Seahorse Assay Research Articles

Adipose tissue/ heart lipid transport determines cardiac diastolic function

Abstract Introduction Heart failure with preserved ejection fraction (HFpEF) is characterized by diastolic dysfunction and often occurring in obese individuals. Previous research has demonstrated that the modification of lipid metabolism can prevent the onset of diastolic dysfunction. In our project we have investigated how lipid transport influences the onset of diastolic dysfunction utilizing heart- and adipose tissue-specific knockdowns of the fatty acid (FA) transport protein 1 (FatP1) in Drosophila melanogaster. Methods We generated Drosophila with heart-specific (+/+; Hand4.2-GAL4/UAS-FatP1; tdtK/+) (cFatP1-KD) and adipose tissue-specific (+/+; ppl-GAL4/UAS-FatP1; tdtK/+) (atFat-P1-KD) FatP1 knockdowns using the UAS/GAL4 system. The flies' cardiomyocytes endogenously express tdTomato, facilitating fluorescence-based live imaging of the heart by high-resolution video fluorescence microscopy, as previously described. Cardiac morphology and cardiac lipid accumulation was monitored by confocal microscopy. Additionally, mitochondrial function was evaluated using the glycolytic Seahorse assay of whole hearts. Results Blocking FA-uptake into adipose tissue in atFatP1-KD flies resulted in a highly significant reduction in relaxation velocity (p=0.0009, WT vs. atFatP1-KD), indicative of diastolic dysfunction in flies, while contraction velocity and fractional shortening (systolic function) remained unchanged. Diastolic dysfunction was associated with a significant increase of cardiac lipid droplet (LD) quantity and size in flies lacking FatP1 in adipose tissue (p=0.0275 and p<0.0001, respectively, WT vs. atFatP1-KD). Cardiac mitochondrial function was significantly impaired in atFatP1-KD flies compared to WT flies. Reducing cardiac FA uptake in heart-specific FatP1 KD flies led to a decrease in end-diastolic diameter and a significant reduction in relaxation and contraction velocity (p<0.0001 and p=0.0001, respectively, WT vs. cFatP1-KD), suggesting impairment in both diastolic and systolic function. Interestingly, the number of cardiac LDs increased in cFATP1-KD, however their size decreased significantly resulting in an overall unchanged lipid content compared to WT flies (p=0.0475 and p=0.0367, respectively, WT vs. atFatP1-KD). Mitochondrial function showed no significant alterations. Conclusion This study demonstrates that reducing FA-uptake in adipose or cardiac tissue results in cardiac dysfunction in Drosophila melanogaster. Reduction of adipose tissue FA-uptake results exclusively in diastolic dysfunction likely mediated by cardiac lipid overload and subsequent mitochondrial dysfunction. In contrast, blockade of Fatp1-mediated cardiac FA-uptake induces diastolic/ systolic dysfunction which was unrelated to alterations in cardiac lipid content and mitochondrial dysfunction suggesting alternative mechanisms. These study identifies FatP1-mediated FA-uptake in adipose tissue as a potential therapeutic target for the treatment of diastolic dysfunction.

Diabetes Mellitus Disrupts LncRNA Malat1 Regulation of Cardiac Mitochondrial Genome-Encoded Protein Expression.

Understanding the cellular mechanisms behind diabetes-related cardiomyopathy is crucial as it is a common and deadly complication of diabetes mellitus. Dysregulation of the mitochondrial genome has been linked to diabetic cardiomyopathy, and can be ameliorated by altering microRNA (miRNA) availability in the mitochondrion. Long non-coding RNAs (lncRNAs) have been identified to downregulate miRNAs. This study aimed to determine if diabetes mellitus impacts the mitochondrial localization of lncRNAs, their interaction with miRNAs, and how this influences mitochondrial and cardiac function. In mouse and human non-diabetic and type 2 diabetic cardiac tissue, RNA was isolated from purified mitochondria and sequenced (Ilumina HiSeq). Malat1 was significantly downregulated in both human and mouse cardiac mitochondria. Use of a mouse model with an insertional deletion of Malat1 transcript expression resulted in exacerbated systolic and diastolic dysfunction when evaluated in conjunction with a high-fat diet. The cardiac effects of a high-fat diet were countered in a mouse model with transgenic overexpression of Malat1. MiR-320a, a miRNA that binds to both mitochondrial genome-encoded gene NADH-ubiquinone oxidoreductase chain 1 (MT-ND1) as well as Malat1, was upregulated in human and mouse diabetic mitochondria. Conversely, MT-ND1 was downregulated in human and mouse diabetic mitochondria. Mice with an insertional inactivation of Malat1 displayed increased recruitment of both miR-320a and MT-ND1 to the RNA-induced silencing complex (RISC). In vitro pulldown assays of Malat1 fragments with conserved secondary structure confirmed binding capacity for miR-320a. In vitro Seahorse assays indicated that Malat1 knockdown and miR-320a overexpression impaired overall mitochondrial bioenergetics and Complex I functionality. In summary, the disruption of Malat1 presence in mitochondria as observed in diabetic cardiomyopathy is linked to cardiac dysfunction and mitochondrial genome regulation.

GDH1-catalytic glutaminolysis feedback activate EGFR/PI3K/AKT pathway and reprogram glioblastoma metabolism.

