Mitochondrial Production Research Articles

Mitochondria: great balls of fire.

Recent experimental studies indicate that mitochondria in mammalian cells are maintained at temperatures of at least 50 °C. While acknowledging the limitations of current experimental methods and their interpretation, we here consider the ramifications of this finding for cellular functions and for evolution. We consider whether mitochondria as heat-producing organelles had a role in the origin of eukaryotes and in the emergence of homeotherms. The homeostatic responses of mitochondrial temperature to externally applied heat imply the existence of a molecular heat-sensing system in mitochondria. While current findings indicate high temperatures for the innermost compartments of mitochondria, those of the mitochondrial surface and of the immediately surrounding cytosol remain to be determined. We ask whether some aspects of mitochondrial dynamics and motility could reflect changes in the supply and demand for mitochondrial heat, and whether mitochondrial heat production could be a factor in diseases and immunity.

Mitochondrial viscosity probes:iridium(III) complexes induce apoptosis in HeLa cells.

Mitochondrial viscosity has emerged as a promising biomarker for diseases such as cancer and neurodegenerative disorders, yet accurately measuring viscosity at the subcellular level remains a significant challenge. In this study, we synthesized and characterized three cyclometalated iridium(III) complexes (Ir1-Ir3) containing 5-fluorouracil derivatives asligands. Among these, Ir1selectively induced apoptosis in HeLa cells by increasing mitochondrial production of reactive oxygen species (ROS), which triggered a cascade of events leading to mitochondrial dysfunction. Additionally, the fluorescence lifetime of Ir1demonstrated high sensitivity to intracellular viscosity changes, enabling real-time fluorescence lifetime imaging microscopy (FLIM) of cellular micro-viscosity during apoptosis. These findings underscore the potential of cyclometalated Ir(III) complexes forboth therapeutic and diagnostic applications at the subcellular level.

Cellular ATP demand creates metabolically distinct subpopulations of mitochondria.

Mitochondria serve a crucial role in cell growth and proliferation by supporting both ATP synthesis and the production of macromolecular precursors. Whereas oxidative phosphorylation (OXPHOS) depends mainly on the oxidation of intermediates from the tricarboxylic acid cycle, the mitochondrial production of proline and ornithine relies on reductive synthesis1. How these competing metabolic pathways take place in the same organelle is not clear. Here we show that when cellular dependence on OXPHOS increases, pyrroline-5-carboxylate synthase (P5CS)-the rate-limiting enzyme in the reductive synthesis of proline and ornithine-becomes sequestered in a subset of mitochondria that lack cristae and ATP synthase. This sequestration is driven by both the intrinsic ability of P5CS to form filaments and the mitochondrial fusion and fission cycle. Disruption of mitochondrial dynamics, by impeding mitofusin-mediated fusion or dynamin-like-protein-1-mediated fission, impairs the separation of P5CS-containing mitochondria from mitochondria that are enriched in cristae and ATP synthase. Failure to segregate these metabolic pathways through mitochondrial fusion and fission results in cells either sacrificing the capacity for OXPHOS while sustaining the reductive synthesis of proline, or foregoing proline synthesis while preserving adaptive OXPHOS. These findings provide evidence of the key role of mitochondrial fission and fusion in maintaining both oxidative and reductive biosyntheses in response to changing nutrient availability and bioenergetic demand.

