Succinate Dehydrogenase Research Articles

Potential effect of fruit and flower extracts of Arbutus unedo L. on Tetrahymena pyriformis exposed to a cobalt-60 source

Exposure of Tetrahymena pyriformis cultures to cobalt-60 for 72 h significantly impacted the cells' growth, appearance, and physiology. This study aims to investigate the protective effects of Arbutus unedo L flowers and fruit extracts on T. pyriformis against gamma radiation. Initially, aqueous and 50% ethanolic extracts of the fruits and flowers were prepared, and their cytotoxicity on the ciliate was evaluated. The irradiated ciliate's cellular viability and morphological aspect improved when a non-toxic concentration of 25 µg/mL was added to the growth medium. The addition of extracts restored glyceraldehyde-3-phosphate dehydrogenase and succinate dehydrogenase activities to their initial levels, similar to non-irradiated cells. In addition, the extracts reduced oxidative stress markers, such as lipid peroxidation, and decreased the activities of antioxidant defence enzymes, catalase, and superoxide dismutase. This may be attributed to the antioxidant properties of the extracts. Results of this study revealed that the flower extracts exhibited better protective effects than the fruit extracts, with superior antioxidant activity in the in-vitro DPPH scavenging assay. These results suggest that A. unedo flower extracts may have potential as exogenous radioprotective agents.

Inhibition of Skin Cancer using Human Epidermal Keratinocytes (HaCaT) Cells from Siam Weeds (Chromolaena odorata L.)

Cancer can usually develop due to exposure to sunlight. UV radiation from sunlight is known to damage DNA and is bad for the skin. Skin P stem cell carcinogenesis is caused by UV-A rays that penetrate deep into the dermis layer. UV-B damages cell DNA by being absorbed by proteins in the epidermis. Chromolaena odorata was extracted using methanol solvent, then partitioned into 5 solutions in the form of n-Hexane, Ethyl Acetate, Acetonitrate, n-Buthanol, and Ethanol. The five extracts obtained were tested with Human Epidermal Keratinocyte cells using the bioassay method. Results obtained from the microplate reader after incubation. Each extract was divided into three concentrations, it is 100, 50, 20(µg/mL). Then in the positive control (Etoposide), it was divided into four concentrations, 100, 50, 20, 10(µg/mL). After being analyzed with the results of the microplate reader, the IC50 of Chromolaena odorata was 48% in the ethyl acetate extract with a concentration of 100µg/mL. HaCaT cell proliferation was determined at indicated intervals using the MTT colorimetric assay. This assay was based on the ability of live cell succinate dehydrogenase to reduce the yellow salt MTT (3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide)) (Sigma-Aldrich, St. Louis, MO, USA) to insoluble purple-blue formazan precipitate. Experiments were carried out on 96-well plates containing a final volume of 100µl of medium/well.

Metabolic Reprogramming: A Byproduct or a Driver of Cardiomyocyte Proliferation?

Defining mechanisms of cardiomyocyte proliferation should guide the understanding of endogenous cardiac regeneration and could lead to novel treatments for diseases such as myocardial infarction. In the neonatal heart, energy metabolic reprogramming (phenotypic alteration of glucose, fatty acid, and amino acid metabolism) parallels cell cycle arrest of cardiomyocytes. The metabolic reprogramming occurring shortly after birth is associated with alterations in blood oxygen levels, metabolic substrate availability, hemodynamic stress, and hormone release. In the adult heart, myocardial infarction causes metabolic reprogramming but these changes cannot stimulate sufficient cardiomyocyte proliferation to replace those lost by the ischemic injury. Some putative pro-proliferative interventions can induce the metabolic reprogramming. Recent data show that altering the metabolic enzymes PKM2 [pyruvate kinase 2], LDHA [lactate dehydrogenase A], PDK4 [pyruvate dehydrogenase kinase 4], SDH [succinate dehydrogenase], CPT1b [carnitine palmitoyl transferase 1b], or HMGCS2 [3-hydroxy-3-methylglutaryl-CoA synthase 2] is sufficient to partially reverse metabolic reprogramming and promotes adult cardiomyocyte proliferation. How metabolic reprogramming regulates cardiomyocyte proliferation is not clearly defined. The possible mechanisms involve biosynthetic pathways from the glycolysis shunts and the epigenetic regulation induced by metabolic intermediates. Metabolic manipulation could represent a new approach to stimulate cardiac regeneration; however, the efficacy of these manipulations requires optimization, and novel molecular targets need to be defined. In this review, we summarize the features, triggers, and molecular regulatory networks responsible for metabolic reprogramming and discuss the current understanding of metabolic reprogramming as a critical determinant of cardiomyocyte proliferation.

