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Molecular Genetics and Metabolism 2020Mitochondrial respiratory chain integrity depends on a number of proteins encoded by nuclear and mitochondrial genomes. Mutations of such factors can result in isolated...
Mitochondrial respiratory chain integrity depends on a number of proteins encoded by nuclear and mitochondrial genomes. Mutations of such factors can result in isolated or combined respiratory chain deficits, some of which can induce abnormal morphology of the mitochondrial network or accumulation of intermediary metabolites. Consequently, affected patients are clinically heterogeneous, presenting with central nervous system, muscular, or neurodegenerative disorders. ATAD3A is a nuclear-encoded ATPase protein of the AAA+ family and has been localized to the inner mitochondrial membrane. Recently reported mutations or large deletions in the ATDA3A gene in patients have been shown to induce altered mitochondrial structure and function and abnormal cholesterol metabolism in a recessive or dominant manner. Here, we report two siblings presenting axonal sensory-motor neuropathy associated with neonatal cataract. Genetic analyses identified two novel mutations in ATAD3A; a point mutation and an intronic 15 bp deletion affecting splicing and leading to exon skipping. Biochemical analysis in patient cells and tissues showed abnormal function of the mitochondrial respiratory chain in muscle and abnormal mitochondrial cristae structure. These new cases underline the large spectrum of biochemical and clinical presentations of ATAD3A deficiency and the different modes of inheritance, making it an atypical mitochondrial disorder.
Topics: ATPases Associated with Diverse Cellular Activities; Adolescent; Adult; Child; Child, Preschool; Electron Transport; Female; Humans; Male; Membrane Proteins; Mitochondria; Mitochondrial Diseases; Mitochondrial Proteins; Mutation; Sensorimotor Cortex; Siblings
PubMed: 32933822
DOI: 10.1016/j.ymgme.2020.09.002 -
Stem Cell Research & Therapy Aug 2022Mesenchymal stem cells (MSCs) have been extensively used for the treatment of various diseases in preclinical and clinical trials. In vitro propagation is needed to...
BACKGROUND
Mesenchymal stem cells (MSCs) have been extensively used for the treatment of various diseases in preclinical and clinical trials. In vitro propagation is needed to attain enough cells for clinical use. However, cell aging and viability reduction caused by long-time culture have not been thoroughly investigated, especially for the function of mitochondria and lysosomes. Therefore, this study was designed to detect mitochondrial and lysosomal activity, morphological and functional changes in human umbilical cord MSCs (UMSCs) after long-time culture.
METHODS
First, we examined cell activities, including proliferation and immigration ability, differentiation potential, and immunosuppressive capacity of UMSCs at an early and late passages as P4 (named UMSC-P4) and P9 (named UMSC-P9), respectively. Then, we compared the mitochondrial morphology of UMSC-P4 and UMSC-P9 using the electronic microscope and MitoTracker Red dyes. Furthermore, we investigated mitochondrial function, including mitochondrial membrane potential, antioxidative ability, apoptosis, and ferroptosis detected by respective probe. Cell energy metabolism was tested by mass spectrometry. In addition, we compared the lysosomal morphology of UMSC-P4 and UMSC-P9 by electronic microscope and lysoTracker Red dyes. Finally, the transcriptome sequence was performed to analyze the total gene expression of these cells.
RESULTS
It was found that UMSC-P9 exhibited a reduced biological activity and showed an impaired mitochondrial morphology with disordered structure, reduced mitochondrial crista, and mitochondrial fragments. They also displayed decreased mitochondrial membrane potential, antioxidative ability, tricarboxylic acid cycle activity and energy production. At the same time, apoptosis and ferroptosis were increased. In addition, UMSC-P9, relative to UMSC-P4, showed undegraded materials in their lysosomes, the enhancement in lysosomal membrane permeability, the reduction in autophagy and phagocytosis. Moreover, transcriptome sequence analysis also revealed a reduction of cell function, metabolism, mitochondrial biogenesis, DNA replication and repair, and an increase of gene expression related to cell senescence, cancer, diseases, and infection in UMSC-P9.
CONCLUSION
This study indicates that in vitro long-time culturing of MSCs can cause mitochondrial and lysosomal dysfunction, probably contributing to the decline of cell activity and cell aging. Therefore, the morphology and function of mitochondria and lysosomes can be regarded as two important parameters to monitor cell viability, and they can also serve as two important indicators for optimizing in vitro culture conditions.
