Increase In Number Of Mitochondria Research Articles

Carcinoembryonic antigen potentiates non-small cell lung cancer progression via PKA-PGC-1ɑ axis

Carcinoembryonic antigen (CEA) is a tumor-associated antigen primarily produced by tumor cells. It has been implicated in various biological processes such as cell adhesion, proliferation, differentiation, and metastasis. Despite this, the precise molecular mechanisms through which CEA enhances tumor cell proliferation remain largely unclear. Our study demonstrates that CEA enhances the proliferation and migration of non-small cell lung cancer (NSCLC) while also inhibiting cisplatin-induced apoptosis in NSCLC cells. Treatment with CEA led to an increase in mitochondrial numbers and accumulation of lipid droplets in A549 and H1299 cells. Additionally, our findings indicate that CEA plays a role in regulating the fatty acid metabolism of NSCLC cells. Inhibiting fatty acid metabolism significantly reduced the CEA-mediated proliferation and migration of NSCLC cells. CEA influences fatty acid metabolism and the proliferation of NSCLC cells by activating the PGC-1α signaling pathway. This regulatory mechanism involves CEA increasing intracellular cAMP levels, which in turn activates PKA and upregulates PGC-1α. In NSCLC, inhibiting the PKA-PGC-1α signaling pathway reduces both fatty acid metabolism and the proliferation and migration induced by CEA, both in vitro and in vivo. These results suggest that CEA contributes to the promotion of proliferation and migration by modulating fatty acid metabolism. Targeting CEA or the PKA-PGC-1ɑ signaling pathway may offer a promising therapeutic approach for treating NSCLC.

The Highs and Lows of Memantine-An Autophagy and Mitophagy Inducing Agent That Protects Mitochondria.

Memantine is an FDA-approved, non-competitive NMDA-receptor antagonist that has been shown to have mitochondrial protective effects, improve cell viability and enhance clearance of Aβ42 peptide. Currently, there are uncertainties regarding the precise molecular targets as well as the most favourable treatment concentrations of memantine. Here, we made use of an imaging-based approach to investigate the concentration-dependent effects of memantine on mitochondrial fission and fusion dynamics, autophagy and mitochondrial quality control using a neuronal model of CCCP-induced mitochondrial injury so as to better unpack how memantine aids in promoting neuronal health. GT1-7 murine hypothalamic cells were cultured under standard conditions, treated with a relatively high and low concentration (100 µM and 50 µM) of memantine for 48 h. Images were acquired using a Zeiss 780 PS1 platform. Utilising the mitochondrial event localiser (MEL), we demonstrated clear concentration-dependent effects of memantine causing a protective response to mitochondrial injury. Both concentrations maintained the mitochondrial network volume whilst the low concentration caused an increase in mitochondrial number as well as increased fission and fusion events following CCCP-induced injury. Additionally, we made use of a customised Python-based image processing and analysis pipeline to quantitatively assess memantine-dependent changes in the autophagosomal and lysosomal compartments. Our results revealed that memantine elicits a differential, concentration-dependent effect on autophagy pathway intermediates. Intriguingly, low but not high concentrations of memantine lead to the induction of mitophagy. Taken together, our findings have shown that memantine is able to protect the mitochondrial network by preserving its volume upon mitochondrial injury with high concentrations of memantine inducing macroautophagy, whereas low concentrations lead to the induction of mitophagy.

Role of the ST6GAL1 sialyltransferase in regulating ovarian cancer cell metabolism.