Exposure to 6-PPD quinone causes damage on mitochondrial complex I/II associated with lifespan reduction in Caenorhabditis elegans

N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine quinone (6-PPDQ) is an emerging pollutant transformed from 6-PPD. However, the effect of 6-PPDQ exposure on mitochondrion and underlying mechanism remains largely unclear. Using Caenorhabditis elegans as animal model, exposed to 6-PPDQ at 0.1–10 μg/L was performed form L1 larvae to adult day-1. Exposure to 6-PPDQ (1 and 10 μg/L) could increase oxygen consumption rate and decease adenosine 5′-triphosphate (ATP) content, suggesting induction of mitochondrial dysfunction. Activities of NADH dehydrogenase (complex I) and succinate dehydrogenase (complex II) were inhibited, accompanied by a decrease in expressions of gas-1, nuo-1, and mev-1. RNAi of gas-1 and mev-1 enhanced mitochondrial dysfunction and reduced lifespan of 6-PPDQ exposed nematodes. GAS-1 and MEV-1 functioned in parallel to regulate 6-PPDQ toxicity to reduce the lifespan. Insulin peptides and the insulin signaling pathway acted downstream of GAS-1 and MEV-1 to control the 6-PPDQ toxicity on longevity. Moreover, RNAi of sod-2 and sod-3, targeted genes of daf-16, caused susceptibility to 6-PPDQ toxicity in reducing lifespan and in causing reactive oxygen species (ROS) production. Therefore, 6-PPDQ at environmentally relevant concentrations (ERCs) potentially caused mitochondrial dysfunction by affecting mitochondrial complexes I and II, which was associated with lifespan reduction by affecting insulin signaling in organisms.

Clinicopathological Profile of Muscle Diseases Presenting the Adult Population in Northern India: Preliminary Analysis in a Limited Resource Setting.

Muscle diseases are of various types, viz., muscular dystrophies, inflammatory myopathies, myotonic disorders, congenital myopathies, and metabolic myopathies. They all present with muscle weakness, be it proximal or distal. The assessment of muscle biopsy with the help of enzyme histochemistry, histopathological, and immunohistochemical methods is an essential component in the diagnosis of neuromuscular disorders. The authors outline brief data on muscle diseases prevalent in the North Indian region. Muscle biopsy was done, and the biopsy was freshly frozen in liquid nitrogen and sections were taken on a cryostat. Slides were then stained with hematoxylin and eosin (H&E), modified Gomori trichome (MGT), nicotinamide adenine dinucleotide hydrogenase (NADH), and succinic dehydrogenase (SDH) stains. Further specific immunohistochemistry tests were also done. Out of n=16 cases, three cases were diagnosed as Becker's muscular dystrophy, two cases were diagnosed as inflammatory myopathy, four cases were diagnosed as Facioscapulohumeral muscular dystrophy, and one each case of dysferlinopathy and alpha sarcoglycanopathy. Muscle diseases can cause different levels of physical disability and thus it is important to diagnose at the appropriate time to ensure proper treatment.

Functional Characterization of a Spectrum of Genetic Variants in a Family with Succinic Semialdehyde Dehydrogenase Deficiency.

Succinic semialdehyde dehydrogenase (SSADH) is a mitochondrial enzyme involved in the catabolism of the neurotransmitter γ-amino butyric acid. Pathogenic variants in the gene encoding this enzyme cause SSADH deficiency, a developmental disease that manifests as hypotonia, autism, and epilepsy. SSADH deficiency patients usually have family-specific gene variants. Here, we describe a family exhibiting four different SSADH variants: Val90Ala, Cys93Phe, and His180Tyr/Asn255Asp (a double variant). We provide a structural and functional characterization of these variants and show that Cys93Phe and Asn255Asp are pathogenic variants that affect the stability of the SSADH protein. Due to the impairment of the cofactor NAD+ binding, these variants show a highly reduced enzyme activity. However, Val90Ala and His180Tyr exhibit normal activity and expression. The His180Tyr/Asn255Asp variant exhibits a highly reduced activity as a recombinant species, is inactive, and shows a very low expression in eukaryotic cells. A treatment with substances that support protein folding by either increasing chaperone protein expression or by chemical means did not increase the expression of the pathogenic variants of the SSADH deficiency patient. However, stabilization of the folding of pathogenic SSADH variants by other substances may provide a treatment option for this disease.