Topics: Coloring Agents; Humans; Lysosomes; Mesenchymal Stem Cells; Mitochondria; Umbilical Cord
PubMed: 35964126
DOI: 10.1186/s13287-022-03107-4 -
European Journal of Cell Biology Dec 2023This review provides an overview of the current methods for quantifying mitochondrial ultrastructure, including cristae morphology, mitochondrial contact sites, and... (Review)
Review
This review provides an overview of the current methods for quantifying mitochondrial ultrastructure, including cristae morphology, mitochondrial contact sites, and recycling machinery and a guide to utilizing electron microscopy to effectively measure these organelles. Quantitative analysis of mitochondrial ultrastructure is essential for understanding mitochondrial biology and developing therapeutic strategies for mitochondrial-related diseases. Techniques such as transmission electron microscopy (TEM) and serial block face-scanning electron microscopy, as well as how they can be combined with other techniques including confocal microscopy, super-resolution microscopy, and correlative light and electron microscopy are discussed. Beyond their limitations and challenges, we also offer specific magnifications that may be best suited for TEM analysis of mitochondrial, endoplasmic reticulum, and recycling machinery. Finally, perspectives on future quantification methods are offered.
Topics: Microscopy, Electron, Scanning; Mitochondria; Microscopy, Electron, Transmission; Endoplasmic Reticulum
PubMed: 37864884
DOI: 10.1016/j.ejcb.2023.151365 -
European Journal of Medical Research Jul 2023Mitochondria play a pivotal role in physiological and metabolic function of the cell. Mitochondrial dynamics orchestrate mitochondrial function and morphology, involving...
Mitochondria play a pivotal role in physiological and metabolic function of the cell. Mitochondrial dynamics orchestrate mitochondrial function and morphology, involving fission and fusion as well as ultrastructural remodeling. Mounting evidence unravels the close link between mitochondria and endometriosis. However, how mitochondrial architecture changes through fission and fusion in eutopic and ectopic tissues of women with ovarian endometriosis remains unknown. We detected the expression of fission and fusion genes and the morphology of mitochondria in eutopic and ectopic endometrium in ovarian endometriosis. The results showed that the expression of DRP1 and LCLAT1 was upregulated in eutopic endometrial stromal cells (ESCs), and the expression of DRP1, OPA1, MFN1, MFN2, and LCLAT1 was significantly downregulated in ectopic ESCs, and reduced number of mitochondria, wider cristae width and narrower cristae junction width was observed, but there was no difference in cell survival rate. The altered mitochondrial dynamics and morphology might, respectively, provide an advantage for migration and adhesion in eutopic ESCs and be the adaptive response in ectopic endometrial cells to survive under hypoxic and oxidative stress environment.
Topics: Female; Humans; Endometriosis; Mitochondria; Cell Survival; Endometrium; Hypoxia
PubMed: 37393390
DOI: 10.1186/s40001-023-01180-w -
Scientific Reports Aug 2019Mitochondria are highly dynamic organelles that exhibit a complex inner architecture. They exhibit a smooth outer membrane and a highly convoluted inner membrane that...
Mitochondria are highly dynamic organelles that exhibit a complex inner architecture. They exhibit a smooth outer membrane and a highly convoluted inner membrane that forms invaginations called cristae. Imaging cristae in living cells poses a formidable challenge for super-resolution light microscopy. Relying on a cell line stably expressing the mitochondrial protein COX8A fused to the SNAP-tag and using STED (stimulated emission depletion) nanoscopy, we demonstrate the visualization of cristae dynamics in cultivated human cells. We show that in human HeLa cells lamellar cristae are often arranged in groups separated by voids that are generally occupied by mitochondrial nucleoids.
Topics: HeLa Cells; Humans; Mitochondria; Mitochondrial Membranes
PubMed: 31455826
DOI: 10.1038/s41598-019-48838-2 -
Current Opinion in Cell Biology Aug 2017Mitochondria evolved as an endosymbiont providing the cell with a dizzying array of catabolic and anabolic processes essential for life. However, mitochondria have... (Review)
Review
Mitochondria evolved as an endosymbiont providing the cell with a dizzying array of catabolic and anabolic processes essential for life. However, mitochondria have retained the ability to kill from within, and are widely considered the final executioners of programmed cell death. The groundbreaking discovery over 25 years ago that mitochondrial cytochrome c is released into the cytosol shone new and unexpected light onto this old organelle, revitalizing the field. The Bcl-2 family of proteins plays a central role in the maintenance of mitochondrial membrane integrity, but other factors are also involved in the cell death program. Indeed, contacts with the endoplasmic reticulum (ER), mitochondrial division and inner membrane cristae remodeling have emerged as key regulators of cytochrome c release. This review will focus on recent progress to define the functional contribution of the apoptotic ER/mitochondrial interface, which couples mitochondrial fission and cristae remodeling to calcium and lipid fluxes.
Topics: Animals; Apoptosis; Calcium; Cytosol; Endoplasmic Reticulum; Humans; Mitochondria; Mitochondrial Dynamics; Mitochondrial Membranes
PubMed: 28391089
DOI: 10.1016/j.ceb.2017.03.007 -
Journal of Cell Science Feb 2023Mitochondria and peroxisomes are dynamic signaling organelles that constantly undergo fission, driven by the large GTPase dynamin-related protein 1 (DRP1; encoded by...
