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Stroke Jul 2024The mitochondrial unfolded protein response (UPR) is an evolutionarily conserved mitochondrial response that is critical for maintaining mitochondrial and energetic...
BACKGROUND
The mitochondrial unfolded protein response (UPR) is an evolutionarily conserved mitochondrial response that is critical for maintaining mitochondrial and energetic homeostasis under cellular stress after tissue injury and disease. Here, we ask whether UPR may be a potential therapeutic target for ischemic stroke.
METHODS
We performed the middle cerebral artery occlusion and oxygen-glucose deprivation models to mimic ischemic stroke in vivo and in vitro, respectively. Oligomycin and meclizine were used to trigger the UPR. We used 2,3,5-triphenyltetrazolium chloride staining, behavioral tests, and Nissl staining to evaluate cerebral injury in vivo. The Cell Counting Kit-8 assay and the Calcein AM Assay Kit were conducted to test cerebral injury in vitro.
RESULTS
Inducing UPR with oligomycin protected neuronal cultures against oxygen-glucose deprivation. UPR could also be triggered with meclizine, and this Food and Drug Administration-approved drug also protected neurons against oxygen-glucose deprivation. Blocking UPR with siRNA against activating transcription factor 5 eliminated the neuroprotective effects of meclizine. In a mouse model of focal cerebral ischemia, pretreatment with meclizine was able to induce UPR in vivo, which reduced infarction and improved neurological outcomes.
CONCLUSIONS
These findings suggest that the UPR is important in maintaining the survival of neurons facing ischemic/hypoxic stress. The UPR mechanism may provide a new therapeutic avenue for ischemic stroke.
Topics: Animals; Neurons; Mice; Glucose; Unfolded Protein Response; Mitochondria; Brain Ischemia; Male; Infarction, Middle Cerebral Artery; Oxygen; Mice, Inbred C57BL; Cells, Cultured; Neuroprotective Agents
PubMed: 38913800
DOI: 10.1161/STROKEAHA.123.045550 -
Neurobiology of Disease Jun 2024Arketamine, the (R)-enantiomer of ketamine, exhibits antidepressant-like effects in mice, though the precise molecular mechanisms remain elusive. It has been shown to...
Arketamine, the (R)-enantiomer of ketamine, exhibits antidepressant-like effects in mice, though the precise molecular mechanisms remain elusive. It has been shown to reduce splenomegaly and depression-like behaviors in the chronic social defeat stress (CSDS) model of depression. This study investigated whether the spleen contributes to the antidepressant-like effects of arketamine in the CSDS model. We found that splenectomy significantly inhibited arketamine's antidepressant-like effects in CSDS-susceptible mice. RNA-sequencing analysis identified the oxidative phosphorylation (OXPHOS) pathway in the prefrontal cortex (PFC) as a key mediator of splenectomy's impact on arketamine's effects. Furthermore, oligomycin A, an inhibitor of the OXPHOS pathway, reversed the suppressive effects of splenectomy on arketamine's antidepressant-like effects. Specific genes within the OXPHOS pathways, such as COX11, UQCR11 and ATP5e, may contribute to these inhibitory effects. Notably, transforming growth factor (TGF)-β1, along with COX11, appears to modulate the suppressive effects of splenectomy and contribute to arketamine's antidepressant-like effects. Additionally, SRI-01138, an agonist of the TGF-β1 receptor, alleviated the inhibitory effects of splenectomy on arketamine's antidepressant-like effects. Subdiaphragmatic vagotomy also counteracted the inhibitory effects of splenectomy on arketamine's antidepressant-like effects in CSDS-susceptible mice. These findings suggest that the OXPHOS pathway and TGF-β1 in the PFC play significant roles in the antidepressant-like effects of arketamine, mediated through the spleen-brain axis via the vagus nerve.
PubMed: 38901783
DOI: 10.1016/j.nbd.2024.106573 -
International Journal of Molecular... Jun 2024This study demonstrated the anticancer efficacy of chalcones with indole moiety (MIPP, MOMIPP) in fibrosarcoma cells for the first time. The results showed that MIPP and...
