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Biomolecules Jul 2023Iron is an essential transition metal for its involvement in several crucial biological functions, the most notable being oxygen storage and transport. Due to its high... (Review)
Review
Iron is an essential transition metal for its involvement in several crucial biological functions, the most notable being oxygen storage and transport. Due to its high reactivity and potential toxicity, intracellular and extracellular iron levels must be tightly regulated. This is achieved through transport systems that mediate cellular uptake and efflux both at the level of the plasma membrane and on the membranes of lysosomes, endosomes and mitochondria. Among these transport systems, the key players are ferroportin, the only known transporter mediating iron efflux from cells; DMT1, ZIP8 and ZIP14, which on the contrary, mediate iron influx into the cytoplasm, acting on the plasma membrane and on the membranes of lysosomes and endosomes; and mitoferrin, involved in iron transport into the mitochondria for heme synthesis and Fe-S cluster assembly. The focus of this review is to provide an updated view of the physiological role of these membrane proteins and of the pathologies that arise from defects of these transport systems.
Topics: Iron; Biological Transport; Membrane Proteins; Cell Membrane; Lysosomes
PubMed: 37627237
DOI: 10.3390/biom13081172 -
Negative modulation of mitochondrial calcium uniporter complex protects neurons against ferroptosis.Cell Death & Disease Nov 2023Ferroptosis is an iron- and reactive oxygen species (ROS)-dependent form of regulated cell death, that has been implicated in Alzheimer's disease and Parkinson's...
Ferroptosis is an iron- and reactive oxygen species (ROS)-dependent form of regulated cell death, that has been implicated in Alzheimer's disease and Parkinson's disease. Inhibition of cystine/glutamate antiporter could lead to mitochondrial fragmentation, mitochondrial calcium ([Ca]) overload, increased mitochondrial ROS production, disruption of the mitochondrial membrane potential (ΔΨ), and ferroptotic cell death. The observation that mitochondrial dysfunction is a characteristic of ferroptosis makes preservation of mitochondrial function a potential therapeutic option for diseases associated with ferroptotic cell death. Mitochondrial calcium levels are controlled via the mitochondrial calcium uniporter (MCU), the main entry point of Ca into the mitochondrial matrix. Therefore, we have hypothesized that negative modulation of MCU complex may confer protection against ferroptosis. Here we evaluated whether the known negative modulators of MCU complex, ruthenium red (RR), its derivative Ru265, mitoxantrone (MX), and MCU-i4 can prevent mitochondrial dysfunction and ferroptotic cell death. These compounds mediated protection in HT22 cells, in human dopaminergic neurons and mouse primary cortical neurons against ferroptotic cell death. Depletion of MICU1, a [Ca] gatekeeper, demonstrated that MICU is protective against ferroptosis. Taken together, our results reveal that negative modulation of MCU complex represents a therapeutic option to prevent degenerative conditions, in which ferroptosis is central to the progression of these pathologies.
Topics: Animals; Humans; Mice; Calcium; Calcium-Binding Proteins; Dopaminergic Neurons; Ferroptosis; Mitochondrial Membrane Transport Proteins; Reactive Oxygen Species
PubMed: 38007529
DOI: 10.1038/s41419-023-06290-1 -
Nature Communications Jul 2023Skeletal muscle is more resilient to ischemia-reperfusion injury than other organs. Tissue specific post-translational modifications of cytochrome c (Cytc) are involved...