Glutamine is an important nutriment for cancer cell growth that provides biological sources for nucleic acid and fatty acid synthesis, but the role of glutaminolysis in signal transduction and glioblastoma (GBM) progression remains little known. Knockdown and overexpression cells were obtained to explore the functional roles of GDH1 in cell proliferation, tumor formation and aerobic glycolysis. RNA-seq, Chromatin immunoprecipitation, luciferase assay and western blot were performed to verify the regulation of EGFR-AKT pathway by the glutamate dehydrogenase 1 (GDH1, also known as GLUD1) and KDM6A. Metabolite-level measurements and Seahorse Assay were performed to assess the functional role of GHD1 in reprogramming glycolysis. Here, we report that GDH1 catalytic glutaminolysis is essential for GBM cell line proliferation and brain tumorigenesis even in high-glucose conditions. Glutamine is metabolized through glutaminolysis to produce α-ketoglutarate (α-KG). We demonstrate that glutamine in combination with leucine activates mammalian TORC1 by enhancing glutaminolysis and α-KG production. α-KG increases the transcription of PDPK1 by reducing the suppressive histone modification H3K27me3, and then promotes the activation of PI3K/AKT/mTOR pathway. This transcriptional activation induced by α-KG requires histone demethylase KDM6A, which is a 2-oxoglutarate oxygenase that plays important roles in converting α-KG to succinate. Furthermore, we show that GDH1-catalytic glutaminolysis also increases the expression of HK2 and promotes glycolysis in high-glucose condition dependent on KDM6A-mediated demethylation of H3K27. These findings suggest a novel function of glutaminolysis in regulation of signal transduction and metabolism reprograming, provide further evidence for unique role of glutaminolysis in GBM progression.

Preclinical assessment of MAGMAS inhibitor as a potential therapy for pediatric medulloblastoma.

DAOY (SHH driven/tp53 mutant) and D425 (non-SHH group 3) were treated with BT9. For in vitro analysis, cell proliferation, death, migration, invasion, and metabolic activity were assessed using MTT assay, TUNEL staining, scratch wound assay, Matrigel invasion chambers, and seahorse assay, respectively. A D425 orthotopic xenograft mouse model was used to evaluate BT9 efficacy in vivo. BT9 treatment resulted in a significant decrease in cell proliferation (DAOY, 24 hours IC50: 3.6 μM, 48 hours IC50: 2.3 μM, 72 hours IC50: 2.1 μM; D425 24 hours IC50: 3.4 μM, 48 hours IC50: 2.2 μM, 72 hours IC50: 2.1 μM) and a significant increase in cell death (DAOY, 24 hours p = 0.0004, 48 hours p<0.0001; D425, 24 hours p = 0.0001, 48 hours p = 0.02). In DAOY cells, 3 μM BT9 delayed migration and significantly reduced DAOY and D425 cell invasion (p < 0.0001). It also modified mitochondrial respiratory function in both medulloblastoma cell lines. Compared to control, however, BT9 administration did not improve survival in a D425 orthotopic xenograft mouse model. Our in vitro data showed BT9 antitumor efficacy in DAOY and D425 cell lines, suggesting that BT9 may represent a promising targeted therapeutic in pediatric medulloblastoma. These data, however, need to be further validated in animal models.

The modified 6-chromanol SUL-238 protects against accelerated vascular aging in vascular smooth muscle Ercc1-deficient mice

Introduction: Vascular aging is marked by increased mitochondrial reactive oxygen species (ROS) production, which leads to decreased nitric oxide (NO)-mediated vasodilation. Loss of NO can be partially compensated by endothelium-derived hyperpolarization (EDH), which partly relies on increased mitochondrial Ca2+ release to maintain vascular dilation. Thus, intervention in mitochondria may target both NO and EDH signaling to alleviate aging-related vascular dysfunction. DNA damage by mitochondrial ROS is an important cause of organismal aging. Previous work showed that local vascular Ercc1 knockout dramatically accelerates vascular aging. The aim of the study was to investigate the effect of chronic treatment with the modified 6-chromanol, SUL-238, an inhibitor of mitochondrial reverse electron flux and ROS, in a mouse model of accelerated vascular smooth muscle aging induced by DNA repair endonuclease Ercc1 knockout (SMC-KO). Aim: The aim of the study was to investigate the effect of chronic treatment with the modified 6-chromanol, SUL-238, an inhibitor of mitochondrial reverse electron flux and ROS, in a mouse model of accelerated vascular smooth muscle aging induced by DNA repair endonuclease Ercc1 knockout (SMC-KO). Methods: SMC-KO mice and healthy wild-type littermates received SUL-238 (90 mg/kg/day) in drinking water from 12 to 22 weeks of age. At the age of 21 weeks, arterial stiffness was measured in vivo with echography and they were euthanized at the age of 22 weeks. Ex vivo vascular function was assessed in wire myography setups and mitochondrial function of the thoracic aorta was assessed using a seahorse assay. Results: SMC-KO mice showed reduced EDH-mediated vasodilation, elevated arterial stiffness, and increased elastin breaks at 22 weeks of age compared to their wild-type littermates. SUL-238 improved EDH, thus restoring aortic and mesenteric relaxation in SMC-KO mice. Furthermore, the number of elastin breaks was reduced and arterial stiffness normalized after treating SMC-KO mice with SUL-238. Mitochondrial respiration measured in the aorta was not different between the groups. Conclusion: Chronic treatment with SUL-238 alleviates features of vascular aging, including decreased vasodilation and increased arterial stiffness. SUL-238 seems to have a more general effect on aging rather than involving a direct coupling between mitochondrial function and vascular signaling. SUL-238 is the first small-molecule drug reported to increase EDH after chronic treatment.

