Reduced ATP Levels Research Articles

Insights into the antifungal and anti-aflatoxin B1 mechanisms of carvone on Aspergillus flavus

Aspergillus flavus (A. flavus) and the carcinogen it produces, aflatoxin B1 (AFB1), often contaminate essential fat-containing crops and cereals, posing a significant risk to food safety and human health, and resulting in substantial economic losses. The development of green, safe, and environmentally friendly chemical fumigants for controlling A. flavus and AFB1 contamination is urgently needed. The effects and mechanisms of the natural compound carvone on A. flavus growth and AFB1 biosynthesis were therefore investigated. Carvone efficiently inhibited A. flavus growth, spore formation, and AFB1 production. The minimum inhibitory concentration (MIC) was 0.8 μL/mL. RNA-seq analysis showed that carvone inhibited spore formation by suppressing the transcription of spore development-related genes, including fluG, flbA, flbD, brlA, abaA, con6, con10, rodA, rodB, and dit2. Physiological and biochemical parameters showed that carvone disrupted the integrity of the cell wall and membrane, induced reactive oxygen species (ROS) accumulation, caused DNA damage, triggered cell autophagy, reduced ATP levels, which ultimately led to cell death. RNA-seq analysis confirmed these results, which found that genes related to chitin and ergosterol synthesis, and DNA replication were downregulated, and genes involved in antioxidants and cell autophagy were upregulated. In addition, carvone downregulated several transcription factors (CreA, SrrA, NsdD, and Crz1) and 11 AFB1 cluster genes, which inhibited AFB1 production. Together, the results provided new insights into the antifungal and anti-AFB1 mechanisms of carvone, as well as providing theoretical support for the development of new fumigants to control A. flavus and AFB1 contamination.

RNA stability is regulated by both RNA polyadenylation and ATP levels, linking RNA and energy metabolisms in Escherichia coli.

The post-transcriptional process of RNA polyadenylation sits at the crossroads of energy metabolism and RNA metabolism. RNA polyadenylation is catalyzed by poly(A) polymerases, which use ATP as a substrate to add adenine to the 3' end of RNAs, which can alter their stability. In Escherichia coli, RNA polyadenylation mediated by the major poly(A) polymerase was previously shown to facilitate degradation of individual RNAs. In this study, we performed the first genome-wide study of RNA stability in the absence of PAP I. Inactivation of the pcnB gene coding for PAP I led to the stabilization of more than a thousand of E. coli RNAs in the form of full-length functional molecules or non-functional fragments. The absence of PAP I altered the energy metabolism, with an almost 20% reduction in ATP levels. To better understand how RNA and energy metabolisms are interconnected, we investigated the role of ATP levels in regulating RNA stability. When we lowered intracellular ATP levels below 0.5 mM, many RNAs were stabilized, demonstrating the causal link between ATP levels and RNA stability for the first time in E. coli. Above this concentration, changes in ATP levels had no impact on RNA stability. We also demonstrated that some RNAs were stabilized when PAP I was inactivated by low ATP availability. These results clearly demonstrate that PAP I mediates an energy-dependent RNA stabilization, which may contribute to cell energy homeostasis under energy-limited conditions.IMPORTANCEPoly(A) polymerases are prime targets for understanding the interactions between RNA polyadenylation, RNA stability, and cellular energy. These enzymes catalyze the process of RNA polyadenylation, which involves ATP hydrolysis and addition of poly(A) tails to the 3' end of RNAs. 3' end poly(A) extensions potentially facilitate RNA degradation in bacteria. In this study, we inactivated the pcnB gene encoding PAP I, the major poly(A) polymerase in E. coli, and investigated the effects on RNA stability and energy levels. Our results show for the first time in E. coli a genome-wide RNA stabilization in the absence of PAP I associated with a decrease in ATP levels. We provide the first evidence in E. coli of a link between ATP levels and RNA stabilization and demonstrate that this is mediated in some cases by PAP I. PAP I-mediated RNA stabilization at low ATP levels could be a means of energy conservation under energy-limited conditions.

Mechanisms of Staphylococcus aureus survival of trimethoprim-sulfamethoxazole-induced thymineless death.