The ST6GAL1 sialyltransferase, which adds α2-6-linked sialic acids to N-glycosylated proteins, is upregulated in many malignancies including ovarian cancer. Through its activity in sialylating select surface receptors, ST6GAL1 modulates intracellular signaling to regulate tumor cell phenotype. ST6GAL1 has previously been shown to act as a survival factor that protects cancer cells from cytotoxic stressors such as hypoxia. In the present study, we investigated a role for ST6GAL1 in tumor cell metabolism. ST6GAL1 was overexpressed (OE) in OV4 ovarian cancer cells, which have low endogenous ST6GAL1, or knocked-down (KD) in ID8 ovarian cancer cells, which have high endogenous ST6GAL1. OV4 and ID8 cells with modulated ST6GAL1 expression were grown under normoxic or hypoxic conditions, and metabolism was assessed using Seahorse technology. Results showed that cells with high ST6GAL1 expression maintained a higher rate of oxidative metabolism than control cells following treatment with the hypoxia mimetic, desferrioxamine (DFO). This enrichment was not due to an increase in mitochondrial number. Glycolytic metabolism was also increased in OV4 and ID8 cells with high ST6GAL1 expression, and these cells displayed greater activity of the glycolytic enzymes, hexokinase and phosphofructokinase. Metabolism maps were generated from the combined Seahorse data, which suggested that ST6GAL1 functions to enhance the overall metabolism of tumor cells. Finally, we determined that OV4 and ID8 cells with high ST6GAL1 expression were more invasive under conditions of hypoxia. Collectively, these results highlight the importance of sialylation in regulating the metabolic phenotype of ovarian cancer cells.

Expansion of the intraepithelial lymphocyte (IEL) compartment results in an increased bioenergetic profile and reduced IFNγ production in γδ IELs.

Abstract Intestinal γδ intraepithelial lymphocytes (γδ IEL) serve as the first line of defense against pathogen invasion. We recently identified a transmissible hyperproliferative γδ IEL (γδ HYP) phenotype that protects against enteric infection, and these mice have no signs of overt intestinal pathology. Given that IELs are metabolically constrained to prevent aberrant activation, we hypothesized that the bioenergetics of γδ HYPIELs may regulate their effector function. Electron microscopy revealed a 70% increase in mitochondrial number (p=0.005) and 24% increase in mitochondrial area (p=0.04) in γδ HYPIELs relative to WT. Seahorse mitochondrial stress assays on γδ IELs showed a 50% increase in spare respiratory capacity in γδ HYPIELs compared to WT (p=0.014). Mitochondrial metabolism was shown to influence γδ T cell cytokine production, and similarly, we found that stimulation with PMA and ionomycin reduced the frequency of IFNγ +γδ IELs by 59% in γδ HYPrelative to WT (p<0.0001). We also observed that γδ HYPIELs exhibit higher CD39 expression compared to WT (p<0.0001), and a CD39 hisubset produces less IFNγ compared to CD39 negand CD39 intcells (p<0.0001) The addition of the ATP-synthase inhibitor oligomycin during IEL stimulation increased IFNγ production by both WT and γδ HYPIELs by 66% and 44%, respectively (p<0.0001). Together, our data demonstrate that the shift towards high CD39 expression and elevated mitochondrial metabolism contribute to decreased IFNγ production in γδ HYPIELs. Further understanding of the mechanisms regulating γδ IEL homeostasis and effector function may ultimately allow fine tuning of mucosal surveillance to confer protection against intestinal injury or infection while limiting aberrant cytotoxicity. Supported by NJCCR (COCR23PRF024)

Loss of a gluconeogenic muscle enzyme contributed to adaptive metabolic traits in hummingbirds.

Hummingbirds possess distinct metabolic adaptations to fuel their energy-demanding hovering flight, but the underlying genomic changes are largely unknown. Here, we generated a chromosome-level genome assembly of the long-tailed hermit and screened for genes that have been specifically inactivated in the ancestral hummingbird lineage. We discovered that FBP2 (fructose-bisphosphatase 2), which encodes a gluconeogenic muscle enzyme, was lost during a time period when hovering flight evolved. We show that FBP2 knockdown in an avian muscle cell line up-regulates glycolysis and enhances mitochondrial respiration, coincident with an increased mitochondria number. Furthermore, genes involved in mitochondrial respiration and organization have up-regulated expression in hummingbird flight muscle. Together, these results suggest that FBP2 loss was likely a key step in the evolution of metabolic muscle adaptations required for true hovering flight.

The Panax ginseng Berry Extract and Soluble Whey Protein Hydrolysate Mixture Ameliorates Sarcopenia-Related Muscular Deterioration in Aged Mice.

