Cellular Energetics Research Articles

Targeting HVEM-GPT2 axis: a novel approach to T cell activation and metabolic reprogramming in non-small cell lung cancer therapy.

The modulation of tumor microenvironments through immune checkpoint pathways is pivotal for the development of effective cancer immunotherapies. This study aims to explore the role of HVEM in non-small cell lung cancer (NSCLC) microenvironment. The lung cancer datasets for this study were directly downloaded from The Cancer Genome Atlas (TCGA). Single-cell data were sourced from the Tumor Immune Single-cell Hub (TISCH). Multiplex immunohistochemistry (mIHC) was used to explore the cellular composition and spatial distribution of HVEM in lung cancer immune microenvironment. Theimmunemicroenvironmentof HVEM KO mice bearing mouse lung cancer cell was also evaluated. Co-cultured system and phenotype assays facilitated the examination of Jurkat T cells' effect on A549 and H1299 lung cancer cells. Quantitative PCR and Western blotting determined gene and protein expression, respectively, cellular respiration was measured through oxygen consumption rate (OCR) assays. Lung cancer cells co-cultured with Jurkat T cells were xenografted into nude mice to evaluate tumor growth and metastatic potential. Next, RNA-seq, COIP, Dual-luciferasereporter experiment, and CHIP-seq were used to explore the potential underlying mechanism. In our study, we investigated the role of HVEM in the microenvironment of NSCLC and its implications in immunotherapy. Crucially, HVEM, part of the tumor necrosis factor receptor superfamily, influences T cell activation, potentially impacting immunotherapeutic outcomes. Using the TIDE algorithm, our results showcased a link between HVEM levels and immune dysfunction in NSCLC patients. Delving deeper into the NSCLC microenvironment, we found HVEM predominantly expressed in T cell subpopulations. CD8 + HVEM + and CD4 + HVEM + indicated better prognosis in lung adenocarcinoma tissue microarray using multiplex immunohistochemistry. Activated T cells, particularly from the Jurkat cell line, significantly inhibited NSCLC progression, reducing both proliferation and invasion capabilities of A549 and H1299 lung cancer cell lines. In vivo models reinforced these observations. Manipulating HVEM expression revealed its essential role in T cell survival and activation. In addition, animal experiments revealed the importance of HVEM in maintaining activated peripheral immunity and inflamed local tumor microenvironment. Furthermore, our data suggest that HVEM is pivotal in T cell metabolic reprogramming, transitioning from oxidative phosphorylation to aerobic glycolysis. RNA sequencing illuminated a potential relationship between HVEM and GPT2, an enzyme tied to amino acid metabolism and cellular energetics. Subsequent experiments confirmed that HVEM's influence on T cell activation and metabolism is potentially mediated through its regulation of GPT2. In addition, GATA1 was validated to regulate HVEM expression in activated Jurkat T cells. Our study establishes that HVEM significantly influences T cell functionality and NSCLC cell dynamics, pinpointing the HVEM-GPT2 axis as a promising target for NSCLC therapy.

Metabolomics approach to evaluate diclazuril-induced developmental toxicity in zebrafish embryo.

Anticoccidials, commonly used in veterinary medicine to treat coccidiosis in food-producing animals, particularly in poultry farming, are associated with potential environmental risks due to their excretion in manure and subsequent land-spreading. Diclazuril, a widely used anticoccidial, has been detected in groundwater, raising concerns about its impact on non-target species. This study investigates the developmental toxicity of diclazuril in zebrafish embryos over a 96-hour exposure period, utilizing biomarkers such as oxidative stress indicators and metabolomic profiles. The acute toxicity assessment determined an LC50 of 255 µg/L for diclazuril. Observed sublethal effects included pericardial edema, curved spine, and yolk sac edema, which worsened with increasing concentrations from 106 µg/L to 515 µg/L. Based on the Lowest Observed Adverse Effect Level (LOAEL), further experiments were conducted at concentrations of 50 µg/L, 100 µg/L, and 200 µg/L. Significant increases in reactive oxygen species (ROS) were noted at 100 µg/L and 200 µg/L, alongside notable reduction in superoxide dismutase (SOD) and glutathione S-transferase (GST) activities at concentrations ≥100 µg/L, while no significant changes observed in catalase (CAT) activity. Metabolomic analysis using GC-MS/MS revealed significant disturbances in pathways such as pyruvate metabolism, the citric acid cycle, and amino acid metabolism, indicating potential mitochondrial dysfunction in groups exposed to concentrations ≥100 µg/L. Furthermore, alterations in histological lesions in brain region and altered neurotransmitter activity suggests possible neurobehavioral disorders. Increased oxidative stress, along with decreased ATP and NADH levels, points to mitochondrial dysfunction, which is further supported by ultrastructural analysis and locomotor behavior confirming mitochondrial disruption. The disruption of cellular energetics is likely a key factor contributing to the neurotoxic effects observed in zebrafish embryos exposed to ≥100 µg/L of diclazuril.

