Changes In Mitochondrial Function Research Articles

Oxidative stress and mitochondrial function among various types of atrial fibrillation

Abstract Introduction Mitochondrial dysfunction has been shown to be associated with atrial fibrillation (AF) in previous studies. Purpose We aimed to determine mitochondrial function in various AF types and AF burden to further delineate whether mitochondrial function has graded or quantal response relationship with AF. Methods This is a cross-sectional study in patients with atrial high-rate episode (AHRE) or AF who have dual-chamber cardiovascular implantable electronic device (CIED). Patients were categorized into clinical AF and subclinical AF. AF burden was measured as AHRE via CIED interrogations. Oxidative stress and mitochondrial function were determined in peripheral blood mononuclear cells (PBMCs). Results There was a total of 54 CIED patients. Mean age was 69.9+12.8 years. There were 9 (16.7%) patients with diabetes mellitus and 36 (66.7%) patients with history of clinical AF. After adjusting with multiple linear regression for age, left ventricular ejection fraction, glomerular filtration rate, history of AF, and diabetes mellitus, we found that clinical AF, as compared to subclinical AF, was independently associated with lower non-mitochondrial respiration (20.8, 6.5-35.6 vs. 48.0, 14.0-60.9 pMol/min, p=0.021) (median, IQR); lower basal respiration (72.1, 47.4-94.4 vs.97.2, 52.1-152.6 pMol/min, p=0.020); and lower ATP production (57.3, 24.7-73.2 vs. 78.6, 45.7-112.0 pMol/min, p=0.014) (Table 1). However, AF burden was not associated with alterations in oxidative stress and mitochondrial function. Conclusions Mitochondrial function from PBMC was significantly lower in patients with clinical AF compared to those with subclinical AF. However, there was no association between AF burden and the change in mitochondrial function. The study revealed a quantal response relationship between PBMC’s mitochondrial function and AF.

RBPJ Knockdown Promotes M2 Macrophage Polarization Through Mitochondrial ROS-mediated Notch1-Jagged1-Hes1 Signaling Pathway in Uveitis.

Uveitis is an autoimmune eye disease that can be involved in the entire body and is one of the leading causes of blindness. Therefore, comprehending the mechanisms underlying the development and regulation of ocular immune responses in uveitis is crucial for designing effective therapeutic interventions. In this study, we investigated how RBPJ regulates macrophage polarization in uveitis. We demonstrated that targeted RBPJ knockdown (RBPJKD) promotes M2 macrophage polarization and ameliorates uveitis through the mtROS-mediated Notch1-Jagged1-Hes1 signaling pathway. Real-time quantitative (Q-PCR) analysis revealed that the Notch1-Jagged1-Hes1 signaling pathway was active in the eye tissues of experimental autoimmune uveitis (EAU) rats. Immunofluorescence double staining confirmed enhanced signaling primarily occurring in macrophages, establishing a correlation between the Notch1 signaling pathway and macrophages. Transmission electron microscopy evaluated the morphological and functional changes of mitochondria in each group's eye tissues. It demonstrated significant swelling and disorganization in the EAU group, which were effectively restored upon RBPJ knockdown intervention. Finally, by employing an antioxidant N-acetyl-L-cysteine (NAC) to eliminate mtROS in vivo, we observed a decrease in the M2 macrophage polarization level, which prevented the cytoprotective effect conferred by RBPJKD. These findings underscore the relevance of the Notch signaling pathway to the immune system while highlighting the potential role of mtROS as a therapeutic target for inflammation and other related diseases.

Carbon monoxide as a cellular protective agent in a swine model of cardiac arrest protocol.

Out-of-hospital cardiac arrest (OHCA) affects over 360,000 adults in the United States each year with a 50-80% mortality prior to reaching medical care. Despite aggressive supportive care and targeted temperature management (TTM), half of adults do not live to hospital discharge and nearly one-third of survivors have significant neurologic injury. The current treatment approach following cardiac arrest resuscitation consists primarily of supportive care and possible TTM. While these current treatments are commonly used, mortality remains high, and survivors often develop lasting neurologic and cardiac sequela well after resuscitation. Hence, there is a critical need for further therapeutic development of adjunctive therapies. While select therapeutics have been experimentally investigated, one promising agent that has shown benefit is CO. While CO has traditionally been thought of as a cellular poison, there is both experimental and clinical evidence that demonstrate benefit and safety in ischemia with lower doses related to improved cardiac/neurologic outcomes. While CO is well known for its poisonous effects, CO is a generated physiologically in cells through the breakdown of heme oxygenase (HO) enzymes and has potent antioxidant and anti-inflammatory activities. While CO has been studied in myocardial infarction itself, the role of CO in cardiac arrest and post-arrest care as a therapeutic is less defined. Currently, the standard of care for post-arrest patients consists primarily of supportive care and TTM. Despite current standard of care, the neurological prognosis following cardiac arrest and return of spontaneous circulation (ROSC) remains poor with patients often left with severe disability due to brain injury primarily affecting the cortex and hippocampus. Thus, investigations of novel therapies to mitigate post-arrest injury are clearly warranted. The primary objective of this proposed study is to combine our expertise in swine models of CO and cardiac arrest for future investigations on the cellular protective effects of low dose CO. We will combine our innovative multi-modal diagnostic platform to assess cerebral metabolism and changes in mitochondrial function in swine that undergo cardiac arrest with therapeutic application of CO.