Sarcopenia is prevalent as the aging population grows. Therefore, the need for supplements for the elderly is increasing. This study aimed to investigate the efficacy and mechanism of a Panax ginseng berry extract (GBE) and soluble whey protein hydrolysate (WPH) mixture on a sarcopenia-related muscular deterioration in aged mice. Ten-month-old male C57BL/6J mice were administered three different doses of the GBE + WPH mixture for 8 weeks; 700 mg/kg, 900 mg/kg, and 1100 mg/kg. Grip strength, serum inflammatory cytokines level, and mass of muscle tissues were estimated. The deteriorating function of aging muscle was investigated via protein or gene expression. Grip strength and mass of three muscle tissues were increased significantly in a dose-dependent manner, and increased anti-inflammatory cytokine alleviated systemic inflammatory state. The mixture resolved the imbalance of muscle protein turnover through activation of the PI3K/Akt pathway and increased gene expression of the muscle regeneration-related factors, while decreasing myostatin, which interferes with muscle protein synthesis and regeneration. Furthermore, we confirmed that increased mitochondria number in muscle with the improvement of mitochondrial biogenesis. These physiological changes were similar to the effects of exercise.

Effect of oxygen concentrations and branched-chain amino acids on the growth and development of sub-seafloor fungus, Schizophyllum commune 20R-7-F01.

Fungi have been reported to be the dominant eukaryotic group in anoxic sub-seafloor sediments, but how fungi subsist in the anoxic sub-marine sedimental environment is rarely understood. Our previous study demonstrated that the fungus, Schizophyllum commune 20R-7-F01 isolated from a ~2km sediment below the seafloor, can grow and produce primordia in the complete absence of oxygen with enhanced production of branched-chain amino acids (BCAAs), but the primordia cannot be developed into fruit bodies without oxygen. Here, we present the individual and synergistic effects of oxygen and BCAAs on the fruit-body development of this strain. It was found that the fungus required a minimum oxygen concentration of 0.5% pO2 to generate primordia and 1% pO2 to convert primordia into mature fruit body. However, if BCAAs (20 mM) were added to the medium, the primordium could be developed into fruit body at a lower oxygen concentration up to 0.5% pO2 where genes fst4 and c2h2 playing an important role in compensating oxygen deficiency. Moreover, under hypoxic conditions, the fungus showed an increase in mitochondrial number and initiation of auto-phagocytosis. These findings suggest that the fruit-body formation of S. commune may have multiple mechanisms, including energy and amino acid metabolism in response to oxygen concentrations.

Dysosmobacter welbionis is a newly isolated human commensal bacterium preventing diet-induced obesity and metabolic disorders in mice

ObjectiveTo investigate the abundance and the prevalence of Dysosmobacter welbionis J115T, a novel butyrate-producing bacterium isolated from the human gut both in the general population and in subjects with metabolic...

TSG101 negatively regulates mitochondrial biogenesis in axons

There is a tight association between mitochondrial dysfunction and neurodegenerative diseases and axons that are particularly vulnerable to degeneration, but how mitochondria are maintained in axons to support their physiology remains poorly defined. In an in vivo forward genetic screen for mutants altering axonal mitochondria, we identified tsg101 Neurons mutant for tsg101 exhibited an increase in mitochondrial number and decrease in mitochondrial size. TSG101 is best known as a component of the endosomal sorting complexes required for transport (ESCRT) complexes; however, loss of most other ESCRT components did not affect mitochondrial numbers or size, suggesting TSG101 regulates mitochondrial biology in a noncanonical, ESCRT-independent manner. The TSG101-mutant phenotype was not caused by lack of mitophagy, and we found that autophagy blockade was detrimental only to the mitochondria in the cell bodies, arguing mitophagy and autophagy are dispensable for the regulation of mitochondria number in axons. Interestingly, TSG101 mitochondrial phenotypes were instead caused by activation of PGC-1ɑ/Nrf2-dependent mitochondrial biogenesis, which was mTOR independent and TFEB dependent and required the mitochondrial fission-fusion machinery. Our work identifies a role for TSG101 in inhibiting mitochondrial biogenesis, which is essential for the maintenance of mitochondrial numbers and sizes, in the axonal compartment.

