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Cells Apr 2019Mitochondrion harbors its own DNA (mtDNA), which encodes many critical proteins for the assembly and activity of mitochondrial respiratory complexes. mtDNA is packed by... (Review)
Review
Mitochondrion harbors its own DNA (mtDNA), which encodes many critical proteins for the assembly and activity of mitochondrial respiratory complexes. mtDNA is packed by many proteins to form a nucleoid that uniformly distributes within the mitochondrial matrix, which is essential for mitochondrial functions. Defects or mutations of mtDNA result in a range of diseases. Damaged mtDNA could be eliminated by mitophagy, and all paternal mtDNA are degraded by endonuclease G or mitophagy during fertilization. In this review, we describe the role and mechanism of mtDNA distribution and elimination. In particular, we focus on the regulation of paternal mtDNA elimination in the process of fertilization.
Topics: DNA, Mitochondrial; Humans; Mitochondria; Mitophagy; Mutation
PubMed: 31027297
DOI: 10.3390/cells8040379 -
International Journal of Molecular... Apr 2021Epigenetic modifications of the nuclear genome, including DNA methylation, histone modifications and non-coding RNA post-transcriptional regulation, are increasingly... (Review)
Review
Epigenetic modifications of the nuclear genome, including DNA methylation, histone modifications and non-coding RNA post-transcriptional regulation, are increasingly being involved in the pathogenesis of several human diseases. Recent evidence suggests that also epigenetic modifications of the mitochondrial genome could contribute to the etiology of human diseases. In particular, altered methylation and hydroxymethylation levels of mitochondrial DNA (mtDNA) have been found in animal models and in human tissues from patients affected by cancer, obesity, diabetes and cardiovascular and neurodegenerative diseases. Moreover, environmental factors, as well as nuclear DNA genetic variants, have been found to impair mtDNA methylation patterns. Some authors failed to find DNA methylation marks in the mitochondrial genome, suggesting that it is unlikely that this epigenetic modification plays any role in the control of the mitochondrial function. On the other hand, several other studies successfully identified the presence of mtDNA methylation, particularly in the mitochondrial displacement loop (D-loop) region, relating it to changes in both mtDNA gene transcription and mitochondrial replication. Overall, investigations performed until now suggest that methylation and hydroxymethylation marks are present in the mtDNA genome, albeit at lower levels compared to those detectable in nuclear DNA, potentially contributing to the mitochondria impairment underlying several human diseases.
Topics: Animals; DNA Methylation; DNA Replication; DNA, Mitochondrial; Epigenesis, Genetic; Gene Expression Regulation; Genome, Mitochondrial; Humans; Mitochondria; Mitochondrial Diseases; Protein Processing, Post-Translational
PubMed: 33925624
DOI: 10.3390/ijms22094594 -
Experimental & Molecular Medicine Mar 2023In addition to constituting the genetic material of an organism, DNA is a tracer for the recognition of foreign pathogens and a trigger of the innate immune system. cGAS... (Review)
Review
In addition to constituting the genetic material of an organism, DNA is a tracer for the recognition of foreign pathogens and a trigger of the innate immune system. cGAS functions as a sensor of double-stranded DNA fragments and initiates an immune response via the adaptor protein STING. The cGAS-STING pathway not only defends cells against various DNA-containing pathogens but also modulates many pathological processes caused by the immune response to the ectopic localization of self-DNA, such as cytosolic mitochondrial DNA (mtDNA) and extranuclear chromatin. In addition, macrophages can cause inflammation by forming a class of protein complexes called inflammasomes, and the activation of the NLRP3 inflammasome requires the release of oxidized mtDNA. In innate immunity related to inflammasomes, mtDNA release is mediated by macropores that are formed on the outer membrane of mitochondria via VDAC oligomerization. These macropores are specifically formed in response to mitochondrial stress and tissue damage, and the inhibition of VDAC oligomerization mitigates this inflammatory response. The rapidly expanding area of research on the mechanisms by which mtDNA is released and triggers inflammation has revealed new treatment strategies not only for inflammation but also, surprisingly, for neurodegenerative diseases such as amyotrophic lateral sclerosis.
