Journal of Bioenergetics and Biomembranes最新文献

Uncoupling proteins (UCPs) are mitochondrial membrane proteins involved in metabolite transportation and proton translocation to the mitochondrial matrix. Seven UCP homologs have been reported in bilaterians; however, UCPs of early-branching animals (i.e., members of Cnidaria, Ctenophora, Placozoa, and Porifera) remain understudied. The presence of UCPs in the cnidarian jellyfish Stomolophus sp.2. was investigated, and its UCP homologs were compared with data from 49 other early-branching species to provide insights into their evolution. Three UCPs were identified in Stomolophus sp.2: UCP4, UCP5, and a novel cnidarian-specific homolog (cnUCP). In addition to cnidarians, placozoans and sponges share UCP4 and UCP5 homologs, while ctenophores lack these but possess three distinct UCPs, two of them related to UCP5. Results suggest that since UCP4 and UCP5 originated at least at the Animalia-Choanoflagellata node and considering the evolutionary gains of UCPs in Cnidaria and Ctenophora, the relevance of these proteins in mitochondrial functions deserves attention. Moreover, to infer the role of UCPs in Stomolophus sp.2 mitochondria, their structural characteristics were identified, and the temperature effect on their gene expression was evaluated. Whereas UCP4 and UCP5 genes showed higher expression at 23 °C, cnUCP was highly expressed at 33 °C, suggesting a potential role in the jellyfish thermal stress response. Besides their role in mitochondrial uncoupling and energy balance, the bilaterian UCPs may mitigate reactive oxygen species production during thermal stress. However, their role in early-branching lineages remains unclear. This study provides key data for future functional research on UCPs in early-branching animals under climate change.

Brain microvascular endothelial cell injury is an important pathological basis for blood-brain barrier damage in ischemic stroke. Mollugin is a bioactive phytochemical constituent from Rubia cordifolia L., which has a protective potential in some diseases. However, the biological mechanism of mollugin in cerebrovascular damage in ischemic stroke is unknown. Human brain microvascular endothelial cells (hBMECs) were subjected to oxygen-glucose deprivation/reperfusion (OGD/R) to mimic the cerebrovascular damage in ischemic stroke. Cell viability was measured via MTT. Cell death was evaluated via flow cytometry, LDH release assay, and western blotting. Cell permeability was examined via FITC-dextran permeability assay and western blotting. Mollugin mitigated OGD/R-induced viability reduction of hBMECs. Moreover, mollugin attenuated OGD/R-induced increase in apoptotic rate, LDH release, and cleaved caspase-3 level and decrease in Bcl-2 level. Furthermore, mollugin attenuated OGD/R-induced increase in permeability and decrease in Zonula occludens-1 (ZO-1) and Claudin-5 levels. In addition, mollugin mitigated OGD/R-induced BDNF/TrkB and Akt pathways. BDNF or Akt knockdown reversed the protective effects of mollugin on cell death and permeability of hBMECs. The findings suggest that mollugin attenuates cell death and permeability of hBMECs induced by OGD/R through activating BDNF/TrkB-modulated Akt pathway.

Glutamine is well recognized as critical to the growth of most cell types. Within mitochondria glutamine is converted to glutamate by glutaminase. Oxaloacetate and glutamate then react to form alpha-ketoglutarate (α-KG) and aspartate catalyzed by glutamic-oxaloacetic transaminase (GOT2) or directly converted to α-KG by glutamate dehydrogenase (GDH). We investigated the role of GOT2 in mediating glutamate metabolism and cell growth in undifferentiated C2C12 cells. CRISPR mediated GOT2 knockout (KO) impaired cell growth, partially overcome by higher concentrations of glutamine. Mitochondrial respiration did not differ between KO and wildtype (WT) cells. Metabolite profiling showed that GOT2KO decreased aspartate by about 50% in KO versus WT cells. In contrast, α-KG increased. Metabolites reflecting the pentose phosphate pathway were significantly increased in KO cells. Metabolic pathway analyses revealed alteration of the TCA cycle, the pentose phosphate pathway, and amino acid metabolism. Glutamine ¹³C-tracing revealed decreased generation of aspartate, increased ribulose phosphate and evidence for reductive carboxylation of α-KG to isocitrate in KO cells. GDH expression was detected in C2C12 cells but did not differ between WT and GOT2KO mitochondria. GDH is not or barely expressed in adult muscle, however, we observed clear expression in pre-weanling mice. Cytosolic glutamic-oxaloacetic transaminase, GOT1, expression did not differ between GOT2KO and WT cells. In summary, GOT2 is necessary for glutamate flux and generation of downstream metabolites needed for the growth of C2C12 myoblasts. Although respiration did not differ, lack of aspartate and other compounds needed for cell proliferation may have been major factors impairing growth.