Envisioning Glucose Transporters (GLUTs and SGLTs) as Novel Intervention against Cancer: Drug Discovery Perspective and Targeting Approach.

Metabolic reprogramming and altered cellular energetics have been recently established as an important cancer hallmark. The modulation of glucose metabolism is one of the important characteristic features of metabolic reprogramming in cancer. It contributes to oncogenic progression by supporting the increased biosynthetic and bio-energetic demands of tumor cells. This oncogenic transformation consequently results in elevated expression of glucose transporters in these cells. Moreover, various cancers exhibit abnormal transporter expression patterns compared to normal tissues. Recent investigations have underlined the significance of glucose transporters in regulating cancer cell survival, proliferation, and metastasis. Abnormal regulation of these transporters, which exhibit varying affinities for hexoses, could enable cancer cells to efficiently manage their energy supply, offering a crucial edge for proliferation. Exploiting the upregulated expression of glucose transporters, GLUTs, and Sodium Linked Glucose Transporters (SGLTs), could serve as a novel therapeutic intervention for anti-cancer drug discovery as well as provide a unique targeting approach for drug delivery to specific tumor tissues. This review aims to discussthe previous and emerging research on the expression of various types of glucose transporters in tumor tissues, the role of glucose transport inhibitors as a cancer therapy intervention as well as emerging GLUT/SGLT-mediated drug delivery strategies that can be therapeutically employed to target various cancers.

The Role of Umbilical Cord Mesenchymal Stem Cell-Derived Extracellular Vesicles in Modulating Dermal Fibroblast Activity: A Pathway to Enhanced Tissue Regeneration

Extracellular vesicles (EVs) secreted by umbilical cord-derived mesenchymal stem cells (UC-MSCs) hold significant promise as therapeutic agents in regenerative medicine. This study investigates the effects of UC-MSC-derived EVs on dermal fibroblast function, and their potential in wound healing applications. EVs were characterized by nanoparticle tracking analysis and transmission electron microscopy, revealing a mean size of 118.6 nm, consistent with exosomal properties. Dermal fibroblasts were treated with varying concentrations of EVs (25–100 µg/mL), and their impacts on cellular metabolism, mitochondrial activity, reactive oxygen species (ROS) production, wound closure, inflammatory cytokine secretion, growth factor production, and extracellular matrix (ECM) gene expression were evaluated. At lower concentrations (25–50 µg/mL), EVs significantly enhanced fibroblast metabolic and mitochondrial activity. However, higher concentrations (≥75 µg/mL) increased ROS levels, suggesting potential hormetic effects. EVs also modulated inflammation by reducing pro-inflammatory cytokines (IL-6, TNF-α) while promoting pro-regenerative cytokines (IL-33, TGF-β). Treatment with 50 µg/mL of EVs optimally stimulated wound closure and growth factor secretion (VEGF, BDNF, KGF, IGF), and upregulated ECM-related gene expression (type I and III collagen, fibronectin). These findings demonstrate that UC-MSC-derived EVs exert multifaceted effects on dermal fibroblast function, including enhanced cellular energetics, stimulation of cell migration, regulation of inflammation, promotion of growth factor production, and increased ECM synthesis. This study highlights the potential of EVs as a novel therapeutic strategy for wound healing and tissue regeneration, emphasizing the importance of optimizing EV concentration for maximal therapeutic efficacy.