Trimethoprim-sulfamethoxazole (SXT) is commonly used to treat diverse Staphylococcus aureus infections, including those associated with cystic fibrosis (CF) pulmonary disease. Studies with Escherichia coli found that SXT impairs tetrahydrofolate production, leading to DNA damage, stress response induction, and accumulation of reactive oxygen species (ROS) in a process known as thymineless death (TLD). TLD survival can occur through the uptake of exogenous thymidine, countering the effects of SXT; however, a growing body of research has implicated central metabolism as another potentially important determinant of bacterial survival of SXT and other antibiotics. Here, we conducted studies to better understand the mechanisms of TLD survival in S. aureus. We found that thymidine abundances in CF sputum were insufficient to prevent TLD of S. aureus, highlighting the importance of alternative survival mechanisms in vivo. In S. aureus cultured in vitro with SXT and low thymidine, we frequently identified adaptive mutations in genes encoding carbohydrate, nucleotide, and amino acid metabolism, supporting reduced metabolism as a common survival mechanism. Although intracellular ROS levels rose with SXT treatment in vitro, survival was not improved in the presence of ROS scavengers, unlike in E. coli. SXT challenge induced the SOS response, which was alleviated by added thymidine. Finally, an inactivating mutation in the phosphotransferase gene ptsI conferred both limitation in cellular ATP and improved survival against TLD. Collectively, these results suggest that alterations in core metabolic functions, particularly those that reduce ATP levels, predominantly confer S. aureus survival and persistence during SXT treatment, potentially identifying novel targets for co-treatment.IMPORTANCEStaphylococcus aureus is a ubiquitous organism and one of the leading causes of human infections, many of which are difficult to treat due to persistence, antibiotic resistance, or antibiotic tolerance. As our arsenal of effective antibiotics dwindles, the need for improved treatments becomes increasingly urgent, necessitating a better understanding of the precise mechanisms by which pathogens evade our most critical antimicrobial agents. Here, we report a systematic characterization of the mechanisms of S. aureus survival to treatment with the first-line antistaphylococcal antibiotic trimethoprim-sulfamethoxazole, identifying pathways and candidate targets for enhancing the efficacy of available antimicrobial agents.

Integrative Human Genetic and Cellular Analysis of the Pathophysiological Roles of AnxA2 in Alzheimer's Disease.

Alzheimer's disease (AD) is an intractable and progressive neurodegenerative disease. Amyloid beta (Aβ) aggregation is the hallmark of AD. Aβ induces neurotoxicity through a variety of mechanisms, including interacting with membrane receptors to alter downstream signaling, damaging cellular or organelle membranes, interfering with protein degradation and synthesis, and inducing an excessive immune-inflammatory response, all of which lead to neuronal death and other pathological changes associated with AD. In this study, we extracted gene expression profiles from the GSE5281 and GSE97760 microarray datasets in the GEO (Gene Expression Omnibus) database, as well as from the Human Gene Database. We identified differentially expressed genes in the brain tissues of AD patients and healthy persons. Through GO, KEGG, and ROC analyses, annexin A2 (AnxA2) was identified as a putative target gene. Notably, accumulating evidence suggests that intracellular AnxA2 is a key regulator in various biological processes, including endocytosis, transmembrane transport, neuroinflammation, and apoptosis. Thus, we conducted a series of cell biology experiments to explore the biological function of AnxA2 in AD. The results indicate that AnxA2 gene knockdown primarily affects oxidative phosphorylation, cell cycle, AD, protein processing in the endoplasmic reticulum, SNARE interactions in vesicular transport, and autophagy. In SH-SY5Y cells secreting Aβ42, AnxA2 gene knockdown exacerbated Aβ42-induced cytotoxicity, including cell death, intracellular ROS levels, and neuronal senescence, altered cell cycle, and reduced ATP levels, suggesting its critical role in mitochondrial function maintenance. AnxA2 gene knockdown also exacerbated the inhibitory effect of Aβ42 on cell migration. AnxA2 overexpression reduced the inflammatory response induced by Aβ42, while its absence increased pro-inflammatory and decreased anti-inflammatory responses. Furthermore, AnxA2 gene knockdown facilitated apoptosis and decreased autophagy. These results indicated potential pathophysiological roles of AnxA2 in AD.