Metabolic network analysis of pre-ASD newborns and 5-year-old children with autism spectrum disorder

Classical metabolomic and new metabolic network methods were used to study the developmental features of autism spectrum disorder (ASD) in newborns (n = 205) and 5-year-old children (n = 53). Eighty percent of the metabolic impact in ASD was caused by 14 shared biochemical pathways that led to decreased anti-inflammatory and antioxidant defenses, and to increased physiologic stress molecules like lactate, glycerol, cholesterol, and ceramides. CIRCOS plots and a new metabolic network parameter, V°\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\dot{{{\\boldsymbol{V}}}}\\!$$\\end{document}net, revealed differences in both the kind and degree of network connectivity. Of 50 biochemical pathways and 450 polar and lipid metabolites examined, the developmental regulation of the purine network was most changed. Purine network hub analysis revealed a 17-fold reversal in typically developing children. This purine network reversal did not occur in ASD. These results revealed previously unknown metabolic phenotypes, identified new developmental states of the metabolic correlation network, and underscored the role of mitochondrial functional changes, purine metabolism, and purinergic signaling in autism spectrum disorder.

Cellular senescence induced by down-regulation of PTBP1 correlates with exon skipping of mitochondrial related gene NDUFV3

Abstract As the most prevalent type of alternative splicing in animal cells, exon skipping plays an important role in expanding the diversity of transcriptome and proteome, thereby participating the regulation of diverse physiological and pathological processes such as development, aging and cancer. Cellular senescence serving as an anti-cancer mechanism could also contribute to individual aging. Although the dynamic changes of exon skipping during cellular senescence were revealed, its biological consequence and upstream regulator remain poorly understood. Here, by using human foreskin fibroblasts (HFF) replicative senescence as a model, we discovered that splicing factor PTBP1 was an important contributor for global exon skipping events during senescence. Down-regulated expression of PTBP1 induced senescence-associated phenotypes and related mitochondrial functional changes. Mechanistically, PTBP1 binds to the third exon of mitochondrial complex I subunit coding gene NDUFV3 and protects the exon from skipping. We further confirmed that exon skipping of NDUFV3 correlates with and partially contributes to cellular senescence and related mitochondrial functional changes upon PTBP1 knockdown. Together, we revealed for the first time that mitochondrial related gene NDUFV3 is a new downstream target for PTBP1-regulated exon skipping to mediate cellular senescence and mitochondrial functional changes.

Abstract PO3-06-08: Epithelial to Mesenchymal Transition Confers Sensitivity to Cytotoxic Agent Ophiobolin A via Alterations in Mitochondrial Function and Metabolic Pathways