Developmental programming: Metabolic tissue-specific changes in endoplasmic reticulum stress, mitochondrial oxidative and telomere length status induced by prenatal testosterone excess in the female sheep

Prenatal testosterone (T) excess-induced metabolic dysfunctions involve tissue specific changes in insulin sensitivity with insulin resistant, oxidative and lipotoxic state in liver/muscle and insulin sensitive but inflammatory and oxidative state in visceral adipose tissues (VAT). We hypothesized that mitochondrial dysfunction, endoplasmic reticulum (ER) stress and premature cellular senescence are contributors to the tissue-specific changes in insulin sensitivity. Markers of mitochondrial number, function, and oxidative phosphorylation (OxPhos), ER stress and cellular senescence (telomere length) were assessed in liver, muscle and 4 adipose (VAT, subcutaneous [SAT], epicardiac [ECAT] and perirenal [PRAT]) depots collected from control and prenatal T-treated female sheep at 21 months of age. Prenatal T treatment led to: (a) reduction in mitochondrial number and OxPhos complexes and increase in ER stress markers in muscle; (b) increase in fibrosis with trend towards increase in short telomere fragments in liver (c) depot-specific mitochondrial changes with OxPhos complexes namely increase in SAT and reduction in PRAT and increase in mitochondrial number in ECAT; (d) depot-specific ER stress marker changes with increase in VAT, reduction in SAT, contrasting changes in ECAT and no changes in PRAT; and (d) reduced shorter telomere fragments in SAT, ECAT and PRAT. These changes indicate insulin resistance may be driven by mitochondrial and ER dysfunction in muscle, fibrosis and premature senescence in liver, and depot-specific changes in mitochondrial function and ER stress without involving cellular senescence in adipose tissue. These findings provide mechanistic insights into pathophysiology of metabolic dysfunction among female offspring from hyperandrogenic pregnancies.

Age and Sex Influence Mitochondria and Cardiac Health in Offspring Exposed to Maternal Glucolipotoxicity.

SummaryInfants of diabetic mothers are at risk of cardiomyopathy at birth and myocardial infarction in adulthood, but prevention is hindered because mechanisms remain unknown. We previously showed that maternal glucolipotoxicity increases the risk of cardiomyopathy and mortality in newborn rats through fuel-mediated mitochondrial dysfunction. Here we demonstrate ongoing cardiometabolic consequences by cross-fostering and following echocardiography, cardiomyocyte bioenergetics, mitochondria-mediated turnover, and cell death following metabolic stress in aged adults. Like humans, cardiac function improves by weaning with no apparent differences in early adulthood but declines again in aged diabetes-exposed offspring. This is preceded by impaired oxidative phosphorylation, exaggerated age-related increase in mitochondrial number, and higher oxygen consumption. Prenatally exposed male cardiomyocytes have more mitolysosomes indicating high baseline turnover; when exposed to metabolic stress, mitophagy cannot increase and cardiomyocytes have faster mitochondrial membrane potential loss and mitochondria-mediated cell death. Details highlight age- and sex-specific roles of mitochondria in developmentally programmed adult heart disease.

Antioxidant Apigenin Relieves Age-Related Muscle Atrophy by Inhibiting Oxidative Stress and Hyperactive Mitophagy and Apoptosis in Skeletal Muscle of Mice.

