic FBXL4 variants, confirm the pathogenicity of the p.Cys584Arg variant. Although treating FBXL4 fibroblasts with DCA improved extracellular acidification, in line with reduced lactate levels in patients, DCA treatment did not improve any of the other mitochondrial functions. Nonetheless, we highlight DCA as a potentially effective drug for the management of elevated lactate and cardiomyopathy in patients with pathogenic FBXL4 variants. Finally, as the exact mechanism through which FBXL4 mutations lead to mtDNA depletion was unknown, we tested the hypothesis that FBXL4 promotes mitochondrial fusion. Using a photo-activatable GFP fusion assay, we found reduced mitochondrial fusion rates in cells harbouring a pathogenic FBXL4 variant. Meanwhile, overexpression of wildtype FBXL4, but not the p.Cys584Arg variant, promoted mitochondrial hyperfusion. Thus, we have uncovered a novel function for FBXL4 in promoting mitochondrial fusion, providing important mechanistic insights into the pathogenic mechanism underlying FBXL4 dysfunction.
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Affiliation(s)
- Rasha Sabouny
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada.
| | - Rachel Wong
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Laurie Lee-Glover
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Steven C Greenway
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada; Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - David S Sinasac
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | | | - Aneal Khan
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Timothy E Shutt
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
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27
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Niemi AK, Chock VY. Near-Infrared Spectroscopy in the Diagnostic Evaluation of Mitochondrial Disorders: A Neonatal Intensive Care Unit Case Series. J Pediatr 2019; 208:282-286. [PMID: 30853194 DOI: 10.1016/j.jpeds.2019.01.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 11/28/2019] [Accepted: 01/08/2019] [Indexed: 10/27/2022]
Abstract
We assessed the utility of near-infrared spectroscopy to evaluate neonates with mitochondrial disorders. We observed abnormally high cerebral oxygen saturation levels indicating insufficient tissue oxygen utilization. We propose that near-infrared spectroscopy may be an additional tool in the diagnostic evaluation of a suspected mitochondrial disorder.
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Affiliation(s)
- Anna-Kaisa Niemi
- Division of Neonatology, Rady Children's Hospital San Diego, University of California San Diego, San Diego, CA
| | - Valerie Y Chock
- Department of Pediatrics, Division of Neonatology, Stanford University, Stanford, CA
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28
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Li CJ, Chen CS, Yiang GT, Tsai APY, Liao WT, Wu MY. Advanced Evolution of Pathogenesis Concepts in Cardiomyopathies. J Clin Med 2019; 8:jcm8040520. [PMID: 30995779 PMCID: PMC6518034 DOI: 10.3390/jcm8040520] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 04/12/2019] [Accepted: 04/12/2019] [Indexed: 12/15/2022] Open
Abstract
Cardiomyopathy is a group of heterogeneous cardiac diseases that impair systolic and diastolic function, and can induce chronic heart failure and sudden cardiac death. Cardiomyopathy is prevalent in the general population, with high morbidity and mortality rates, and contributes to nearly 20% of sudden cardiac deaths in younger individuals. Genetic mutations associated with cardiomyopathy play a key role in disease formation, especially the mutation of sarcomere encoding genes and ATP kinase genes, such as titin, lamin A/C, myosin heavy chain 7, and troponin T1. Pathogenesis of cardiomyopathy occurs by multiple complex steps involving several pathways, including the Ras-Raf-mitogen-activated protein kinase-extracellular signal-activated kinase pathway, G-protein signaling, mechanotransduction pathway, and protein kinase B/phosphoinositide 3-kinase signaling. Excess biomechanical stress induces apoptosis signaling in cardiomyocytes, leading to cell loss, which can induce myocardial fibrosis and remodeling. The clinical features and pathophysiology of cardiomyopathy are discussed. Although several basic and clinical studies have investigated the mechanism of cardiomyopathy, the detailed pathophysiology remains unclear. This review summarizes current concepts and focuses on the molecular mechanisms of cardiomyopathy, especially in the signaling from mutation to clinical phenotype, with the aim of informing the development of therapeutic interventions.
