Search Results (1,470)

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) closely interacts with host cellular mechanisms, with mitochondria playing a crucial role in this process. As essential organelles that control cellular energy production, apoptosis, reactive oxygen species (ROS) metabolism, and innate immune responses, mitochondria are vital to the development of COVID-19. However, the exact molecular interactions between mitochondria and SARS-CoV-2 remain under active investigation. Gaining a comprehensive understanding of mitochondrial involvement in SARS-CoV-2 infection is therefore essential for uncovering complex disease mechanisms, identifying prognostic biomarkers, and developing effective treatments. Ultimately, exploring these virus–host interactions may provide new insights into the fundamental and complex aspects of mitochondrial physiology and pathophysiology. Full article

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by a gradual decline in cognitive abilities and a progressive loss of the neuronal system resulting from neuronal damage and death. The maintenance of neuronal homeostasis is intricately connected to the crosstalk and balance among organelles. Indeed, intracellular organelles are not just isolated compartments in the cell; instead, they are interdependent structures that can communicate through membrane contact sites (MCSs), forming physical connection points represented by proteinaceous tethers. Mitochondria and lysosomes have fundamental physiological functions within neurons, and accumulating evidence highlights their dysfunctions as AD features, strongly associated with the neurodegenerative process underlying the development and progression of AD. This review explores mitochondria-lysosome communication through MCSs, the tethering proteins and their functions in the cell, discussing the methodological challenges in measuring the structure and dynamics of contacts, and the potential role of altered mitochondria-lysosome communication in the context of organelle dysfunction related to neuron impairment in AD pathogenesis. The different abundance of the tethering proteins was considered in healthy physiological and in AD-related conditions to assess the possible organelle communication dysregulation and the subsequent cellular function alterations, and to evaluate the role of mitochondria-lysosome MCSs in the pathogenesis of this disorder. Full article

The persistent residual tumor cells that survive after chemotherapy are a major cause of treatment failure, but their survival mechanisms remain largely elusive. These cancer cells are typically characterized by a quiescent state with suppressed activity of MYC and MTOR. We observed that the MYC-suppressed persistent triple-negative breast cancer (TNBC) cells are metabolically flexible and can upregulate mitochondrial oxidative phosphorylation (OXPHOS) genes and respiratory function (“OXPHOS-high” cell state) in response to DNA-damaging anthracyclines such as doxorubicin, but not to taxanes. The elevated biomass and respiratory function of mitochondria in OXPHOS-high persistent cancer cells were associated with mitochondrial elongation and remodeling, suggestive of increased mitochondrial fusion. A genome-wide CRISPR editing screen in doxorubicin-persistent OXPHOS-high TNBC cells revealed the BCL-XL gene as the top survival dependency in these quiescent tumor cells, but not in their untreated proliferating counterparts. Quiescent OXPHOS-high TNBC cells were highly sensitive to BCL-XL inhibitors, but not to inhibitors of BCL2 and MCL1. Interestingly, inhibition of BCL-XL in doxorubicin-persistent OXPHOS-high TNBC cells rapidly abrogated mitochondrial elongation and respiratory function, followed by caspase 3/7 activation and cell death. The platelet-sparing proteolysis-targeted chimera (PROTAC) BCL-XL degrader DT2216 enhanced the efficacy of doxorubicin against TNBC xenografts in vivo without induction of thrombocytopenia that is often observed with the first-generation BCL-XL inhibitors, supporting the development of this combinatorial treatment strategy for eliminating dormant tumor cells that persist after treatment with anthracycline-based chemotherapy. Full article

Autophagy is a conserved process that involves the degradation of damaged proteins and organelles to restore cellular homeostasis. Autophagy plays a critical role in cell differentiation, immune responses, and protection against pathogens, as well as the development and progression of allergic inflammation. Crosstalk between autophagy and signaling pathways modulates immune responses to inflammatory signals. Here, we discuss the regulatory roles of autophagy in allergic inflammation. Autophagy can promote allergic inflammation by enhancing the secretion of inflammatory mediators. Impaired autophagy resulting from the accumulation of autophagosomes can exacerbate allergic inflammation. Mast cell degranulation and activation require energy provided by mitochondrial respiration. Mast cell activation is accompanied by morphological changes and mitochondrial fragmentation. Mitochondrial fragmentation (mitophagy) induced by oxidative stress involves the degradation of defective mitochondria. Therefore, we discuss the relationship between mitophagy and allergic inflammation. Targeting autophagy and oxidative stress can be a strategy for developing anti-allergy therapeutics. In this review, we also discuss future research directions to better understand allergic diseases with respect to autophagy and develop effective anti-allergy drugs. Full article