Topics: Humans; DNA, Mitochondrial; Immunity, Innate; Inflammasomes; Inflammation; Mitochondria; Nucleotidyltransferases; Signal Transduction; Membrane Proteins
PubMed: 36964253
DOI: 10.1038/s12276-023-00965-7 -
Biochimica Et Biophysica Acta.... Jun 2017The maintenance of mitochondrial DNA (mtDNA) depends on a number of nuclear gene-encoded proteins including a battery of enzymes forming the replisome needed to... (Review)
Review
The maintenance of mitochondrial DNA (mtDNA) depends on a number of nuclear gene-encoded proteins including a battery of enzymes forming the replisome needed to synthesize mtDNA. These enzymes need to be in balanced quantities to function properly that is in part achieved by exchanging intramitochondrial contents through mitochondrial fusion. In addition, mtDNA synthesis requires a balanced supply of nucleotides that is achieved by nucleotide recycling inside the mitochondria and import from the cytosol. Mitochondrial DNA maintenance defects (MDMDs) are a group of diseases caused by pathogenic variants in the nuclear genes involved in mtDNA maintenance resulting in impaired mtDNA synthesis leading to quantitative (mtDNA depletion) and qualitative (multiple mtDNA deletions) defects in mtDNA. Defective mtDNA leads to organ dysfunction due to insufficient mtDNA-encoded protein synthesis, resulting in an inadequate energy production to meet the needs of affected organs. MDMDs are inherited as autosomal recessive or dominant traits, and are associated with a broad phenotypic spectrum ranging from mild adult-onset ophthalmoplegia to severe infantile fatal hepatic failure. To date, pathogenic variants in 20 nuclear genes known to be crucial for mtDNA maintenance have been linked to MDMDs, including genes encoding enzymes of mtDNA replication machinery (POLG, POLG2, TWNK, TFAM, RNASEH1, MGME1, and DNA2), genes encoding proteins that function in maintaining a balanced mitochondrial nucleotide pool (TK2, DGUOK, SUCLG1, SUCLA2, ABAT, RRM2B, TYMP, SLC25A4, AGK, and MPV17), and genes encoding proteins involved in mitochondrial fusion (OPA1, MFN2, and FBXL4).
Topics: Animals; DNA Damage; DNA, Mitochondrial; Humans; Mitochondrial Diseases; Mitochondrial Proteins
PubMed: 28215579
DOI: 10.1016/j.bbadis.2017.02.017 -
Cells Jan 2019As the primary cellular location for respiration and energy production, mitochondria serve in a critical capacity to the cell. Yet, by virtue of this very function of... (Review)
Review
As the primary cellular location for respiration and energy production, mitochondria serve in a critical capacity to the cell. Yet, by virtue of this very function of respiration, mitochondria are subject to constant oxidative stress that can damage one of the unique features of this organelle, its distinct genome. Damage to mitochondrial DNA (mtDNA) and loss of mitochondrial genome integrity is increasingly understood to play a role in the development of both severe early-onset maladies and chronic age-related diseases. In this article, we review the processes by which mtDNA integrity is maintained, with an emphasis on the repair of oxidative DNA lesions, and the cellular consequences of diminished mitochondrial genome stability.