Skeletal muscle atrophy in the aged causes loss in muscle mass and functions. Naturally occurring antioxidant flavonoid apigenin is able to ameliorate obesity- and denervation-induced muscle atrophies, but its effects on age-related muscle atrophy remain unknown. We hypothesized that apigenin can relieve muscle atrophy in aged mice, probably through special effects on reactive oxygen species and enzymes with antioxidant functions. For the male mice of the study, apigenin showed significant dose-dependent effects in relieving aging-related muscle atrophy according to results of frailty index as indicator of frailty associated with aging, grip strength, and running distance. Apigenin also improved myofiber size and morphological features and increased mitochondria number and volume, as manifested by succinate dehydrogenase staining and transmission electron microscopy. Our tests also suggested that apigenin promoted activities of enzymes such as superoxide dismutase and glutathione peroxidase for antioxidation and those for aerobic respiration such as mitochondrial respiratory enzyme complexes I, II, and IV, increased ATP, and enhanced expression of genes such as peroxisome proliferator-activated receptor-γ coactivator 1α, mitochondrial transcription factor A, nuclear respiratory factor-1, and ATP5B involved in mitochondrial biogenesis. The data also suggested that apigenin inhibited Bcl-2/adenovirus E1B 19kD-interacting protein 3 and DNA fragmentation as indicators of mitophagy and apoptosis in aged mice with skeletal muscle atrophy. Together, the results suggest that apigenin relieves age-related skeletal muscle atrophy through reducing oxidative stress and inhibiting hyperactive autophagy and apoptosis.

Lipopolysaccharide promotes Drp1-dependent mitochondrial fission and associated inflammatory responses in macrophages.

Mitochondria have a multitude of functions, including energy generation and cell signaling. Recent evidence suggests that mitochondrial dynamics (i.e. the balance between mitochondrial fission and fusion) also regulate immune functions. Here, we reveal that lipopolysaccharide (LPS) stimulation increases mitochondrial numbers in mouse bone marrow‐derived macrophages (BMMs) and human monocyte‐derived macrophages. In BMMs, this response requires Toll‐like receptor 4 (Tlr4) and the TLR adaptor protein myeloid differentiation primary response 88 (MyD88) but is independent of mitochondrial biogenesis. Consistent with this phenomenon being a consequence of mitochondrial fission, the dynamin‐related protein 1 (Drp1) GTPase that promotes mitochondrial fission is enriched on mitochondria in LPS‐activated macrophages and is required for the LPS‐mediated increase in mitochondrial numbers in both BMMs and mouse embryonic fibroblasts. Pharmacological agents that skew toward mitochondrial fusion also abrogated this response. LPS triggered acute Drp1 phosphorylation at serine 635 (S635), followed by sustained Drp1 dephosphorylation at serine 656 (S656), in BMMs. LPS‐induced S656 dephosphorylation was abrogated in MyD88‐deficient BMMs, suggesting that this post‐translational modification is particularly important for Tlr4‐inducible fission. Pharmacological or genetic targeting of Tlr4‐inducible fission had selective effects on inflammatory mediator production, with LPS‐inducible mitochondrial fission promoting the expression and/or secretion of a subset of inflammatory mediators in BMMs and mouse embryonic fibroblasts. Thus, triggering of Tlr4 results in MyD88‐dependent activation of Drp1, leading to inducible mitochondrial fission and subsequent inflammatory responses in macrophages.

1966-P: Induction of Beige Adipocyte Markers in 3T3-L1 Cells by Clk1 and PKCbetaII Inhibitors

Excessive dietary intake of fat results in its storage in white adipose tissue (WAT), whereas energy expenditure by lipid oxidation occurs in brown adipose tissue. A third type of fat is beige, and it is observed in WAT depots. Certain WAT can undergo beiging. Numerous factors have roles in beiging. However, little is known about the signaling pathways inducing pre-adipocytes to become beige adipocytes. Known participants are activators of PPARgamma, PGC1alpha, and PRDM16 that induce UCP1-containing mitochondria upon cold exposure. We found a signaling pathway that regulates alternative pre-mRNA splicing is also involved in beiging when it is inhibited. Clk1 kinase phosphorylates proteins with serine and arginine rich domains. Clk1 inhibition by 50 nM TG003 during differentiation of 3T3-L1 adipocytes (post day 3) results in beige-like adipocytes demonstrating increased PGC1alpha and UCP1 mRNA and proteins. TG003 inhibits Clk1, 2, and 4. We demonstrate using siRNA for Clk1, 2, and 4, that Clk1 inhibition increased UCP1, PGC1alpha and PPARgamma mRNA whereas Clk1 and 4 siRNA did not. TG003-treated adipocytes contained fewer lipid droplets and more mitochondria which resulted in significant proton leak. In addition to TG003, CG53353, a PKCbetaII inhibitor, also increased mitochondria number and decreased lipid droplet size. PKCbetaII is an mRNA splice variant regulated by Clk1. Others previously showed that TG003 treatment of mice on high fat diets (HFD) resulted in weight loss, and PKCbeta(I+II) knockout mice did not gain weight on HFD. Using bioinformatics, we determined that PGC1alpha was a substrate for Clk1 and PKCbetaII. PGC1alpha was shown to be phosphorylated by Clk2 previously. Hence, we believe that inhibition of Clk1 and PKCbetaII phosphorylation of PGC1alpha results in upregulation of UCP1 expression in adipocytes. This newly identified pathway supports a role for Clk1 and PKCbetaII as potential targets for inhibition to treat weight loss in obesity. Disclosure A. Patel: None. T. Dobbins: None. S. Kong: None. N.A. Patel: None. D.R. Cooper: None. Funding U.S. Department of Veterans Affairs (5|01BX003689)

