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Oxidative Medicine and Cellular... 2022Mitochondria are essential for eukaryotic cell activity and function, and their dysfunction is associated with the development and progression of renal diseases. In... (Review)
Review
Mitochondria are essential for eukaryotic cell activity and function, and their dysfunction is associated with the development and progression of renal diseases. In recent years, there has been a rapid development in mitochondria-targeting pharmacological strategies as mitochondrial biogenesis, morphology, and function, as well as dynamic changes in mitochondria, have been studied in disease states. Mitochondria-targeting drugs include nicotinamide mononucleotide, which supplements the NAD+ pool; mitochondria-targeted protective compounds, such as MitoQ; the antioxidant coenzyme, Q10; and cyclosporin A, an inhibitor of the mitochondrial permeability transition pore. However, traditional drugs targeting mitochondria have limited clinical applications due to their inability to be effectively absorbed by mitochondria and their high toxicity. Recently, SS-31, a mitochondria-targeting antioxidant, has received significant research attention as it decreases mitochondrial reactive oxygen species production and prevents mitochondrial depolarization, mitochondrial permeability transition pore formation, and Ca-induced mitochondrial swelling, and has no effects on normal mitochondria. At present, few studies have evaluated the effects of SS-31 against renal diseases, and the mechanism underlying its action is unclear. In this review, we first discuss the pharmacokinetics of SS-31 and the possible mechanisms underlying its protective effects against renal diseases. Then, we analyze its renal disease-improving effects in various experimental models, including animal and cell models, and summarize the clinical evidence of its benefits in renal disease treatment. Finally, the potential mechanism underlying the action of SS-31 against renal diseases is explored to lay a foundation for future preclinical studies and for the evaluation of its clinical applications.
Topics: Animals; Antioxidants; Kidney Diseases; Mitochondria; Mitochondrial Permeability Transition Pore; Peptides; Reactive Oxygen Species
PubMed: 35707274
DOI: 10.1155/2022/1295509 -
Liver International : Official Journal... Nov 2023This thematic review aims to provide an overview of the current state of knowledge about the occurrence of giant mitochondria or megamitochondria in liver parenchymal... (Review)
Review
This thematic review aims to provide an overview of the current state of knowledge about the occurrence of giant mitochondria or megamitochondria in liver parenchymal cells. Their presence and accumulation are considered to be a major pathological hallmark of the health and fate of liver parenchymal cells that leads to overall tissue deterioration and eventually results in organ failure. The first description on giant mitochondria dates back to the 1960s, coinciding with the availability of the first generation of electron microscopes in clinical diagnostic laboratories. Detailed accounts on their ultrastructure have mostly been described in patients suffering from alcoholic liver disease, chronic hepatitis, hepatocellular carcinoma and non-alcoholic fatty liver disease. Interestingly, from this extensive literature survey, it became apparent that giant mitochondria or megamitochondria present themselves with or without highly organised crystal-like intramitochondrial inclusions. The origin, formation and potential role of giant mitochondria remain to-date largely unanswered. Likewise, the biochemical composition of the well-organised crystal-like inclusions and their possible impact on mitochondrial function is unclear. Herein, concepts about the possible mechanism of their formation and three-dimensional architecture will be approached. We will furthermore discuss their importance in diagnostics, including future research outlooks and potential therapeutic interventions to cure liver disease where giant mitochondria are implemented.
Topics: Humans; Mitochondrial Swelling; Mitochondria, Liver; Liver Diseases, Alcoholic; Non-alcoholic Fatty Liver Disease; Hepatitis, Chronic; Liver
PubMed: 37615254
DOI: 10.1111/liv.15711 -
Cell Biology and Toxicology Apr 2023Mitochondrial metabolism and function are modulated by changes in matrix Ca. Small increases in the matrix Ca stimulate mitochondrial bioenergetics, whereas excessive Ca...