Dysfunctional copper homeostasis in Caenorhabditis elegans affects genomic and neuronal stability

While copper (Cu) is an essential trace element for biological systems due to its redox properties, excess levels may lead to adverse effects partly due to overproduction of reactive species. Thus, a tightly regulated Cu homeostasis is crucial for health. Cu dyshomeostasis and elevated labile Cu levels are associated with oxidative stress and neurodegenerative disorders, but the underlying mechanisms have yet to be fully characterized. Here, we used Caenorhabditis elegans loss-of-function mutants of the Cu chaperone ortholog atox-1 and the Cu binding protein ortholog ceruloplasmin to model Cu dyshomeostasis, as they display a shifted ratio of total Cu towards labile Cu. We applied highly selective and sensitive techniques to quantify metabolites associated to oxidative stress with focus on mitochondrial integrity, oxidative DNA damage and neurodegeneration all in the context of a disrupted Cu homeostasis. Our novel data reveal elevated oxidative stress, compromised mitochondria displaying reduced ATP levels and cardiolipin content. Cu dyshomeostasis further induced oxidative DNA damage and impaired DNA damage response as well as neurodegeneration characterized by behavior and neurotransmitter analysis. Our study underscores the essentiality of a tightly regulated Cu homeostasis as well as mitochondrial integrity for both genomic and neuronal stability.

HIF1 activation safeguards cortical bone formation against impaired oxidative phosphorylation.

Energy metabolism, through pathways such as oxidative phosphorylation (OxPhos) and glycolysis, plays a pivotal role in cellular differentiation and function. Our study investigates the impact of OxPhos disruption in cortical bone development by deleting mitochondrial transcription factor A (TFAM). TFAM controls OxPhos by regulating the transcription of mitochondrial genes. The cortical bone, constituting the long bones' rigid shell, is sheathed by the periosteum, a connective tissue layer populated with skeletal progenitors that spawn osteoblasts, the bone-forming cells. TFAM-deficient mice presented with thinner cortical bone, spontaneous midshaft fractures, and compromised periosteal cell bioenergetics, characterized by reduced ATP levels. Additionally, they exhibited an enlarged periosteal progenitor cell pool with impaired osteoblast differentiation. Increasing hypoxia-inducible factor 1a (HIF1) activity within periosteal cells substantially mitigated the detrimental effects induced by TFAM deletion. HIF1 is known to promote glycolysis in all cell types. Our findings underscore the indispensability of OxPhos for the proper accrual of cortical bone mass and indicate a compensatory mechanism between OxPhos and glycolysis in periosteal cells. The study opens new avenues for understanding the relationship between energy metabolism and skeletal health and suggests that modulating bioenergetic pathways may provide a therapeutic avenue for conditions characterized by bone fragility.

Exendin-4 Caused Growth Arrest by Regulating Sugar Metabolism in Hyphantria cunea (Lepidoptera: Erebidae) Larvae.

Insects' growth and development are highly dependent on energy supply, with sugar metabolism playing a pivotal role in maintaining homeostasis and regulating physiological processes. The present study investigated the effects of exendin-4, a glucagon-like peptide-1 receptor (GLP-1R) agonist, on the growth, development, glycolysis, and energy metabolism of fourth-instar larvae of the fall webworm, Hyphantria cunea. We determined the impact of exendin-4 on larval growth and nutritional indices, analyzed the responses of glycolytic and metabolic pathways, and revealed the underlying regulatory mechanisms. Exendin-4 treatment significantly decreased growth and nutritional indices, influenced the activity of digestive enzymes, and induced changes in metabolite profiles, particularly affecting energy substance metabolism. We observed an increase in the glycogen content and a decrease in glucose and trehalose levels in the hemolymph, suggesting a regulatory effect on blood sugar homeostasis. Furthermore, exendin-4 promoted glycolysis by enhancing the activities and expressions of key glycolytic enzymes, leading to an increase in pyruvate production. This was accompanied by a reduction in ATP levels and the activation of AMP-activated protein kinase (AMPK), which may underlie the growth arrest in larvae. Our findings provide novel insights into the effects of exendin-4 on insect responses from an energy metabolism perspective and may contribute to the development of GLP-1R agonists for pest management.