Linking warmer nest temperatures to reduced body size in seabird nestlings: Possible mitochondrial bioenergetic and proteomic mechanisms.

Rapid reduction of body size in populations responding to global warming suggests the involvement of temperature-dependent physiological adjustments during growth, such as mitochondrial alterations, in the efficiency of producing metabolic energy, a process that is poorly explored, especially in endotherms. Here, we examined the mitochondrial metabolism and proteomic profile of red blood cells in relation to body size and cellular energetics in nestling shearwaters (Calonectris diomedea) developing at different natural temperatures. We found that nestlings of warmer nests had lighter bodies and smaller beaks at fledging. Despite there was no effect of environmental temperature on cellular metabolic rate, mitochondria had a higher inefficiency in coupling metabolism to allocable energy production, as evidenced by bioenergetic and proteomic analyses. Mitochondrial inefficiency was positively related to cellular stress represented by heat shock proteins, antioxidant enzymes and markers of mitochondrial stress. The observed temperature-related mitochondrial inefficiency was associated with reduced beak size and body mass and was linked to a downregulation of cellular growth factors and growth promoters determining body size. By analyzing the links between environmental temperature, mitochondrial inefficiency and body size we discuss the physiological alterations that free-living birds, and probably other endotherms, need to trigger to cope with a warming world.

Therapeutic Potential of Simvastatin: Cellular Mechanism, Binding Energetics, and Resistance Developments.

Statins are a class of hypolipidemic agents that have been shown to promote osteogenic differentiation through enhanced alveolar bone recovery, inserted osseointegration, and cartilage regeneration. This review uses Molecular Docking (MD) simulations and additional Computer- Aided Drug Design (CADD) methods to present the state of the art in statin therapy. Furthermore, several studies have shown that factors such as limited overall absorption, metabolism in the first pass, and systemic side effects are among those that affect the oral administration of statins. In addition, these variables include susceptibility to efflux mechanisms, drug permeability, dissolution percentage, aqueous solubility, initial metabolism, and pre-systemic metabolism. Additionally examined are the pharmacokinetics of the statin and in vivo mechanisms of action. As a result of the numerous problems associated with the consumption of statins, including their low total bioavailability, first-pass metabolism, low aqueous solubility, and systemic adverse reactions, a non-oral mode of administration was looked into for this crucial and primary class of pharmacokinetic agents. However, to optimize bioavailability and minimize side effects, more research is required.

Exogenously and Endogenously Sequential Regulation of DNA Nanodevices Enables Organelle-Specific Signal Amplification in Subcellular ATP Profiling.

Adenosine triphosphate (ATP), the primary energy currency in cells, is dynamically regulated across different subcellular compartments. The ATP interplay between mitochondria and endoplasmic reticulum (ER) underscores their coordinated roles in various biochemical processes, highlighting the necessity for precise profiling of subcellular ATP dynamics. Here we present an exogenously and endogenously dual-regulated DNA nanodevice for spatiotemporally selective, subcellular-compartment specific signal amplification in ATP sensing. The system allows for exogenous NIR light-controlled spatiotemporal localization and activation of the aptamer sensor in mitochondria or ER, while a specific endogenous enzyme in the organelles further drives signal amplification via the consumption of molecular beacon fuels, resulting in significantly enhanced sensitivity and spatial precision for the subcellular ATP profiling in the organelle of interest. Furthermore, we demonstrate the application of this system for robust monitoring of ATP fluctuations in mitochondria and ER following drug interventions. This advancement provides a powerful tool for improving our understanding of cellular energetics at the subcellular level and holds potential for the development of targeted therapeutics.

Discovery of gallic acid-based mitochondriotropic antioxidant attenuates LPS-induced neuroinflammation.