Background: Cataracts are a significant cause of vision loss, adversely affecting the quality of human life. Numerous studies have reported that lens epithelial cells (LECs) play a crucial role in age-related cataract (ARC). However, the roles of carboxypeptidase B 1 (CPB1) and transcription factor BTB and CNC homologue 2 (BACH2) in the pathogenesis of ARC remain unclear. In this study, we aim to explore the contributions of CPB1 and BACH2 to the development of ARC.

Methods: The Gene Expression Omnibus (GEO) was utilized to screen for differentially expressed genes. mRNA and protein levels were assessed using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analysis. Flow cytometry was conducted to analyze apoptosis. The levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and malondialdehyde (MDA) were measured using a commercial kit. Dual-luciferase reporter assays and chromatin immunoprecipitation (CHIP) were performed to investigate the interaction between CPB1 and BACH2. The methylation site of BACH2 was analyzed using the RNA-protein binding sites prediction suite and the sequence-based RNA adenosine methylation site predictor suite. Methylated RNA immunoprecipitation (Me-RIP) was employed to detect m6A modification level of BACH2.

Results: In ARC and H₂O₂-induced human lens epithelial cells (HLECs), CPB1, BACH2, and METTL3 were found to be up-regulated. Silencing CPB1 reduced apoptosis and MDA levels while enhancing the activities of SOD and GSH-PX in H₂O₂-induced HLECs. Additionally, CPB1 was shown to bind to BACH2, and knockdown of BACH2 attenuated apoptosis and oxidative stress in H₂O₂-induced HLECs by targeting CPB1. Notably, METTL3 promoted the BACH2 expression by enhancing CPB1 expression in H₂O₂-induced HLECs. Finally, silencing METTL3 inhibited apoptosis and oxidative stress in H₂O₂-induced HLECs by hampering BACH2 expression.

Conclusions: METTL3 facilitates apoptosis and oxidative stress in H₂O₂-induced HLECs by promoting the modification of BACH2 and CPB1 expression.

Hypoxia has been reported to induce high expression of HIF-1α in multiple cancer tissues, and HIF-1α significantly influences cancer progression, including gastric cancer (GC). However, the mechanism of HIF-1α in the GC process is not clearly elucidated. HIF-1α and JMJD3 expressions in GC tissues were first determined by qRT-PCR and western blot. Meanwhile, the prognosis of HIF-1α, and the relationship between HIF-1α and JMJD3 were analyzed through bioinformatics. Then, we silenced HIF-1α, knocked down or overexpressed JMJD3, or treated gamma-secretase inhibitor (DAPT) in GC cells under hypoxic conditions. Cell proliferation, apoptosis, and Notch activation was determined both in vivo and vitro. We initially proved that both HIF-1α and JMJD3 were highly expressed in GC tissues, high expression of HIF-1α was associated with a poor prognosis. Functionally, we observed that HIF-1α knockdown attenuated GC cell proliferation and enhanced apoptosis under hypoxic conditions, while JMJD3 knockdown exerted the opposite effect in hypoxia-induced GC cells. Besides, JMJD3 overexpression promoted proliferation and reduced apoptosis by upregulating Notch in GC cells under hypoxia conditions. Furthermore, HIF-1α knockdown inhibited tumor growth and altered the pathological structure in the tumors of GC model nude mouse. In GC cells, HIF-1α knockdown inhibited cell proliferation and promoted apoptosis by affecting JMJD3/Notch axis. Therefore, we demonstrated that HIF-1α/JMJD3/Notch axis might be a new therapeutic target for GC.