YTHDF2 regulates MSS51 expression contributing to mitochondria dysfunction of granulosa cells in polycystic ovarian syndrome patients

Research questionGranulosa cells (GCs) dysfunction plays a crucial role in the pathogenesis of polycystic ovary syndrome (PCOS). It is reported that YTH domain-containing family protein 2 (YTHDF2) is upregulated in mural GCs of PCOS patients. What effect does the differential expression of YTHDF2 have in PCOS patients? DesignMural GCs and cumulus GCs from 15 patients with PCOS and 15 ovulatory controls and 4 cases of pathological sections in each group were collected. Real-time PCR, Western Blot, immunohistochemistry, and immunofluorescence experiments were conducted to detect gene and protein expression. RNA immunoprecipitation assay was performed to evaluate the binding relationship between YTHDF2 and MSS51. Mitochondrial morphology, cellular ATP and ROS levels and glycolysis-related gene expression were detected after YTHDF2 overexpression or MSS51 inhibition. ResultsIn the present study, we found that YTHDF2 was upregulated in GCs of PCOS patients while MSS51 was downregulated. YTHDF2 protein can bind to MSS51 mRNA and affect MSS51 expression. The reduction of MSS51 expression or the increase in YTHDF2 expression can lead to mitochondrial damage, reduced ATP levels, increased ROS levels and reduced expression of LDHA, PFKP and PKM. ConclusionsYTHDF2 may regulate the expression of MSS51, affecting the structure and function of mitochondria in GCs and interfering with cellular glycolysis, which may disturb the normal biological processes of GCs and follicle development in PCOS patients.

Silver nanoparticle-induced cell damage via impaired mtROS-JNK/MnSOD signaling pathway

This study investigated the mechanism of silver nanoparticle (AgNP) cytotoxicity from a mitochondrial perspective. The effect of AgNP on manganese superoxide dismutase (MnSOD), a mitochondrial antioxidant enzyme, against oxidative stress has not been studied in detail. We demonstrated that AgNP decreased MnSOD mRNA level, protein expression, and activity in human Chang liver cells in a time-dependent manner. AgNP induced the production of mitochondrial reactive oxygen species (mtROS), particularly superoxide anion. AgNP was found to increase mitochondrial calcium level and disrupt mitochondrial function, leading to reduced ATP level, succinate dehydrogenase activity, and mitochondrial permeability. AgNP induced cytochrome c release from the mitochondria into the cytoplasm, attenuated the expression of the anti-apoptotic proteins phospho Bcl-2 and Mcl-1, and induced the expression of the pro-apoptotic proteins Bim and Bax. In addition, c-Jun N-terminal kinase (JNK) phosphorylation was significantly increased by AgNP. Treatment with elamipretide (a mitochondria-targeted antioxidant) and SP600125 (a JNK inhibitor) showed the involvement of MnSOD and JNK in these processes. These results indicated that AgNP damaged human Chang liver cells by destroying mitochondrial function through the accumulation of mtROS.

Mitochondria targeted drug delivery system overcoming drug resistance in intrahepatic cholangiocarcinoma by reprogramming lipid metabolism

The challenge of drug resistance in intrahepatic cholangiocarcinoma (ICC) is intricately linked with lipid metabolism reprogramming. The hepatic lipase (HL) and the membrane receptor CD36 are overexpressed in BGJ398-resistant ICC cells, while they are essential for lipid uptake, further enhancing lipid utilization in ICC. Herein, a metal-organic framework-based drug delivery system (OB@D-pMOF/CaP-AC, DDS), has been developed. The specifically designed DDS exhibits a successive targeting property, enabling it to precisely target ICC cells and their mitochondria. By specifically targeting the mitochondria, DDS produces reactive oxygen species (ROS) through its sonodynamic therapy effect, achieving a more potent reduction in ATP levels compared to non-targeted approaches, through the impairment of mitochondrial function. Additionally, the DDS strategically minimizes lipid uptake through the incorporation of the anti-HL drug, Orlistat, and anti-CD36 monoclonal antibody, reducing lipid-derived energy production. This dual-action strategy on both mitochondria and lipids can hinder energy utilization to restore drug sensitivity to BGJ398 in ICC. Moreover, an orthotopic mice model of drug-resistant ICC was developed, which serves as an exacting platform for evaluating the multifunction of designed DDS. Upon in vivo experiments with this model, the DDS demonstrated exceptional capabilities in suppressing tumor growth, reprogramming lipid metabolism and improving immune response, thereby overcoming drug resistance. These findings underscore the mitochondria-targeted DDS as a promising and innovative solution in ICC drug resistance.

Genetic Analysis of the ts-Lethal Mutant Δpa0665/pTS-pa0665 Reveals Its Role in Cell Morphology and Oxidative Phosphorylation in Pseudomonas aeruginosa.