Abstract Epithelial to Mesenchymal Transition Confers Sensitivity to Cytotoxic Agent Ophiobolin A via Alterations in Mitochondrial Function and Metabolic Pathways Haleigh Parker1, Kayla Haberman1, Alexander Kornienko2, Antonio Evidente3, Daniel Romo4, Benny Abraham Kaipparettu5,6, Joseph Taube1,6 1 Department of Biology, Baylor University, Waco, TX, USA 2 Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX, USA 3 Department of Chemical Sciences, University of Naples Federico II, Complesso Universitario Monte Sant’Angelo, Naples, Italy 4 Department of Chemistry and Biochemistry, Baylor University, Waco, TX, USA 5 Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA 6 Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA Background Metastatic progression in patients with triple negative breast cancer (TNBC) occurs in approximately half of all patients, reducing median overall survival. Metastasis may be facilitated through the epithelial to mesenchymal transition (EMT), which generates cancer cells with enhanced metastatic capacity and resistance to chemotherapeutics, features which are partially mediated by alterations in metabolic pathways and mitochondrial function. Here, we show a drug-like small molecule possesses EMT-specific cytotoxic activity via EMT-imparted variations in metabolic and mitochondrial functions. The fungus-derived sesterterpenoid, Ophiobolin A (OpA), possesses nanomolar cytotoxic activity and a high therapeutic index, though its target and mechanism of action remain unknown. Objectives The objectives of this study are to characterize alterations in metabolic pathways and mitochondrial function in the context of EMT, determine OpA induced alterations in specific metabolic pathways involved in metastasis and identify metabolic targets for the treatment of chemotherapeutic-resistant, metastatic triple negative breast cancer. Methods This study identifies distinct, novel metabolic alterations associated with EMT status and specific changes in mitochondrial and metabolic function associated with OpA treatment via analysis of intermediate metabolites, rates of oxidative phosphorylation and glycolysis, metabolic pathway capacity and dependency, protein expression, iron localization, reactive oxygen species accumulation and transmission electron microscopy. Results Our analysis indicates that OpA acts in a mitochondria-specific manner to cause a loss of membrane potential in EMT-positive, but not EMT-negative, cells with specific effects on complex III of the electron transport chain and oxidative phosphorylation as a whole. Furthermore, distinct shifts in glycolysis not only support previous data, but also provides insight as to mitochondrial functionality. Cells were also found to have distinct metabolic pathway capacities/dependencies and ROS and iron accumulation, depending on EMT status and OpA treatment. Finally, specific morphological alterations were uncovered via TEM image analysis. Therefore, we conclude that EMT imparts alterations in mitochondrial function and metabolic pathways, conferring sensitivity to the cytotoxic effects of OpA. Citation Format: Haleigh Parker, Kayla Haberman, Joseph Taube, Alexander Kornienko, Antonio Evidente, Daniel Romo, Benny Kaipparettu. Epithelial to Mesenchymal Transition Confers Sensitivity to Cytotoxic Agent Ophiobolin A via Alterations in Mitochondrial Function and Metabolic Pathways [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-06-08.

Beta adrenergic agonist induces a shift in mitochondria metabolism in porcine skeletal muscle

During phases of skeletal muscle growth, the metabolic processes regulating muscle tissue exhibit remarkable adaptability. This metabolic flexibility is an essential component of maintaining the health and functionality of skeletal muscle, which allows the capacity to transition between oxidative and glycolytic metabolic pathways. Within the occurrence of these metabolic shifts, the exact underlying mechanisms that orchestrate these transitions within the context of mitochondrial function remain unresolved. Therefore, our objective is to determine the role of mitochondria during a shift in metabolism, through measuring functional capacity, gene expression, and protein abundance. To investigate this shift, we utilized β-adrenergic agonists (BAA) supplementation, due to its ability to increase the proportion of fast-twitch fibers in skeletal muscle. To assess the role of the mitochondria, we utilized a mutated pig, containing a constitutively active adenosine monophosphate activated protein kinase (AMPKγ3R200Q) that contains a greater oxidative capacity in a habitually glycolytic skeletal muscle. In this current study, mature pigs (wildtype and AMPKγ3R200Q) were fed BAA (0 and 9ppm) for 1 week, then euthanized and longissimus dorsi muscle samples were collected. Mitochondria of AMPK mutated pigs had a higher ( P = 0.08) oxygen consumption rate with pyruvate/malate substrates when stimulated with ADP when compared to their wildtype (WT) counterpart. When given succinate/rotenone substrates, there was an interaction ( P = 0.04) noted for basal respiration, where WT pigs fed control diets had lower oxygen consumption compared to that of AMPK mutated pigs and those fed BAA. These data suggest that BAA has more of an effect on WT pigs than AMPK mutated pigs, possibly due to the inherent increased oxidative metabolism in mutant pigs. In addition, skeletal muscle mitochondria of AMPK mutated pigs had higher ( P = 0.04) maximal respiration compared to that of their WT counterpart. After 1 week of feeding BAA, there were no differences in mitochondrial DNA content, but there was an increase in β1-adrenergic receptor gene expression in pigs fed BAA (Diet, P = 0.06; Interaction P = 0.08). Oxidative protein abundance increased for succinate dehydrogenase ( P < 0.01) and citrate synthase ( P = 0.08) in the skeletal muscle of AMPK mutated pigs. Glycolytic proteins were increased for lactate dehydrogenase ( P < 0.05) and glyceraldehyde 3-phosphate dehydrogenase ( P < 0.01) in the muscle of WT pigs. No interactions between genotype and diet on the protein abundance level was noted. Together, these data show that mitochondria function is altered in porcine skeletal muscle when pigs are supplemented with 1 week of BAA; however, it is not detected in protein levels after 1 week. These data suggest part of the mechanism by which BAA supplementation augments muscle growth in pigs lies within the regulation of β1-adrenergic receptors and changes in mitochondrial function. 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.