Mitochondria are complex organelle that plays a pivotal role in energy metabolism, regulation of stress responses, and also serve as a major hub for biosynthetic processes. In addition to their well-established function in cellular energetics, it also serves as the primary site for the origin of intracellular reactive oxygen species (ROS), which function as signaling molecules and can lead to oxidative stress when generated in excess. Moreover, mitochondrial dysfunction is one of the leading cause of neuroinflammation. In this regard, we have rationally designed a triazine derived mitochondriotropic antioxidants (Mito-TBA), based on gallic acid and triphenylphosphonium (TPP) cation to specifically target mitochondria to mitigate neuroinflammation. In vitro Mito-TBA-3 inhibits mitoautophagy, offers neuroprotection by inhibiting the LPS induced TLR-4 activation and activating the Nrf-2/ARE pathway in PC-12 derived neurons. In vivo Mito-TBA-3 rescue memory deficit, reversed depression like behavior, inhibited neuroinflammation, and decreased proinflammatory cytokines in LPS induced neuroinflammation rat model. Overall, based on biophysical, in vitro and in vivo analysis, Mito-TBA-3 offers valuable insights as a potent therapeutic lead molecule to combat neurodegeneration even outperforming a well-known non-steroidal anti-inflammatory drug (Aspirin), it also has the potential to use as a promising therapeutic candidate for other mitochondrial oxidative stress related disorders.

Sexual Dimorphism in Lipidomic Changes in Maternal Blood and Placenta Associated with Obesity and Gestational Diabetes: A Discovery Study

The placenta uses lipids and other nutrients to support its own metabolism hence impacting the type and amount of these substrates available to the growing fetus. Maternal obesity and gestational diabetes (GDM) can disrupt placental lipid metabolism and thus lead to altered fetal growth contributing to adverse pregnancy outcomes and developmentally programing the offspring for disease in later life. Understanding obesity and GDM driven changes in placental lipid metabolism is thus important. We collected maternal plasma and placental villous tissue following elective cesarean section at term from women who were lean (pre-pregnancy BMI 18.5-24.9), obese (BMI>30) or obese with type A2 GDM n=8 each group (4 male and 4 female placentas). Fatty acid composition of different lipid classes was analyzed by LC-MS/MS analysis. Significant changes in GDM vs obese, GDM vs lean, and obese vs lean were determined in both a fetal sex-dependent and independent manner. In placenta 436 lipids were identified, among which 85 showed significant changes. We report significant changes in placental triglyceride, phosphatidylcholine, and phosphatidylinositol lipids containing essential fatty acids- DHA and AA in GDM, with male placentas driving these changes. In maternal plasma, 284 lipids were identified with 14 showing significant changes, but we observed no changes based on fetal sex. Maternal obesity and GDM impact placental lipid composition in a sexually dimorphic manner. The alteration in specific lipid classes can impact cellular energetics and placental function.

A Practical Guideline for MicroRNA Sequencing Data Analysis in Chronic Lymphocytic Leukemia.

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression. They have been associated with several diseases and cancers, including chronic lymphocytic leukemia (CLL). CLL is the most common form of adult leukemia, and its pathogenesis is driven by the deletion of miRNAs, such as the miR-15a/16-1 cluster. In addition to initiating the development of CLL, the function of miRNAs in regulating the progression of this tumor remains to be investigated. Here, we present a computational pipeline, from the processing of miRNA sequencing files to functional analysis, including differential gene expression and gene set enrichment analysis.We exemplified the utility of the pipeline by applying it to genome-wide small RNA sequencing data from a cohort of CLL patients. The analysis revealed dysregulated expression profiles of miRNAs in CLL. The target genes of these miRNAs are not only associated with the response of CLL patients to current therapies but also involved in several cancer hallmarks, including the avoidance of cell death, the deregulation of cellular energetics, the activation of invasion and metastasis, and genome instability. The identified miRNA-gene interactions offer valuable insights for developing targeted therapies for CLL. In addition, we underscored the importance of a practical and robust computational pipeline to ensure the reliability and reproducibility of miRNA sequencing data analysis.