This study demonstrated the anticancer efficacy of chalcones with indole moiety (MIPP, MOMIPP) in fibrosarcoma cells for the first time. The results showed that MIPP and MOMIPP reduced the viability of HT-1080 cells in a concentration-dependent manner. MOMIPP was more active than MIPP in HT-1080 cells, showing lower IC values (3.67 vs. 29.90 μM). Both compounds at a concentration of 1 μM induced apoptosis in HT-1080 cells, causing death strictly related to caspase activation, as cell viability was restored when the caspase inhibitor Z-VAD was added. Reactive oxygen species production was approximately 3-fold higher than in control cells, and cotreatment with the inhibitor of mitochondrial ATPase oligomycin diminished this effect. Such effects were also reflected in mitochondrial dysfunction, including decreased membrane potential. Interestingly, the compounds that were studied caused massive vacuolization in HT-1080 cells. Immunocytochemical staining and TEM analysis showed that HT-1080 cells exhibited increased expression of the LC3-II protein and the presence of autophagosomes with a double membrane, respectively. Both compounds induced apoptosis, highlighting a promising link between autophagy and apoptosis. This connection could be a new target for therapeutic strategies to overcome chemoresistance, which is a significant cause of treatment failure and tumour recurrence in fibrosarcoma following traditional chemotherapy.
Topics: Humans; Apoptosis; Fibrosarcoma; Autophagy; Indoles; Cell Line, Tumor; Reactive Oxygen Species; Chalcones; Membrane Potential, Mitochondrial; Cell Survival; Antineoplastic Agents; Mitochondria
PubMed: 38892288
DOI: 10.3390/ijms25116100 -
International Journal of Obesity (2005) Jun 2024Dual amylin and calcitonin receptor agonists (DACRAs) are therapeutic candidates in the treatment of obesity with beneficial effects on weight loss superior to...
BACKGROUND AND OBJECTIVES
Dual amylin and calcitonin receptor agonists (DACRAs) are therapeutic candidates in the treatment of obesity with beneficial effects on weight loss superior to suppression of food intake. Hence, suggesting effects on energy expenditure by possibly targeting mitochondria in metabolically active tissue.
METHODS
Male rats with HFD-induced obesity received a DACRA, KBP-336, every third day for 8 weeks. Upon study end, mitochondrial respiratory capacity (MRC), - enzyme activity, - transcriptional factors, and -content were measured in perirenal (pAT) and inguinal adipose tissue. A pair-fed group was included to examine food intake-independent effects of KBP-336.
RESULTS
A vehicle-corrected weight loss (23.4 ± 2.8%) was achieved with KBP-336, which was not observed to the same extent with the food-restricted weight loss (12.4 ± 2.8%) (P < 0.001). Maximal coupled respiration supported by carbohydrate and lipid-linked substrates was increased after KBP-336 treatment independent of food intake in pAT (P < 0.01). Moreover, oligomycin-induced leak respiration and the activity of citrate synthase and β-hydroxyacetyl-CoA-dehydrogenase were increased with KBP-336 treatment (P < 0.05). These effects occurred without changes in mitochondrial content in pAT.
CONCLUSIONS
These findings demonstrate favorable effects of KBP-336 on MRC in adipose tissue, indicating an increased energy expenditure and capacity to utilize fatty acids. Thus, providing more mechanistic insight into the DACRA-induced weight loss.
PubMed: 38879729
DOI: 10.1038/s41366-024-01564-w -
FEBS Open Bio Jun 2024Exploring cellular responses necessitates studying real-time metabolic pathway kinetics, considering the adaptable nature of cells. Glycolysis and glutaminolysis are...
Exploring cellular responses necessitates studying real-time metabolic pathway kinetics, considering the adaptable nature of cells. Glycolysis and glutaminolysis are interconnected pathways fundamental to driving cellular metabolism, generating both energy and essential biosynthetic molecules. While prior studies explored glycolysis tracking, this research focuses on monitoring the kinetics of the glutaminolysis pathway by evaluating the effect of glutamine availability on glycolytic kinetics and by investigating the impact of a stimulator (oligomycin) and inhibitor (2DG) on the glycolytic flux in the presence of glutamine. Additionally, we adapted a rate equation model to provide improved understanding of the pathway kinetics. The experimental and simulated results indicate a significant reduction in extracellular lactate production in the presence of glutamine, reflecting a shift from glycolysis towards oxidative phosphorylation, due to the additional contribution of glutamine to energy production through the ETC (electron transport chain), reducing the glycolytic load. Oligomycin, an ETC inhibitor, increases lactate production to the original glycolytic level, despite the presence of glutamine. Nevertheless, its mechanism is influenced by the presence of glutamine, as predicted by the model. Conversely, 2DG notably reduces lactate production, affirming its glycolytic origin. The gradual increase in lactate production under the influence of 2DG implies increased activation of glutaminolysis as an alternative energy source. The model also simulates the varying metabolic responses under varying carbon/modulator concentrations. In conclusion, the kinetic model described here contributes to the understanding of changes in intracellular metabolites and their interrelationships in a way which would be challenging to obtain solely through kinetic assays.