Skeletal Muscle Derived Cells from Old Human Donors Show Increased Mitochondrial Lipid Peroxidation and Reduced Mitochondrial Function

Skeletal muscle undergoes atrophy with age progression resulting in decreased mitochondrial function. Similarly, age-related increases in mitochondrial oxidant generation can promote mitochondrial oxidative damage, but the relationship between increased oxidant stress and mitochondrial function is not well understood. Here, we profiled changes in mitochondrial function and mitochondrial lipid peroxidation in intact primary skeletal muscle progenitor cells (myoblasts) derived from the Rectus abdominis muscle of healthy young (19.67 ± 1.70 years) and old (67.0 ± 1.41 years) humans. Using metabolic flux assays, we found that cells derived from young humans showed higher basal and maximal oxygen consumption rates compared to cells derived from old humans (basal: 22.67 ± 6.53 vs. 10.81 ± 5.69; maximal: 41.02 ± 15.20 vs. 17.33 ± 4.84 pmol/min/protein, p < 0.001). Similarly, cells derived from young humans also showed higher ATP production and spare respiratory capacity (ATP: 18.79 ± 5.17 vs. 9.15 ± 4.91; SRC: 18.35 ± 9.62 vs. 6.52 ± 3.42 pmol/min/protein, p < 0.001). In contrast, using live-cell fluorescence microscopy, MitoTracker red and the mitochondrial-target lipid peroxide probe MitoPeDPP, we found higher mitochondrial lipid peroxidation levels in cells derived from old than young humans ( p = 0.0007). We then evaluated whether peroxiredoxin 6 (Prdx6), an enzyme that repairs lipid peroxidation through its phospholipid glutathione peroxidase and phospholipase A2 activities, impacts mitochondrial function using CRISPR/Cas9-mediated knockouts of Prdx6 in C2C12 myoblasts and extracellular flux assays. Spare respiratory capacity was lower in cells with full Prdx6-KO than in cells transfected with non-target gRNAs (NT: 295.10 ± 18.59 vs. Prdx6-KO: 242.20 ± 17.93; p = 0.05). These results show that mitochondrial function decreases with age along with increases in mitochondrial lipid peroxidation in primary muscle cells derived from old humans. Similarly, these results show that the Prdx6 supports mitochondrial function. Overall, our data contributes to our understanding of the mechanistic drivers of age-related skeletal muscle mitochondrial dysfunction. NIGMS-R35GM146951 NIA-R01AG059715. 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.

Analysis of Cellular Stress Assay Parameters and Intracellular ATP in Platelets: Comparison of Platelet Preparation Methods.

Platelets are metabolically active, anucleated and small circulating cells mainly responsible for the prevention of bleeding and maintenance of hemostasis. Previous studies showed that platelets mitochondrial content, function, and energy supply change during several diseases such as HIV/AIDS, COVID-19, pulmonary arterial hypertension, and in preeclampsia during pregnancy. These changes in platelets contributed to the severity of diseases and mortality. In our previous studies, we have shown that the seahorse-based cellular stress assay (CSA) parameters are crucial to the understanding of the mitochondrial performance in peripheral blood mononuclear cells (PBMCS). Moreover, the results of CSA parameters were significantly influenced by the PBMC preparation methods. In this study, we assessed the correlation of CSA parameters and intracellular ATP content in platelets and evaluated the effects of platelet preparation methods on the results of CSA parameters and intracellular ATP content. We compared the results of CSA parameters and intracellular ATP content in platelets isolated by density centrifugation with Optiprep and simple centrifugation of blood samples without Optiprep. Platelets isolated by centrifugation with Optiprep showed a higher spare capacity, basal respiration, and maximal respiration than those isolated without Optiprep. There was a clear correlation between basal respiration and maximal respiration, and the whole-ATP content in both isolation methods. Moreover, a positive correlation was observed between the relative spare capacity and whole-cell ATP content. In conclusion, the results of seahorse-based CSA parameters and intracellular ATP content in platelets are markedly influenced by the platelet isolation methods employed. The results of basal respiration and maximal respiration are hallmarks of cellular activity in platelets, and whole-cell ATP content is a potential hint for basic platelet viability. We recommend further studies to evaluate the role of CSA parameters and intracellular ATP content in platelets as biomarkers for the diagnosis and prediction of disease states.

Clinical and genetic analysis of essential hypertension with mitochondrial tRNAMet 4435A>G and YARS2 mutation.

To investigate the role of m.4435A>G and YARS2 c.572G>T (p.G191V) mutations in the development of essential hypertension. A hypertensive patient with m.4435A>G and YARS2 p.G191V mutations was identified from previously collected mitochondrial genome and exon sequencing data. Clinical data were collected, and a molecular genetic study was conducted in the proband and his family members. Peripheral venous blood was collected, and immortalized lymphocyte lines constructed. The mitochondrial transfer RNA (tRNA), mitochondrial protein, adenosine triphosphate (ATP), mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) in the constructed lymphocyte cell lines were measured. Mitochondrial genome sequencing showed that all maternal members carried a highly conserved m.4435A>G mutation. The m.4435A>G mutation might affect the secondary structure and folding free energy of mitochondrial tRNA and change its stability, which may influence the anticodon ring structure. Compared with the control group, the cell lines carrying m.4435A>G and YARS2 p.G191V mutations had decreased mitochondrial tRNA homeostasis, mitochondrial protein expression, ATP production and MMP levels, as well as increased ROS levels (all P<0.05). The YARS2 p.G191V mutation aggravates the changes in mitochondrial translation and mitochondrial function caused by m.4435A>G through affecting the steady-state level of mitochondrial tRNA and further leads to cell dysfunction, indicating that YARS2 p.G191V and m.4435A>G mutations have a synergistic effect in this family and jointly participate in the occurrence and development of essential hypertension.