Pa0665 in Pseudomonas aeruginosa shares homologous sequences with that of the essential A-type iron-sulfur (Fe-S) cluster insertion protein ErpA in Escherichia coli. However, its essentiality in P. aeruginosa and its complementation with E. coli erpA has not been experimentally examined. To fulfill this task, we constructed plasmid-based ts-mutant Δpa0665/pTS-pa0665 using a three-step protocol. The mutant displayed growth defects at 42 °C, which were complemented by expressing ec.erpA. Microscopic observations indicated a petite cell phenotype for Δpa0665/pTS-pa0665 at 42 °C, correlated with the downregulation of the oprG gene. RNA sequencing revealed significant transcriptional changes in genes associated with the oxidative phosphorylation (OXPHOS) system, aligning with reduced ATP levels in Δpa0665/pTS-pa0665 under 42 °C. Additionally, the ts-mutant showed heightened sensitivity to H2O2 at 42 °C. Overall, our study demonstrates the essential role of pa0665 for OXPHOS function and is complemented by ec.erpA. We propose that the plasmid-based ts-allele is useful for genetic analysis of essential genes of interest in P. aeruginosa.

Impaired Long-Chain Fatty Acid Metabolism in Carnitine Palmitoyltransferase II Knockout Mouse Leads to Chronic Pancreatitis

Background: To support high rates of protein synthesis, pancreatic acinar cells must generate large quantities of ATP. Mitochondrial dysfunction and impaired energy metabolism play a significant role in the development of pancreatitis. Patients with elevated plasma triglycerides are at increased risk for development of severe acute pancreatitis. Carnitine palmitoyltransferase II (CPT2) is required for importing and thus metabolizing long-chain fatty acids (LCFAs) in mitochondria. To inhibit LCFA metabolism, we utilized the CPT2acinarKO mouse to probe the consequences of impaired LCFA import on pancreatic function. Hypothesis: Loss of CPT2 causes an accumulation of long-chain acylcarnitines and disruption of the tissue acylcarnitine/free carnitine ratio which is thought to alter cellular function. Given acinar cells’ high metabolic requirement, impaired LCFA utilization would reduce energy production, secretory function, and alter pancreatic lipid composition. Methods: We generated mice lacking CPT2 specifically in acinar cells (CPT2acinarKO) by crossing tamoxifen-inducible, Elastase-Cre mice with CPT2 floxed mice. Mice were fed a high fat (60% kcal fat), low fat (10% kcal fat), or chow (14% kcal fat) diet for 12 weeks. Analysis of fat accumulation, edema, and fibrosis was performed with H&E and picrosirius staining. Mass Spec. lipid profiling was performed in pancreas and serum. Acinar cells were isolated from wildtype, CPT2 floxed, and CPT2acinarKO mice to assess secretory function, ATP levels, and necrosis via lactate dehydrogenase (LDH) release. Results: Histologic examination revealed CPT2acinarKO mice on all three diets displayed pancreatic fat accumulation. Strikingly, CPT2acinarKO mice fed a chow or low fat diet developed chronic pancreatitis with a 25% loss in pancreatic weight, immune cell infiltration, edema, and fibrosis. As anticipated, long-chain acylcarnitines were significantly elevated in CPT2acinarKO pancreas. Assessment of secretion in 2 weeks post tamoxifen cells revealed significantly reduced maximal (10 pM) and supramaximal (1 nM) cholecystokinin (CCK) stimulated amylase release as a percent of total cellular amylase. Acini isolated at 4 weeks post tamoxifen revealed significantly increased basal secretion and reduced maximal and supramaximal CCK stimulated amylase release. When normalized to cellular DNA, secretion was similar between CPT2acinarKO and CPT2 floxed acinar cells indicating CPT2acinarKO cells had reduced amylase levels. Wildtype acinar cells treated with unsaturated and saturated free fatty acid concentrations as low as 100 μM for 3 hours caused significant necrosis. CPT2acinarKO pancreas had significantly decreased ATP levels indicative of mitochondrial dysfunction. Conclusion: Loss of CPT2 in the pancreatic acinar cells impairs LCFA import, reduces ATP levels, disrupts the secretory pathway, promoting chronic pancreatitis. In contrast to other CPT2 knockout models, pancreatitis occurs independent of high fat feeding in CPT2acinarKO mice. Further investigation is needed to identify metabolic alterations leading to acinar damage and mitochondrial dysfunction following the loss of CPT2. UW-Madison Comprehensive Diabetes Center Pilot Grant. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Characterization of Sex-Dependent Differences in Brain Microvascular Bioenergetics