Skeletal muscle is more resilient to ischemia-reperfusion injury than other organs. Tissue specific post-translational modifications of cytochrome c (Cytc) are involved in ischemia-reperfusion injury by regulating mitochondrial respiration and apoptosis. Here, we describe an acetylation site of Cytc, lysine 39 (K39), which was mapped in ischemic porcine skeletal muscle and removed by sirtuin5 in vitro. Using purified protein and cellular double knockout models, we show that K39 acetylation and acetylmimetic K39Q replacement increases cytochrome c oxidase (COX) activity and ROS scavenging while inhibiting apoptosis via decreased binding to Apaf-1, caspase cleavage and activity, and cardiolipin peroxidase activity. These results are discussed with X-ray crystallography structures of K39 acetylated (1.50 Å) and acetylmimetic K39Q Cytc (1.36 Å) and NMR dynamics. We propose that K39 acetylation is an adaptive response that controls electron transport chain flux, allowing skeletal muscle to meet heightened energy demand while simultaneously providing the tissue with robust resilience to ischemia-reperfusion injury.
Topics: Animals; Swine; Lysine; Cytochromes c; Phosphorylation; Acetylation; Protein Processing, Post-Translational; Apoptosis; Cell Respiration; Reperfusion Injury; Muscle, Skeletal
PubMed: 37443314
DOI: 10.1038/s41467-023-39820-8 -
Seminars in Cancer Biology May 2024Mitochondria are the major sink for oxygen in the cell, consuming it during ATP production. Therefore, when environmental oxygen levels drop in the tumor, significant... (Review)
Review
Mitochondria are the major sink for oxygen in the cell, consuming it during ATP production. Therefore, when environmental oxygen levels drop in the tumor, significant adaptation is required. Mitochondrial activity is also a major producer of biosynthetic precursors and a regulator of cellular oxidative and reductive balance. Because of the complex biochemistry, mitochondrial adaptation to hypoxia occurs through multiple mechanisms and has significant impact on other cellular processes such as macromolecule synthesis and gene regulation. In tumor hypoxia, mitochondria shift their location in the cell and accelerate the fission and quality control pathways. Hypoxic mitochondria also undergo significant changes to fundamental metabolic pathways of carbon metabolism and electron transport. These metabolic changes further impact the nuclear epigenome because mitochondrial metabolites are used as enzymatic substrates for modifying chromatin. This coordinated response delivers physiological flexibility and increased tumor cell robustness during the environmental stress of low oxygen.
Topics: Humans; Mitochondria; Hypoxia; Oxygen; Cell Hypoxia; Stress, Physiological; Adaptation, Physiological
PubMed: 38556040
DOI: 10.1016/j.semcancer.2024.03.004 -
PLoS Computational Biology Feb 2024Physiological abnormalities in pulmonary granulomas-pathological hallmarks of tuberculosis (TB)-compromise the transport of oxygen, nutrients, and drugs. In prior...
Physiological abnormalities in pulmonary granulomas-pathological hallmarks of tuberculosis (TB)-compromise the transport of oxygen, nutrients, and drugs. In prior studies, we demonstrated mathematically and experimentally that hypoxia and necrosis emerge in the granuloma microenvironment (GME) as a direct result of limited oxygen availability. Building on our initial model of avascular oxygen diffusion, here we explore additional aspects of oxygen transport, including the roles of granuloma vasculature, transcapillary transport, plasma dilution, and interstitial convection, followed by cellular metabolism. Approximate analytical solutions are provided for oxygen and glucose concentration, interstitial fluid velocity, interstitial fluid pressure, and the thickness of the convective zone. These predictions are in agreement with prior experimental results from rabbit TB granulomas and from rat carcinoma models, which share similar transport limitations. Additional drug delivery predictions for anti-TB-agents (rifampicin and clofazimine) strikingly match recent spatially-resolved experimental results from a mouse model of TB. Finally, an approach to improve molecular transport in granulomas by modulating interstitial hydraulic conductivity is tested in silico.
Topics: Animals; Mice; Rabbits; Oxygen; Tuberculosis; Granuloma; Disease Models, Animal; Nutrients; Mycobacterium tuberculosis
PubMed: 38335224
DOI: 10.1371/journal.pcbi.1011847 -
Cell Death & Disease Aug 2023Ferroptosis, a form of programed cell death, can be promoted by inhibitors of the xCT transporter (erastin) or GPX4 (RSL3). We found that GPX4, but not the xCT...