Mitochondrial metabolism and function are modulated by changes in matrix Ca. Small increases in the matrix Ca stimulate mitochondrial bioenergetics, whereas excessive Ca leads to cell death by causing massive matrix swelling and impairing the structural and functional integrity of mitochondria. Sustained opening of the non-selective mitochondrial permeability transition pores (PTP) is the main mechanism responsible for mitochondrial Ca overload that leads to mitochondrial dysfunction and cell death. Recent studies suggest the existence of two or more types of PTP, and adenine nucleotide translocator (ANT) and FF-ATP synthase were proposed to form the PTP independent of each other. Here, we elucidated the role of ANT in PTP opening by applying both experimental and computational approaches. We first developed and corroborated a detailed model of the ANT transport mechanism including the matrix (ANT), cytosolic (ANT), and pore (ANT) states of the transporter. Then, the ANT model was incorporated into a simple, yet effective, empirical model of mitochondrial bioenergetics to ascertain the point when Ca overload initiates PTP opening via an ANT switch-like mechanism activated by matrix Ca and is inhibited by extra-mitochondrial ADP. We found that encoding a heterogeneous Ca response of at least three types of PTPs, weakly, moderately, and strongly sensitive to Ca, enabled the model to simulate Ca release dynamics observed after large boluses were administered to a population of energized cardiac mitochondria. Thus, this study demonstrates the potential role of ANT in PTP gating and proposes a novel mechanism governing the cryptic nature of the PTP phenomenon.
Topics: Mitochondrial Membrane Transport Proteins; Adenine Nucleotides; Mitochondrial Swelling; Mitochondria; Mitochondrial Permeability Transition Pore; Calcium
PubMed: 35606662
DOI: 10.1007/s10565-022-09724-2 -
Shock (Augusta, Ga.) Aug 2023Background: Hyperbilirubinemia is a common perioperative complication, which is associated with acute kidney injury. Bilirubin permeabilizes mitochondrial membranes...
Background: Hyperbilirubinemia is a common perioperative complication, which is associated with acute kidney injury. Bilirubin permeabilizes mitochondrial membranes leading to mitochondrial swelling and dysfunction. In this study, we aimed to determine the association between PINK1-PARKIN-mediated mitophagy and renal ischemia-reperfusion (IR) injury aggravated by hyperbilirubinemia. Methods: A C57BL/6 mouse hyperbilirubinemia model was induced via intraperitoneal injection of bilirubin solution. In addition, a hypoxia/reoxygenation (H/R) injury model of TCMK-1 cells was established. In these models, we determined the effects of hyperbilirubinemia on oxidative stress, apoptosis, mitochondrial damage, and fibrosis. Results:In vitro , colocalization of GFP-LC3 puncta and Mito-Tracker Red showed that the number of mitophagosomes increased in TCMK-1 cells under H/R and bilirubin condition. Silencing of PINK1 or inhibition of autophagy alleviated mitochondrial damage, oxidative stress, and apoptosis in H/R injury aggravated by bilirubin and decreased cell death detected by methyl-thiazolyl-tetrazolium. In vivo , hyperbilirubinemia increased serum creatinine level in the renal IR injury mice model. Hyperbilirubinemia enhanced apoptosis induced by renal IR. In addition, hyperbilirubinemia increased mitophagosomes and autophagosomes and disrupted mitochondrial cristae in the IR kidney. Inhibition of PINK1 or autophagy reduced histological damages by alleviating apoptosis in renal IR injury, aggravated by hyperbilirubinemia. 3-MA or PINK1-shRNA-AAV9 treatment decreased the area of collagen and proteins related to fibrosis in renal IR injury, aggravated by hyperbilirubinemia. Conclusions: We have demonstrated that hyperbilirubinemia aggravated oxidative stress, apoptosis, mitochondrial damage, and fibrosis in renal IR injury by exacerbating PINK1-PARKIN-mediated mitophagy.