Background: Women experience increased incidence of stroke-related deaths and lifetime risk of Alzheimer's disease (AD). Microvascular dysfunction has been implicated in the pathogenesis of ischemic stroke and AD. Our objective is to investigate the sex-dependent differences in bioenergetics of young mouse brain microvessels (BMVs). Methods: BMVs were isolated from young male and female mice (3-4 months), using a combination of gradient centrifugation and filtration (300μm and 40μm filters) methods. Extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) of BMVs were measured utilizing the Agilent Seahorse XFe 24 analyzer. The levels of proteins and mRNAs of mitochondrial respiratory complexes were measured by western blot and RT-PCR, respectively. Citrate synthase (CS) enzyme activity and ATP levels were determined in lysates of BMVs. Results: Real-Time ATP Rate assay demonstrated a decreased total ATP production rate and ATP contribution from both glycolysis and oxidative phosphorylation (OxPhos) in BMVs from females compared to males. Mitochondrial stress test assay revealed significantly lower values of several mitochondrial respiratory parameters, including basal respiration, ATP production, maximal respiration, spare respiratory capacity, and proton leak in BMVs from females compared to males. Glycolytic Rate assay uncovered reduced basal glycolysis, proton efflux rate (PER) originating from basal glycolysis, and the mitoOCR/glycoPER ratio in BMVs from females compared to males. Interestingly, no sex-dependent differences were observed in basal PER and post-2-DG acidification rates in BMVs. Mito Fuel Flex Test assay showed no sex-dependent difference in the utilization of glucose, glutamine, and long-chain fatty acids as fuel substrates in BMVs. ATP measurements confirmed the reduced ATP levels in BMVs from females compared to males. Measurements of CS activity revealed no sex-dependent difference in the BMVs. Lastly, Western blot and RT-PCR experiments indicated no differences in either protein or mRNA levels of various mitochondrial complex protein levels.Conclusions: Female BMVs showed reduced mitochondrial respiratory and glycolytic parameters compared to male BMVs although relative contribution of various substrates for energy production were not different. These sex-dependent differences involving glycolysis and OxPhos make the microvasculature vulnerable to injury in females. Funding sources: NIH grants AG074489 and NS114286 (PVGK and RM). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Hippo pathway activated by circulating reactive oxygen species mediates cardiac diastolic dysfunction after acute kidney injury

Acute kidney injury (AKI) can cause distal cardiac dysfunction; however, the underlying mechanism is unknown. Oxidative stress is proved prominent in AKI-induced cardiac dysfunction, and a possible bridge role of oxidative-stress products in cardio-renal interaction has been reported. Therefore, this study aimed to investigate the critical role of circulating reactive oxygen species (ROS) in mediating cardiac dysfunction after bilateral renal ischemia-reperfusion injury (IRI). We observed the diastolic dysfunction in the mice following renal IRI, accompanied by reduced ATP levels, oxidative stress, and branched-chain amino acids (BCAA) accumulation in the heart. Notably, ROS levels showed a sequential increase in the kidneys, circulation, and heart. Treatment with tempol, an ROS scavenger, significantly restored cardiac diastolic function in the renal IRI mice, corroborating the bridge role of circulating ROS. Accumulating evidence has identified oxidative stress as upstream of Mst1/Hippo in cardiac injury, which could regulate the expression of downstream genes related to mitochondrial quality control, leading to lower ATP, higher ROS and metabolic disorder. To verify this, we examined the activation of the Mst1/Hippo pathway in the heart of renal IRI mice, which was alleviated by tempol treatment as well. In vitro, analysis revealed that Mst1-knockdown cardiomyocytes could be activated by hydrogen peroxide (H2O2). Analysis of Mst1-overexpression cardiomyocytes confirmed the critical role of the Mst1/Hippo pathway in oxidative stress and BCAA dysmetabolism. Therefore, our results indicated that circulating ROS following renal IRI activates the Mst1/Hippo pathway of myocardium, leading to cardiac oxidative stress and diastolic dysfunction. This finding provides new insights for the clinical exploration of improved treatment options for cardiorenal syndrome.

Novel Tannic Acid-Modified Cobalt-Based Metal-Organic Framework: Synthesis, Characterization, and Antimicrobial Activity.