Accumulating studies have unraveled that dexmedetomidine (DEX) is neuroprotective against brain damage. However, it remains largely unknown about the mechanism involved in the neuroprotective effect of DEX. Therefore, this study explored whether DEX could affect mitophagy and pyroptosis in hypoxic-ischemic brain damage. We established a hippocampal neuron model of oxygen glucose-deprivation (OGD) and a rat model of cerebral ischemia/reperfusion (I/R) injury, which were then intervened with DEX and the autophagy inhibitor (3-MA). It was found that DEX intervention significantly increased neuron viability and mitophagy. Additionally, DEX intervention reversed increased oxidative stress and pyroptosis caused by OGD. DEX intervention further maintained the activation of the PINK1/Parkin pathway, while 3-MA treatment partly counteracted the protective effect of DEX on OGD-induced hippocampal neurons, suggesting that the inhibition of the PINK1/Parkin pathway reversed the function of DEX to increase cell viability and mitophagy and inhibit oxidative stress, pyroptosis, and apoptosis. Animal experiments also revealed that DEX intervention induced PINK1/Parkin pathway activation, reduced cerebral infarction and mitochondrial damage, promoted mitophagy, and inhibited pyroptosis, which was nullified by 3-MA treatment. Conclusively, DEX protects against pyroptosis and activates mitophagy in OGD/R-induced brain damage by activating the PINK1/Parkin pathway.

Otto Warburg originally proposed that cancer arose from a two-step process. The first step involved a chronic insufficiency of mitochondrial oxidative phosphorylation (OxPhos), while the second step involved a protracted compensatory energy synthesis through lactic acid fermentation. His extensive findings showed that oxygen consumption was lower while lactate production was higher in cancerous tissues than in non-cancerous tissues. Warburg considered both oxygen consumption and extracellular lactate as accurate markers for ATP production through OxPhos and glycolysis, respectively. Warburg's hypothesis was challenged from findings showing that oxygen consumption remained high in some cancer cells despite the elevated production of lactate suggesting that OxPhos was largely unimpaired. New information indicates that neither oxygen consumption nor lactate production are accurate surrogates for quantification of ATP production in cancer cells. Warburg also did not know that a significant amount of ATP could come from glutamine-driven mitochondrial substrate level phosphorylation in the glutaminolysis pathway with succinate produced as end product, thus confounding the linkage of oxygen consumption to the origin of ATP production within mitochondria. Moreover, new information shows that cytoplasmic lipid droplets and elevated aerobic lactic acid fermentation are both biomarkers for OxPhos insufficiency. Warburg's original hypothesis can now be linked to a more complete understanding of how OxPhos insufficiency underlies dysregulated cancer cell growth. These findings can also address several questionable assumptions regarding the origin of cancer thus allowing the field to advance with more effective therapeutic strategies for a less toxic metabolic management and prevention of cancer.

Acute lung injury characterized by overactive pulmonary inflammation is a common and serious complication of sepsis. Esomeprazole (ESO), a potent proton pump inhibitor (PPI), has been demonstrated as a promising anti-inflammatory agent in treating sepsis at high concentrations, the efficacy of which in sepsis-induced lung injury has not been explored. This research aimed to investigate the role of ESO in septic lung injury and the potential mechanism. The mice were pretreated by ESO prior to the construction of cecal ligation and puncture (CLP) sepsis model. MH-S lung macrophages were exposed to lipopolysaccharide (LPS) to induce inflammatory injury. The severity of lung damage was detected by H&E staining, measurement of lactic dehydrogenase (LDH) and lung wet/dry weight (W/D) ratio. The levels of inflammatory cytokines were detected by ELISA and Western blotting. The number of inflammatory cells was counted. Macrophage distribution was measured by immunohistochemical staining of macrophage markers. Western blotting also determined the expression of endoplasmic reticulum stress (ERS) and NLR family pyrin domain containing 3 (NLRP3) inflammasome-related proteins. CCK-8 method was used to detect cell viability. ESO concentration-dependently mitigated the pathological damage of lung tissues, reduced LDH activity, lung W/D ratio, decreased inflammatory cell counts and F4/80 expression in the lung tissues of sepsis mice. Besides, ESO suppressed inflammatory response, NLRP3 inflammasome activation and inactivated activating transcription factor 6 (ATF6)-CCAAT-enhancer-binding protein homologous protein (CHOP)-mediated ERS signaling both in vitro and in vivo. ATF6 overexpression partially reversed the impacts of ESO on NLRP3 inflammasome and the levels of inflammatory cytokines in LPS-induced MH-S cells. Anyway, ESO may inhibit ATF6/CHOP pathway to protect against inflammation in septic lung injury.