Mitochondria and peroxisomes are dynamic signaling organelles that constantly undergo fission, driven by the large GTPase dynamin-related protein 1 (DRP1; encoded by DNM1L). Patients with de novo heterozygous missense mutations in DNM1L present with encephalopathy due to defective mitochondrial and peroxisomal fission (EMPF1) - a devastating neurodevelopmental disease with no effective treatment. To interrogate the mechanisms by which DRP1 mutations cause cellular dysfunction, we used human-derived fibroblasts from patients who present with EMPF1. In addition to elongated mitochondrial morphology and lack of fission, patient cells display lower coupling efficiency, increased proton leak and upregulation of glycolysis. Mitochondrial hyperfusion also results in aberrant cristae structure and hyperpolarized mitochondrial membrane potential. Peroxisomes show a severely elongated morphology in patient cells, which is associated with reduced respiration when cells are reliant on fatty acid oxidation. Metabolomic analyses revealed impaired methionine cycle and synthesis of pyrimidine nucleotides. Our study provides insight into the role of mitochondrial dynamics in cristae maintenance and the metabolic capacity of the cell, as well as the disease mechanism underlying EMPF1.
Topics: Humans; Membrane Potential, Mitochondrial; Dynamins; Brain Diseases; GTP Phosphohydrolases; Mutation; Mitochondria; Mitochondrial Dynamics; Mitochondrial Proteins
PubMed: 36763487
DOI: 10.1242/jcs.260370 -
Biochimica Et Biophysica Acta 2006Three-dimensional images of mitochondria provided by electron tomography reveal that the micro-compartments (cristae) defined by the inner membrane are connected to the... (Review)
Review
Three-dimensional images of mitochondria provided by electron tomography reveal that the micro-compartments (cristae) defined by the inner membrane are connected to the periphery of this membrane by narrow tubular junctions, which likely restrict diffusion. The tomograms also strongly suggest that inner membrane topology represents a balance between membrane fusion and fission processes. The hypothesis being developed is that inner membrane topology is a regulated property of mitochondria. This review summarizes the evidence about how inner membrane shape influences mitochondrial function and, conversely, what is known about the factors that determine this membrane's topology.
Topics: Animals; Mitochondrial Membranes; Submitochondrial Particles
PubMed: 16730811
DOI: 10.1016/j.bbamcr.2006.04.006 -
The International Journal of... Mar 2020Mitochondria are known as dynamic organelles that fuse and divide under the control of certain proteins. These dynamics are important to shape mitochondria, maintain a...
Mitochondria are known as dynamic organelles that fuse and divide under the control of certain proteins. These dynamics are important to shape mitochondria, maintain a healthy mitochondrial population, and enable physiological adaptations, to name just a few key processes. We are less aware that mitochondrial membrane lipids and proteins also exhibit dynamics in terms of lateral mobility and translocation. This single molecule dynamics is equally important for the above processes as it enables interaction with other proteins and complexes. Here we discuss some mitochondrial proteins and the role of their specific dynamic spatiotemporal organization for function and adaptation. For example, respiratory proteins are preferentially localized in cristae sheets, ATP synthase at the edges of cristae and compounds of the MICOS complex at cristae junctions. Trajectory patterns show how and whether molecules are restricted in their mobility and how this determines their distribution. The formation of supercomplexes has an influence on this. Recent studies have also shown that the distribution of proteins is not absolutely static. For example, the metabolic state of the cell obviously determines the activity of the mitochondria and finally the organization of the bioenergetic and structure-determining proteins inside. The ATP synthase has both classifications and additionally shows functional interactions with other cristae shaping proteins at cristae junctions. To understand the dynamics of mitochondria we have to consider all scales: from the dynamics of the molecular structure of the proteins to the dynamics of the molecules with respect to their localization and lateral mobility to the dynamics of the organelle structure.
Topics: Humans; Mitochondria; Mitochondrial Membranes; Mitochondrial Proteins; Mitochondrial Proton-Translocating ATPases; Oxidative Phosphorylation
PubMed: 31931164
DOI: 10.1016/j.biocel.2020.105694 -
Philosophical Transactions of the Royal... Aug 2017The permeabilization of the mitochondrial outer membrane by Bax and Bak during apoptosis is considered a key step and a point of no return in the signalling pathway. It... (Review)
Review
The permeabilization of the mitochondrial outer membrane by Bax and Bak during apoptosis is considered a key step and a point of no return in the signalling pathway. It is always closely related to the reorganization of mitochondrial cristae that frees cytochrome to the intermembrane space and to massive mitochondrial fragmentation mediated by the dynamin-like protein Drp1. Despite multiple evidence in favour of a functional link between these processes, the molecular mechanisms that connect them and their relevance for efficient apoptosis signalling remain obscure. In this review, we discuss recent progress on our understanding of how Bax forms pores in the context of Drp1-stabilized signalling platforms at apoptotic foci in mitochondria.This article is part of the themed issue 'Membrane pores: from structure and assembly, to medicine and technology'.
Topics: Animals; Apoptosis; Mitochondria; Mitochondrial Membranes; Signal Transduction; bcl-2-Associated X Protein
PubMed: 28630156
DOI: 10.1098/rstb.2016.0217