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

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

Design, Synthesis, Antifungal Activity, and Action Mechanism of Pyrazole-4-carboxamide Derivatives Containing Oxime Ether Active Fragment As Succinate Dehydrogenase Inhibitors.

The dearomatization at the hydrophobic tail of the boscalid was carried out to construct a series of novel pyrazole-4-carboxamide derivatives containing an oxime ether fragment. By using fungicide-likeness analyses and virtual screening, 24 target compounds with theoretical strong inhibitory effects against fungal succinate dehydrogenase (SDH) were designed and synthesized. Antifungal bioassays showed that the target compound E1 could selectively inhibit the in vitro growth of R. solani, with the EC50 value of 1.1 μg/mL that was superior to that of the agricultural fungicide boscalid (2.2 μg/mL). The observations by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that E1 could reduce mycelial density and significantly increase the mitochondrial number in mycelia cytoplasm, which was similar to the phenomenon treated with boscalid. Enzyme activity assay showed that the E1 had the significant inhibitory effect against the SDH from R. solani, with the IC50 value of 3.3 μM that was superior to that of boscalid (7.9 μM). The mode of action of the target compound E1 with SDH was further analyzed by molecular docking and molecular dynamics simulation studies. Among them, the number of hydrogen bonds was significantly more in the SDH-E1 complex than that in the SDH-boscalid complex. This research on the dearomatization strategy of the benzene ring for constructing pyrazole-4-carboxamides containing an oxime ether fragment provides a unique thought to design new antifungal drugs targeting SDH.

Acetate Alleviates Gut Microbiota Depletion-Induced Retardation of Skeletal Muscle Growth and Development in Young Mice.

The normal growth and development of skeletal muscle is essential for the health of the body. The regulation of skeletal muscle by intestinal microorganisms and their metabolites has been continuously demonstrated. Acetate is the predominant short-chain fatty acids synthesized by gut microbiota through the fermentation of dietary fiber; however, the underlying molecular mechanisms governing the interaction between acetate and skeletal muscle during the rapid growth stage remains to be further elucidated. Herein, specific pathogen-free (SPF) mice, germ-free (GF) mice, and germ-free mice supplemented with sodium acetate (GS) were used to evaluate the effects of acetate on the skeletal muscle growth and development of young mice with gut microbiota deficiency. We found that the concentration of serum acetate, body mass gain, succinate dehydrogenase activity, and expression of the myogenesis maker gene of skeletal muscle in the GS group were higher than those in the GF group, following sodium acetate supplementation. Furthermore, the transcriptome analysis revealed that acetate activated the biological processes that regulate skeletal muscle growth and development in the GF group, which are otherwise inhibited due to a gut microbiota deficiency. The in vitro experiment showed that acetate up-regulated Gm16062 to promote skeletal muscle cell differentiation. Overall, our findings proved that acetate promotes skeletal muscle growth and development in young mice via increasing Gm16062 expression.

Unveiling the molecular basis of paracetamol-induced hepatotoxicity: Interaction of N-acetyl-p-benzoquinone imine with mitochondrial succinate dehydrogenase

Background and aimN-acetyl-p-benzoquinoneimine (NAPQI), a toxic byproduct of paracetamol (Acetaminophen, APAP), can accumulate and cause liver damage by depleting glutathione and forming protein adducts in the mitochondria. These adducts disrupt the respiratory chain, increasing superoxide production and reducing ATP. The goal of this study was to provide computational proof that succinate dehydrogenase (SDH), a subunit of complex II in the mitochondrial respiratory chain, is a favorable binding partner for NAPQI in this regard. MethodMolecular docking, molecular dynamics simulation, protein-protein interaction networks (PPI), and KEGG metabolic pathway analysis were employed to identify binding characteristics, interaction partners, and their associations with metabolic pathways. A lipid membrane was added to the experimental apparatus to mimic the natural cellular environment of SDH. This modification made it possible to develop a context for investigating the role and interactions of SDH within a cellular ecosystem that was more realistic and biologically relevant. ResultThe molecular binding affinity score for APAP and NAPQI with SDH was predicted −6.5 and −6.7 kcal/mol, respectively. Furthermore, RMSD, RMSF, and Rog from the molecular dynamics simulations study revealed that NAPQI has slightly higher stability and compactness compared to APAP at 100 ns timeframe with mitochondrial SDH. ConclusionThis study serves to predict the mechanistic process of paracetamol toxicity by using different computational approaches. In addition, this study will provide information about the drug target against APAP hepatotoxicity.