Preventing excessive autophagy protects from the pathology of mtDNA mutations in Drosophila melanogaster

AbstractAberration of mitochondrial function is a shared feature of many human pathologies, characterised by changes in metabolic flux, cellular energetics, morphology, composition, and dynamics of the mitochondrial network. While some of these changes serve as compensatory mechanisms to maintain cellular homeostasis, their chronic activation can permanently affect cellular metabolism and signalling, ultimately impairing cell function. Here, we use a Drosophila melanogaster model expressing a proofreading-deficient mtDNA polymerase (POLγexo-) in a genetic screen to find genes that mitigate the harmful accumulation of mtDNA mutations. We identify critical pathways associated with nutrient sensing, insulin signalling, mitochondrial protein import, and autophagy that can rescue the lethal phenotype of the POLγexo- flies. Rescued flies, hemizygous for dilp1, atg2, tim14 or melted, normalise their autophagic flux and proteasome function and adapt their metabolism. Mutation frequencies remain high with the exception of melted-rescued flies, suggesting that melted may act early in development. Treating POLγexo- larvae with the autophagy activator rapamycin aggravates their lethal phenotype, highlighting that excessive autophagy can significantly contribute to the pathophysiology of mitochondrial diseases. Moreover, we show that the nucleation process of autophagy is a critical target for intervention.

Remote Ischemic Post-Conditioning (RIC) Mediates Anti-Inflammatory Signaling via Myeloid AMPKα1 in Murine Traumatic Optic Neuropathy (TON).

Traumatic optic neuropathy (TON) has been regarded a vision-threatening condition caused by either ocular or blunt/penetrating head trauma, which is characterized by direct or indirect TON. Injury happens during sports, vehicle accidents and mainly in military war and combat exposure. Earlier, we have demonstrated that remote ischemic post-conditioning (RIC) therapy is protective in TON, and here we report that AMPKα1 activation is crucial. AMPKα1 is the catalytic subunit of the heterotrimeric enzyme AMPK, the master regulator of cellular energetics and metabolism. The α1 isoform predominates in immune cells including macrophages (Mφs). Myeloid-specific AMPKα1 KO mice were generated by crossing AMPKα1Flox/Flox and LysMcre to carry out the study. We induced TON in mice by using a controlled impact system. Mice (mixed sex) were randomized in six experimental groups for Sham (mock); Sham (RIC); AMPKα1F/F (TON); AMPKα1F/F (TON+RIC); AMPKα1F/F LysMCre (TON); AMPKα1F/F LysMCre (TON+RIC). RIC therapy was given every day (5-7 days following TON). Data were generated by using Western blotting (pAMPKα1, ICAM1, Brn3 and GAP43), immunofluorescence (pAMPKα1, cd11b, TMEM119 and ICAM1), flow cytometry (CD11b, F4/80, CD68, CD206, IL-10 and LY6G), ELISA (TNF-α and IL-10) and transmission electron microscopy (TEM, for demyelination and axonal degeneration), and retinal oxygenation was measured by a Unisense sensor system. First, we observed retinal morphology with funduscopic images and found TON has vascular inflammation. H&E staining data suggested that TON increased retinal inflammation and RIC attenuates retinal ganglion cell death. Immunofluorescence and Western blot data showed increased microglial activation and decreased retinal ganglion cell (RGCs) marker Brn3 and axonal regeneration marker GAP43 expression in the TON [AMPKα1F/F] vs. Sham group, but TON+RIC [AMPKα1F/F] attenuated the expression level of these markers. Interestingly, higher microglia activation was observed in the myeloid AMPKα1F/F KO group following TON, and RIC therapy did not attenuate microglial expression. Flow cytometry, ELISA and retinal tissue oxygen data revealed that RIC therapy significantly reduced the pro-inflammatory signaling markers, increased anti-inflammatory macrophage polarization and improved oxygen level in the TON+RIC [AMPKα1F/F] group; however, RIC therapy did not reduce inflammatory signaling activation in the myeloid AMPKα1 KO mice. The transmission electron microscopy (TEM) data of the optic nerve showed increased demyelination and axonal degeneration in the TON [AMPKα1F/F] group, and RIC improved the myelination process in TON [AMPKα1F/F], but RIC had no significant effect in the AMPKα1 KO mice. The myeloid AMPKα1c deletion attenuated RIC induced anti-inflammatory macrophage polarization, and that suggests a molecular link between RIC and immune activation. Overall, these data suggest that RIC therapy provided protection against inflammation and neurodegeneration via myeloid AMPKα1 activation, but the deletion of myeloid AMPKα1 is not protective in TON. Further investigation of RIC and AMPKα1 signaling is warranted in TON.