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Affiliation(s)
- Chia-Jung Li
- Department of Obstetrics and Gynecology, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan.
| | - Chien-Sheng Chen
- Department of Emergency Medicine, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei 231, Taiwan.
- Department of Emergency Medicine, School of Medicine, Tzu Chi University, Hualien 970, Taiwan.
| | - Giou-Teng Yiang
- Department of Emergency Medicine, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei 231, Taiwan.
- Department of Emergency Medicine, School of Medicine, Tzu Chi University, Hualien 970, Taiwan.
| | - Andy Po-Yi Tsai
- Department of Medical Research, Buddhist Tzu Chi General Hospital, Hualien 970, Taiwan.
| | - Wan-Ting Liao
- Institute of Medicine, Chung Shan Medical University, Taichung 402, Taiwan.
- Chinese Medicine Department, Show Chwan Memorial Hospital, Changhua 500, Taiwan.
| | - Meng-Yu Wu
- Department of Emergency Medicine, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei 231, Taiwan.
- Department of Emergency Medicine, School of Medicine, Tzu Chi University, Hualien 970, Taiwan.
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29
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Whole exome sequencing revealed mutations in FBXL4, UNC80, and ADK in Thai patients with severe intellectual disabilities. Gene 2019; 696:21-27. [PMID: 30771478 DOI: 10.1016/j.gene.2019.01.049] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 12/25/2018] [Accepted: 01/04/2019] [Indexed: 01/20/2023]
Abstract
Intellectual disabilities (ID) are etiologically heterogeneous. Advanced molecular techniques could be helpful in identification of the underlying genetic defects. We aimed to characterize clinical and molecular features of three Thai patients with ID. Patient 1 had ID, hypotonia and lactic acidosis. Patient 2 had ID and growth failure. Patient 3 had ID, seizure, diarrhea and hypoglycemia. Whole exome sequencing found that Patient 1 was homozygous for a nonsense, c.1303C>T (p.Arg435Ter), mutation in FBXL4, a gene responsible for encephalomyopathic mitochondrial DNA depletion syndrome-13 (MTDPS13). Patient 2 was compound heterozygous for two novel mutations, c.3226C>T (p.Arg1076Ter) and c.3205C>T (p.Arg1069Ter), in UNC80, a known gene of infantile hypotonia with psychomotor retardation and characteristic facies-2 (IHPRF2). Patient 3 was homozygous for a novel missense, c.427T>C (p.Cys143Arg), mutation in ADK, a known gene of adenosine kinase deficiency leading to hypermethioninemia. This study expands the mutational spectra of ID genes.
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30
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Ballout RA, Al Alam C, Bonnen PE, Huemer M, El-Hattab AW, Shbarou R. FBXL4-Related Mitochondrial DNA Depletion Syndrome 13 (MTDPS13): A Case Report With a Comprehensive Mutation Review. Front Genet 2019; 10:39. [PMID: 30804983 PMCID: PMC6370620 DOI: 10.3389/fgene.2019.00039] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 01/18/2019] [Indexed: 01/28/2023] Open
Abstract
Mitochondrial DNA depletion syndromes (MTDPS) are a group of rare genetic disorders caused by defects in multiple genes involved in mitochondrial DNA (mtDNA) maintenance. Among those, FBXL4 mutations result in the encephalomyopathic mtDNA depletion syndrome 13 (MTDPS13; OMIM #615471), which commonly presents as a combination of failure to thrive, neurodevelopmental delays, encephalopathy, hypotonia, and persistent lactic acidosis. We report here the case of a Lebanese infant presenting to us with profound neurodevelopmental delays, generalized hypotonia, facial dysmorphic features, and extreme emaciation. Whole-exome sequencing (WES) showed the girl as having MTDPS13 with an underlying FBXL4 missense mutation that has been previously reported only twice in unrelated individuals (c.1303C > T). Comprehensive literature search marked our patient as being the 94th case of MTDPS13 reported to date worldwide, and the first from Lebanon. We include at the end of this report a comprehensive mutation review table of all the pathological FBXL4 mutations reported in the literature, using it to highlight, for the first time, a possible founder effect of Arab origins to the disorder, being most prevalent in patients of Arab descent as shown in our mutation table. Finally, we provide a direct comparison of the disorder's clinical manifestations across two unrelated patients harboring the same disease-causing mutation as our patient, emphasizing the remarkable variability in genotype-to-phenotype correlation characteristic of the disease.