12560 RIMOC1, A Novel Regulator Of Mitochondrial Function, And Its Role In Pancreatic Beta-cell Survival, Mitophagy, And Diabetogenesis

Abstract Disclosure: D. Filingeri: None. R. Liu: None. V. Negi: None. J. Lee: None. A. Kumar: None. V. Mandi: None. M. Moulik: None. V. Yechoor: None. Background: Literature supports preserving beta-cell function as an approach to slowing diabetes progression. Mitochondria emerge as an interesting area of focus, driving cellular respiration and glucose-stimulated insulin secretion (GSIS) within beta-cells in physiologic conditions, and leading to increased intracellular ROS generation when damaged. Damaged mitochondria are recycled via lysosomes by mitophagy, and defects in mitophagy have been linked to numerous disease states, with more recent data implicating impaired mitophagy with beta-cell death. Our previous work on the Hippo-TEAD pathway and beta-cell survival led to the isolation of the TEAD binding partner RIMOC1 (RAB7A-Interacting MON1-CCZ1 Complex Subunit 1), a protein highly expressed in pancreatic beta-cells, though its role in beta-cells remains unknown. The overarching hypothesis is that RIMOC1 is protective against the development of diabetes by preserving beta-cell mitophagy and mitochondrial function, and that impaired RIMOC1 function would lead to beta-cell failure and diabetes.Methods: We have generated both a stable INS2 RIMOC1 KO (knockout) cell line and an INS1-Cre RIMOC1 KO mouse model, that are beta-cell specific knockouts of RIMOC1. Mitochondrial membrane potentials were measured using TMRE and JC1 stains, and mitophagy was quantified using the mtKeima probe via flow cytometry. Protein expression was quantified via western blotting. Ongoing studies involving our mouse model include in vivo GTTs (glucose tolerance testing), ex vitro GSIS experiments to assess beta-cell function from mouse islets, and seahorse assays to quantify mitochondrial function. Results: Published GEO datasets show RIMOC1 expression is positively correlated with beta-cell maturity and negatively correlated with glucose load and HgbA1c. Our in vitro data demonstrates RIMOC1 knockout leads to decreased insulin mRNA expression, decreased insulin content, and increased beta-cell cycle inhibition. Early in vivo data shows worsened hyperglycemia with oral refeeding after fasting. In vitro mitophagy experiments demonstrate significantly diminished mitochondrial membrane potential in RIMOC1 KO INS2 cells. Conclusions: RIMOC1 is highly expressed in beta-cells and has a significant role in maintaining euglycemia through mitochondrial functioning, insulin processing, and altered mitophagy. This research highlights RIMOC1 as a promising target of further diabetes research. Presentation: 6/2/2024

Mechanical Loading Modulates AMPK and mTOR Signaling in Muscle Cells.

Skeletal muscle adaptation to exercise involves various phenotypic changes that enhance the metabolic and contractile functions. One key regulator of these adaptive responses is the activation of AMPK, which is influenced by exercise intensity. However, the mechanistic understanding of AMPK activation during exercise remains incomplete. In this study, we utilized an in vitro model to investigate the effects of mechanical loading on AMPK activation and its interaction with the mTOR signaling pathway. Proteomic analysis of muscle cells subjected to static loading (SL) revealed distinct quantitative protein alterations associated with RNA metabolism, with 10% SL inducing the most pronounced response compared to lower intensities of 5% and 2% as well as the control. Additionally, 10% SL suppressed RNA and protein synthesis while activating AMPK and inhibiting the mTOR pathway. We also found that SRSF2, necessary for pre-mRNA splicing, is regulated by AMPK and mTOR signaling, which, in turn, is regulated in an intensity-dependent manner by SL with the highest expression in 2% SL. Further examination showed that the ADP/ATP ratio was increased after 10% SL compared to the control and that SL induced changes in mitochondrial biogenesis. Furthermore, Seahorse assay results indicate that 10% SL enhances mitochondrial respiration. These findings provide novel insights into the cellular responses to mechanical loading and shed light on the intricate AMPK-mTOR regulatory network in muscle cells.

Inhibition of ACSS2 triggers glycolysis inhibition and nuclear translocation to activate SIRT1/ATG5/ATG2B deacetylation axis, promoting autophagy and reducing malignancy and chemoresistance in ovarian cancer