Human airway macrophages are metabolically reprogrammed by IFN-γ resulting in glycolysis-dependent functional plasticity

Airway macrophages (AM) are the predominant immune cell in the lung and play a crucial role in preventing infection, making them a target for host directed therapy. Macrophage effector functions are associated with cellular metabolism. A knowledge gap remains in understanding metabolic reprogramming and functional plasticity of distinct human macrophage subpopulations, especially in lung resident AM. We examined tissue-resident AM and monocyte-derived macrophages (MDM; as a model of blood derived macrophages) in their resting state and after priming with IFN-γ or IL-4 to model the Th1/Th2 axis in the lung. Human macrophages, regardless of origin, had a strong induction of glycolysis in response to IFN-γ or upon stimulation. IFN-γ significantly enhanced cellular energetics in both AM and MDM by upregulating both glycolysis and oxidative phosphorylation. Upon stimulation, AM do not decrease oxidative phosphorylation unlike MDM which shift to ‘Warburg’-like metabolism. IFN-γ priming promoted cytokine secretion in AM. Blocking glycolysis with 2-deoxyglucose significantly reduced IFN-γ driven cytokine production in AM, indicating that IFN-γ induces functional plasticity in human AM, which is mechanistically mediated by glycolysis. Directly comparing responses between macrophages, AM were more responsive to IFN-γ priming and dependent on glycolysis for cytokine secretion than MDM. Interestingly, TNF production was under the control of glycolysis in AM and not in MDM. MDM exhibited glycolysis-dependent upregulation of HLA-DR and CD40, whereas IFN-γ upregulated HLA-DR and CD40 on AM independently of glycolysis. These data indicate that human AM are functionally plastic and respond to IFN-γ in a manner distinct from MDM. These data provide evidence that human AM are a tractable target for inhalable immunomodulatory therapies for respiratory diseases.

Human airway macrophages are metabolically reprogrammed by IFN-γ resulting in glycolysis-dependent functional plasticity.

Airway macrophages (AM) are the predominant immune cell in the lung and play a crucial role in preventing infection, making them a target for host directed therapy. Macrophage effector functions are associated with cellular metabolism. A knowledge gap remains in understanding metabolic reprogramming and functional plasticity of distinct human macrophage subpopulations, especially in lung resident AM. We examined tissue-resident AM and monocyte-derived macrophages (MDM; as a model of blood derived macrophages) in their resting state and after priming with IFN-γ or IL-4 to model the Th1/Th2 axis in the lung. Human macrophages, regardless of origin, had a strong induction of glycolysis in response to IFN-γ or upon stimulation. IFN-γ significantly enhanced cellular energetics in both AM and MDM by upregulating both glycolysis and oxidative phosphorylation. Upon stimulation, AM do not decrease oxidative phosphorylation unlike MDM which shift to 'Warburg'-like metabolism. IFN-γ priming promoted cytokine secretion in AM. Blocking glycolysis with 2-deoxyglucose significantly reduced IFN-γ driven cytokine production in AM, indicating that IFN-γ induces functional plasticity in human AM, which is mechanistically mediated by glycolysis. Directly comparing responses between macrophages, AM were more responsive to IFN-γ priming and dependent on glycolysis for cytokine secretion than MDM. Interestingly, TNF production was under the control of glycolysis in AM and not in MDM. MDM exhibited glycolysis-dependent upregulation of HLA-DR and CD40, whereas IFN-γ upregulated HLA-DR and CD40 on AM independently of glycolysis. These data indicate that human AM are functionally plastic and respond to IFN-γ in a manner distinct from MDM. These data provide evidence that human AM are a tractable target for inhalable immunomodulatory therapies for respiratory diseases.

An update on the role of sex hormones in the function of the cardiorenal mitochondria.