STUDY OF THE INHIBITORY EFFECTS OF VITAMIN E DERIVATIVES ON MITOCHONDRIAL COMPLEX II SUBUNIT USING MOLECULAR DOCKING

Objective: The goal of this study was to create vitamin E derivatives and explore their potential anticancer properties using a computational approach. Methods: The Steglich method was used for the synthesis of the vitamin E-fatty acid (pentanoic acid, heptanoic acid, and octanoic acid) derivatives, with N,N'-dicyclohexylcarbodiimide (DCC) and 4-dimethylaminopyridine (DMAP) as the catalysts. The structure of the synthesized products was determined by ultraviolet-visible (UV-Vis) spectroscopy, fourier transform infrared (FTIR) spectroscopy, and liquid chromatography-mass spectrometry (LC-MS). Molecular docking was carried out on the succinate dehydrogenase (SDH) enzyme using AutoDockTools. Results: α–Tocopherol pentanoate (α–TP), α–tocopherol heptanoate (α–TH), and α–tocopherol octanoate (α–TO) were the three vitamin E derivatives synthesized in this study. Based on the results of molecular docking, the novel compounds (α–TP, α–TH, and α–TO) generated bond energies of-10.57,-9.61, and-9.20 kcal/mol, respectively. Conclusion: All newly synthesized compounds exhibited lower binding affinity values than α–tocopherol (α–T). This confirms that these compounds might not provide greater advantages than α-tocopherol in terms of inhibitory effects on mitochondrial complex II (CII).

Geldanamycin confers fungicidal properties to azole by triggering the activation of succinate dehydrogenase

AimsAzoles have been widely employed for the treatment of invasive fungal diseases; however, their efficacy is diminished as pathogenic fungi tolerate them due to their fungistatic properties. Geldanamycin (GdA) can render azoles fungicidal by inhibiting the ATPase and molecular chaperone activities of heat shock protein 90 (Hsp90). Nonetheless, the clinical applicability of GdA is restricted due to its cytotoxic ansamycin scaffold structure, its induction of cytoprotective heat shock responses, and the conservative nature of Hsp90. Hence, it is imperative to elucidate the mechanism of action of GdA to confer fungicidal properties to azoles and mitigate the toxic adverse effects associated with GdA. Materials and methodsThrough various experimental methods, including the construction of gene-deleted Candida albicans mutants, in vitro drug sensitivity experiments, Western blot analysis, reactive oxygen species (ROS) assays, and succinate dehydrogenase activity assays, we identified Hsp90 client proteins associated with the tolerance of C. albicans to azoles. Key findingsIt was observed that GdA effectively hindered the entry of Hsp90 into mitochondria, resulting in the alleviation of inhibitory effect of Hsp90 on succinate dehydrogenase. Consequently, the activation of succinate dehydrogenase led to an increased production of ROS. within the mitochondria, thereby facilitating the antifungal effects of azoles against C. albicans. SignificanceThis research presents a novel approach for conferring fungicidal properties to azoles, which involves specifically disrupting the interaction of between Hsp90 and succinate dehydrogenase rather than employing a non-specific inhibition of ATPase activity of Hsp90.

125 Effects of Saccharmyces yeast postbiotics on nursey pig muscle fiber cross-sectional area and oxidative capacity

Abstract This study aimed to determine effects of dietary supplementation of Saccharomyces yeast postbiotics (celluTEIN, Puretein Bioscience, LLC, Minneapolis, MN) on nursery pig muscle fiber cross-sectional area (CSA), isoform, and succinate dehydrogenase (SDH) staining intensity. Newly weaned pigs [n = 32; 16 barrows and 16 gilts; 21 d of age, body weight (BW) 6.05 ± 0.24 kg] were stratified by BW within sex, placed in individual pens, and randomly assigned to one of two dietary treatments within each two-pig strata. Dietary treatments included pigs supplemented 0 (CON; n = 16) or 175 g/ton (CT; n = 16) of celluTEIN to their standard three-phase nursery ration. Pigs were harvested at d 35 of feeding and the longissimus lumborum muscle was collected for mean SDH staining intensity and immunohistochemistry analyses. Data were analyzed as a completely randomized design with pig as the experimental unit and treatment as the fixed effect. Statistical significance was determined at P ≤ 0.05. There were no treatment effects on type I and type IIB muscle fiber CSA (P > 0.14), but CT pigs had greater type IIA and type IIX muscle fiber CSA compared with CON (P < 0.05). When not analyzed by fiber isoform, pigs fed CT had a greater (P = 0.02) average muscle fiber CSA than CON pigs. There were no treatment effects on muscle fiber type percentage or SDH intensity of all fiber types (P ≥ 0.23); however, when calculated as a muscle fiber CSA ratio, CT type IIA fibers had a smaller ratio (darker staining/µm2) than CON type IIA fibers (P = 0.05). There were no treatment effects for type I, IIX, and IIB ratios (P > 0.21). In conclusion, supplementing Saccharomyces yeast postbiotics during the nursery period increased muscle fiber hypertrophy and type IIA fiber oxidative capacity.