Frequency-dependent changes in mitochondrial number and generation of reactive oxygen species in a rat model of vibration-induced injury

ABSTRACTRegular use of vibrating hand tools results in cold-induced vasoconstriction, finger blanching, and a reduction in tactile sensitivity and manual dexterity. Depending upon the length and frequency, vibration induces regeneration, or dysfunction and apoptosis, inflammation and an increase in reactive oxygen species (ROS) levels. These changes may be associated with mitochondria, this study examined the effects of vibration on total and functional mitochondria number. Male rats were exposed to restraint or tail vibration at 62.5, 125, or 250 Hz. The frequency-dependent effects of vibration on mitochondrial number and generation of oxidative stress were examined. After 10 days of exposure at 125 Hz, ventral tail arteries (VTA) were constricted and there was an increase in mitochondrial number and intensity of ROS staining. In the skin, the influence of vibration on arterioles displayed a similar but insignificant response in VTA. There was also a reduction in the number of small nerves with exposure to vibration at 250 Hz, and a reduction in mitochondrial number in nerves in restrained and all vibrated conditions. There was a significant rise in the size of the sensory receptors with vibration at 125 Hz, and an elevation in ROS levels. Based upon these results, mitochondria number and activity are affected by vibration, especially at frequencies at or near resonance. The influence of vibration on the vascular system may either be adaptive or maladaptive. However, the effects on cutaneous nerves might be a precursor to loss of innervation and sensory function noted in workers exposed to vibration.

Persistent low body weight in humans is associated with higher mitochondrial activity in white adipose tissue

ABSTRACTBackgroundConstitutional thinness (CT) is a state of low but stable body weight (BMI ≤18 kg/m2). CT subjects have normal-range hormonal profiles and food intake but exhibit resistance to weight gain despite living in the modern world's obesogenic environment.ObjectiveThe goal of this study is to identify molecular mechanisms underlying this protective phenotype against weight gain.MethodsWe conducted a clinical overfeeding study on 30 CT subjects and 30 controls (BMI 20–25 kg/m2) matched for age and sex. We performed clinical and integrative molecular and transcriptomic analyses on white adipose and muscle tissues.ResultsOur results demonstrate that adipocytes were markedly smaller in CT individuals (mean ± SEM: 2174 ± 142 μm 2) compared with controls (3586 ± 216 μm2) (P < 0.01). The mitochondrial respiratory capacity was higher in CT adipose tissue, particularly at the level of complex II of the electron transport chain (2.2-fold increase; P < 0.01). This higher activity was paralleled by an increase in mitochondrial number (CT compared with control: 784 ± 27 compared with 675 ± 30 mitochondrial DNA molecules per cell; P < 0.05). No evidence for uncoupled respiration or “browning” of the white adipose tissue was found. In accordance with the mitochondrial differences, CT subjects had a distinct adipose transcriptomic profile [62 differentially expressed genes (false discovery rate of 0.1 and log fold change >0.75)], with many differentially expressed genes associating with positive metabolic outcomes. Pathway analyses revealed an increase in fatty acid oxidation ( P = 3 × 10−04) but also triglyceride biosynthesis (P = 3.6 × 10−04). No differential response to the overfeeding was observed in the 2 groups.ConclusionsThe distinct molecular signature of the adipose tissue in CT individuals suggests the presence of augm ented futile lipid cycling, rather than mitochondrial uncoupling, as a way to increase energy expenditure in CT individuals. We propose that increased mitochondrial function in adipose tissue is an important mediator in sustaining the low body weight in CT individuals. This knowledge could ultimately allow more targeted approaches for weight management treatment strategies. This trial was registered at clinicaltrials.gov as NCT02004821.