Tau protein misfolding and aggregation are central to Tauopathies, yet the temporal dynamics of Tau interactions in vivo remain poorly understood. Here, we applied quantitative proteomics to demonstrate that the interactome of human Tau in adult Drosophila brains changes dynamically over a 12-day time course, revealing a progressive shift from early cytosolic and ribosomal associations to late enrichment of mitochondrial and synaptic partners. Notably, the mitochondrial pore protein Porin/VDAC1 was identified as a late-stage interactor and functional analyses demonstrated that Tau overexpression impairs mitochondrial respiration, elevates oxidative damage, and disrupts carbohydrate homeostasis. To validate this temporally specific interaction, Porin was downregulated, resulting in reduced Tau mitochondrial association, phosphorylation and aggregation. Paradoxically, however, Porin attenuation exacerbated Tau-induced toxicity, including shortened lifespan, locomotor deficits, and impaired learning. These findings indicate that while Porin facilitates pathological Tau modifications, it is also essential for neuronal resilience, highlighting a complex role in modulating Tau toxicity. Our study provides a temporal map of Tau-associated proteome changes in vivo and identifies mitochondria as critical mediators of Tau-driven neurodegeneration. Full article

Obesity contributes to the development of metabolic disorders such as type 2 diabetes mellitus (T2DM) and metabolic dysfunction-associated steatotic liver disease (MASLD) through sustained low-grade inflammation and mitochondrial dysfunction. In obesity, hypertrophied adipose tissue release high levels of pro-inflammatory cytokines, including TNF-α, IL-6, and IL-1β, and elevates circulating free fatty acids. These changes promote systemic insulin resistance and ectopic lipid deposition. Mitochondrial dysfunction, including reduced oxidative phosphorylation, excess reactive oxygen species (ROS) production, and mitochondrial DNA damage, further stimulate inflammatory pathways such as the NLRP3 inflammasome, creating a feedback loop that worsens metabolic stress. Ultimately, this interaction disrupts energy balance, weakens insulin signaling, and accelerates β-cell dysfunction and hepatic steatosis. In both T2DM and MASLD, oxidative stress, defective mitochondrial quality control, and dysregulated immunometabolic responses are consistently observed pathophysiological features. Interventions aimed at reducing inflammation and restoring mitochondrial function—including lifestyle modification, mitochondria-targeted therapies, inflammasome regulation, and enhancement of mitochondrial biogenesis or mitophagy—may retard disease progression. Full article

Mitochondria are crucial for a wide range of cellular processes. One of the most important is innate immunity regulation. Apart from functioning as a signaling hub in immune reactions, mitochondrial nucleic acids can themselves act as damage-associated molecular patterns (DAMPs) to participate in immune processes directly. This review synthesizes the current understanding of mitochondrial RNA (mtRNA) biology and its link to immune activation through aberrant accumulation. We focus on its origin through bidirectional mitochondrial transcription and metabolism, encompassing maturation (cleavage, polyadenylation, modification) and degradation. Dysregulation of mtRNA metabolism leads to mt-dsRNA (mitochondrial double-stranded RNA) accumulation, which escapes mitochondria via specific channels into the cytosol and serves as DAMPs to trigger an immune response. We discuss the critical roles of key regulatory factors, including PNPT1 (PNPase, Polyribonucleotide Nucleotidyltrans ferase 1), in controlling mt-dsRNA levels and preventing inappropriate immune activation. Finally, we review the implications of mt-dsRNA-driven inflammation in human diseases, including autoimmune disorders, cellular senescence, and viral infection pathologies, highlighting unresolved questions regarding mt-dsRNA release mechanisms. Full article

