Journal of Bioenergetics and Biomembranes最新文献

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.

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.

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.

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.

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.

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.

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.

Fibrillation of the amyloid beta (Aβ) peptide has often been associated with neurodegenerative pathologies such as Alzheimer's disease. In this study we examined the influence of several potential compositions of the lipid membrane on Aβ fibrillation by using liposomes as a basic model membrane. Firstly, it was revealed that Aβ fibrillation kinetics were enhanced and had the potential to occur at a faster rate on more fluid membranes compared to solid membranes. Next, the extent of fibril-related damage to membranes was examined with analysis of membrane polarity via the steady-state emission spectra of 6-dodecanoyl-2-dimethylaminonaphthalene (Laurdan). It was revealed that there was slight hydration behavior of the membrane during the lag phase (t_lag) of the kinetic process, possibly coinciding with Aβ monomer binding. However, as the fibrillation kinetic process continued the membrane gradually dehydrated. Hydration states of membranes during and after Aβ fibrillation processes were further examined via deconvolution analysis of the obtained Laurdan spectra. This allows a mapping of membrane hydration from the interior to exterior regions of the lipid membrane. Results revealed slight but definitive variations in deeper region membrane polarity during the time course of Aβ fibrillation, suggesting Aβ aggregation impacts not only the surface level aggregating region but also the inner regions of the membrane. These results can ultimately contribute to the future investigations of the nature of the membrane damage caused by Aβ aggregation.

The main therapeutic strategy for the treatment of patients with toxic liver failure is the elimination of the toxic agent in combination with the targeted mitigation of pathological processes that have been initiated due to the toxicant. In the current research we evaluated the strategy of metabolic supplementation to improve mitochondrial bioenergetics during acute liver intoxication. In our study, we have shown that acute CCl₄-induced intoxication negatively affects Complex I (in the presence of glutamate-malate as energy substrates) based respiration, generation of mitochondrial membrane potential (ΔΨ_m), mitochondrial NAD(P)H pool and NADH redox index, mitochondrial calcium retention capacity (CRC) and structure and functions of the liver. Boosting of mitochondrial bioenergetics through the complex II, using succinate as metabolic substrate in vitro, significantly improved mitochondrial respiration and generation of ΔΨ_m, but not mitochondrial CRC. Co-application of rotenone along with succinate, to prevent possible reverse electron flow, didn't show significant differences compared to the effects of succinate alone. Treatment of animals with acute liver failure, using a metabolic supplement containing succinate, inosine, methionine and nicotinamide improved Complex I based respiration, generation of ΔΨ_m, mitochondrial NAD(P)H pool and NADH redox index, mitochondrial CRC and slightly decreased the level of oxidative stress. These changes resulted in averting destructive and dystrophic changes in the structure of rat liver tissue caused by CCl₄ intoxication, concomitantly enhancing hepatic functionality. Thus, we propose that metabolic supplementation targeting complex II could serve as a potential adjunctive therapy in the management of acute liver intoxication.