MORPHOLOGICAL CHANGES OF THE RETICULAR ZONE OF THE CORTEX OF ADRENAL GLANDS AND OF THE SECRETORY ACTIVITY OF ITS CORTICOSTEROCYTES IN THE PUBERTAL PERIOD IN RATS DEVELOPING AT THE INFLUENCE OF THE ENDOCRINAL DISRUPTER DICHLORODIPHENYLTRICHLOROETHANE

Affection of developing organism by endocrine disruptors is an actively studied topic of scientific research in medicine, caused by a progressive increase in the number of diseases and disorders in the development of the reproductive and endocrine systems. Dichlorodiphenyltrichloroethane (DDT) is the most wide-spread endocrine disruptor. Low-dose exposure to DDT disrupts production of sex steroids by poorly known mechanisms. The research was focused on assessment of morphology of adrenal zona reticularis and fine structure of reticularis endocrine cells and changes in their secretory machinery in rats exposed to low doses of DDT during prenatal and postnatal development. The experimental group consisted of the male offspring of dams, who daily consumed solution of o, p-DDT at a concentration of 20 µg/l, from mating until the end of the suckling period in offspring, which then consumed a similar solution of DDT. Daily consumption of DDT by the offspring was 2,90±0,12 µg/kg body weight. These doses corresponds to levels of exposure of humans to DDT with food products taking to account the differences in metabolism of DDT in rats and humans. The control and experimental rats were sacrificed on the 42nd day of postnatal development (pubertal period). Light microscopy of adrenal sections found hypoplasia of zona reticularis in rats after developmental exposure to endocrine disruptor. Electron microscopy revealed prevalence of cells with low lipid content in cytoplasm, less developed endoplasmatic reticulum and Golgi complex and signs of lowered functional activity of mitochondria indicated decreased steroidogenic activity of zona reticularis. These findings explain previously found impaired production of sex steroids in DDT-exposed rats. Electron microscopy also found that disruption of steroid secretion in reticularis cells by DDT led to compensatory enlargement of cells and increase in number of mitochondria per m2 of cytoplasm indicating development of structural support for long-term enhancement of steroidogenic activity.

Elucidation of the mechanism of changes in the antioxidant function with the aging in the liver of the senescence-accelerated mouse P10 (SAMP10)

Senescence-accelerated mice are known to display a variety of deficits and signs of accelerated aging, but the specific mechanisms involved in this process are still unclear. In this study, we examined the expression levels of antioxidant enzymes, transcription factors responsible for the regulation of expression of these enzymes, and mitochondrial proteins in the liver of SAMP10 and SAMR1 mice at 3 and 12 months of age using western blotting analysis. To investigate the amount of oxidative damage to DNA, levels of 8-OHdG were measured in the liver of these mice. At 3 months of age, the levels of catalase, Mn-SOD, GPx, UQCRC2 and COXIV were significantly upregulated in SAMP10 mice compared with that in SAMR1 mice. However, NDUFS3 levels were not significantly different at this young age. In contrast, the expression level of catalase was significantly lower, and the levels of phosphorylated FoxO-1a and UQCRC2 were significantly higher in SAMP10 mice compared to those in SAMR1 mice; however, at 12 months of age, there were no significant differences in Mn-SOD, GPx, total -FoxO-1a, COXIV, and NDUFS3 expression between the two groups of mice. The levels of 8-OHdG in the liver were markedly higher in 12-month-old SAMP10 mice than those in 3-month-old SAMP10 and SAMR1 mice. These results suggest that an increase in number of mitochondria or a collapse in the balance between the levels of complexes I and III results in an increase in the amount of ROS and induces the expression of antioxidant enzymes in the liver of SAMP10 mice at 3 months of age. Although young SAMP10 mice produce a large amount of ROS, they also produce suitable levels of antioxidant enzymes that decompose ROS; consequently accelerated aging does not occur in young SAMP10 mice. In addition to excessive ROS production which is an important cause of aging, the level of catalase was significantly lower in SAMP10 than that in SAMR1 mice. These results suggested that overexpression of ROS and a decrease in the levels of catalase resulted in the accelerated aging observed in older SAMP10 mice. Moreover, the level of phosphorylated FoxO-1a was increased in SAMP10 compared to that in SAMR1 mice though the total amount of FoxO-1a was not significantly different between the two groups in old age. These results suggest that some impairment in the regulation mechanism of FoxO-1a phosphorylation is responsible for abnormal catalase expression and that a significant decrease in the level of catalase with aging decisively affects the metabolic balance of ROS; thus, ROS that cannot be metabolized contributes to the accelerated aging of SAMP10 mice.