BackgroundMetabolic reprogramming is a hallmark of cancer, characterized by a high dependence on glycolysis and an enhanced utilization of acetate as an alternative carbon source. ACSS2 is a critical regulator of acetate metabolism, playing a significant role in the development and progression of various malignancies. ACSS2 facilitates the conversion of acetate to acetyl-CoA, which participates in multiple metabolic pathways and functions as an epigenetic regulator of protein acetylation, thereby modulating key cellular processes such as autophagy. However, the roles and intrinsic connections of ACSS2, glycolysis, protein acetylation, and autophagy in ovarian cancer (OC) remain to be elucidated. Basic proceduresUtilizing clinical specimens and online databases, we analysed the expression of ACSS2 in OC and its relationship with clinical prognosis. By knocking down ACSS2, we evaluated its effects on the malignant phenotype, acetate metabolism, glycolysis, and autophagy. The metabolic alterations in OC cells were comprehensively analysed using Seahorse assays, transmission electron microscopy, membrane potential measurements, and stable-isotope labeling techniques. CUT&TAG and co-immunoprecipitation techniques were employed to explore the deacetylation of autophagy-related proteins mediated by ACSS2 via SIRT1. Additionally, through molecular docking, transcriptome sequencing, and metabolomics analyses, we validated the pharmacological effects of paeonol on ACSS2 and the glycolytic process in OC cells. Finally, both in vitro and in vivo experiments were performed to investigate the impact of paeonol on autophagy and its anti-OC effects mediated through the ACSS2/SIRT1 deacetylation axis. Main findingsACSS2 is significantly upregulated in OC and is associated with poor prognosis. Knockdown of ACSS2 inhibits OC cells proliferation, migration, invasion, angiogenesis, and platinum resistance, while reducing tumour burden in vivo. Mechanistically, inhibiting ACSS2 reduces acetate metabolism and suppresses glycolysis by targeting HXK2. This glycolytic reduction promotes the translocation of ACSS2 from the cytoplasm to the nucleus, leading to increased expression of the deacetylase SIRT1. SIRT1 mediates the deacetylation of autophagy-related proteins, such as ATG5 and ATG2B, thereby significantly activating autophagy in OC cells and exerting antitumor effects. Paeonol inhibits acetate metabolism and glycolysis in OC cells by targeting ACSS2. Paeonol activates autophagy through the ACSS2/SIRT1/ATG5/ATG2B deacetylation axis, demonstrating inhibition of OC in vitro and in vivo. Principal conclusionsPae can serve as an effective, low-toxicity, multi-targeted drug targeting ACSS2 and glycolysis. It activates autophagy through the ACSS2/SIRT1/ATG5/ATG2B deacetylation signalling cascade, thereby exerting anti-OC effects. Our study provides new insights into the malignant mechanisms of OC and offers a novel strategy for its treatment.

Proteomics reveals dynamic metabolic changes in human hematopoietic stem progenitor cells from fetal to adulthood

BackgroundHematopoietic stem progenitor cells (HSPCs) undergo phenotypical and functional changes during their emergence and development. Although the molecular programs governing the development of human hematopoietic stem cells (HSCs) have been investigated broadly, the relationships between dynamic metabolic alterations and their functions remain poorly characterized.MethodsIn this study, we comprehensively described the proteomics of HSPCs in the human fetal liver (FL), umbilical cord blood (UCB), and adult bone marrow (aBM). The metabolic state of human HSPCs was assessed via a Seahorse assay, RT‒PCR, and flow cytometry-based metabolic-related analysis. To investigate whether perturbing glutathione metabolism affects reactive oxygen species (ROS) production, the metabolic state, and the expansion of human HSPCs, HSPCs were treated with buthionine sulfoximine (BSO), an inhibitor of glutathione synthetase, and N-acetyl-L-cysteine (NAC).ResultsWe investigated the metabolomic landscape of human HSPCs from the fetal, perinatal, and adult developmental stages by in-depth quantitative proteomics and predicted a metabolic switch from the oxidative state to the glycolytic state during human HSPC development. Seahorse assays, mitochondrial activity, ROS level, glucose uptake, and protein synthesis rate analysis supported our findings. In addition, immune-related pathways and antigen presentation were upregulated in UCB or aBM HSPCs, indicating their functional maturation upon development. Glutathione-related metabolic perturbations resulted in distinct responses in human HSPCs and progenitors. Furthermore, the molecular and immunophenotypic differences between human HSPCs at different developmental stages were revealed at the protein level for the first time.ConclusionThe metabolic landscape of human HSPCs at three developmental stages (FL, UCB, and aBM), combined with proteomics and functional validations, substantially extends our understanding of HSC metabolic regulation. These findings provide valuable resources for understanding human HSC function and development during fetal and adult life.

Shenqi Pill alleviates acetaminophen-induced liver injury: a comprehensive strategy of network pharmacology and spectrum-effect relationship reveals mechanisms and active components

BackgroundAcetaminophen (APAP), commonly used for its antipyretic and analgesic properties, can cause severe liver injury or even acute liver failure when overdosed. However, the options for treating APAP-induced liver toxicity are limited. Shenqi Pill (SQP), a traditional Chinese herbal formula, has shown effectiveness in treating various liver ailments. SQP consists of cinnamon, aconite, rehmannia, cornus, peony bark, Chinese yam, poria, and alisma in a ratio of 1:1:8:4:3:4:3:3. However, the mechanisms and active components of SQP that counteract drug-induced liver injury (DILI) are not well understood. PurposeThis study aimed to explore the protective effects of SQP against APAP-induced liver injury in both laboratory and animal settings. It seeks to identify the active components and potential mechanisms by which SQP targets mitochondria to alleviate liver damage. MethodsA mouse model with APAP-induced liver injury was established to assess SQP's therapeutic impact. This study then analyzed the components of SQP using UPLC-Q-TOF-MS in both in vivo and in vitro environments. Network pharmacology and the GEO database helped predict potential pathways and targets. Potential active components were identified through spectrum-effect relationship analysis and validated their efficacy using Seahorse assays and molecular docking. ResultsTreatment with SQP significantly reduced liver dysfunction, tissue damage, lipid metabolic disruptions, and inflammation caused by APAP in mice. In cellular tests, SQP-treated serum notably enhanced mitochondrial function, maintained membrane potential, decreased ROS levels, and prevented mitochondrial permeability transition pore opening. Biochemically, SQP reversed the suppression of p-AMPK, p-ACC, CPT1, and ACADM expression caused by APAP overdose. This study identified 97 in vitro and 24 in vivo components of SQP, with eight showing significant mitochondrial benefits. Molecular docking studies suggest that fuziline and paeoniflorin could activate AMPK. ConclusionSQP effectively mitigates APAP-induced liver injury by enhancing mitochondrial function via the AMPK-ACC-CPT1-ACADM pathway. Moreover, this study introduces a novel strategy for analyzing the relationship between the chemical and pharmacological properties of drug-containing serum, successfully identifying compounds with mitochondrial activity. Fuziline and paeoniflorin, in particular, emerge as promising mitochondrial protectants and warrant further investigation. This research underpins the development of innovative treatments for DILI using SQP and its components.