The relevance of well-structured mitochondria in sustaining the integrity of the retinal pigment epithelium (RPE) is increasingly evident. Conversely, altered mitochondria are a culprit of age-related macular degeneration (AMD), which is influenced by the activity of mechanistic target of rapamycin (mTOR). In the present manuscript, the mitochondrial status of RPE cells was investigated by light and electron microscopy following the administration of various doses of compounds, which modulate mTOR. The study combines MitoTracker dyes and mitochondrial immunohistochemistry with in situ mitochondrial morphometry. Various doses of 3-methyladenine (3-MA), curcumin, and rapamycin were administered alone or in combination. The activity of autophagy and mTOR was quantified following each treatment. Administration of 3-MA led to activation of mTOR, which was associated with severe cell death, altered membrane permeability, and altered ZO-1 expression. In this condition, mitochondrial mass was reduced, despite a dramatic increase in damaged mitochondria being reported. The decrease in healthy mitochondria was concomitant with alterations in key mitochondria-related antigens such as Tomm20, Pink1, and Parkin. Specific mitochondrial alterations were quantified through in situ ultrastructural morphometry. Both curcumin and rapamycin counteract mTOR activation and rescue mitochondrial status, while preventing RPE cell loss and misplacement of decreased ZO-1 expression. Mitigation of mTOR may protect mitochondria in retinal degeneration. Full article

Chronic social isolation (CSIS), a known risk factor for the development of major depressive disorders, is associated with hippocampal dysfunction. In rodent models, CSIS produces two phenotypes: CSIS-susceptible, which develop depressive- and anxiety-like behaviors, and CSIS-resilient, which maintain normal behavior despite stress. However, the biological mechanisms underlying resilience to stress remain elusive. Mitochondria, as central regulators of neuronal energy metabolism and redox balance, are potential mediators of stress susceptibility and resilience. This review summarizes comparative proteomic analyses of hippocampal nonsynaptic mitochondria (NSM) and synaptosome-enriched mitochondria from CSIS-susceptible and CSIS-resilient rats along with controls. In NSM of resilient rats relative to susceptible rats, remodeling enhanced energy production, limited reactive oxygen species, stabilized phosphate transport, and promoted removal of damaged components. Compared with controls, these changes optimized energy production, and selectively downregulated oxidative stress-promoting proteins. Conversely, synaptosome-enriched mitochondria from resilient rats showed downregulation of proteins related to synaptic energy metabolism and redox balance relative to CSIS-susceptible rats, but demonstrated upregulation of bioenergetic and antioxidant enzymes, molecular chaperones, and neuroprotective factors compared with controls. These proteomic signatures both highlight mitochondrial adaptability in promoting stress resilience and identify mitochondria as promising targets for the development of novel antidepressant therapies. Full article

Background and objectives: Hypertension is a worldwide burden, for which fetal malnutrition is a risk factor. Another societal challenge is environmental waste. Our research focusses on cocoa shell extract (CSE), a cocoa by-product with antioxidant bioactive components. Male rats exposed to fetal malnutrition develop hypertension and endothelial dysfunction, which are improved by CSE supplementation. We hypothesized that effects of CSE are related to an antioxidant action. Methods: Adult male and female offspring of dams exposed to 50% food restriction during gestation (MUN) and controls were supplemented for 3 weeks with CSE (250 mg/kg/day) or a vehicle. We assessed plasma SOD activity, GSH and carbonyls (via spectrophotometry) and aortic expression of enzymes related to ROS degradation or production (via Western blotting). Results: MUN males showed lower Nrf2 expression and increased carbonyls, SOD activity and mitochondrial SOD2 expression, without alterations in GSH or the related enzyme CGLM. No changes in xanthine oxidase or NADPH subunits (p22phox and p47phox) were detected, suggesting a different origin of superoxide anion. Phosphorylated-eNOS/eNOS and 3-nitrotyrosine expression were increased without changes in plasma nitrates. MUN females only showed plasma SOD and aortic 3-nitrotyrosine elevation. CSE supplementation reduced SOD2 and p-eNOS/eNOS expression and SOD activity and increased Nrf2 expression. Conclusions: MUN arteries exhibit oxidative damage, with a higher impact on males. SOD2 and p-eNOS/e-NOS overexpression may be a counteracting mechanism that compensates for superoxide anion overproduction, likely involving mitochondria. The reversal of these alterations by CSE supplementation is probably related to a reduction in vascular superoxide anion through a direct scavenging action of its bioactive components. A longer supplementation period may be needed to increase endogenous antioxidants through Nrf2 and to reduce oxidative–nitrosative damage. Full article