Restoring energy metabolism by NAD+ supplement prevents alcohol‐induced liver injury and boosts liver regeneration

AbstractOur previous clinical metabolomics study illustrated that energy metabolism disorder is an underlying pathogenesis mechanism for the development of alcoholic liver disease (ALD). Supplementation of nicotinamide (NAM), the precursor of nicotinamide adenine dinucleotide (NAD+), may restore the energy metabolism homeostasis of ALD and thus serves as potential therapeutics to treat ALD. In this bedside‐to‐bench study, the protective effect of NAM against ALD was investigated by using the NIAAA mice model (chronic‐plus‐binge ethanol), and the liver regeneration boosting capability of NAM was evaluated by the partial hepatectomy mice model. Our results showed that NAM supplements not only protected the liver from alcohol‐induced injury and improved alcohol‐induced mitochondrial structure and function change, but also boosted liver regeneration in postpartial hepatectomy mice by increasing liver NAD+ content. These findings suggested that NAM, a water‐soluble form of vitamin B3, can promote liver regeneration and improves liver function by alleviating alcohol‐induced energy metabolism disorder.

A transcriptomic analysis of correlation between mitochondrial function and energy metabolism remodeling in mice with myocardial fibrosis following myocardial infarction

To investigate the changes of mitochondrial respiratory function during myocardial fibrosis in mice with myocardial infarction (MI) and its correlation with the increase of glycolytic flux. Forty C57BL/6N mice were randomized into two equal groups to receive sham operation or ligation of the left anterior descending coronary artery to induce acute MI. At 28 days after the operation, 5 mice from each group were euthanized and left ventricular tissue samples were collected for transcriptomic sequencing. FPKM method was used to calculate gene expression levels to identify the differentially expressed genes (DEGs) in MI mice, which were analyzed using GO and KEGG databases to determine the pathways affecting the disease process. Heat maps were drawn to show the differential expressions of the pathways and the related genes in the enrichment analysis. In primary cultures of neonatal mouse cardiac fibroblasts (CFs), the changes in mitochondrial respiration and glycolysis levels in response to treatment with the pro-fibrotic agonist TGF-β1 were analyzed using Seahorse experiment. The mouse models of MI showed significantly increased diastolic and systolic left ventricular diameter (P < 0.05) and decreased left ventricular ejection fraction (P < 0.0001). A total of 124 up-regulated and 106 down-regulated DEGs were identified in the myocardial tissues of MI mice, and GO and KEGG enrichment analysis showed that these DEGs were significantly enriched in fatty acid metabolism, organelles and other metabolic pathways and in the mitochondria. Heat maps revealed fatty acid beta oxidation, mitochondrial dysfunction and increased glycolysis levels in MI mice. In the primary culture of CFs, treatment with TGF-β1 significantly reduced the basal and maximum respiratory levels and increased the basal and maximum glycolysis levels (P < 0.0001). During myocardial fibrosis, energy metabolism remodeling occurs in the CFs, manifested by lowered mitochondrial function and increased energy generation through glycolysis.

Attenuating mitochondrial dysfunction and morphological disruption with PT320 delays dopamine degeneration in MitoPark mice

BackgroundMitochondria are essential organelles involved in cellular energy production. Changes in mitochondrial function can lead to dysfunction and cell death in aging and age-related disorders. Recent research suggests that mitochondrial dysfunction is closely linked to neurodegenerative diseases. Glucagon-like peptide-1 receptor (GLP-1R) agonist has gained interest as a potential treatment for Parkinson's disease (PD). However, the exact mechanisms responsible for the therapeutic effects of GLP-1R-related agonists are not yet fully understood.MethodsIn this study, we explores the effects of early treatment with PT320, a sustained release formulation of the GLP-1R agonist Exenatide, on mitochondrial functions and morphology in a progressive PD mouse model, the MitoPark (MP) mouse.ResultsOur findings demonstrate that administration of a clinically translatable dose of PT320 ameliorates the reduction in tyrosine hydroxylase expression, lowers reactive oxygen species (ROS) levels, and inhibits mitochondrial cytochrome c release during nigrostriatal dopaminergic denervation in MP mice. PT320 treatment significantly preserved mitochondrial function and morphology but did not influence the reduction in mitochondria numbers during PD progression in MP mice. Genetic analysis indicated that the cytoprotective effect of PT320 is attributed to a reduction in the expression of mitochondrial fission protein 1 (Fis1) and an increase in the expression of optic atrophy type 1 (Opa1), which is known to play a role in maintaining mitochondrial homeostasis and decreasing cytochrome c release through remodeling of the cristae.ConclusionOur findings suggest that the early administration of PT320 shows potential as a neuroprotective treatment for PD, as it can preserve mitochondrial function. Through enhancing mitochondrial health by regulating Opa1 and Fis1, PT320 presents a new neuroprotective therapy in PD.Graphical