Resistance exercise improves cardiac function and mitochondrial efficiency in diabetic rat hearts.

Metabolic disturbance and mitochondrial dysfunction are a hallmark of diabetic cardiomyopathy (DC). Resistance exercise (RE) not only enhances the condition of healthy individuals but could also improve the status of those with disease. However, the beneficial effects of RE in the prevention of DC and mitochondrial dysfunction are uncertain. Therefore, this study investigated whether RE attenuates DC by improving mitochondrial function using an in vivo rat model of diabetes. Fourteen Otsuka Long-Evans Tokushima Fatty rats were assigned to sedentary control (SC, n=7) and RE (n=7) groups at 28weeks of age. Long-Evans Tokushima Otsuka rats were used as the non-diabetic control. The RE rats were trained by 20 repetitions of climbing a ladder 5days per week. RE rats exhibited higher glucose uptake and lower lipid profiles, indicating changes in energy metabolism. RE rats significantly increased the ejection fraction and fractional shortening compared with the SC rats. Isolated mitochondria in RE rats showed increase in mitochondrial numbers, which were accompanied by higher expression of mitochondrial biogenesis proteins such as proliferator-activated receptor-γ coactivator-1α and TFAM. Moreover, RE rats reduced proton leakage and reactive oxygen species production, with higher membrane potential. These results were accompanied by higher superoxide dismutase 2 and lower uncoupling protein 2 (UCP2) and UCP3 levels in RE rats. These data suggest that RE is effective at ameliorating DC by improving mitochondrial function, which may contribute to the maintenance of diabetic cardiac contractility.

Ursolic acid induces mitochondrial biogenesis through the activation of AMPK and PGC-1 in C2C12 myotubes: a possible mechanism underlying its beneficial effect on exercise endurance.

Mitochondrial biogenesis, which involves an increase in mitochondrial number and the overall capacity of oxidative phosphorylation, is a critical determinant of skeletal muscle function. Recent findings have shown that some natural products can enhance mitochondrial adaptation to aerobic exercise, which in turn improves exercise performance, presumably by delaying muscle fatigue. Ursolic acid (UA), a natural triterpene, is commonly found in various vegetables and fruits. In the current study, UA was shown to increase mitochondrial mass and ATP generation capacity, with a concomitant production of a low level of mitochondrial reactive oxygen species (ROS) in C2C12 myotubes. Mitochondrial ROS, in turn, activated the redox sensitive adenosine monophosphate-dependent protein kinase (AMPK)/peroxisome proliferator-activated receptor γ coactivator-1(PGC-1) pathway. The activation of AMPK/PGC-1 further increased the expression of cytochrome c oxidase (COX) and uncoupling protein 3. Animal studies showed that UA can also dose-dependently increase the endurance exercise capacity in mice, as assessed by a weight-loaded swimming test and a hanging wire test. Our findings suggest that UA may induce mitochondrial biogenesis through the activation of AMPK and PGC-1 pathways in skeletal muscle, thereby offering a promising prospect for its use to enhance exercise endurance and alleviating fatigue in humans.