Ferroptosis, a form of programed cell death, can be promoted by inhibitors of the xCT transporter (erastin) or GPX4 (RSL3). We found that GPX4, but not the xCT transporter, is selectively elevated in luminal breast cancer. Consistent with this observation, the majority of luminal breast cancer cell lines are exquisitely sensitive to RSL3 with limited sensitivity to erastin. In RSL3-resistant, but not sensitive, luminal breast cancer cell lines, RSL3 induces HER2 pathway activation. Irreversible HER2 inhibitors including neratinib reversed RSL3 resistance in constitutively RSL3-resistant cell lines. Combination treatment with RSL3 and neratinib increases ferroptosis through mitochondrial iron-dependent reactive oxygen species production and lipid peroxidation. RSL3 also activated replication stress and concomitant S phase and G2/M blockade leading to sensitivity to targeting the DNA damage checkpoint. Together, our data support the exploration of RSL3 combined with irreversible HER2 inhibitors in clinical trials.
Topics: Humans; Ferroptosis; Apoptosis; Lipid Peroxidation; Iron; MCF-7 Cells; Membrane Transport Proteins; Neoplasms
PubMed: 37596261
DOI: 10.1038/s41419-023-06042-1 -
ELife Dec 2023Based on studies with a fluorescent reporter dye, Mito Thermo Yellow (MTY), and the genetically encoded gTEMP ratiometric fluorescent temperature indicator targeted to...
Based on studies with a fluorescent reporter dye, Mito Thermo Yellow (MTY), and the genetically encoded gTEMP ratiometric fluorescent temperature indicator targeted to mitochondria, the temperature of active mitochondria in four mammalian and one insect cell line was estimated to be up to 15°C above that of the external environment to which the cells were exposed. High mitochondrial temperature was maintained in the face of a variety of metabolic stresses, including substrate starvation or modification, decreased ATP demand due to inhibition of cytosolic protein synthesis, inhibition of the mitochondrial adenine nucleotide transporter and, if an auxiliary pathway for electron transfer was available via the alternative oxidase, even respiratory poisons acting downstream of oxidative phosphorylation (OXPHOS) complex I. We propose that the high temperature of active mitochondria is an inescapable consequence of the biochemistry of OXPHOS and is homeostatically maintained as a primary feature of mitochondrial metabolism.
Topics: Animals; Temperature; Mitochondria; Cell Respiration; Oxidative Phosphorylation; Body Temperature Regulation; Stress, Physiological; Mammals
PubMed: 38079477
DOI: 10.7554/eLife.89232 -
EMBO Reports Aug 2023Sepsis is a leading cause of in-hospital mortality resulting from a dysregulated response to infection. Novel immunomodulatory therapies targeting macrophage metabolism...
Sepsis is a leading cause of in-hospital mortality resulting from a dysregulated response to infection. Novel immunomodulatory therapies targeting macrophage metabolism have emerged as an important focus for current sepsis research. However, understanding the mechanisms underlying macrophage metabolic reprogramming and how they impact immune response requires further investigation. Here, we identify macrophage-expressed Spinster homolog 2 (Spns2), a major transporter of sphingosine-1-phosphate (S1P), as a crucial metabolic mediator that regulates inflammation through the lactate-reactive oxygen species (ROS) axis. Spns2 deficiency in macrophages significantly enhances glycolysis, thereby increasing intracellular lactate production. As a key effector, intracellular lactate promotes pro-inflammatory response by increasing ROS generation. The overactivity of the lactate-ROS axis drives lethal hyperinflammation during the early phase of sepsis. Furthermore, diminished Spns2/S1P signaling impairs the ability of macrophages to sustain an antibacterial response, leading to significant innate immunosuppression in the late stage of infection. Notably, reinforcing Spns2/S1P signaling contributes to balancing the immune response during sepsis, preventing both early hyperinflammation and later immunosuppression, making it a promising therapeutic target for sepsis.