Inhibitory Activities of Five Fungicides on Alternaria suffruticosae and Their Field Control Efficacy Against Tree Peony Black Spot.

Tree peony black spot (TPBS), mainly caused by Alternaria suffruticosae, is a common leaf disease on the ornamental peony, which poses a great threat to the flower buds in the current year and the flowering quality in the next year. However, there is only one fungicide registered for the control of this disease, difenoconazole. In order to avoid the severe problem of pathogen resistance caused by long-term use of difenoconazole, it is necessary to screen more chemical fungicides for the prevention and control of TPBS. In this study, the biological activities of flutolanil, phenamacril, pyraclostrobin, and boscalid on mycelial growth, conidial germination, germ tube elongation, and sporulation quantity of A. suffruticosae were determined, and the field control efficacy was tested to evaluate the preventive and therapeutic activities. Difenoconazole was used as a control simultaneously. The results showed that pyraclostrobin had the strongest inhibitory effects on the conidial germination, mycelium growth, germ tube elongation, and sporulation quantity, with the average EC50 values of 0.0517, 0.5343, 0.0008, and 0.8068 μg/ml, respectively. The inhibitory activity of flutolanil on the four developmental stages of A. suffruticosae was weaker than that of the other three fungicides. Compared with flutolanil, boscalid, the other succinate dehydrogenase inhibitor, had more strong inhibitory effects on the mycelial growth and sporulation quantity, with the average EC50 values of 3.8603 and 1.4760 μg/ml, respectively. Phenamacril had a moderate inhibitory level and had more inhibitory activity on conidial germination and germ tube elongation, with the average EC50 values of 31.5349 and 5.2597 μg/ml, respectively. All of the four fungicides had no significant effects on the shape of spores and germ tubes. The control fungicide difenoconazole had the strongest inhibitory activity on mycelial growth, and the average EC50 value was only 0.3297 μg/ml. However, its inhibitory activity on the other three growth stages was not high. In the field trials, pyraclostrobin had high control efficacy on TPBS even at low concentrations, reaching a minimum of 62.6293%, which was higher than that of difenoconazole. The other three fungicides had higher control efficacy at high concentrations but decreased significantly at low concentrations. Considering the dosage and control efficacy, pyraclostrobin was the first choice for the control of TPBS. Pyraclostrobin is the preferred alternative fungicide to difenoconazole for the prevention and control of TPBS in production.

Knockdown of the SDHB Subunit Induces Mitochondrial Remodeling in Human Airway Smooth Muscle Cells

Succinate dehydrogenase (SDH) is a mitochondrial enzyme that serves a dual role in mitochondrial respiration: catalyzing the oxidation of succinate to fumarate in the tricarboxylic acid (TCA) cycle and transferring electrons from succinate to ubiquinone as complex II in the electron transport chain (ETC). SDH is composed of four subunits (SDHA-SDHD) and the loss of SDHB subunit, specifically, has been shown to increase oxidative stress. As a part of the catalytic core of the SDH complex, the SDHB subunit mediates electron transfer to ubiquinone. In human airway smooth muscle (hASM) cells with siRNA-mediated knockdown of SDHB, the maximum velocity of the SDH reaction (SDHmax) is decreased. Moreover, SDHB-knockdown leads to an increase in mitochondrial volume density, indicating a role of SDH in mitochondrial remodeling. However, the impact of SDHB-knockdown on mitochondrial dynamics has not been explored. Therefore, we hypothesize that SDHB-knockdown promotes mitochondrial fragmentation as part of mitochondrial remodeling in hASM cells. To investigate this hypothesis, bronchiolar tissue samples were collected in female and male patients undergoing lung surgery with no current history of smoking or respiratory diseases, the smooth muscle layer was dissected and hASM cells were dissociated. The targeted knockdown of SDHB was achieved by siRNA-mediated knockdown. Mitochondria in hASM cells were labeled with MitoTracker Green (200 nM) and imaged in 3D with a Z optical slice of 0.5 μm using an oil-immersion ×60/1.4 NA objective on a Nikon Eclipse A1 laser scanning confocal system. Optical slices were deconvolved to enhance contrast and the MitoTracker labeling was thresholded to create binary images, which were then reconstructed in 3D. From these images, the mitochondrial complexity index (MCI) was calculated to quantify the extent of fragmentation. To identify the signaling pathway involved in mitochondrial fragmentation, the expression and phosphorylation of dynamin-related protein 1 (DRP1) was quantified by Western blot. Mitochondrial fragmentation is associated with increased phosphorylation of DRP1 at Ser616 (pDRP1s616). Furthermore, mitophagy was assessed by determining the mitochondrial expression of PINK1 and the phosphorylation of Parkin at Ser65 (pParkinS65). Mitochondrial biogenesis was also evaluated through the expression of PGC1α, NRF1/2 and TFAM. Our results show that SDHB-knockdown increased mitochondrial fragmentation (reduced MCI) in hASM cells, and increased pDRP1s616 phosphorylation and its translocation to mitochondria. SDHB-knockdown also increased mitochondrial expression of PINK1 and pParkins65 phosphorylation indicating activation of mitophagy. We also confirmed that SDHB-knockdown increased expression of PGC1α, NRF1/2 and TFAM consistent with mitochondrial biogenesis. These findings unveil the mechanisms underlying SDHB-knockdown-mediated mitochondrial remodeling. Supported by NIH grant R01-HL157984 (GCS). 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.