A semi-automatic method for extracting mitochondrial cristae characteristics from 3D focused ion beam scanning electron microscopy data

Mitochondria are the main suppliers of energy for cells and their bioenergetic function is regulated by mitochondrial dynamics: the constant changes in mitochondria size, shape, and cristae morphology to secure cell homeostasis. Although changes in mitochondrial function are implicated in a wide range of diseases, our understanding is challenged by a lack of reliable ways to extract spatial features from the cristae, the detailed visualization of which requires electron microscopy (EM). Here, we present a semi-automatic method for the segmentation, 3D reconstruction, and shape analysis of mitochondria, cristae, and intracristal spaces based on 2D EM images of the murine hippocampus. We show that our method provides a more accurate characterization of mitochondrial ultrastructure in 3D than common 2D approaches and propose an operational index of mitochondria’s internal organization. With an improved consistency of 3D shape analysis and a decrease in the workload needed for large-scale analysis, we speculate that this tool will help increase our understanding of mitochondrial dynamics in health and disease.

The inhibition of MARCO by PolyG alleviates pulmonary fibrosis via regulating mitochondrial function in a silicotic rat model.

Silicon dioxide (SiO2)-induced pulmonary fibrosis is potentially associated with the impairment of mitochondrial function. Previous research found that inhibition of macrophage receptor with collagenous structure (MARCO) could alleviate particle-induced lung injury by regulating phagocytosis and mitigating mitochondrial damage. The present study aims to explore the underlying anti-fibrosis mechanism of polyguanylic acid (PolyG, MARCO inhibitor) in a silicotic rat model. Hematoxylin and eosin and Masson staining were performed to visualize lung tissue pathological changes. Confocal microscopy, transmission electron microscope, western blot analysis, quantitative real-time PCR (qPCR), andadenosine triphosphate (ATP) content assay were performed to evaluate collagen content, mitochondrial function, and morphology changes in SiO2-induced rat pulmonary fibrosis. The results suggested that SiO2 exposure contributed to reactive oxygen species aggregation and the reduction of respiratory complexes and ATP synthesis. PolyG treatment could effectively reduce MARCO expression and ameliorate lung injury and fibrosis by rectifying the imbalance of mitochondrial respiration and energy synthesis. Furthermore, PolyG could maintain mitochondrial homeostasis by promoting peroxisome proliferator-activated receptor-coactivator 1 α (PGC1α)-mediated mitochondrial biogenesis and regulating fusion and fission. Together, PolyG could ameliorate SiO2-induced pulmonary fibrosis via inhibiting MARCO to protect mitochondrial function.

Abstract 3077: Integrin expression during ovarian cancer progression

Abstract During peritoneal dissemination, ovarian cancer cells exfoliate from the primary tumor and aggregate in the peritoneal fluid. This elicits survival signals via changes in mitochondrial morphology and function. As spheroids adhere to secondary sites, mitochondrial function is restored in the form of recovery of mitochondrial morphology, increased mitochondrial membrane potential, glucose uptake and increased proliferation. These findings suggested a mitochondrial phenotypic switch from mitophagy in spheroids to upregulation of mitobiogenesis upon spheroids adhesion to secondary sites. Hence, our objective was to identify critical receptors that facilitate the adhesion of spheroids to secondary sites, focusing on integrins that facilitate cell-extracellular matrix (ECM) attachment and activate downstream signaling cascades. To investigate changes in integrin expression, we mimicked three major stages of ovarian cancer progression by developing adherent stage, spheroid stage and adherent spheroid stage using our mouse ovarian surface epithelial (MOSE) cell lines representing benign (MOSE-E) stage as well as slow-developing (MOSE-L) and fast-developing disease (MOSE-LTICv) in biologically relevant conditions. Using RT qPCR and Western blotting, we determined gene and protein expression levels of integrins and adhesion related genes. Confocal microscopy was used to determine protein localization during ovarian cancer progression. RT qPCR result indicated differential up-regulated expression of integrins in both spheroid and adherent spheroid stage, suggesting the role of different integrins during the stages of ovarian cancer progression. Specifically, we observed a decrease (integrin ɑ5, ɑ6) or increase (ɑ2𝛃;1) of integrins after aggregation and an upregulation of 𝛃;1, α2, αV, α3, α5 and immunomodulatory integrins such as αE and αM in adherent spheroids, indicating their role in mediating specific steps during progression of ovarian cancer from tumorigenesis to metastatic implantation. We also observed increased expression levels of extracellular matrix proteins and their modulators, and cell-to-cell adhesion genes during ovarian cancer progression that was more pronounced in the MOSE-LTICv cells which suggests their association with an aggressive cancer phenotype. Overall, this project will aid in the identification of adhesion targets to develop new anti-metastatic treatments that will reduce mortality in women with ovarian cancer. Citation Format: Nazia Bano, Eva M. Schmelz. Integrin expression during ovarian cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3077.