Topics: DNA Damage; DNA Replication; DNA, Mitochondrial; Disease; Health; Humans; Transcription, Genetic
PubMed: 30700008
DOI: 10.3390/cells8020100 -
The Journal of Biological Chemistry Dec 2020Mitochondria are specialized compartments that produce requisite ATP to fuel cellular functions and serve as centers of metabolite processing, cellular signaling, and... (Review)
Review
Mitochondria are specialized compartments that produce requisite ATP to fuel cellular functions and serve as centers of metabolite processing, cellular signaling, and apoptosis. To accomplish these roles, mitochondria rely on the genetic information in their small genome (mitochondrial DNA) and the nucleus. A growing appreciation for mitochondria's role in a myriad of human diseases, including inherited genetic disorders, degenerative diseases, inflammation, and cancer, has fueled the study of biochemical mechanisms that control mitochondrial function. The mitochondrial transcriptional machinery is different from nuclear machinery. The re-constituted transcriptional complexes of (yeast) and humans, aided with high-resolution structures and biochemical characterizations, have provided a deeper understanding of the mechanism and regulation of mitochondrial DNA transcription. In this review, we will discuss recent advances in the structure and mechanism of mitochondrial transcription initiation. We will follow up with recent discoveries and formative findings regarding the regulatory events that control mitochondrial DNA transcription, focusing on those involved in cross-talk between the mitochondria and nucleus.
Topics: DNA, Mitochondrial; Gene Expression Regulation; Humans; Mitochondrial Proteins; Transcription Factors; Transcription Initiation Site; Transcription, Genetic
PubMed: 33127643
DOI: 10.1074/jbc.REV120.011202 -
Frontiers in Immunology 2022Acute lung injury(ALI)/acute respiratory distress syndrome(ARDS) is a form of acute-onset hypoxemic respiratory failure characterised by an acute, diffuse, inflammatory... (Review)
Review
Acute lung injury(ALI)/acute respiratory distress syndrome(ARDS) is a form of acute-onset hypoxemic respiratory failure characterised by an acute, diffuse, inflammatory lung injury, and increased alveolar-capillary permeability, which is caused by a variety of pulmonary or nonpulmonary insults. Recently, aberrant mitochondria and mitochondrial DNA(mtDNA) level are associated with the development of ALI/ARDS, and plasma mtDNA level shows the potential to be a promising biomarker for clinical diagnosis and evaluation of lung injury severity. In mechanism, the mtDNA and its oxidised form, which are released from impaired mitochondria, play a crucial role in the inflammatory response and histopathological changes in the lung. In this review, we discuss mitochondrial outer membrane permeabilisation (MOMP), mitochondrial permeability transition pore(mPTP), extracellular vesicles (EVs), extracellular traps (ETs), and passive release as the principal mechanisms for the release of mitochondrial DNA into the cytoplasm and extracellular compartments respectively. Further, we explain how the released mtDNA and its oxidised form can induce inflammatory cytokine production and aggravate lung injury through the Toll-like receptor 9(TLR9) signalling, cytosolic cGAS-stimulator of interferon genes (STING) signalling (cGAS-STING) pathway, and inflammasomes activation. Additionally, we propose targeting mtDNA-mediated inflammatory pathways as a novel therapeutic approach for treating ALI/ARDS.
Topics: Acute Lung Injury; DNA, Mitochondrial; Humans; Inflammation; Mitochondria; Nucleotidyltransferases; Respiratory Distress Syndrome
PubMed: 36059472
DOI: 10.3389/fimmu.2022.973089 -
Ageing Research Reviews Nov 2020Mitochondrial dysfunction is one of the hallmarks of aging. Consistently mitochondrial DNA (mtDNA) copy number and function decline with age in various tissues. There is... (Review)
Review
Mitochondrial dysfunction is one of the hallmarks of aging. Consistently mitochondrial DNA (mtDNA) copy number and function decline with age in various tissues. There is increasing evidence to support that mitochondrial dysfunction drives ovarian aging. A decreased mtDNA copy number is also reported during ovarian aging. However, the mitochondrial mechanisms contributing to ovarian aging and infertility are not fully understood. Additionally, investigations into mitochondrial therapies to rejuvenate oocyte quality, select viable embryos and improve mitochondrial function may help enhance fertility or extend reproductive longevity in the future. These therapies include the use of mitochondrial replacement techniques, quantification of mtDNA copy number, and various pharmacologic and lifestyle measures. This review aims to describe the key evidence and current knowledge of the role of mitochondria in ovarian aging and identify the emerging potential options for therapy to extend reproductive longevity and improve fertility.