The effect of biocide chloromethylisothiazolinone/methylisothiazolinone (CMIT/MIT) mixture on C2C12 muscle cell damage attributed to mitochondrial reactive oxygen species overproduction and autophagy activation

ABSTRACT The mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one (CMIT/MIT) is a biocide widely used as a preservative in various commercial products. This biocide has also been used as an active ingredient in humidifier disinfectants in South Korea, resulting in serious health effects among users. Recent evidence suggests that the underlying mechanism of CMIT/MIT-initiated toxicity might be associated with defects in mitochondrial functions. The aim of this study was to utilize the C2C12 skeletal muscle model to investigate the effects of CMIT/MIT on mitochondrial function and relevant molecular pathways associated with skeletal muscle dysfunction. Data demonstrated that exposure to CMIT/MIT during myogenic differentiation induced significant mitochondrial excess production of reactive oxygen species (ROS) and a decrease in intracellular ATP levels. Notably, CMIT/MIT significantly inhibited mitochondrial oxidative phosphorylation (Oxphos) and reduced mitochondrial mass at a lower concentration than the biocide amount, which diminished the viability of myotubes. CMIT/MIT induced activation of autophagy flux and decreased protein expression levels of myosin heavy chain (MHC). Taken together, CMIT/MIT exposure produced damage in C2C12 myotubes by impairing mitochondrial bioenergetics and activating autophagy. Our findings contribute to an increased understanding of the underlying mechanisms associated with CMIT/MIT-induced adverse skeletal muscle health effects.

Loss of long-chain acyl-CoA dehydrogenase protects against acute kidney injury.

Proximal tubular epithelial cells (PTECs) are particularly vulnerable to acute kidney injury (AKI). While fatty acids are the preferred energy source for PTECs via fatty acid oxidation (FAO), FAO-mediated H 2 O 2 production in mitochondria has been shown to be a major source of oxidative stress. We have previously shown that a mitochondrial flavoprotein, long-chain acyl-CoA dehydrogenase (LCAD), which catalyzes a key step in mitochondrial FAO, directly produces H 2 O 2 in vitro . Further we have established that loss of a lysine deacylase, Sirtuin 5 ( Sirt5 -/- ), induces hypersuccinylation and inhibition of mitochondrial FAO genes to stimulate peroxisomal FAO and to protect against AKI. However, the role of LCAD has yet to be determined. Mass spectrometry data acquisition revealed that LCAD is hypersuccinylated in Sirt5 -/- kidneys after AKI. Following two distinct models of AKI, cisplatin treatment or renal ischemia/reperfusion (IRI), LCAD knockout mice ( LCAD -/- ) demonstrated renoprotection against AKI. Specifically, LCAD -/- kidneys displayed mitigated renal tubular injury, decreased oxidative stress, preserved mitochondrial function, enhanced peroxisomal FAO, and decreased ferroptotic cell death. LCAD deficiency confers protection against two distinct models of AKI. This suggests a therapeutically attractive mechanism whereby preserved mitochondrial respiration as well as enhanced peroxisomal FAO by loss of LCAD mediates renoprotection against AKI.

Systematic Review and Meta-Analysis on the Association Between Daily Niacin Intake and Glaucoma.

Glaucoma is a progressive optic neuropathy, characterised by a complex pathophysiology, with mitochondrial dysfunction playing a significant role in the cellular damage and apoptosis of ganglion cells. Niacin is a precursor to several molecules acting as coenzymes in the mitochondrial production of ATP, in DNA repair and in the reduction of reactive oxygen species. The objective of this systematic review is to assess the impact of daily niacin intake on glaucoma. Case-control and cohort studies regarding niacin and glaucoma, indexed in PubMed, Web of Science, Cochrane and Scopus, were included. Other study methodologies, studies regarding niacin in other ocular disease or other nutrients in glaucoma were excluded. Bias was assessed using the Newcastle-Ottawa Scale. The study protocol was registered in the PROSPERO database (no. CRD42024578889). Five case-control studies were included. In the pooled analysis, a significantly higher proportion of patients with high niacin consumption was found in the group without glaucoma compared to those with glaucoma as defined by ISGEO criteria (p-value < 0.00001; OR = 0.66, 95% CI 0.55-0.79) or as defined by retinal imaging (p-value = 0.02; OR = 0.63, 95% CI 0.43-0.94). Daily dietary intake of niacin is significantly lower in patients with glaucoma compared to the general population. Given different average daily intakes of niacin in these populations, different glaucoma definitions and several confounding variables which weaken the associations, large sample, standardised randomised controlled trials are needed to confirm the potential benefits of niacin in glaucoma.