Punicalagin prevents obesity-related cardiac dysfunction through promoting DNA demethylation in mice

The aim of this study was to investigate whether punicalagin (PU) could prevent obesity-related cardiac dysfunction by promoting DNA demethylation, and to explore its possible mechanism. C57BL/6J mice were fed with standard diet, high-fat diet (HFD), HFD supplemented with resveratrol, low-dose PU (LPU) and high-dose PU (HPU) for 8 weeks. Compared with HFD group, body weight was significantly lower in PU treatment groups, number of cardiomyocytes and the protein level of myosin heavy chain 7B were significantly higher in PU treatment groups. Levels of 5-hydroxymethylcytosine and 5-formylcytosine were significantly lower in HFD group than in other groups. Compared with the HFD group, the protein level of ten-eleven translocation enzyme (TET) 2 was significantly higher in PU treatment groups, p-AMP-activated protein kinase (AMPK) was significantly higher in LPU group. Levels of total antioxidant capacity and the protein levels of complexes II/III/V, oxoglutarate dehydrogenase, succinate dehydrogenase B and fumarate hydrolase were significantly lower in HFD group than PU treatment group. The ratio of (succinic acid + fumaric acid)/α-ketoglutarate was significantly higher in HFD group than other groups. In conclusion, PU up-regulated TETs enzyme activities and TET2 protein stability through alleviating mitochondrial dysfunction and activating AMPK, so as to promote DNA demethylation, thus preventing obesity-related cardiac dysfunction.

Antifungal mechanisms of binary combinations of volatile organic compounds produced by lactic acid bacteria strains against Aspergillusflavus

Aspergillus flavus（A. flavus）, a common humic fungus known for its ability to infect agricultural products, served as the subject of investigation in this study. The primary objective was to assess the antifungal efficacy and underlying mechanisms of binary combinations of five volatile organic compounds (VOCs) produced by lactic acid bacteria, specifically in their inhibition of A. flavus. This assessment was conducted through a comprehensive analysis, involving biochemical characterization and transcriptomic scrutiny. The results showed that VOCs induce notable morphological abnormalities in A. flavus conidia and hyphae. Furthermore, they disrupt the integrity of the fungal cell membrane and cell wall, resulting in the leakage of intracellular contents and an increase in extracellular electrical conductivity. In terms of cellular components, VOC exposure led to an elevation in malondialdehyde content while concurrently inhibiting the levels of total lipids, ergosterol, soluble proteins, and reducing sugars. Additionally, the impact of VOCs on A. flavus energy metabolism was evident, with significant inhibition observed in the activities of key enzymes, such as Na+/K+-ATPase, malate dehydrogenase, succinate dehydrogenase, and chitinase. And they were able to inhibit aflatoxin B1 synthesis. The transcriptomic analysis offered further insights, highlighting that differentially expressed genes (DEGs) were predominantly associated with membrane functionality and enriched in pathways about carbohydrate and amino acid metabolism. Notably, DEGs linked to cellular components and energy-related mechanisms exhibited down-regulation, thereby corroborating the findings from the biochemical analyses. In summary, these results elucidate the principal antifungal mechanisms of VOCs, which encompass the disruption of cell membrane integrity and interference with carbohydrate and amino acid metabolism in A. flavus.