Topics: Animals; Mice; Bilirubin; Hyperbilirubinemia; Kidney; Mice, Inbred C57BL; Mitochondria; Mitophagy; Protein Kinases; Reperfusion Injury; Ubiquitin-Protein Ligases
PubMed: 37278995
DOI: 10.1097/SHK.0000000000002160 -
Methods in Molecular Biology (Clifton,... 2022The loss of mitochondrial cristae integrity and mitochondrial swelling are hallmarks of multiple forms of necrotic cell death. One of the most well-studied and relevant...
The loss of mitochondrial cristae integrity and mitochondrial swelling are hallmarks of multiple forms of necrotic cell death. One of the most well-studied and relevant inducers of mitochondrial swelling is matrix calcium (Ca). Respiring mitochondria will intake available Ca into their matrix until a threshold is reached which triggers the opening of the mitochondrial permeability transition pore (MPTP). Upon opening of the pore, mitochondrial membrane potential dissipates and the mitochondria begin to swell, rendering them dysfunctional. The total amount of Ca taken up by a mitochondrion prior to the engagement of the MPTP is referred to as mitochondrial Ca retention capacity (CRC). The CRC/swelling assay is a useful tool for observing the dose-dependent event of mitochondrial dysfunction in real-time. In this technique, isolated mitochondria are treated with specific boluses of Ca until they reach CRC and undergo swelling. A fluorometer is utilized to detect an increase in transmitted light passing through the sample as the mitochondria lose cristae density, and simultaneously measures calcium uptake by way of a Ca-specific membrane impermeable fluorescent dye. Here we provide a detailed protocol describing the mitochondrial CRC/swelling assay and we discuss how varying amounts of mitochondria and Ca added to the system affect the dose-dependency of the assay. We also report how to validate the assay by using MPTP and calcium uptake inhibitors and troubleshooting common mistakes that occur with this approach.
Topics: Calcium; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Mitochondrial Swelling; Permeability
PubMed: 35771440
DOI: 10.1007/978-1-0716-2309-1_9 -
Progress in Biophysics and Molecular... Aug 2022Existing theoretical approaches were considered that allow modelling of mitochondrial swelling (MS) dynamics. Simple phenomenological kinetic models were reviewed.... (Review)
Review
Existing theoretical approaches were considered that allow modelling of mitochondrial swelling (MS) dynamics. Simple phenomenological kinetic models were reviewed. Simple and extended biophysical and bioenergetic models that ignore mechanical properties of inner mitochondrial membrane (IMM), and similar models that include these mechanical properties were also reviewed. Limitations of these models we considered, as regards correct modelling of MS dynamics. It was found that simple phenomenological kinetic models have significant limitations, due to dependence of the kinetic parameter values estimated by fitting of the experimental data on the experimental conditions. Additionally, such simple models provide no understanding of the detailed mechanisms behind the MS dynamics, nor of the dynamics of various system parameters during MS. Thus, biophysical and bioenergetic models ignoring IMM mechanical properties can't be used to model the transition between reversible and irreversible MS. However, simple and extended biophysical models that include IMM mechanical properties allow modelling the transition to irreversible swelling. These latter models are still limited due to significantly simplified description of biochemistry, compared to those of bioenergetic models. Finally, a strategy of model development is proposed, towards correct interpretation of the mitochondrial life cycle, including the effects of MS dynamics.
Topics: Energy Metabolism; Kinetics; Mitochondria; Mitochondrial Membranes; Mitochondrial Swelling
PubMed: 35447196
DOI: 10.1016/j.pbiomolbio.2022.04.004 -
Critical Care (London, England) Dec 2023Brain injury is a leading cause of morbidity and mortality in patients resuscitated from cardiac arrest. Mitochondrial dysfunction contributes to brain injury following...
BACKGROUND
Brain injury is a leading cause of morbidity and mortality in patients resuscitated from cardiac arrest. Mitochondrial dysfunction contributes to brain injury following cardiac arrest; therefore, therapies that limit mitochondrial dysfunction have the potential to improve neurological outcomes. Generation of reactive oxygen species (ROS) during ischemia-reperfusion injury in the brain is a critical component of mitochondrial injury and is dependent on hyperactivation of mitochondria following resuscitation. Our previous studies have provided evidence that modulating mitochondrial function with specific near-infrared light (NIR) wavelengths can reduce post-ischemic mitochondrial hyperactivity, thereby reducing brain injury during reperfusion in multiple small animal models.