Targeting hexokinase 2 to enhance anticancer efficacy of trichosanthin in HeLa and SCC25 cell models

Background and purpose: Trichosanthin (TCS) is a plant-based ribosome-inactivating protein exhibiting a range of pharmacological properties, including abortifacient and anticancer. However, the routine clinical use in cancer treatment was hampered by its antigenicity. Hexokinase 2 (HK2) is a pivotal regulator of glycolysis, where aberrant expression is observed in many cancers. This study investigates the anticancer effects and mechanisms of TCS in combination with benserazide (Benz), a HK2 inhibitor, in Hela and SCC25 cancer models. Experimental approach: MTT, colony-formation and cell cycle assays were performed to assess the cytotoxic effects of TCS and Benz in HeLa and SCC25 cells. Seahorse assay, western blotting, flow cytometry analysis and RNA sequencing were employed to investigate the pharmacological effects of the combo treatment. SCC25 cell xenograft mouse model was established for in vivo efficacy study. Key results: Combined use of TCS and Benz exhibited synergistic anticancer effects in both Hela and SCC25 cell models. The observed synergistic effects were attributed to the modulation of glycolysis by targeting HK2, leading to reduced lactate production and increased ROS accumulation which further inhibited colony formation and cell cycle progression, as well as triggered apoptosis. Moreover, this combination effectively inhibited NFκB/ERK signalling pathways, which were found to be significantly activated upon single use of TCS. It was found that the combination significantly suppressed the tumour growth in SCC25 cell xenograft mouse model. Conclusion: Our findings suggested that targeting HK2 and modulating glycolysis may offer a promising avenue for improving the therapeutic outcomes of TCS-based anticancer treatments.

FDA-approved PDE4 inhibitors alleviate the dominant toxicity of ALS-FTD-associated CHCHD10S59L by reducing the PINK1/Parkin pathway.

Mutations in coiled-coil-helix-coiled-coil-helix domain containing 10 (CHCHD10) have been identified as a genetic cause of amyotrophic lateral sclerosis and/or frontotemporal dementia(ALS-FTD). In our previous studies using in vivo Drosophila model expressing CHCHD10S59L, and human cell models expressing CHCHD10S59L, we have identified that the PINK1/Parkin pathway is activated and causes cellular toxicity. Furthermore, we demonstrated that pseudo-substrate inhibitors for PINK1 and mitofusin2 agonists mitigated the cellular toxicity of CHCHD10S59L. Evidences using in vitro, in vivo genetic, and chemical tools indicate that inhibiting PINK1 would be the most promising treatment for CHCHD10S59L-induced diseases. An in vivo human cell culture and in vivo Drosophila models expressing CHCHD10S59L mutant were utilized in this study to evaluate the effect of PDE4 inhibitors in PINK-parkin mediated cytotoxicity through immunohistochemical and seahorse assays. Data were analysed using one-way ANOVA and post-hoc Dunnett's test for statistical significance. We investigated cellular pathways that can modulate the PINK1/Parkin pathway and reduce CHCHD10S59L-induced cytotoxicity. Here, we report that FDA-approved PDE4 inhibitors reduced CHCHD10S59L-induced morphological and functional mitochondrial defects in human cells and an in vivo Drosophila model expressing C2C10HS81L. Multiple PDE4 inhibitors decreased PINK1 accumulation and downstream mitophagy induced by CHCHD10S59L. These findings suggest that PDE4 inhibitors currently available in the market may be repositioned to treat CHCHD10S59L-induced ALS-FTD and possibly other related diseases, and that disease treatment with PDE4 inhibitors should include careful consideration of the PINK1/Parkin pathway, as it is generally recognized as a protective pathway.

Glucosamine-Mediated Hexosamine Biosynthesis Pathway Activation Uses ATF4 to Promote "Exercise-Like" Angiogenesis and Perfusion Recovery in PAD.