The Enhanced Anti-anxiety Potentiality and Relevant Material Basis for the Extracts of Bile Processed Coptidis Rhizoma

Objective Bile-processed Coptidis Rhizoma (CR) exhibits stronger cold properties and central effect. However, the commonly used bile includes pig/cattle/sheep bile. It is currently unclear which kind of bile performs the best synergistic effect, and the enhanced efficacy is mainly contributed by what components. In this work, a comparative study on pig/cattle/sheep bile processed CR (pCR/cCR/sCR) was carried out. Materials and Methods Firstly, the anxiety model of sthenic heat type was established. Then, pharmacological research involving general state observation, biochemical examination (succinate dehydrogenase, glucokinase, corticosterone, adrenocor ticotropic hormore), pathological evaluation (liver and hippocampus tissue), and behavioral tests (elevated plus maze, open field test) was implemented. Finally, chemical assessment involving high-performance liquid chromatography (HPLC) fingerprints of pCR/cCR/sCR extracts and mass spectrograms of pig/cattle/sheep bile were performed in combination. Results cCR performed the most prominent enhancement in improving hyperactive energy metabolism in liver and abnormal hyperactivity of hypothalamic–pituitary–adrenal axis axis. As for chemical assessment, HPLC fingerprints of pCR/cCR/sCR extracts indicated that alkaloid components detected in cCR extracts were relatively low, mass spectrograms of pig/cattle/sheep bile suggested that bile acids in cattle bile were relatively abundant, and the contents of taurocholic acid, glycocholic acid, and glycodeoxycholic acid were particularly high. Conclusion Cattle bile could be specified as the processing excipient for bile-processed CR, and the high levels of taurocholic acid, glycocholic acid, and glycodeoxycholic acid mainly contributed to the enhanced efficacy of cCR.

Mitochondrial DNA control of gene expression and cell function in HeLa cybrids of HeLa ρ0 cells with transferred mtDNA of A549 cells

Asthma is a disease characterized by airway inflammation and hyperreactivity. Mitochondria have their own DNA (mtDNA) that encodes essential components of Electron Transport Chain complexes and is inherited exclusively maternally. Variants in mtDNA (haplogroups) are linked to risks and severity of other diseases but have not been studied in asthma. We hypothesized that mitochondrial genome can regulate expression of nDNA genes important in asthma pathophysiology. Haplogroup H mtDNA from A549 lung epithelial cells was transferred to mtDNA-deleted HeLa cells (ρ0) to create HeLa[H] cybrids that have identical nuclei but varied mitochondrial genome as compared to HeLa cells with haplogroup L mtDNA. Cells were analyzed for mtDNA copy number by quantitative polymerase chain reaction (qPCR), energy metabolism by monitoring the cellular respiration and glycolysis using Seahorse analyzer, and mtDNA sequencing for haplogroup. Single-cell RNA sequencing technology, SeqGeq bioinformatics program, and western blot were used to analyze differential gene expression and involved pathways among these cells. ρ0 cells have mtDNA copy number <1, while cybrids have mtDNA copy number similar to A549 cells and different from HeLa cells {mtDNA copy number (mean±SD), HeLa 636±115, ρ0 0.13±0.08, cybrid 1956±354, A549 1738±504, n≥2 replicate experiments, ANOVA p<0.001}. ρ0 have no mitochondrial oxygen consumption and maintain energy generation by increased glycolysis, whereas cybrids have similar oxygen consumption and glycolytic rates to HeLa and A549 {mitochondrial basal oxygen consumption pmole/min/mg protein (mean±SD), HeLa 7.78±0.43, ρ0 0.51±0.56, cybrid 6.76±2.34, A549 4.86±0.41, n≥3, ANOVA p<0.001; glycolysis mpH/min/mg protein (mean±SD), HeLa 0.91±0.08, ρ0 1.96±0.16, cybrid 0.52±0.14, A549 0.72±0.48, n≥3, ANOVA p<0.001}. Compared to HeLa, ρ0 cells lack expression of all 13 mtDNA-encoded proteins and have changes in nuclear-encoded DNA (nDNA) gene expression (4,047 nDNA up, and 5,552 nDNA down). Switching from L to H haplogroup results in greater changes in gene expression (9,320 nDNA up, 4,376 nDNA down, 9 mtDNA up, and 4 mtDNA down). Compared to HeLa, cybrids have greater expression of genes important in bioenergetics and asthma, i.e., TCA pathway genes (aconitase, isocitrate dehydrogenase, oxoglutarate dehydrogenase, succinate dehydrogenase), cytokines, and inducible NO synthase (iNOS) pathway genes. Overall, these studies suggest that mitochondria are not only important for energy generation but relevant to cell signaling, inflammation, and metabolism in asthma. This work is supported by the National Heart, Lung, and Blood Institute HL081064, HL103453. 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.