Mitochondrial H2S Production Regulates Stomatal Immunity.

Mitochondrial H2S Production Regulates Stomatal Immunity.

Aripiprazole, but Not Olanzapine, Alters the Response to Oxidative Stress in Fao Cells by Reducing the Activation of Mitogen-Activated Protein Kinases (MAPKs) and Promoting Cell Survival.

Prolonged use of atypical antipsychotics (AAPs) is commonly associated with increased cardiovascular disease risk. While weight gain and related health issues are generally considered the primary contributors to this risk, direct interference with mitochondrial bioenergetics, particularly in the liver where these drugs are metabolized, is emerging as an additional contributing factor. Here, we compared the effects of two AAPs with disparate metabolic profiles on the response of Fao hepatoma cells to oxidative stress: olanzapine (OLA), which is obesogenic, and aripiprazole (ARI), which is not. Results showed that cells treated with ARI exhibited resistance to H2O2-induced oxidative stress, while OLA treatment had the opposite effect. Despite enhanced survival, ARI-treated cells exhibited higher apoptotic rates than OLA-treated cells when exposed to H2O2. Gene expression analysis of pro- and anti-apoptotic factors revealed that ARI-treated cells had a generally blunted response to H2O2, contrasting with a heightened response in OLA-treated cells. This was further supported by the reduced activation of MAPKs and STAT3 in ARI-treated cells in response to H2O2, whereas OLA pre-treatment enhanced their activation. The loss of stress response in ARI-treated cells was consistent with the observed increase in the mitochondrial production of O2•-, a known desensitizing factor. The physiological relevance of O2•- in ARI-treated cells was demonstrated by the increase in mitophagy flux, likely related to mitochondrial damage. Notably, OLA treatment protected proteasome activity in Fao cells exposed to H2O2, possibly due to the better preservation of stress signaling and mitochondrial function. In conclusion, this study highlights the underlying changes in cell physiology and mitochondrial function by AAPs. ARI de-sensitizes Fao cells to stress signaling, while OLA has the opposite effect. These findings contribute to our understanding of the metabolic risks associated with prolonged AAP use and may inform future therapeutic strategies.

Lactobacillus Eats Amyloid Plaque and Post-Biotically Attenuates Senescence Due to Repeat Expansion Disorder and Alzheimer's Disease.

Patients with Alzheimer's disease and related dementia (ADRD) are faced with a formidable challenge of focal amyloid deposits and cerebral amyloid angiopathy (CAA). The treatment of amyloid deposits in ADRD by targeting only oxidative stress, inflammation and hyperlipidemia has not yielded significant positive clinical outcomes. The chronic high-fat diet (HFD), or gut dysbiosis, is one of the major contributors of ADRD in part by disrupted transport, epigenetic DNMT1 and the folate 1-carbon metabolism (FOCM) cycle, i.e., rhythmic methylation/de-methylation on DNA, an active part of epigenetic memory during genes turning off and on by the gene writer (DNMT1) and eraser (TET2/FTO) and the transsulfuration pathway by mitochondrial 3-mercaptopyruvate sulfur transferase (3MST)-producing H2S. The repeat CAG expansion and m6A disorder causes senescence and AD. We aim to target the paradigm-shift pathway of the gut-brain microbiome axis that selectively inhibits amyloid deposits and increases mitochondrial transsulfuration and H2S. We have observed an increase in DNMT1 and decreased FTO levels in the cortex of the brain of AD mice. Interestingly, we also observed that probiotic lactobacillus-producing post-biotic folate and lactone/ketone effectively prevented FOCM-associated gut dysbiosis and amyloid deposits. The s-adenosine-methionine (SAM) transporter (SLC25A) was increased by hyperhomocysteinemia (HHcy). Thus, we hypothesize that chronic gut dysbiosis induces SLC25A, the gene writer, and HHcy, and decreases the gene eraser, leading to a decrease in SLC7A and mitochondrial transsulfuration H2S production and bioenergetics. Lactobacillus engulfs lipids/cholesterol and a tri-directional post-biotic, folic acid (an antioxidant and inhibitor of beta amyloid deposits; reduces Hcy levels), and the lactate ketone body (fuel for mitochondria) producer increases SLC7A and H2S (an antioxidant, potent vasodilator and neurotransmitter gas) production and inhibits amyloid deposits. Therefore, it is important to discuss whether lactobacillus downregulates SLC25A and DNMT1 and upregulates TET2/FTO, inhibiting β-amyloid deposits by lowering homocysteine. It is also important to discuss whether lactobacillus upregulates SLC7A and inhibits β-amyloid deposits by increasing the mitochondrial transsulfuration of H2S production.