Metal-organic frameworks (MOFs) are a class of hybrid inorganic-organic materials with typical porous structures and a unique morphology. Due to their diversity, they are extensively used in a wide range of applications such as environmental, catalysis, biomedicine, etc. In this study, a novel cobalt-based MOF modified with tannic acid (Co-TPA/TA) (TPA: terephthalic acid; TA: tannic acid) as a promising material for antimicrobial agents was synthesized and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma-optical emission spectrometry, and thermogravimetric analysis and compared with an as-synthesized cobalt-based framework. Co-TPA/TA demonstrated good antimicrobial efficiency under optimum conditions against yeast Candida albicans ATCC 10231, Gram-negative Escherichia coli ATCC 8739, and Gram-positive Staphylococcus aureus ATCC 6538 with an inhibition zone ranging from 14 to 20 mm. Reduced ATP levels, generation of reactive oxygen species, membrane damage from cobalt ion release, and development of an alkaline microenvironment could all be contributing factors to the possible antimicrobial pathways. The novel framework can be obtained using simple, affordable, and easily accessible commercial ligands and is considered to have the potential to be used as an antimicrobial material in the future.

Co-exposure to PVC microplastics and cadmium induces oxidative stress and fibrosis in duck pancreas

PVC microplastics (PVC-MPs) are environmental pollutants that interact with cadmium (Cd) to exert various biological effects. Ducks belong to the waterfowl family of birds and therefore are at a higher risk of exposure to PVC-MPs and Cd than other animals. However, the effects of co-exposure of ducks to Cd and PVC-MPs are poorly understood. Here, we used Muscovy ducks to establish an in vivo model to explore the effects of co-exposure to 1 mg/L PVC-MPs and 50 mg/kg Cd on duck pancreas. After 2 months of treatment with 50 mg/kg Cd, pancreas weight decreased by 21 %, and the content of amylase and lipase increased by 25 % and 233 %. However, exposure to PVC-MPs did not significantly affect the pancreas. Moreover, co-exposure to PVC-MPs and Cd worsened the reduction of pancreas weight and disruption of pancreas function compared to exposure to either substance alone. Furthermore, our research has revealed that exposure to PVC-MPs or Cd disrupted mitochondrial structure, reduced ATP levels by 10 % and 18 %, inhibited antioxidant enzyme activity, and increased malondialdehyde levels by 153.8 % and 232.5 %. It was found that exposure to either PVC-MPs or Cd can induce inflammation and fibrosis in the duck pancreas. Notably, co-exposure to PVC-MPs and Cd exacerbated inflammation and fibrosis, with the content of IL-1, IL-6, and TNF-α increasing by 169 %, 199 %, and 98 %, compared to Cd exposure alone. The study emphasizes the significance of comprehending the potential hazards linked to exposure to these substances. In conclusion, it presents promising preliminary evidence that PVC-MPs accumulate in duck pancreas, and increase the accumulation of Cd. Co-exposure to PVC-MPs and Cd disrupts the structure and function of mitochondria and promotes the development of pancreas inflammation and fibrosis.

Involution of brown adipose tissue through a Syntaxin 4 dependent pyroptosis pathway

Aging, chronic high-fat diet feeding, or housing at thermoneutrality induces brown adipose tissue (BAT) involution, a process characterized by reduction of BAT mass and function with increased lipid droplet size. Single nuclei RNA sequencing of aged mice identifies a specific brown adipocyte population of Ucp1-low cells that are pyroptotic and display a reduction in the longevity gene syntaxin 4 (Stx4a). Similar to aged brown adipocytes, Ucp1-STX4KO mice display loss of brown adipose tissue mass and thermogenic dysfunction concomitant with increased pyroptosis. Restoration of STX4 expression or suppression of pyroptosis activation protects against the decline in both mass and thermogenic activity in the aged and Ucp1-STX4KO mice. Mechanistically, STX4 deficiency reduces oxidative phosphorylation, glucose uptake, and glycolysis leading to reduced ATP levels, a known triggering signal for pyroptosis. Together, these data demonstrate an understanding of rapid brown adipocyte involution and that physiologic aging and thermogenic dysfunction result from pyroptotic signaling activation.