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Affiliation(s)
- Rami A Ballout
- Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Chadi Al Alam
- Division of Pediatric Neurology, Department of Pediatrics, American University of Beirut Medical Center, Beirut, Lebanon
| | - Penelope E Bonnen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Martina Huemer
- Department of Pediatrics, Landeskrankenhaus Bregenz, Bregenz, Austria.,Division of Metabolism, University Children's Hospital Zürich, Zurich, Switzerland
| | - Ayman W El-Hattab
- Genetics Clinic, KidsHeart Medical Center, Dubai, United Arab Emirates
| | - Rolla Shbarou
- Division of Pediatric Neurology, Department of Pediatrics, American University of Beirut Medical Center, Beirut, Lebanon
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31
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El-Hattab AW, Suleiman J, Almannai M, Scaglia F. Mitochondrial dynamics: Biological roles, molecular machinery, and related diseases. Mol Genet Metab 2018; 125:315-321. [PMID: 30361041 DOI: 10.1016/j.ymgme.2018.10.003] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 10/15/2018] [Indexed: 01/09/2023]
Abstract
Mitochondria are dynamic organelles that undergo fusion, fission, movement, and mitophagy. These processes are essential to maintain the normal mitochondrial morphology, distribution, and function. Mitochondrial fusion allows the exchange of intramitochondrial material, whereas the fission process is required to replicate the mitochondria during cell division, facilitate the transport and distribution of mitochondria, and allow the isolation of damaged organelles. Mitochondrial mobility is essential for mitochondrial distribution depending on the cellular metabolic demands. Mitophagy is needed for the elimination of dysfunctional and damaged mitochondria to maintain a healthy mitochondrial population. The mitochondrial dynamic processes are mediated by a number of nuclear-encoded proteins that function in mitochondrial transport, fusion, fission, and mitophagy. Disorders of mitochondrial dynamics are caused by pathogenic variants in the genes encoding these proteins. These diseases have a high clinical variability, and range in severity from isolated optic atrophy to lethal encephalopathy. These disorders include defects in mitochondrial fusion (caused by pathogenic variants in MFN2, OPA1, YME1L1, MSTO1, and FBXL4), mitochondrial fission (caused by pathogenic variants in DNM1L and MFF), and mitochondrial autophagy (caused by pathogenic variants in PINK1 and PRKN). In this review, the molecular machinery and biological roles of mitochondrial dynamic processes are discussed. Subsequently, the currently known diseases related to mitochondrial dynamic defects are presented.
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Affiliation(s)
- Ayman W El-Hattab
- Division of Clinical Genetics and Metabolic Disorders, Pediatrics Department, Tawam Hospital, Al-Ain, United Arab Emirates
| | - Jehan Suleiman
- Division of Neurology, Pediatrics Department, Tawam Hospital, Al Ain, United Arab Emirates
| | - Mohammed Almannai
- Medical Genetics Division, King Fahad Medical City, Riyadh, Saudi Arabia
| | - Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Texas Children's Hospital, Houston, TX, USA; Joint BCM-CUHK Center of Medical Genetics, Prince of Wales Hospital, ShaTin, Hong Kong Special Administrative Region.