Topics: Humans; Anion Transport Proteins; Immunosuppression Therapy; Lactates; Macrophages; Reactive Oxygen Species; Sepsis
PubMed: 37358015
DOI: 10.15252/embr.202256635 -
International Journal of Biological... Dec 2023Glioblastoma Multiforme (GBM) is a malignant primary brain tumor. Radiotherapy, one of the standard treatments for GBM patients, could induce GBM radioresistance via...
Glioblastoma Multiforme (GBM) is a malignant primary brain tumor. Radiotherapy, one of the standard treatments for GBM patients, could induce GBM radioresistance via rewiring cellular metabolism. However, the precise mechanism attributing to GBM radioresistance or targeting strategies to overcome GBM radioresistance are lacking. Here, we demonstrate that SLC25A22, a mitochondrial bi-directional glutamate transporter, is upregulated and showed uni-directionality from mitochondria to cytosol in radioresistant GBM cells, resulting in accumulating cytosolic glutamate. However, mitochondrial glutaminolysis-mediated TCA cycle metabolites and OCR are maintained constantly. The accumulated cytosolic glutamate enhances the glutathione (GSH) production and proline synthesis in radioresistant GBM cells. Increased GSH protects cells against ionizing radiation (IR)-induced reactive oxygen species (ROS) whereas increased proline, a rate-limiting substrate for collagen biosynthesis, induces extracellular matrix (ECM) remodeling, leading to GBM invasive phenotypes. Finally, we discover that genetic inhibition of SLC25A22 using miR-184 mimic decreases GBM radioresistance and aggressiveness both in vitro and in vivo. Collectively, our study suggests that SLC25A22 upregulation confers GBM radioresistance by rewiring glutamate metabolism, and SLC25A22 could be a significant therapeutic target to overcome GBM radioresistance.
Topics: Humans; Glioblastoma; Glutamic Acid; Radiation Tolerance; Cell Line, Tumor; Brain Neoplasms; Mitochondria; Proline; Mitochondrial Membrane Transport Proteins
PubMed: 37866557
DOI: 10.1016/j.ijbiomac.2023.127511 -
Advanced Science (Weinheim,... Aug 2023Extracellular microRNAs (miRNAs) play a critical role in horizontal gene regulation. Uptake of extracellular miRNAs by recipient cells and their intracellular transport,...
Extracellular microRNAs (miRNAs) play a critical role in horizontal gene regulation. Uptake of extracellular miRNAs by recipient cells and their intracellular transport, however, remains elusive. Here RNA phase separation is shown as a novel pathway of miRNA uptake. In the presence of serum, synthetic miRNAs rapidly self-assembly into ≈110 nm discrete nanoparticles, which enable miRNAs' entry into different cells. Depleting serum cationic proteins prevents the formation of such nanoparticles and thus blocks miRNA uptake. Different from lipofectamine-mediated miRNA transfection in which majority of miRNAs are accumulated in lysosomes of transfected cells, nanoparticles-mediated miRNA uptake predominantly delivers miRNAs into mitochondria in a polyribonucleotide nucleotidyltransferase 1(PNPT1)-dependent manner. Functional assays further show that the internalized miR-21 via miRNA phase separation enhances mitochondrial translation of cytochrome b (CYB), leading to increase in adenosine triphosphate (ATP) and reactive oxygen species (ROS) reduction in HEK293T cells. The findings thus reveal a previously unrecognized mechanism for uptake and delivery functional extracellular miRNAs into mitochondria.
Topics: Humans; MicroRNAs; HEK293 Cells; Gene Expression Regulation; Biological Transport; Mitochondria; Exoribonucleases; Mitochondrial Proteins
PubMed: 37357137
DOI: 10.1002/advs.202300452