Viruses can induce various mitochondrial morphological changes, which are associated with the type of immune response. Therefore, characterization and analysis of mitochondrial ultrastructural changes could provide insights into the kind of immune response elicited, especially when compared to uninfected cells. However, this analysis is highly time-consuming and susceptible to observer bias. This work presents the development of a deep learning-based approach for the automatic identification, segmentation, and analysis of mitochondria from thin-section transmission electron microscopy images of cells infected with two SARS-CoV-2 variants or the Zika virus, utilizing a convolutional neural network with a U-Net architecture. A comparison between manual and automatic segmentations, along with morphological metrics, was performed, yielding an accuracy greater than 85% with no statistically significant differences between the manual and automatic metrics. This approach significantly reduces processing time and enables a prediction of the immune response to viral infections by allowing the detection of both intact and damaged mitochondria. Therefore, the proposed deep learning-based tool may represent a significant advancement in the study and understanding of cellular responses to emerging pathogens. Additionally, its applicability could be extended to the analysis of other organelles, thereby opening up new opportunities for automated studies in cell biology. Full article

Post-acute sequelae of SARS-CoV-2 infection (long COVID) present with persistent fatigue, cognitive impairment, and autonomic and multisystem dysfunctions that often go unnoticed by standard diagnostic tests. Increasing evidence suggests that mitochondrial dysfunction and oxidative stress are central drivers of these post-viral sequelae. Viral infections, particularly SARS-CoV-2, disrupt mitochondrial bioenergetics by altering membrane integrity, increasing mitochondrial reactive oxygen species (mtROS), and impairing mitophagy, leading to sustained immune activation and metabolic imbalance. This review synthesizes an understanding of how mitochondrial redox signaling and impaired clearance of damaged mitochondria contribute to chronic inflammation and multisystem organ symptoms in both long COVID and post-vaccine injury. We discuss translational biomarkers and non-invasive techniques, exploring therapeutic strategies that include pharmacological, non-pharmacological, and nutritional approaches, as well as imaging modalities aimed at assessing and restoring mitochondrial health. Recognizing long COVID as a mitochondrial disorder that stems from redox imbalance will open new options for personalized treatment and management guided by biomarkers. Future clinical trials are essential to validate these approaches and translate mitochondrial resuscitation into effective care for patients suffering from long COVID and related post-viral syndromes. Full article

During the pathological process of spinal cord injury (SCI), ferroptosis is closely related to mitochondrial homeostasis. Following the occurrence of SCI, the interruption of local blood supply leads to mitochondrial damage within cells and a reduction in Adenosine triphosphate (ATP) production. This results in the loss of transmembrane ion gradients, causing an influx of Ca²⁺ into the cells, which in turn generates a significant amount of Reactive oxygen species (ROS) and reactive nitrogen species. This leads to severe mitochondrial dysfunction and an imbalance in mitochondrial homeostasis. Ferroptosis is a form of programmed cell death that differs from other types of apoptosis, as it is dependent on the accumulation of iron and lipid peroxides, along with their byproducts. The double bond structures in intracellular polyunsaturated fatty acids (PUFA) are particularly susceptible to attack by ROS, leading to the formation of lipid alkyl free radicals. This accumulation of lipid peroxides within the cells triggers ferroptosis. After SCI, the triggering of ferroptosis is closely associated with the “death triangle”—a core network that catalyzes cell death through the interaction of three factors: local iron overload, collapse of antioxidant defenses, and dysregulation of PUFA metabolism (where PUFA are susceptible to attack by reactive ROS leading to lipid peroxidation). These three elements interact to form a central network driving cell death. In the pathological cascade of SCI, mitochondria serve as both a major source of ROS and a primary target of their attack, playing a crucial role in the initiation and execution of cellular ferroptosis. Mitochondrial homeostasis imbalance is not only a key inducer of the “death triangle” (such as the intensification of lipid peroxidation by mitochondrial ROS), but is also reverse-regulated by the “death triangle” (such as the destruction of mitochondrial structure by lipid peroxidation products). Through the cascade reaction of this triangular network, mitochondrial homeostasis imbalance and the “death triangle” jointly drive the progression of secondary damage. This study aims to synthesize the mechanisms by which various therapeutic approaches mitigate SCI through targeted regulation of mitochondrial homeostasis and inhibition of ferroptosis. Unlike previous research, we integrate the bidirectional regulatory relationship between “mitochondrial homeostasis disruption” and “ferroptosis” in SCI, and emphasize their importance as a synergistic therapeutic target. We not only elaborate in detail how mitochondrial homeostasis—including biogenesis, dynamics, and mitophagy—modulates the initiation and execution of ferroptosis, but also summarize recent strategies that simultaneously target both processes to achieve neuroprotection and functional recovery. Furthermore, this review highlights the translational potential of various treatments in blocking the pathological cascade driven by oxidative stress and lipid peroxidation. These insights provide a novel theoretical framework and propose combinatory therapeutic approaches, thereby laying the groundwork for designing precise and effective comprehensive treatment strategies for SCI in clinical settings. Full article