α-Synuclein pathology disrupts mitochondrial function in dopaminergic and cholinergic neurons at-risk in Parkinson's disease.

Pathological accumulation of aggregated α-synuclein (aSYN) is a common feature of Parkinson's disease (PD). However, the mechanisms by which intracellular aSYN pathology contributes to dysfunction and degeneration of neurons in the brain are still unclear. A potentially relevant target of aSYN is the mitochondrion. To test this hypothesis, genetic and physiological methods were used to monitor mitochondrial function in substantia nigra pars compacta (SNc) dopaminergic and pedunculopontine nucleus (PPN) cholinergic neurons after stereotaxic injection of aSYN pre-formed fibrils (PFFs) into the mouse brain. aSYN PFFs were stereotaxically injected into the SNc or PPN of mice. Twelve weeks later, mice were studied using a combination of approaches, including immunocytochemical analysis, cell-type specific transcriptomic profiling, electron microscopy, electrophysiology and two-photon-laser-scanning microscopy of genetically encoded sensors for bioenergetic and redox status. In addition to inducing a significant neuronal loss, SNc injection of PFFs induced the formation of intracellular, phosphorylated aSYN aggregates selectively in dopaminergic neurons. In these neurons, PFF-exposure decreased mitochondrial gene expression, reduced the number of mitochondria, increased oxidant stress, and profoundly disrupted mitochondrial adenosine triphosphate production. Consistent with an aSYN-induced bioenergetic deficit, the autonomous spiking of dopaminergic neurons slowed or stopped. PFFs also up-regulated lysosomal gene expression and increased lysosomal abundance, leading to the formation of Lewy-like inclusions. Similar changes were observed in PPN cholinergic neurons following aSYN PFF exposure. Taken together, our findings suggest that disruption of mitochondrial function, and the subsequent bioenergetic deficit, is a proximal step in the cascade of events induced by aSYN pathology leading to dysfunction and degeneration of neurons at-risk in PD.

SS-31 modification alleviates ferroptosis induced by superparamagnetic iron oxide nanoparticles in hypoxia/reoxygenation cardiomyocytes