Exploring the Interplay between Mitochondrial DNA and Lifestyle Factors in the Pathogenesis of Psychiatric Disorders

The objectives of this study were to investigate the interaction of mitochondrial DNA (mtDNA) and lifestyle factors in the development of psychiatric disorders and to gain greater insight into their pathogenesis and comorbidity. We analyzed data from approximately 150,000 individuals from the UK Biobank. Mitochondrial gene-by-environment interaction studies (mtGEIS) were performed to assess the relationships between mtDNA and psychiatric disorders, such as anxiety, depression, and self-harm. These disorders were defined using diagnostic and severity indicators derived from the General Anxiety Disorder (GAD-7) and Patient Health Questionnaire (PHQ-9). Smoking and drinking behaviors were characterized based on UK Biobank criteria. For the mtGEIS, logistic and linear regression models from PLINK 2.0 were employed, accounting for covariates like age, sex, PC1-10, Townsend Deprivation Index (TDI), and educational attainment. We also conducted sex-stratified analyses to detect any gender-specific effects. Our findings highlighted significant associations between mtDNA and three psychiatric disorders. Moreover, the interplay between mtDNA and lifestyle factors showed significant associations with psychiatric disorders (all P values &lt; 0.05). Specifically, two mutant loci, T5004C (BAnx_self=−0.0026, BDep_self=−0.0024, BSelf−harm=−0.0018) and G9123A (BAnx_self=−0.0030, BDep_self=−0.0024, BSelf−harm=−0.0017), were found to reduce the risk of three disorders after interacting with alcohol. Sex-specific differences were also observed. In summary, the expression of mitochondrial genes could be modulated by lifestyle factors like smoking and drinking, potentially affecting psychiatric disorders. These habits might influence mitochondrial respiratory chain activity and the replication and transcriptional regulation of mitochondrial genes, culminating in changes in mitochondrial functionality and subsequently psychiatric disorders.

Quercetin attenuates cisplatin-induced mitochondrial apoptosis via PI3K/Akt mediated inhibition of oxidative stress in pericytes and improves the blood labyrinth barrier permeability

Cisplatin (CDDP) is broadly employed to treat different cancers, whereas there are no drugs approved by the Food and Drug Administration (FDA) for preventing its side effects, including ototoxicity. Quercetin (QU) is a widely available natural flavonoid compound with anti-tumor and antioxidant properties. The research was designed to explore the protective effects of QU on CDDP-induced ototoxicity and its underlying mechanisms in male C57BL/6 J mice and primary cultured pericytes (PCs). Hearing changes, morphological changes of stria vascularis, blood labyrinth barrier (BLB) permeability and expression of apoptotic proteins were observed in vivo by using the auditory brainstem response (ABR) test, HE staining, Evans blue staining, immunohistochemistry, western blotting, etc. Oxidative stress levels, mitochondrial function and endothelial barrier changes were observed in vitro by using DCFH-DA probe detection, flow cytometry, JC-1 probe, immunofluorescence and the establishment in vitro BLB models, etc. QU pretreatment activates the PI3K/AKT signaling pathway, inhibits CDDP-induced oxidative stress, protects mitochondrial function, and reduces mitochondrial apoptosis in PCs. However, PI3K/AKT specific inhibitor (LY294002) partially reverses the protective effects of QU. In addition, in vitro BLB models were established by coculturing PCs and endothelial cells (ECs), which suggests that QU both reduces the CDDP-induced apoptosis in PCs and improves the endothelial barrier permeability. On the whole, the research findings suggest that QU can be used as a novel treatment to reduce CDDP-induced ototoxicity.

Enhancement of Frozen-Thawed Human Sperm Quality with Zinc as a Cryoprotective Additive.