Age-related mitochondrial dysfunction is involved in the progressive loss of mass and strength of skeletal muscle with aging. The effects of a short-term calorie restriction (ST-CR) were assessed in the oxidative skeletal soleus muscle (Sol) from 27-month-old rats and compared with those of a CR in combination with resveratrol (RSV) (ST-CR + RSV). PGC-1α and PRXIII proteins showed a marked decrease in both ST-CR and ST-CR + RSV rats. The SIRT3 protein presented a very relevant increase in both ST groups. ST-CR and ST-CR + RSV elicited a marked increase in SOD2 protein amount and activity. ST-CR and ST-CR + RSV led to recovery of the SIRT3-SOD2 axis as a fast/early response. ST-CR and ST-CR + RSV did not affect the MFN2 protein, whereas both treatments induced a relevant increase in DRP1 protein. ST-CR and ST-CR + RSV induced a decrease in Parkin protein, suggestive of rescued mitophagy, leading to the elimination of dysfunctional mitochondria. Such a response likely enhanced the fission-mediated elimination of mitochondria, supported by the marked increase in DRP1. MtDNA copy number and TFAM protein were not changed by any ST treatment. The mtDNA oxidative damage level was strongly increased by both ST treatments. All the effects elicited by ST-CR and ST-CR + RSV were specific to the oxidative type fibers. Full article

Plant-insect mutualisms often drive the evolution of adaptive morphological and physiological traits, enabling ecological specialization and diversification. Fig trees (Ficus spp., Moraceae) and their pollinating wasps (Agaonidae) are engaged in a brood-site pollination mutualism that exemplifies such adaptive specializations. This study investigates the morphological and ecological roles of maculae, characterized as distinct-pigmented regions on the fig surface, in the mutualistic interaction between Ficus citrifolia and fig wasps. Through morphological analyses using light and electron microscopy, we demonstrated that maculae concentrate numerous stomata and exhibit secretory activity. This activity is evidenced by the exudation of a sugary-like solution and by the presence of epidermal and subepidermal cells with features consistent with sugar- and terpene-secreting cells, such as abundant starch reserves, numerous mitochondria, plastids containing osmiophilic droplets, a Golgi complex with dilated cisternae, oil bodies, and extensive endoplasmic reticulum. Histochemical tests confirmed a terpenic-sugary secretion in the macula cells. We demonstrated that non-pollinating fig wasps avoid ovipositing through macular regions. This behavior may reflect a selective pressure to prevent structural damage to maculae caused by ovipositor insertion, thus preserving their functional integrity. Temperature measurements revealed that figs are up to 10% cooler on average than the ambient air. Therefore, our findings suggest that fig maculae are multifunctional structures, simultaneously performing the roles of extrafloral nectaries, gas exchange, and thermal regulation, which are crucial for maintaining suitable internal conditions for wasp larval development. These results provide novel insights into previously underexplored plant adaptations supporting specialized brood-site pollination mutualisms. Full article