Superparamagnetic iron oxide nanoparticles (SPION) are widely used in cardiovascular applications. However, their potential to induce ferroptosis in myocardial cells post-ischemia-reperfusion hinders clinical adoption. We investigated the mechanisms behind SPION-induced cytotoxicity in myocardial cells and explored whether co-loading SPION with SS-31 (a kind of mitochondrial-targeted antioxidant peptide) could counteract this toxicity.To create SPION@SS-31, SS-31 was physically adsorbed onto SPION. To study the dose- and time-dependent cytotoxic effects and assess the influence of SS-31 on reducing SPION-induced damage, hypoxia/reoxygenation(H/R) H9C2 cells were treated with either SPION or SPION@SS-31. We examined the relationship between SPION and ferroptosis by measuring mitochondrial ROS, mitochondrial membrane potential (MMP), lipid peroxidation products, ATP, GSH, GPX4, mitochondrial structure, nonheme iron content, cellular iron regulation, and typical ferroptosis markers.The findings showed that SPION induced concentration- and time-dependent toxicity, marked by a significant cell viability loss and an increase in LDH levels. In contrast, SPION@SS-31 produced results comparable to the H/R group, implying that SS-31 can notably reduce cell damage induced by SPION. SPION disrupted cellular iron homeostasis, with FtH and FtMt expression increased and reduced levels of FPN1 and ABCB8, which led to the overload of mitochondrial iron. This iron dysregulation damaged mitochondrial function and integrity, causing ATP depletion, MMP loss, and decreased GPX4 and GSH levels, accompanied by a burst of mitochondrial lipid peroxidation, ultimately resulting in ferroptosis in H/R cardiomyocytes. Notably, SS-31 significantly alleviated SPION-induced ferroptosis by decreasing mitochondrial MDA production and maintaining GSH and GPX4 levels, indicating its possibility to reverse SPION-induced cytotoxicity. The viability of H/R cells and cells treated with SPION and Fer-1 did not differ statistically, whereas cells exposed to SPION along with inhibitors like 3-MA, zVAD, or Nec-1 showed a substantial loss in viability, implying that ferroptosis is the primary mechanism behind SPION-induced myocardial toxicity.SPION triggers mitochondrial lipid peroxidation by causing overload of iron, leading to ferroptosis in H/R H9C2 cells. Mitochondria appear to be the primary target of SPION-induced toxic effects. SS-31 demonstrates potential in inhibiting this ferroptosis by acting as a mitochondria-targeted antioxidant, suggesting that the modification of mitochondria-targeted antioxidant peptides represents an innovative and practical approach to attenuate the myocardial toxicity associated with SPION.

Mitonuclear effects on sex ratio persist across generations in interpopulation hybrids.

Eukaryotic energy production requires tight coordination between nuclear and mitochondrial gene products. Because males and females often have different energetic strategies, optimal mitonuclear coordination may be sex-specific. Previous work found evidence for sex-specific mitonuclear effects in the copepod Tigriopus californicus by comparing two parental lines and their reciprocal F1 crosses. However, an alternative hypothesis is that the patterns were driven by the parental source of nuclear alleles. Here we test this alternative hypothesis by extending the same cross to F2 hybrids, who receive both maternal and paternal nuclear alleles from F1 hybrids. Results confirm mitonuclear effects on sex ratio, with distorted ratios persisting from the F1 to F2 generations, despite reduced fitness in F2 hybrids. No sex by cross interactions were found for other phenotypic traits measured. Mitochondrial DNA content was higher in females. Both routine metabolic rate and oxidative DNA damage were lower in F2 hybrids than in parentals. The persistence of sex-specific mitonuclear effects, even in the face of F2 hybrid breakdown, attests to the magnitude of these effects, which contribute to the maintenance of within-population mitochondrial DNA polymorphisms.

Differential mitochondrial adaptation and FNDC5 production in brown and white adipose tissue in response to cold and obesity.

Fibronectin type III domain-containing protein 5 (FNDC5) modulates adipocyte metabolism by increasing white and brown adipose tissue (WAT and BAT) browning and activity, respectively. We investigated whether FNDC5 can regulate visceral WAT and BAT adaptive thermogenesis by improving mitochondrial homeostasis in response to cold and obesity. Adipose tissue expression of FNDC5 and factors involved in mitochondrial homeostasis were determined in patients with normal weight and obesity (n = 159) and in rats with diet-induced obesity after 1 week of cold exposure (n = 61). The effect of different FNDC5 concentrations on mitochondrial biogenesis, dynamics, and mitophagy was evaluated in vitro in human adipocytes. In human visceral adipocytes, FNDC5/irisin triggered mitochondrial biogenesis (TFAM) and fusion (MFN1, MFN2, and OPA1) while inhibiting peripheral fission (DNM1L and FIS1) and mitophagy (PINK1 and PRKN). Circulating and visceral WAT expression of FNDC5 wasdecreased in patients and experimental animals with obesity, whereas its receptor, integrin αV, was upregulated. Obesity increased mitochondrial fusion while decreasing mitophagy in visceral WAT from patients and rats. By contrast, in rat BAT, an upregulation of Fndc5 and genes involved in mitochondrial biogenesis and fission was observed. Cold exposure promoted mitochondrial biogenesis and healthy peripheral fission while repressing Fndc5 expression and mitophagy in BAT from rats. Depot differences in FNDC5 production and mitochondrial adaptations in response to obesity and cold might indicate a self-regulatory mechanism to control thermogenesis in response to energy needs.