Interleukin-6/Glycoprotein130 Signaling Inhibition Ameliorates Renal Mitochondrial Dysfunction And Associated Renal Injury In Polycystic Ovary Syndrome

Background: Polycystic ovary syndrome (PCOS) is characterized by hyperandrogenism and polycystic ovaries. Renal injury, increased central adiposity, and chronic low-grade systemic inflammation are common characteristics of PCOS. Renal inflammation can induce mitochondrial dysfunction, which plays a pivotal role in renal pathophysiology and chronic kidney disease progression. Interleukin-6 (IL-6) is a key inflammatory cytokine that is involved in renal injury progression by activating its soluble receptor (sIL-6R) and a membrane-bound glycoprotein130 (gp130). Serum IL-6 levels are elevated in women with PCOS; however, its role in inducing renal mitochondrial dysfunction and consequently PCOS-mediated renal injury is unknown. Therefore, we aimed to test the hypothesis that hyperandrogenemia increases systemic and renal IL-6 levels, leading to the activation of IL-6/gp130 signaling, which in turn triggers intrarenal mitochondrial dysfunction and renal injury in a well-characterized mouse model of PCOS. Methods: Three-week-old peripubertal female mice were implanted with Silastic tubes filled with the non-aromatizable androgen dihydrotestosterone (DHT, 8 mg) or vehicle for 12 weeks. Eight weeks post-Silastic tubes implantation, the animals were treated with the IL-6/gp130 signaling inhibitor SC144 (10 mg/kg, SC, 3x/week) or its vehicle for 4 weeks. Body weight (gravimetry), fat mass (EchoMRI), kidney weight (gravimetry), serum IL-6 (Bioplex), glomerular filtration rate (GFR, transcutaneous fluorescence), as well as the renal injury markers urinary albumin to creatinine ratio (UACR, clinical chemistry analyzer), and NGAL (ELISA) were assessed. Renal gp130 protein and IL-6 mRNA expression were quantified by Western blot and RT-qPCR, respectively. The mitochondrial markers cytochrome C, succinate dehydrogenase A (SDHA), the mitochondrial stress protein HSP60, and voltage-dependent anion channel (VDAC) were assessed in the renal tissue by Western blot. H&E stained renal sections were used for histopathological analysis. Freshly isolated kidney mitochondria were used to measure mitochondrial reactive oxygen species (mtROS) by Amplex Red assay. Moreover, mitochondrial complex I and complex II-driven respiration along with complex IV activity were assessed using Oroboros Fluorespirometer. Results: DHT significantly (p<0.05) increased body weight (26.2±0.9 vs. 22.23±0.4 g), fat mass (3.2±0.4 vs. 1.9±0.4 g), kidney weight (365.6 ± 13.1 vs. 257.1 ± 3.7 mg), UACR (1,227±420 vs. 404±169 μg albumin/mg creatinine), urinary NGAL (2-fold), and serum IL-6 levels (2.2-fold). Additionally, DHT increased the expression of renal gp130 and IL-6 (1.5-fold) and decreased GFR (1067.2 ± 59.9 vs. 1335.6 ± 60.3 uL/min/100g body weight). Moreover, cytochrome c levels in PCOS mice were significantly lower (32%), while HSP60 levels were higher (4-fold). The latter changes were associated with higher mtROS generation (2-fold), as well as lower complexes I, II, III, and IV respiration (43-71%). PCOS mice also showed a worsen renal histological structure with congested glomeruli, exfoliation of luminal epithelial lining, and interstitial hemorrhage. SC144 therapy had no effect on kidney weight or GFR; however, it abolished DHT-induced increases in body weight and fat mass. Excitingly, SC144 treatment normalized the levels of UACR, and decreased both glomerular and tubular injury in PCOS mice. It also decreased renal HSP60 levels and mtROS generation and increased complex IV derived respiration. Conclusion and significance: Our findings suggest that IL-6/gp130 activation plays a significant role in renal outcomes in PCOS. Targeting IL-6 signaling could be a novel therapeutic approach to ameliorate renal injury in PCOS women. Supported by NIH grants NIGMS P20GM121334 to KSE, LLYC, and DGR; NIH-NIGMS P30GM149404 to SR. 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.