PubMed: 38867138
DOI: 10.1002/2211-5463.13841 -
MSphere Jun 2024is a necrotrophic phytopathogen able to attack more than 200 different plant species causing strong yield losses worldwide. Many synthetic fungicides have been...
UNLABELLED
is a necrotrophic phytopathogen able to attack more than 200 different plant species causing strong yield losses worldwide. Many synthetic fungicides have been developed to control this disease, resulting in the rise of fungicide-resistance strains. The aim of this study was to identify strains showing antagonistic activity against to contribute to plant protection in an environmentally friendly way. We isolated 15 Actinomycete strains from 9 different Swiss soils. The culture filtrates of three isolates showing antifungal activity inhibited spore germination and delayed mycelial growth of . Infection experiments showed that plants were more resistant to this pathogen after leaf treatment with the filtrates. Bioassay-guided isolation of the active compounds revealed the presence of germicidins A and B as well as of oligomycins A, B, and E. While germicidins were mostly inactive, oligomycin B reduced the mycelial growth of significantly. Moreover, all three oligomycins inhibited this fungus' spore germination, suggesting that these molecules might contribute to the 's ability to protect plants against infection by the broad host-pathogen .
IMPORTANCE
This study reports the isolation of new strains with strong plant-protective potential mediated by their production of specialized metabolites. Using the broad host range pathogenic fungus , we demonstrate that the cell-free filtrate of selected isolates efficiently inhibits different developmental stages of the fungus, including mycelial growth and the epidemiologically relevant spore germination. Beyond experiments, the strains and their metabolites also efficiently protected plants against the disease caused by this pathogen. This work further identifies oligomycins as active compounds involved in the observed antifungal activity of the strains. This work shows that we can harness the natural ability of soil-borne microbes and of their metabolites to efficiently fight other microbes responsible for significant crop losses. This opens the way to the development of environmentally friendly health protection measures for crops of agronomical relevance, based on these newly isolated strains or their metabolic extracts containing oligomycins.
PubMed: 38864637
DOI: 10.1128/msphere.00667-23 -
International Journal of Medical... 2024The mitochondrial unfolded protein response (UPRmt) is a pivotal cellular mechanism that ensures mitochondrial homeostasis and cellular survival under stress conditions....
The mitochondrial unfolded protein response (UPRmt) is a pivotal cellular mechanism that ensures mitochondrial homeostasis and cellular survival under stress conditions. This study investigates the role of UPRmt in modulating the response of nasopharyngeal carcinoma cells to cisplatin-induced stress. We report that the inhibition of UPRmt via AEB5F exacerbates cisplatin cytotoxicity, as evidenced by increased lactate dehydrogenase (LDH) release and apoptosis, characterized by a surge in TUNEL-positive cells. Conversely, the activation of UPRmt with oligomycin attenuates these effects, preserving cell viability and reducing apoptotic markers. Immunofluorescence assays reveal that UPRmt activation maintains mitochondrial membrane potential and ATP production in the presence of cisplatin, countering the rise in reactive oxygen species (ROS) and inhibiting caspase-9 activation. These findings suggest that UPRmt serves as a cytoprotective mechanism in cancer cells, mitigating cisplatin-induced mitochondrial dysfunction and apoptosis. The data underscore the therapeutic potential of modulating UPRmt to improve the efficacy and reduce the side effects of cisplatin chemotherapy. This study provides a foundation for future research on the exploitation of UPRmt in cancer treatment, with the aim of enhancing patient outcomes by leveraging the cellular stress response pathways.