Glial swip-10 controls systemic mitochondrial function, oxidative stress, and neuronal viability via copper ion homeostasis

Cuprous copper [Cu(I)] is an essential cofactor for enzymes that support many fundamental cellular functions including mitochondrial respiration and suppression of oxidative stress. Neurons are particularly reliant on mitochondrial production of ATP, with many neurodegenerative diseases, including Parkinson's disease, associated with diminished mitochondrial function. The gene MBLAC1 encodes a ribonuclease that targets pre-mRNA of replication-dependent histones, proteins recently found in yeast to reduce Cu(II) to Cu(I), and when mutated disrupt ATP production, elevates oxidative stress, and severely impacts cell growth. Whether this process supports neuronal and/or systemic physiology in higher eukaryotes is unknown. Previously, we identified swip-10, the putative Caenorhabditis elegans ortholog of MBLAC1, establishing a role for glial swip-10 in limiting dopamine (DA) neuron excitability and sustaining DA neuron viability. Here, we provide evidence from computational modeling that SWIP-10 protein structure mirrors that of MBLAC1 and locates a loss of function coding mutation at a site expected to disrupt histone RNA hydrolysis. Moreover, we find through genetic, biochemical, and pharmacological studies that deletion of swip-10 in worms negatively impacts systemic Cu(I) levels, leading to deficits in mitochondrial respiration and ATP production, increased oxidative stress, and neurodegeneration. These phenotypes can be offset in swip-10 mutants by the Cu(I) enhancing molecule elesclomol and through glial expression of wildtype swip-10. Together, these studies reveal a glial-expressed pathway that supports systemic mitochondrial function and neuronal health via regulation of Cu(I) homeostasis, a mechanism that may lend itself to therapeutic strategies to treat devastating neurodegenerative diseases.

Atomic vacancies of molybdenum disulfide nanoparticles stimulate mitochondrial biogenesis

Diminished mitochondrial function underlies many rare inborn errors of energy metabolism and contributes to more common age-associated metabolic and neurodegenerative disorders. Thus, boosting mitochondrial biogenesis has been proposed as a potential therapeutic approach for these diseases; however, currently we have a limited arsenal of compounds that can stimulate mitochondrial function. In this study, we designed molybdenum disulfide (MoS2) nanoflowers with predefined atomic vacancies that are fabricated by self-assembly of individual two-dimensional MoS2 nanosheets. Treatment of mammalian cells with MoS2 nanoflowers increased mitochondrial biogenesis by induction of PGC-1α and TFAM, which resulted in increased mitochondrial DNA copy number, enhanced expression of nuclear and mitochondrial-DNA encoded genes, and increased levels of mitochondrial respiratory chain proteins. Consistent with increased mitochondrial biogenesis, treatment with MoS2 nanoflowers enhanced mitochondrial respiratory capacity and adenosine triphosphate production in multiple mammalian cell types. Taken together, this study reveals that predefined atomic vacancies in MoS2 nanoflowers stimulate mitochondrial function by upregulating the expression of genes required for mitochondrial biogenesis.

Skeletal Muscle Involvement in Friedreich Ataxia.