BACKGROUND Cryopreservation preserves male fertility, crucial in oncology, advanced age, and infertility. However, it damages sperm motility, membrane, and DNA. Zinc (Zn), an antioxidant, shows promise in improving sperm quality after thawing, highlighting its potential as a cryoprotectant in reproductive medicine. MATERIAL AND METHODS Gradient concentration of ZnSO₄ (0, 12.5, 25, 50, and 100 &micro;M) was added in the Glycerol-egg yolk-citrate (GEYC) cryopreservative medium as an extender. Alterations in sperm viability and motility parameters after cryopreservation were detected in each group. Sperm plasma membrane integrity (PMI), acrosome integrity (ACR), DNA fragment index (DFI), and changes in sperm mitochondrial function were examined, including: mitochondrial potential (MMP), sperm reactive oxygen species (ROS), and sperm ATP. RESULTS We found that 50 &micro;M ZnSO₄ was the most effective for the curvilinear velocity (VCL) and the average path velocity (VAP) of sperm after cryo-resuscitation. Compared to the Zn-free group, sperm plasma membrane integrity (PMI) was increased, DNA fragmentation index (DFI) was decreased, reactive oxygen species (ROS) was reduced, and mitochondrial membrane potential (MMP) was increased after cryorevival in the presence of 50 &micro;M ZnSO₄. CONCLUSIONS Zn ion is one of the antioxidants in the cell. The results of our current clinical study are sufficient to demonstrate that Zn can improve preserves sperm quality during cryopreservation when added to GEYC. The addition of 50 &micro;M ZnSO₄ increased curve velocity, mean path velocity, sperm survival (or plasma membrane integrity), and mitochondrial membrane potential while reducing ROS production and DNA breaks compared to GEYC thawed without ZnSO₄.

Abstract B111: Mechanism-informed photochemical strategies to overcome fluid shear stress-induced platinum resistance in ovarian cancer

Abstract Background: Over 75% of patients with disseminated ovarian cancer develop resistance to platinum-based chemotherapies (carboplatin or cisplatin). Patients with a high volume of malignant ascites or excessive fluid buildup in the peritoneum are more likely to present with primary platinum-resistant disease. It is hypothesized that the physical forces generated by ascites may contribute to the dissemination and progression of ovarian cancer. Our research group has shown that fluid shear stress (FSS) induces carboplatin resistance and a motile and aggressive phenotype in monolayer cultures and 3D models for adherent ovarian cancer. In this study, the effects of FSS on treatment response to cisplatin and doxorubicin were examined. The latter is used to manage recurrent platinum-resistant disease. Changes in mitochondrial function under FSS as they relate to platinum resistance were also characterized. Finally, the use of photodynamic therapy (PDT), which utilizes 690 nm light and a clinical photosensitizer benzoporphyrin derivative (BPD) to locally generate cytotoxic reactive molecular species as a means of overcoming FSS-induced platinum resistance, was explored. Methods: Human epithelial ovarian adenocarcinoma cells OVCAR-3 and Caov-3 (ATCC) were cultured in tissue culture plates (static culture) or chamber slides (ibidi) connected to a perfusion pump for 48 h (flow rate: 0.11 mL/min, shear stress: 0.41 dyn/cm2). Cells in static and flow cultures were exposed to cisplatin, doxorubicin, BPD-PDT or combinations thereof and survival fractions were measured 72 h post-treatment. Mitochondrial membrane potential was measured using JC-1 fluorescence assay, and mitochondrial DNA (mtDNA) copy number was quantified using qPCR. ATP content per cell was measured with a CellTiterGlo luminescence assay. Results: OVCAR-3 and Caov-3 cells grown under FSS developed significant resistance to cisplatin. Specifically, 3.13 µM cisplatin induced a 50% decrease in the survival fraction in OVCAR-3 static cultures but failed to decrease the survival fraction under flow. In contrast to these findings with platins, no resistance to doxorubicin was observed under flow. Evaluation of the mitochondrial function revealed increased ATP content and mtDNA copy number in flow cultures, suggesting that increased mitochondrial activity may contribute to platinum resistance. Finally, low-dose BPD-PDT (IC10, 0.15 J/cm2) enhanced the efficacy of cisplatin in OVCAR-3 cells under flow, indicating that PDT is a viable strategy to sensitize tumors exposed to FSS to platinum-based chemotherapy. Conclusions: Our data suggest that ovarian cancer cells that acquired resistance to platinum due to FSS remain sensitive to doxorubicin. Changes in mitochondrial function, including increased ATP content per cell and mtDNA copy number, have been identified as potential contributing factors to platinum resistance under FSS. Finally, low-dose BPD-PDT can be used to re-sensitize cells to cisplatin and overcome platinum resistance. Citation Format: Marta Overchuk, Brittany P. Rickard, Justin Tulino, Frances S. Ligler, Imran Rizvi. Mechanism-informed photochemical strategies to overcome fluid shear stress-induced platinum resistance in ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr B111.