Topics: Humans; Unfolded Protein Response; Mitochondria; Cisplatin; Apoptosis; Cell Line, Tumor; Reactive Oxygen Species; Membrane Potential, Mitochondrial; Nasopharyngeal Neoplasms; Nasopharyngeal Carcinoma; Antineoplastic Agents; Cell Survival
PubMed: 38818479
DOI: 10.7150/ijms.95624 -
The Journal of Experimental Biology May 2024Very few vertebrates survive without oxygen (anoxia) for more than a few minutes. The crucian carp (Carassius carassius) survive months of anoxia at low temperatures and...
Very few vertebrates survive without oxygen (anoxia) for more than a few minutes. The crucian carp (Carassius carassius) survive months of anoxia at low temperatures and we hypothesised that they maintain mitochondrial membrane potential and function. Isolated crucian carp cardiomyocytes indeed maintained mitochondrial membrane potential after blocking complex-IV of the electron transport system with cyanide, while those of anoxia-intolerant trout depolarized. When complexes I-III were inhibited, crucian carp mitochondria depolarized, indicating that these complexes need to function during anoxia. Mitochondrial membrane potential depended on reversal of ATP synthase in chemical anoxia, as blocking with cyanide combined with oligomycin to inhibit ATP-synthase lead to depolarization. ATP-synthase activity was reduced in the heart after one week of anoxia in crucian carp, together with a downregulation of ATP-synthase subunit gene expression. However, the morphology of cardiac mitochondria were not affected by one-week anoxia, even with a large increase in mitofusin-2 expression. Cardiac citrate synthase activity was not affected by anoxia, while cytochrome-C oxidase activity was increased. We show how mitochondria respond to anoxia. A mechanistic understanding of how mitochondrial function can be maintained in anoxia may provide new perspectives to reduce mitochondrial damage in anoxia-sensitive organisms.
PubMed: 38779846
DOI: 10.1242/jeb.247409 -
BioRxiv : the Preprint Server For... May 2024Studies on the dynamics of single cell phenotyping have been hampered by the lack of quantitative high-throughput metabolism assays. Extracellular acidification, a...
Studies on the dynamics of single cell phenotyping have been hampered by the lack of quantitative high-throughput metabolism assays. Extracellular acidification, a prominent phenotype, yields significant insights into cellular metabolism, including tumorigenicity. Here, we develop a versatile microfluidic system for single cell optical pH analysis (SCO-pH), which compartmentalizes single cells in 140-pL droplets and immobilizes approximately 40,000 droplets in a two-dimensional array for temporal extracellular pH analysis. SCO-pH distinguishes cells undergoing hyperglycolysis induced by oligomycin A from untreated cells by monitoring their extracellular acidification. To facilitate pH sensing in each droplet, we encapsulate a cell-impermeable pH probe whose fluorescence intensities are quantified. Using this approach, we can differentiate hyperglycolytic cells and concurrently observe single cell heterogeneity in extracellular acidification dynamics. This high-throughput system will be useful in applications that require dynamic phenotyping of single cells with significant heterogeneity.
PubMed: 38766224
DOI: 10.1101/2024.05.08.593179 -
Biology Open May 2024There is evidence that indicates that temperature modulates the reproduction of the tropical species Octopus maya, through the over- or under-expression of many genes in...
There is evidence that indicates that temperature modulates the reproduction of the tropical species Octopus maya, through the over- or under-expression of many genes in the brain. If the oxygen supply to the brain depends on the circulatory system, how temperature affects different tissues will begin in the heart, responsible for pumping the oxygen to tissues. The present study examines the impact of heat stress on the mitochondrial function of the systemic heart of adult O. maya. The mitochondrial metabolism and antioxidant defense system were measured in the systemic heart tissue of female organisms acclimated to different temperatures (24, 26, and 30°C). The results show that acclimation temperature affects respiratory State 3 and State 4o (oligomycin-induced) with higher values observed in females acclimated at 26°C. The antioxidant defense system is also affected by acclimation temperature with significant differences observed in superoxide dismutase, glutathione S-transferase activities, and glutathione levels. The results suggest that high temperatures (30°C) could exert physical limitations on the circulatory system through the heart pumping, affecting nutrient and oxygen transport to other tissues, including the brain, which exerts control over the reproductive system. The role of the cardiovascular system in supporting aerobic metabolism in octopus females is discussed.
Topics: Animals; Female; Oxidative Phosphorylation; Octopodiformes; Antioxidants; Climate Change; Acclimatization; Temperature; Heart; Myocardium; Superoxide Dismutase
PubMed: 38752595
DOI: 10.1242/bio.060103