Friedreich Ataxia (FRDA) is an inherited neuromuscular disorder triggered by a deficit of the mitochondrial protein frataxin. At a cellular level, frataxin deficiency results in insufficient iron-sulfur cluster biosynthesis and impaired mitochondrial function and adenosine triphosphate production. The main clinical manifestation is a progressive balance and coordination disorder which depends on the involvement of peripheral and central sensory pathways as well as of the cerebellum. Besides the neurological involvement, FRDA affects also the striated muscles. The most prominent manifestation is a hypertrophic cardiomyopathy, which also represents the major determinant of premature mortality. Moreover, FRDA displays skeletal muscle involvement, which contributes to the weakness and marked fatigue evident throughout the course of the disease. Herein, we review skeletal muscle findings in FRDA generated by functional imaging, histology, as well as multiomics techniques in both disease models and in patients. Altogether, these findings corroborate a disease phenotype in skeletal muscle and support the notion of progressive mitochondrial damage as a driver of disease progression in FRDA. Furthermore, we highlight the relevance of skeletal muscle investigations in the development of biomarkers for early-phase trials and future therapeutic strategies in FRDA.

HIF-2α drives hepatic Kupffer cell death and proinflammatory recruited macrophage activation in nonalcoholic steatohepatitis.

Proinflammatory hepatic macrophage activation plays a key role in the development of nonalcoholic steatohepatitis (NASH). This involves increased embryonic hepatic Kupffer cell (KC) death, facilitating the replacement of KCs with bone marrow-derived recruited hepatic macrophages (RHMs) that highly express proinflammatory genes. Moreover, phago/efferocytic activity of KCs is diminished in NASH, enhancing liver inflammation. However, the molecular mechanisms underlying these changes in KCs are not known. Here, we show that hypoxia-inducible factor 2α (HIF-2α) mediates NASH-associated decreased KC growth and efferocytosis by enhancing lysosomal stress. At the molecular level, HIF-2α stimulated mammalian target of rapamycin (mTOR)- and extracellular signal-regulated kinase-dependent inhibitory transcription factor EB (TFEB) phosphorylation, leading to decreased lysosomal and phagocytic gene expression. With increased metabolic stress and phago/efferocytic burden in NASH, these changes were sufficient to increase lysosomal stress, causing decreased efferocytosis and lysosomal cell death. Of interest, HIF-2α-dependent TFEB regulation only occurred in KCs but not RHMs. Instead, in RHMs, HIF-2α promoted mitochondrial reactive oxygen species production and proinflammatory activation by increasing ANT2 expression and mitochondrial permeability transition. Consequently, myeloid lineage-specific or KC-specific HIF-2α depletion or the inhibition of mTOR-dependent TFEB inhibition using antisense oligonucleotide treatment protected against the development of NASH in mice. Moreover, treatment with an HIF-2α-specific inhibitor reduced inflammatory and fibrogenic gene expression in human liver spheroids cultured under a NASH-like condition. Together, our results suggest that macrophage subtype-specific effects of HIF-2α collectively contribute to the proinflammatory activation of liver macrophages, leading to the development of NASH.

Human neural stem cell-derived artificial organelles to improve oxidative phosphorylation

Oxidative phosphorylation (OXPHOS) in the mitochondrial inner membrane is a therapeutic target in many diseases. Neural stem cells (NSCs) show progress in improving mitochondrial dysfunction in the central nervous system (CNS). However, translating neural stem cell-based therapies to the clinic is challenged by uncontrollable biological variability or heterogeneity, hindering uniform clinical safety and efficacy evaluations. We propose a systematic top-down design based on membrane self-assembly to develop neural stem cell-derived oxidative phosphorylating artificial organelles (SAOs) for targeting the central nervous system as an alternative to NSCs. We construct human conditionally immortal clone neural stem cells (iNSCs) as parent cells and use a streamlined closed operation system to prepare neural stem cell-derived highly homogenous oxidative phosphorylating artificial organelles. These artificial organelles act as biomimetic organelles to mimic respiration chain function and perform oxidative phosphorylation, thus improving ATP synthesis deficiency and rectifying excessive mitochondrial reactive oxygen species production. Conclusively, we provide a framework for a generalizable manufacturing procedure that opens promising prospects for disease treatment.