Multiple studies have highlighted the crucial role of mitochondrial bioenergetics in understanding the progression of cardiorenal diseases, revealing new potential treatment targets related to mitochondrial metabolism. There are well-established sexual dimorphisms in cardiac and renal physiology, with premenopausal females being generally protected from pathology compared with males. The mechanisms of this protection remain to be fully elucidated, however, they clearly depend, at least in part, on sex hormones. Sex hormones contribute to regulating mitochondrial function, and vice versa, highlighting the existence of a bidirectional relationship pivotal for cellular energy metabolism; however, there are still large gaps in knowledge when the sex differences in mitochondrial bioenergetics in health and disease are concerned. This manuscript provides an overview of the new evidence that has been accumulated regarding the role of sex hormones in renal and cardiac mitochondria-dependent cellular energetics, metabolism, and signaling, mainly focusing on the data obtained within the last 3-5 years. We briefly discuss mitochondrial function and different types of sex hormones for the reader and then focus on novel research underscoring the emerging mitochondrial pathways regulated by sex hormones, which might be of interest for the development of novel therapeutic strategies for cardiorenal conditions.

Polyamines mediate cellular energetics and lipid metabolism through mitochondrial respiration to facilitate virus replication.

Polyamines are critical cellular components that regulate a variety of processes, including translation, cell cycling, and nucleic acid metabolism. The polyamines, putrescine, spermidine, and spermine, are found abundantly within cells and are positively-charged at physiological pH. Polyamine metabolism is connected to distinct other metabolic pathways, including nucleotide and amino acid metabolism. However, the breadth of the effect of polyamines on cellular metabolism remains to be fully understood. We recently demonstrated a role for polyamines in cholesterol metabolism, and following these studies, we measured the impact of polyamines on global lipid metabolism. We find that lipid droplets increase in number and size with polyamine depletion. We further demonstrate that lipid anabolism is markedly decreased, and lipid accumulation is due to reduced mitochondrial fatty acid oxidation. In fact, mitochondrial structure and function are largely ablated with polyamine depletion. To compensate, cells depleted of polyamines switch from aerobic respiration to glycolysis in a polyamine depletion-mediated Warburg-like effect. Finally, we show that inhibitors of lipid metabolism are broadly antiviral, suggesting that polyamines and lipids are promising antiviral targets. Together, these data demonstrate a novel role for polyamines in mitochondrial function, lipid metabolism, and cellular energetics.

L-arginine Supplementation in Endurance Athletes: A Systematic Review of Recovery Mechanisms and Performance Enhancement

L-arginine, a semi-essential amino acid, has garnered significant attention for its potential to enhance athletic performance, particularly within endurance sports. Recognized for its multifaceted roles in cardiovascular, immune, and metabolic functions, L-arginine serves as a precursor to biologically active molecules, including nitric oxide (NO), creatine, and polyamines, which are integral to muscle function and recovery. Through its ability to stimulate NO production, L-arginine promotes vasodilation, enhancing blood flow and oxygen delivery to active muscles, thereby improving exercise efficiency and endurance. Additionally, L-arginine influences muscle protein synthesis (MPS) via activation of the mTOR signaling pathway, aids in ammonia detoxification within the urea cycle, and supports cellular energetics by facilitating ATP production. These mechanisms collectively underscore its potential to support prolonged physical exertion, reduce muscle fatigue, and expedite post-exercise recovery. This systematic review examines current evidence on L-arginine supplementation in endurance athletes, focusing on its physiological impacts, mechanisms of action, and potential to enhance recovery and performance. Despite promising findings, variability in individual responses and mixed results across studies highlight the need for refined dosing strategies and further research into long-term safety and efficacy. This review provides a comprehensive overview of L-arginine's potential as a supplement in sports nutrition, aiming to inform evidence-based recommendations for its application in endurance training and recovery strategies.

Longitudinal mitochondrial bioenergetic signatures of blood monocytes and lymphocytes improve during treatment of drug-susceptible pulmonary tuberculosis patients Monocyte/lymphocyte bioenergetic signatures post-TB treatment.