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32
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McCormick EM, Zolkipli-Cunningham Z, Falk MJ. Mitochondrial disease genetics update: recent insights into the molecular diagnosis and expanding phenotype of primary mitochondrial disease. Curr Opin Pediatr 2018; 30:714-724. [PMID: 30199403 PMCID: PMC6467265 DOI: 10.1097/mop.0000000000000686] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
PURPOSE OF REVIEW Primary mitochondrial disease (PMD) is a genetically and phenotypically diverse group of inherited energy deficiency disorders caused by impaired mitochondrial oxidative phosphorylation (OXPHOS) capacity. Mutations in more than 350 genes in both mitochondrial and nuclear genomes are now recognized to cause primary mitochondrial disease following every inheritance pattern. Next-generation sequencing technologies have dramatically accelerated mitochondrial disease gene discovery and diagnostic yield. Here, we provide an up-to-date review of recently identified, novel mitochondrial disease genes and/or pathogenic variants that directly impair mitochondrial structure, dynamics, and/or function. RECENT FINDINGS A review of PubMed publications was performed from the past 12 months that identified 16 new PMD genes and/or pathogenic variants, and recognition of expanded phenotypes for a wide variety of mitochondrial disease genes. SUMMARY Broad-based exome sequencing has become the standard first-line diagnostic approach for PMD. This has facilitated more rapid and accurate disease identification, and greatly expanded understanding of the wide spectrum of potential clinical phenotypes. A comprehensive dual-genome sequencing approach to PMD diagnosis continues to improve diagnostic yield, advance understanding of mitochondrial physiology, and provide strong potential to develop precision therapeutics targeted to diverse aspects of mitochondrial disease pathophysiology.
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Affiliation(s)
- Elizabeth M. McCormick
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, The Children’s Hospital of Philadelphia, PA 19104
| | - Zarazuela Zolkipli-Cunningham
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, The Children’s Hospital of Philadelphia, PA 19104
| | - Marni J. Falk
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, The Children’s Hospital of Philadelphia, PA 19104
- Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104
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33
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Mitochondrial DNA replication: clinical syndromes. Essays Biochem 2018; 62:297-308. [PMID: 29950321 DOI: 10.1042/ebc20170101] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 03/17/2018] [Accepted: 05/23/2018] [Indexed: 02/08/2023]
Abstract
Each nucleated cell contains several hundreds of mitochondria, which are unique organelles in being under dual genome control. The mitochondria contain their own DNA, the mtDNA, but most of mitochondrial proteins are encoded by nuclear genes, including all the proteins required for replication, transcription, and repair of mtDNA. MtDNA replication is a continuous process that requires coordinated action of several enzymes that are part of the mtDNA replisome. It also requires constant supply of deoxyribonucleotide triphosphates(dNTPs) and interaction with other mitochondria for mixing and unifying the mitochondrial compartment. MtDNA maintenance defects are a growing list of disorders caused by defects in nuclear genes involved in different aspects of mtDNA replication. As a result of defects in these genes, mtDNA depletion and/or multiple mtDNA deletions develop in affected tissues resulting in variable manifestations that range from adult-onset mild disease to lethal presentation early in life.
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34
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Natural history of mitochondrial disorders: a systematic review. Essays Biochem 2018; 62:423-442. [DOI: 10.1042/ebc20170108] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 05/09/2018] [Accepted: 05/15/2018] [Indexed: 11/17/2022]
Abstract
The natural history of a disease defines the age of onset, presenting features, clinical phenotype, morbidity and mortality outcomes of disease that is unmodified by treatments. A clear understanding of the natural history of mitochondrial disorders is essential for establishing genotype-phenotype–prognosis correlations. We performed a systematic review of the reported natural history of mitochondrial disease by searching the literature for all published natural history studies containing at least 20 individuals. We defined a phenotype as ‘common’ if it was observed in ≥30% of cases in a study, thereby highlighting common and uncommon phenotypes for each disorder. Thirty-seven natural history studies were identified encompassing 29 mitochondrial disease entities. Fifty-nine percent of disorders had an onset before 18 months and 81% before 18 years. Most disorders had multisystemic involvement and most often affected were the central nervous system, eyes, gastrointestinal system, skeletal muscle, auditory system and the heart. Less frequent involvement was seen for respiratory, renal, endocrine, hepatic, haematological and genitourinary systems. Elevated lactate was the most frequent biochemical abnormality, seen in 72% of disorders. Age of death was <1 y in 13% of disorders, <5 y in 57% and <10 y in 74%. Disorders with high mortality rates were generally associated with earlier deaths. The most robust indicators of poor prognosis were early presentation of disease and truncating mutations. A thorough knowledge of natural history has helped to redefine diagnostic criteria for classical clinical syndromes and to establish a clinical baseline for comparison in single-arm clinical trials of novel therapies.
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