Cold atmospheric plasma (CAP) recently it has been introduced as an innovative therapeutic approach for cancer cell treatment. However the cancer treatment faces questions about the selective anti-cancer capacity of CAP, the distinct molecular responses between cancer and normal cells. In present work 3T3 fibroblast and MCF-7 breast cancer epithelial cells were subjected to treatment of CAP with atmospheric discharge with runaway electrons. We have shown that a decrease in the 3T3 and MCF-7 cell viability under the influence of CAP. In addition, there was an increase in lactate dehydrogenase activity and an increase in the amount of NAD(P)H. An increase in the duration and dose of cold plasma exposure to living systems leaded to a change in the metabolic activity of cells. It was noted that after exposure to the culture of normal and cancer cells, there variability in biochemical and metabolic effects (lactate and growth of free form NAD(P)H), which was primarily accompanied shift in the equilibrium between oxidative phosphorylation and glycolysis. Therefore, cold plasma, at the same dose of radiation, has a stimulating effect on 3T3 cells and an apoptotic effect on MCF-7 cells, leading to a reduction in their metabolic activity. This results in a shift in the metabolic balance towards glycolysis for both 3T3 and MCF-7 cell cultures.

The KunMingShanHaiTang Formula (KMSHTF), adjusted by Professor Zhong Chuanhua for the treatment of ulcerative colitis (UC), is the work of a renowned veteran practitioner of Chinese medicine. However, its specific mechanism remains unknown. Consequently, it is intriguing to investigate the molecular mechanism by which KMSHTF treats UC. To elucidate the mechanism of KMSHTF in the treatment of UC in rats. Initially, the active ingredients and key target genes of KMSHTF in treating UC were analyzed using network pharmacology. Protein-Protein interaction and gene enrichment analyses were performed to predict key targets and pathways. Subsequently, UC rats were treated with KMSHTF, and the expression proteins in intestinal tissue were detected. Finally, the active compounds of KMSHTF intreating ulcerative colitis were further screened using Molecular Docking, and their pharmacological effects were validated through cell experiments. A total of 47 active compounds and 365 key target genes of KMSHTF for UC treatment were identified through the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform,along with the GeneCards database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) Enrichment Analysis revealed that KMSHTF exerted its therapeutic effects on UC through regulating multiple pathways. In this study, the HIF-1α pathway was selected as the main molecular pathway of KMSHTF treating UC, and further validation was conducted through in vivo and in vitro experiments.Animal studies revealed that KMSHTF significantly ameliorated UC symptoms in rats, including diarrhea,rectal bleeding and specific pathological alterations in the intestinal wall. Furthermore, KMSHTF reduced pro-inflammatory cytokines IL-6 and TNF-α, up-regulated IL-4 of M2 macrophages and down-regulated iNOS and IL-1β of M1 macrophages. Additionally, it decreased the expression levels of HKII and GLUT1 related HIF-1α pathway. The three active compounds of KMSHTF, Baicalein, Palmatine and Triptonide-were selected based on their strong binding affinity with HIF-1α and HKII through computational molecular docking. Cellular experiments demonstrated that each of these compounds downregulated the protein expression levels of HIF-1α, HKII, GLUT1 and IL-6 in an intestinal wall cell model. Of Note, Baicalein exhibited the most pronounced effect. However, the overexpression of HIF-1α reversed the Baicalein-induced downregulation of HKII, GLUT1 and IL-6 at the protein level in vitro. KMSHTF may modulate macrophage metabolism to promote M2 polarization through the HIF-1α pathway, thereby contributing to its therapeutic efficacy in ulcerative colitis (UC). Baicalein, Palmatine, and Triptonide are the three core active compounds of KMSHTF that primarily contribute to this hypothesis.