Changes in bioenergetic characteristics of the murine lymphoma cells under the action of a thiazole derivative in complex with polymeric nanoparticles

Background. Mitochondria can influence cancer cells both indirectly via reactive oxygen species mediation and directly through mitochondrial biogenesis. Energy production in mitochondria is crucial as it facilitates the synthesis of essential molecules needed for cellular biosynthesis, growth, and proliferation. The development of new anticancer drugs that target the energy metabolism of tumor cells shows promise in cancer treatment. Our study aimed to investigate how the thiazole derivative N-(5-benzyl-1,3-thiazol-2-yl)-3,5-dimethyl-1-benzofuran-2-carboxamide (BF1), the polymeric nanoparticles based on the polyethylene glycol (PEG-PN, Th5), and their complex with BF1 (Th6) affect respiration and mitochondrial membrane potential in murine NK/Ly tumor cells. Materials and Methods. The study was performed on white wild-type male mice with grafted NK/Ly lymphoma. The test substances were added to the cell suspension at a final concentration of 10 μM and incubated for 15 min at 37 °C. Oxygen uptake rates in NK/Ly cells were measured using a polarographic method with Clark electrode. Changes in mitochondrial membrane potential were assessed using the tetramethylrhodamine methyl ester fluorescence dye. The fluorescence intensity was evaluated using the ImageJ computer program. Results. After incubating NK/Ly cells with BF1 (10 µM), Th5, or the BF1 + PEG-PN complex (Th6) for 15 min, no changes were observed in glucose-fueled basal respiration. However, the Th6 complex significantly activated FCCP-stimulated respiratory processes in NK/Ly lymphoma cells. Fluorescent microscopy data indicated that BF1 or Th5 alone did not affect mitochondrial membrane potential values. However, the Th6 complex significantly decreased mitochondrial membrane potential, suggesting a reduction in NK/Ly cell viability. Conclusions The investigated complex of thiazole derivative BF1 with PEG-based polymeric nanoparticles may realize its cytotoxic effect by depolarization of mitochondrial membrane in NK/Ly lymphoma cells.

Hovenia dulcis Thunb. monofloral honey attenuates LPS-induced inflammation and endotoxemia through the activation of the Nrf2/HO-1 axis

Monofloral honey derived from Hovenia dulcis Thunb. (HMH) is known for its antimicrobial and antioxidant properties. However, its potential to alleviate the inflammatory response has not yet been explored. The aim of this study was to investigate the anti-inflammatory and anti-endotoxemic effects of HMH. The findings showed that HMH did not exhibit toxicity to RAW 264.7 macrophages at low concentrations and suppressed the production of proinflammatory mediators, such as nitric oxide and prostaglandin E2, as well as cytokines, including tumor necrosis factor-α and interleukin-12 in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages, by inhibiting NF-κB activation. Additionally, HMH prevented mortality and abnormalities in LPS-microinjected zebrafish larvae along with the inhibition of proinflammatory genes. In addition, HMH was found to reduce mitochondrial membrane potential depolarization and mitochondrial reactive oxygen species production in both LPS-stimulated RAW 264.7 macrophages and zebrafish larvae. Furthermore, HMH induced the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) and promotes the nuclear translocation of Nrf2. The anti-inflammatory effects of HMH are mediated via the Nrf2-HO-1 axis, and an HO-1 inhibitor reverses HMH-induced responses. This study is the first to demonstrate the anti-inflammatory and anti-endotoxemic effects of HMH, highlighting its potential as a therapeutic.