Endothelial cells (ECs) use glycolysis to produce energy. In preclinical models of peripheral arterial disease, further activation of EC glycolysis was ineffective or deleterious in promoting hypoxia-dependent angiogenesis, whereas pentose phosphate pathway activation was effective. Hexosamine biosynthesis pathway, pentose phosphate pathway, and glycolysis are closely linked. Glucosamine directly activates hexosamine biosynthesis pathway. Hind-limb ischemia in endothelial nitric oxide synthase knockout (eNOS-/-) and BALB/c mice was used. Glucosamine (600 μg/g per day) was injected intraperitoneally. Blood flow recovery was assessed using laser Doppler perfusion imaging and angiogenesis was studied by CD31 immunostaining. In vitro, human umbilical vein ECs and mouse microvascular ECs with glucosamine, L-glucose, or vascular endothelial growth factor (VEGF165a) were tested under hypoxia and serum starvation. Cell Counting Kit-8, tube formation, intracellular reactive oxygen species, electric cell-substrate impedance sensing, and fluorescein isothiocyanate dextran permeability were assessed. Glycolysis and oxidative phosphorylation were assessed by seahorse assay. Gene expression was assessed using RNA sequencing, real-time quantitative polymerase chain reaction, and Western blot. Human muscle biopsies from patients with peripheral arterial disease were assessed for EC O-GlcNAcylation before and after supervised exercise versus standard medical care. On day 3 after hind-limb ischemia, glucosamine-treated versus control eNOS-/- mice had less necrosis (n=4 or 5 per group). Beginning on day 7 after hind-limb ischemia, glucosamine-treated versus control BALB/c mice had higher blood flow, which persisted to day 21, when ischemic muscles showed greater CD31 staining per muscle fiber (n=8 per group). In vitro, glucosamine versus L-glucose ECs showed improved survival (n=6 per group) and tube formation (n=6 per group). RNA sequencing of glucosamine versus L-glucose ECs showed increased amino acid metabolism (n=3 per group). That resulted in increased oxidative phosphorylation (n=8-12 per group) and serine biosynthesis pathway without an increase in glycolysis or pentose phosphate pathway genes (n=6 per group). This was associated with better barrier function (n=6-8 per group) and less reactive oxygen species (n=7 or 8 per group) compared with activating glycolysis by VEGF165a. These effects were mediated by activating transcription factor 4, a driver of exercise-induced angiogenesis. In muscle biopsies from humans with peripheral arterial disease, EC/O-GlcNAcylation was increased by 12 weeks of supervised exercise versus standard medical care (n=6 per group). In cells, mice, and humans, activation of hexosamine biosynthesis pathway by glucosamine in peripheral arterial disease induces an "exercise-like" angiogenesis and offers a promising novel therapeutic pathway to treat this challenging disorder.

Abstract P203: Nicotine Exposure: A Catalyst for Nitrosative and Oxidative Stress in Glomerular Podocytes and Renal Impairment

Introduction: Nicotine consumption through vaping, cigarettes, or nicotine replacement therapy poses major risks for renal health, especially in individuals with hypertension or kidney disease. Nicotine induces oxidative stress and nitric oxide synthase (NOS) remodeling in endothelial cells, but a gap in knowledge persists regarding its impact on glomerular epithelial cells, particularly podocytes. We hypothesize that nicotine promotes nitrosative stress in podocytes, generating peroxynitrite (ONOO - ), causing mitochondrial damage, and glomerular impairment. Methods: We performed confocal imaging on human cultured podocytes to detect ONOO - , Ca 2+ , and nitric oxide (NO) in response to nicotine. We used Seahorse assay (Agilent XFe24) to test mitochondrial respiration. Nicotine was then chronically infused in Dahl SS rats (0.2 mg/kg/day s.c., 0.4% NaCl diet) for 21 days, and recorded blood pressure with telemetry. Glomerular damage was evaluated, and electron microscopy was employed to assess mitochondrial ultrastructure. Electron paramagnetic resonance (EPR) spectroscopy was used to access the NO levels in cultured podocytes and in vivo . OriginPro was used for statistical analysis. Results: Acute application of nicotine promoted intracellular Ca 2+ and ONOO - transients in podocytes. The ONOO - response was blocked in the presence of SOD, indicating that ONOO - production requires superoxide. The application of specific α7, α4β2, α2β4, α4β4, and α3β4 nicotinic acetylcholine receptor (nAChR) agonists elicited Ca 2+ transients but did not produce ONOO - , suggesting that nitrosative stress occurs independently from nAChR activation. Incubation with nicotine (12 hrs) resulted in a decrease in podocytes’ mitochondrial respiration (two-sample t-test, p&lt;0.05). In vivo , nicotine infusion did not affect blood pressure but promoted mitochondrial damage in podocytes, which exhibited swelling, loss of cristae, and mitophagy (t-test, p&lt;0.05). Histopathological assessment showed higher glomerular damage in nicotine-exposed rats (t-test, p&lt;0.05). Both EPR and confocal approaches demonstrated nicotine-mediated changes in NO bioavailability and an increase in NOS2 activity (t-test, p&lt;0.05). Conclusion: Nicotine products promote NOS uncoupling in podocytes, leading to ONOO - formation, redox stress, mitochondrial impairment, and glomerular damage. Understanding nicotine's impact on podocytes is crucial for preventing or developing therapies against smoking and vaping-related pathologies.

Prenylated xanthones from mangosteen (Garcinia mangostana) target oxidative mitochondrial respiration in cancer cells

Mangosteen (Garcinia mangostana) is well-known for its nutritional value and health benefits. Breast cancer is the most common cancer and the leading cause of cancer-related mortality among females worldwide. Here we show that the prenylated xanthones, α-mangostin, γ-mangostin, 9-hydroxycalabaxanthone (9-HCX), and garcinone E from the mangosteen pericarp exhibit cytotoxicity against a panel of human cancer cell lines including lung adenocarcinoma (A549), cervical carcinoma (HeLa), prostatic carcinoma (DU 145), pancreatic carcinoma (MIA PaCa-2), hepatocellular carcinoma (Hep G2), bladder urothelial cancer (5637), as well as the triple-negative breast cancer cells MDA-MB-231. In line with its higher predicted bioactivity score compared to other prenylated xanthones, 9-HCX induced the strongest antiproliferative and proapoptotic effects in MDA-MB-231 breast cancer xenografts in vivo. In different in vitro models, we demonstrate that prenylated xanthones from G. mangostana target mitochondria in cancer cells by inhibition of the mitochondrial respiratory chain complex II (α-mangostin, γ-mangostin, and garcinone E) and complex III (9-HCX) as shown in isolated mitochondria. Accordingly, oxidative mitochondrial respiration (OXPHOS) was inhibited, mitochondrial proton leak increased, and adenosine triphosphate (ATP) synthesis decreased as analyzed by Seahorse assay in MDA-MB-231 cells. Hence, the prenylated xanthones increased mitochondrial superoxide levels, induced mitochondrial membrane permeabilization, and initiated caspase 3/7-mediated apoptosis in MDA-MB-231 triple-negative breast cancer cells. Thus, prenylated xanthones from Garcinia mangostana exhibit anticancer activity based on interference with the mitochondrial respiration.