Topics: Aging; DNA, Mitochondrial; Humans; Longevity; Mitochondria; Oocytes
PubMed: 32896666
DOI: 10.1016/j.arr.2020.101168 -
Cellular & Molecular Immunology Dec 2023Various cellular stress conditions trigger mitochondrial DNA (mtDNA) release from mitochondria into the cytosol. The released mtDNA is sensed by the cGAS-MITA/STING... (Review)
Review
Various cellular stress conditions trigger mitochondrial DNA (mtDNA) release from mitochondria into the cytosol. The released mtDNA is sensed by the cGAS-MITA/STING pathway, resulting in the induced expression of type I interferon and other effector genes. These processes contribute to the innate immune response to viral infection and other stress factors. The deregulation of these processes causes autoimmune diseases, inflammatory metabolic disorders and cancer. Therefore, the cGAS-MITA/STING pathway is a potential target for intervention in infectious, inflammatory and autoimmune diseases as well as cancer. In this review, we focus on the mechanisms underlying the mtDNA-triggered activation of the cGAS-MITA/STING pathway, the effects of the pathway under various physiological and pathological conditions, and advances in the development of drugs that target cGAS and MITA/STING.
Topics: Humans; DNA, Mitochondrial; Signal Transduction; Immunity, Innate; Nucleotidyltransferases; Mitochondria; Autoimmune Diseases; Neoplasms
PubMed: 37932533
DOI: 10.1038/s41423-023-01086-x -
Journal of Experimental & Clinical... Feb 2022Mitochondrial dynamics homeostasis is important for cell metabolism, growth, proliferation, and immune responses. The critical GTPase for mitochondrial fission, Drp1 is...
BACKGROUND
Mitochondrial dynamics homeostasis is important for cell metabolism, growth, proliferation, and immune responses. The critical GTPase for mitochondrial fission, Drp1 is frequently upregulated in many cancers and is closely implicated in tumorigenesis. However, the mechanism underling Drp1 to influence tumor progression is largely unknown, especially in esophageal squamous cell carcinoma (ESCC).
METHODS
Immunohistochemistry was used to examine Drp1 and LC3B expression in tissues of ESCC patients. Autophagic vesicles were investigated by transmission electron microscopy. Fluorescent LC3B puncta and mitochondrial nucleoid were observed by fluorescent and confocal microscopy. Mitochondrial function was evaluated by mitochondrial membrane potential, ROS and ATP levels. Xenograft tumor model was performed in BALB/c nude mice to analyze the role of Drp1 on ESCC progression.
RESULTS
We found that Drp1 high expression is correlated with poor overall survival of ESCC patients. Drp1 overexpression promotes cell proliferation and xenograft ESCC tumor growth by triggering autophagy. Furthermore, we demonstrated that Drp1 overexpression disturbs mitochondrial function and subsequent induces mitochondrial DNA (mtDNA) released into the cytosol thereby inducing cytosolic mtDNA stress. Mechanistically, cytosolic mtDNA activates the cGAS-STING pathway and facilitates autophagy, which promotes ESCC cancer growth. Moreover, mtDNA digestion with DNase I and autophagy inhibition with chloroquine attenuates the cGAS-STING pathway activation and ESCC cancer growth.
CONCLUSIONS
Our finding reveals that Drp1 overexpression induces mitochondrial dysfunction and cytosolic mtDNA stress, which subsequently activates the cGAS-STING pathway, triggers autophagy and promotes ESCC progression.
Topics: Animals; Autophagy; Cell Line, Tumor; Cell Proliferation; DNA, Mitochondrial; Disease Progression; Dynamins; Female; Humans; Mice; Mice, Knockout; Mice, Nude; Nucleotidyltransferases
PubMed: 35209954
DOI: 10.1186/s13046-022-02262-z