METHODS
Isolated porcine brain cytochrome c oxidase (COX) was used to investigate the mechanism of NIR-induced mitochondrial modulation. Cultured primary neurons from mice expressing mitoQC were utilized to explore the mitochondrial mechanisms related to protection with NIR following ischemia-reperfusion. Anesthetized pigs were used to optimize the delivery of NIR to the brain by measuring the penetration depth of NIR to deep brain structures and tissue heating. Finally, a model of out-of-hospital cardiac arrest with CPR in adult pigs was used to evaluate the translational potential of NIR as a noninvasive therapeutic approach to protect the brain after resuscitation.
RESULTS
Molecular evaluation of enzyme activity during NIR irradiation demonstrated COX function was reduced in an intensity-dependent manner with a threshold of enzyme inhibition leading to a moderate reduction in activity without complete inhibition. Mechanistic interrogation in neurons demonstrated that mitochondrial swelling and upregulation of mitophagy were reduced with NIR treatment. NIR therapy in large animals is feasible, as NIR penetrates deep into the brain without substantial tissue heating. In a translational porcine model of CA/CPR, transcranial NIR treatment for two hours at the onset of return of spontaneous circulation (ROSC) demonstrated significantly improved neurological deficit scores and reduced histologic evidence of brain injury after resuscitation from cardiac arrest.
CONCLUSIONS
NIR modulates mitochondrial function which improves mitochondrial dynamics and quality control following ischemia/reperfusion. Noninvasive modulation of mitochondria, achieved by transcranial treatment of the brain with NIR, mitigates post-cardiac arrest brain injury and improves neurologic functional outcomes.
Topics: Humans; Mice; Animals; Swine; Mitochondria; Brain Injuries; Out-of-Hospital Cardiac Arrest; Ischemia; Mitochondrial Diseases; Cardiopulmonary Resuscitation; Disease Models, Animal
PubMed: 38098060
DOI: 10.1186/s13054-023-04745-7 -
International Journal of Molecular... Feb 2022Analysis of the function, structure, and intracellular organization of mitochondria is important for elucidating energy metabolism and intracellular energy transfer. In... (Review)
Review
Analysis of the function, structure, and intracellular organization of mitochondria is important for elucidating energy metabolism and intracellular energy transfer. In addition, basic and clinically oriented studies that investigate organ/tissue/cell dysfunction in various human diseases, including myopathies, cardiac/brain ischemia-reperfusion injuries, neurodegenerative diseases, cancer, and aging, require precise estimation of mitochondrial function. It should be noted that the main metabolic and functional characteristics of mitochondria obtained in situ (in permeabilized cells and tissue samples) and in vitro (in isolated organelles) are quite different, thereby compromising interpretations of experimental and clinical data. These differences are explained by the existence of the mitochondrial network, which possesses multiple interactions between the cytoplasm and other subcellular organelles. Metabolic and functional crosstalk between mitochondria and extra-mitochondrial cellular environments plays a crucial role in the regulation of mitochondrial metabolism and physiology. Therefore, it is important to analyze mitochondria in vivo or in situ without their isolation from the natural cellular environment. This review summarizes previous studies and discusses existing approaches and methods for the analysis of mitochondrial function, structure, and intracellular organization in situ.
Topics: Animals; Cell Respiration; Energy Metabolism; Humans; Mitochondria, Heart; Muscle, Skeletal; Myocytes, Cardiac
PubMed: 35216368
DOI: 10.3390/ijms23042252 -
The Journal of Neuroscience : the... Jun 2022Zn is an important contributor to ischemic brain injury, and recent studies support the hypothesis that mitochondria are key sites of its injurious effects. In murine...