Betaine delays age-related muscle loss by mitigating Mss51-induced impairment in mitochondrial respiration via Yin Yang1.

Mitochondrial dysfunction is one of the hallmarks of aging and a leading contributor to sarcopenia. Nutrients are essential for improving mitochondrial function and skeletal muscle health during the aging process. Betaine is a nutrient with potential muscle-preserving properties. However, whether and how betaine could regulate the mitochondria function in aging muscle are poorly understood. We aimed to explore the molecular target and underlying mechanism of betaine in attenuating the age-related mitochondrial dysfunction in skeletal muscle. Young mice (YOU, 2months), old mice (OLD, 15months), and old mice with betaine treatment (BET, 15months) were fed for 12weeks. The effects of betaine on muscle mass, strength, function, and subcellular structure of muscle fibres were assessed. RNA sequencing (RNA-seq) was conducted to identify the molecular target of betaine. The impacts of betaine on mitochondrial-related molecules, superoxide accumulation, and oxidative respiration were examined using western blotting (WB), immunofluorescence (IF) and seahorse assay. The underlying mechanism of betaine regulation on the molecular target to maintain mitochondrial function was investigated by luciferase reporter assay, chromatin immunoprecipitation and electrophoretic mobility shift assay. Adenoassociated virus transfection, succinate dehydrogenase staining (SDH), and energy expenditure assessment were performed on 20-month-old mice for validating the mechanism in vivo. Betaine intervention demonstrated anti-aging effects on the muscle mass (P=0.017), strength (P=0.010), and running distance (P=0.013). Mitochondrial-related markers (ATP5a, Sdha, and Uqcrc2) were 1.1- to 1.5-fold higher in BET than OLD (all P≤0.036) with less wasted mitochondrial vacuoles accumulating in sarcomere. Bioinformatic analysis from RNA-seq displayed pathways related to mitochondrial respiration activity was higher enriched in BET group (NES=-0.87, FDR=0.10). The quantitative real time PCR (qRT-PCR) revealed betaine significantly reduced the expression of a novel mitochondrial regulator, Mss51 (-24.9%, P=0.002). In C2C12 cells, betaine restored the Mss51-mediated suppression in mitochondrial respiration proteins (all P≤0.041), attenuated oxygen consumption impairment, and superoxide accumulation (by 20.7%, P=0.001). Mechanically, betaine attenuated aging-induced repression in Yy1 mRNA expression (BET vs. OLD: 2.06 vs. 1.02, P=0.009). Yy1 transcriptionally suppressed Mss51 mRNA expression both in vitro and in vivo. This contributed to the preservation of mitochondrial respiration, improvement for energy expenditure (P=0.008), and delay of muscle loss during aging process. Altogether, betaine transcriptionally represses Mss51 via Yy1, improving age-related mitochondrial respiration in skeletal muscle. These findings suggest betaine holds promise as a dietary supplement to delay skeletal muscle degeneration and improve age-related mitochondrial diseases.

Upregulation of Mitochondrial Sirt3 and Alleviation of the Inflammatory Phenotype in Macrophages by Estrogen.

Aging and comorbidities like type 2 diabetes and obesity contribute to the development of chronic systemic inflammation, which impacts the development of heart failure and vascular disease. Increasing evidence suggests a role of pro-inflammatory M1 macrophages in chronic inflammation. A shift of metabolism from mitochondrial oxidation to glycolysis is essential for the activation of the pro-inflammatory M1 phenotype. Thus, reprogramming the macrophage metabolism may alleviate the pro-inflammatory phenotype and protect against cardiovascular diseases. In the present study, we hypothesized that the activation of estrogen receptors leads to the elevation of the mitochondrial deacetylase Sirt3, which supports mitochondrial function and mitigates the pro-inflammatory phenotype in macrophages. Experiments were performed using the mouse macrophage cell line RAW264.7, as well as primary male or female murine bone marrow macrophages (BMMs). Macrophages were treated for 24 h with estradiol (E2) or vehicle (dextrin). The effect of E2 on Sirt3 expression was investigated in pro-inflammatory M1, anti-inflammatory/immunoregulatory M2, and naïve M0 macrophages. Mitochondrial respiration was measured by Seahorse assay, and protein expression and acetylation were determined by western blotting. E2 treatment upregulated mitochondrial Sirt3, reduced mitochondrial protein acetylation, and increased basal mitochondrial respiration in naïve RAW264.7 macrophages. Similar effects on Sirt3 expression and mitochondrial protein acetylation were observed in primary female but not in male murine BMMs. Although E2 upregulated Sirt3 in naïve M0, pro-inflammatory M1, and anti-inflammatory/immunoregulatory M2 macrophages, it reduced superoxide dismutase 2 acetylation and suppressed mitochondrial reactive oxygen species formation only in pro-inflammatory M1 macrophages. E2 alleviated the pro-inflammatory phenotype in M1 RAW264.7 cells. The study suggests that E2 treatment upregulates Sirt3 expression in macrophages. In primary BMMs, female-specific Sirt3 upregulation was observed. The Sirt3 upregulation was accompanied by mitochondrial protein deacetylation and the alleviation of the oxidative and pro-inflammatory phenotype in M1 macrophages. Thus, the E2-Sirt3 axis might be used in a therapeutic strategy to fight chronic systemic inflammation and prevent the development of inflammation-linked diseases.