The impact of human pulmonary tuberculosis (TB) on the bioenergetic metabolism of circulating immune cells remains elusive, as does the resolution of these effects with TB treatment. In this study, the rates of oxidative phosphorylation (OXPHOS) and glycolysis in circulating lymphocytes and monocytes of patients with drug-susceptible TB at diagnosis, 2 months, and 6 months during treatment, and 12 months after diagnosis were investigated using extracellular flux analysis. At diagnosis, the bioenergetic parameters of both blood lymphocytes and monocytes of TB patients were severely impaired in comparison to non-TB and non-HIV-infected controls. However, most bioenergetic parameters were not affected by HIV status or glycemic index. Treatment of TB patients restored the % spare respiratory capacity (%SRC) of the circulating lymphocytes to that observed in non-TB and non-HIV infected controls by 12 months. Treatment also improved the maximal respiration of circulating lymphocytes and the %SRC of circulating monocytes of the TB patients. Notably, the differential correlation of the clinical and bioenergetic parameters of the monocytes and lymphocytes from the controls and TB patients at baseline and month 12 was consistent with improved metabolic health and resolution of inflammation following successful TB treatment. Network analysis of the bioenergetic parameters of circulating immune cells with serum cytokine levels indicated a highly coordinated immune response at month 6. These findings underscore the importance of metabolic health in combating TB, supporting the need for further investigation of the bioenergetic immunometabolism associated with TB infection for novel therapeutic approaches aimed at bolstering cellular energetics to enhance immune responses and expedite recovery in TB patients.

Exploration of vanoxerine analogues as antibacterial agents.

Mycobacterium tuberculosis is a bacterial pathogen, responsible for approximately 1.3 million deaths in 2022 through tuberculosis infections. The complex treatment regimen required to treat tuberculosis and growing rates of drug resistance, necessitates the development of new anti-mycobacterial agents. One approach is to repurpose drugs from other clinical applications. Vanoxerine (GBR 12909) was previously shown to have anti-mycobacterial activity, through dissipating the membrane electric potential and hence, cellular energetics. Several vanoxerine analogues were synthesised in this study, which exhibited a range of activities against mycobacteria and enterococcus. All active analogues had similar impacts on the membrane electric potential and inhibition of ethidium bromide efflux. The most active compound displayed reduced inhibitory activity against the known human target of vanoxerine, the dopamine transporter. This work has identified a promising analogue, which could provide a starting point for further medicinal chemistry and drug development efforts to target mycobacteria.

Dramatic changes in mitochondrial subcellular location and morphology accompany activation of the CO2 concentrating mechanism

Dynamic changes in intracellular ultrastructure can be critical for the ability of organisms to acclimate to environmental conditions. Microalgae, which are responsible for ~50% of global photosynthesis, compartmentalize their Ribulose 1,5 Bisphosphate Carboxylase/Oxygenase (Rubisco) into a specialized structure known as the pyrenoid when the cells experience limiting CO2 conditions; this compartmentalization is a component of the CO2 Concentrating Mechanism (CCM), which facilitates photosynthetic CO2 fixation as environmental levels of inorganic carbon (Ci) decline. Changes in the spatial distribution of mitochondria in green algae have also been observed under CO2 limitation, although a role for this reorganization in CCM function remains unclear. We used the green microalga Chlamydomonas reinhardtii to monitor changes in mitochondrial position and ultrastructure as cells transition between high CO2 and Low/Very Low CO2 (LC/VLC). Upon transferring cells to VLC, the mitochondria move from a central to a peripheral cell location and orient in parallel tubular arrays that extend along the cell's apico-basal axis. We show that these ultrastructural changes correlate with CCM induction and are regulated by the CCM master regulator CIA5. The apico-basal orientation of the mitochondrial membranes, but not the movement of the mitochondrion to the cell periphery, is dependent on microtubules and the MIRO1 protein, with the latter involved in membrane-microtubule interactions. Furthermore, blocking mitochondrial respiration in VLC-acclimated cells reduces the affinity of the cells for Ci. Overall, our results suggest that mitochondrial repositioning functions in integrating cellular architecture and energetics with CCM activities and invite further exploration of how intracellular architecture can impact fitness under dynamic environmental conditions.