Zn is an important contributor to ischemic brain injury, and recent studies support the hypothesis that mitochondria are key sites of its injurious effects. In murine hippocampal slices (both sexes) subjected to oxygen glucose deprivation (OGD), we found that Zn accumulation and its entry into mitochondria precedes and contributes to the induction of acute neuronal death. In addition, if the ischemic episode is short (and sublethal), there is ongoing Zn accumulation in CA1 mitochondria after OGD that may contribute to their delayed dysfunction. Using this slice model of sublethal OGD, we have examined Zn contributions to the progression of changes evoked by OGD and occurring over 4-5 h. We detected progressive mitochondrial depolarization occurring from ∼2 h after ischemia, a large increase in spontaneous synaptic activity between 2 and 3 h, and mitochondrial swelling and fragmentation at 4 h. Blockade of the primary route for Zn entry, the mitochondrial Ca uniporter (with ruthenium red [RR]) or Zn chelation shortly after OGD withdrawal substantially attenuated the mitochondrial depolarization and the changes in synaptic activity. RR also largely reversed the mitochondrial swelling. Finally, using an rat (male) asphyxial cardiac arrest model of transient global ischemia, we found that ∼8 min asphyxia induces considerable injury of CA1 neurons 4 h later that is associated with strong Zn accumulation within many damaged mitochondria. These effects were substantially attenuated by infusion of RR on reperfusion. Our findings highlight mitochondrial Zn accumulation after ischemia as a possible target for neuroprotective therapy. Brain ischemia is a leading cause of mortality and long-term disability that still lacks effective treatment. After transient ischemia, delayed death of neurons occurs in vulnerable brain regions. There is a critical need to understand mechanisms of this delayed neurodegeneration which can be targeted for neuroprotection. We found progressive and long-lasting mitochondrial Zn accumulation to occur in highly vulnerable CA1 neurons after ischemia. Here we demonstrate that this Zn accumulation contributes strongly to deleterious events occurring after ischemia, including mitochondrial dysfunction, swelling, and structural changes. We suggest that this mitochondrial Zn entry may constitute a promising target for development of therapeutic interventions to be delivered after termination of an episode of transient global ischemia.
PubMed: 35623885
DOI: 10.1523/JNEUROSCI.0874-21.2022 -
Biochemical and Biophysical Research... Jul 2020We here used fluorescence imaging to explore the effect of co-overexpression of Mcl-1 and Bak/BH3-only proteins on mitochondrial morphology. The cells co-expressing...
We here used fluorescence imaging to explore the effect of co-overexpression of Mcl-1 and Bak/BH3-only proteins on mitochondrial morphology. The cells co-expressing CFP-Mcl-1 and YFP-Bak/BimL/Puma/tBid showed co-localization of Mcl-1 with Bak/Puma/BimL/tBid and also showed the inhibitory action of Mcl-1 on the Bak-, BimL-, Puma- or tBid-mediated cell death. Co-expression of Mcl-1 and Bak but not BH3-only proteins induced time-dependent mitochondrial swelling. Fluorescence resonance energy transfer (FRET) imaging proved the direct binding of Mcl-1 to Bak, BimL, Puma and tBid, respectively. In addition, Mcl-1 prevented Bak oligomerization by retrotranslocating Bak from mitochondria into cytoplasm. Moreover, Mcl-1-Bak complex exhibited a good co-localization with mitochondria, and co-expression of Mcl-1 and Bak for more than 24 h not only induced mitochondrial swelling but also impaired mitochondrial membrane potential. Collectively, co-expression of Mcl-1 and Bak but not BH3-only proteins significantly induced mitochondrial swelling and subsequent loss of mitochondrial membrane potential.
Topics: Apoptosis; Gene Expression; HeLa Cells; Humans; Mitochondria; Mitochondrial Swelling; Myeloid Cell Leukemia Sequence 1 Protein; bcl-2 Homologous Antagonist-Killer Protein
PubMed: 32430171
DOI: 10.1016/j.bbrc.2020.04.154