Circulating extracellular vesicle-derived miR-1299 disrupts hepatic glucose homeostasis by targeting the STAT3/FAM3A axis in gestational diabetes mellitus

BackgroundExtracellular vesicles (EVs) are membrane-enclosed structures containing lipids, proteins, and RNAs that play a crucial role in cell-to-cell communication. However, the precise mechanism through which circulating EVs disrupt hepatic glucose homeostasis in gestational diabetes mellitus (GDM) remains unclear.ResultsCirculating EVs isolated from human plasma were co-cultured with mammalian liver cells to investigate the potential induction of hepatic insulin resistance by GDM-EVs using glucose output assays, Seahorse assays, metabolomics, fluxomics, qRT-PCR, bioinformatics analyses, and luciferase assays. Our findings demonstrated that hepatocytes exposed to GDM-EVs exhibited increased gluconeogenesis, attenuated energy metabolism, and upregulated oxidative stress. Particularly noteworthy was the discovery of miR-1299 as the predominant miRNA in GDM-EVs, which directly targeting the 3′-untranslated regions (UTR) of STAT3. Our experiments involving loss- and gain‐of‐function revealed that miR-1299 inhibits the insulin signaling pathway by regulating the STAT3/FAM3A axis, resulting in increased insulin resistance through the modulation of mitochondrial function and oxidative stress in hepatocytes. Moreover, experiments conducted in vivo on mice inoculated with GDM-EVs confirmed the development of glucose intolerance, insulin resistance, and downregulation of STAT3 and FAM3A.ConclusionsThese results provide insights into the role of miR-1299 derived from circulating GDM-EVs in the progression of insulin resistance in hepatic cells via the STAT3/FAM3A axis and downstream metabolic reprogramming.

The effects of the atrial natriuretic peptide deficiency on renal cortical mitochondrial bioenergetics in the Dahl SS rat.

Atrial Natriuretic Peptide (ANP) plays an important role in blood pressure regulation. Low levels of ANP correlate with the development of salt-sensitive hypertension (SS-HTN). Our previous studies indicated that ANP deficiency exacerbated renal function decline in SS-HTN. In the heart and fat tissue, ANP was reported to affect lipid peroxidation and mitochondrial bioenergetics but the effects of ANP on mitochondrial function in the kidney are unexplored. We hypothesized that ANP deficiency in SS-HTN causes renal bioenergetic shift, leading to disruption of mitochondrial network and oxidative stress. To address the hypothesis, we placed Dahl SS wild-type (SSWT) and ANP knockout (SSNPPA-/-) rats on 4% NaCl high salt (HS) diet to induce HTN or maintained them on 0.4% NaCl normal salt (NS) diet and assessed mitochondrial bioenergetics and dynamics using spectrofluorimetry, Seahorse assay, electron paramagnetic resonance (EPR) spectroscopy, Western blotting, electron microscopy, PCR and cytokine assays. We report that under high salt conditions, associated with hypertension and renal damage, the SSNPPA-/- rats exhibit a decrease in mitochondrial membrane potential and elevation in mitochondrial ROS levels compared to SSWT. The redox shift is also evident by the presence of more pronounced medullar lipid peroxidation in the SSNPPA-/- strain. We also revealed fragmented, more damaged mitochondria in the SSNPPA-/- rats, accompanied by increased turnover and biogenesis. Overall, our data indicate that ANP deficiency causes disruptions in mitochondrial bioenergetics and dynamics which likely contributes to aggravation of the renal damage and hypertension in the Dahl SS rat; the major pathological effects are evident in the groups subjected to a combined salt and ANP deficiency-induced mitochondrial stress.

Pulsed electromagnetic fields regulate metabolic reprogramming and mitochondrial fission in endothelial cells for angiogenesis

Pulsed electromagnetic field (PEMF) therapy has been extensively investigated in clinical studies for the treatment of angiogenesis-related diseases. However, there is a lack of research on the impact of PEMFs on energy metabolism and mitochondrial dynamics during angiogenesis. The present study included tube formation and CCK-8 assays. A Seahorse assay was conducted to analyze energy metabolism, and mitochondrial membrane potential assays, mitochondrial imaging, and reactive oxygen species assays were used to measure changes in mitochondrial structure and function in human umbilical vein endothelial cells (HUVECs) exposed to PEMFs. Real-time polymerase chain reaction was used to analyze the mRNA expression levels of antioxidants, glycolytic pathway-related genes, and genes associated with mitochondrial fission and fusion. The tube formation assay demonstrated a significantly greater tube network in the PEMF group compared to the control group. The glycolysis and mitochondrial stress tests revealed that PEMFs promoted a shift in the energy metabolism pattern of HUVECs from oxidative phosphorylation to aerobic glycolysis. Mitochondrial imaging revealed a wire-like mitochondrial morphology in the control group, and treatment with PEMFs led to shorter and more granular mitochondria. Our major findings indicate that exposure to PEMFs accelerates angiogenesis in HUVECs, likely by inducing energy metabolism reprogramming and mitochondrial fission.