Disrupting pro-survival and inflammatory pathways with dimethyl fumarate sensitizes chronic lymphocytic leukemia to cell death

Microenvironmental signals strongly influence chronic lymphocytic leukemia (CLL) cells through the activation of distinct membrane receptors, such as B-cell receptors, and inflammatory receptors, such as Toll-like receptors (TLRs). Inflammatory pathways downstream of these receptors lead to NF-κB activation, thus protecting leukemic cells from apoptosis. Dimethyl fumarate (DMF) is an anti-inflammatory and immunoregulatory drug used to treat patients with multiple sclerosis and psoriasis in which it blocks aberrant NF-κB pathways and impacts the NRF2 antioxidant circuit. Our in vitro analysis demonstrated that increasing concentrations of DMF reduce ATP levels and lead to the apoptosis of CLL cells, including cell lines, splenocytes from Eµ-TCL1-transgenic mice, and primary leukemic cells isolated from the peripheral blood of patients. DMF showed a synergistic effect in association with BTK inhibitors in CLL cells. DMF reduced glutathione levels and activated the NRF2 pathway; gene expression analysis suggested that DMF downregulated pathways related to NFKB and inflammation. In primary leukemic cells, DMF disrupted the TLR signaling pathways induced by CpG by reducing the mRNA expression of NFKBIZ, IL6, IL10 and TNFα. Our data suggest that DMF targets a vulnerability of CLL cells linked to their inflammatory pathways, without impacting healthy donor peripheral blood mononuclear cells.

A Comparative Analysis of the Antibacterial Spectrum of Ultrasmall Manganese Ferrite Nanozymes with Varied Surface Modifications.

Bacterial infectious diseases pose a significant global challenge. However, conventional antibacterial agents exhibit limited therapeutic effectiveness due to the emergence of drug resistance, necessitating the exploration of novel antibacterial strategies. Nanozymes have emerged as a highly promising alternative to antibiotics, owing to their particular catalytic activities against pathogens. Herein, we synthesized ultrasmall-sized MnFe2O4 nanozymes with different charges (MnFe2O4-COOH, MnFe2O4-PEG, MnFe2O4-NH2) and assessed their antibacterial capabilities. It was found that MnFe2O4 nanozymes exhibited both antibacterial and antibiofilm properties attributed to their excellent peroxidase-like activities and small sizes, enabling them to penetrate biofilms and interact with bacteria. Moreover, MnFe2O4 nanozymes effectively expedite wound healing within 12 days and facilitate tissue repair and regeneration while concurrently reducing inflammation. MnFe2O4-COOH displayed favorable antibacterial activity against Gram-positive bacteria, with 80% bacterial removal efficiency against MRSA by interacting with phosphatidylglycerol (PG) and cardiolipin (CL) of the membrane. By interacting with negatively charged bacteria surfaces, MnFe2O4-NH2 demonstrated the most significant and broad-spectrum antibacterial activity, with 95 and 85% removal efficiency against methicillin-resistant Staphylococcus aureus (MRSA) and P. aeruginosa, respectively. MnFe2O4-PEG dissipated membrane potential and reduced ATP levels in MRSA and P. aeruginosa, showing relatively broad-spectrum antibacterial activity. To conclude, MnFe2O4 nanozymes offer a promising therapeutic approach for treating wound infections.

AMPK/PGC-1α and p53 modulate VDAC1 expression mediated by reduced ATP level and metabolic oxidative stress in neuronal cells.

Voltage-dependent anion channel 1 (VDAC1) is a pore protein located in the outer mitochondrial membrane. Its channel gating mediates mitochondrial respiration and cell metabolism, and it has been identified as a critical modulator of mitochondria-mediated apoptosis. In many diseases characterized by mitochondrial dysfunction, such as cancer and neurodegenerative diseases, VDAC1 is considered a promising potential therapeutic target. However, there is limited research on the regulatory factors involved in VDAC1 protein expression in both normal and pathological states. In this study, we find that VDAC1 protein expression is up-regulated in various neuronal cell lines in response to intracellular metabolic and oxidative stress. We further demonstrate that VDAC1 expression is modulated by intracellular ATP level. Through the use of pharmacological agonists and inhibitors and small interfering RNA (siRNA), we reveal that the AMPK/PGC-1α signaling pathway is involved in regulating VDAC1 expression. Additionally, based on bioinformatics predictions and biochemical verification, we identify p53 as a potential transcription factor that regulates VDAC1 promoter activity during metabolic oxidative stress. Our findings suggest that VDAC1 expression is regulated by the AMPK/PGC-1α and p53 pathways, which contributes to the maintenance of stress adaptation and apoptotic homeostasis in neuronal cells.