Mitochondrial Oxidative Capacity Research Articles

Obesity-induced tissue alterations resist weight loss: A mechanistic review.

Interventions aimed at weight control often have limited effectiveness in combating obesity. This review explores how obesity-induced dysfunction in white (WAT) and brown adipose tissue (BAT), skeletal muscle, and the brain blunt weight loss, leading to retention of stored fat. In obesity, increased adrenergic stimulation and inflammation downregulate β-adrenoreceptors and impair catecholaminergic signalling in adipocytes. This disrupts adrenergic-mediated lipolysis, diminishing lipid oxidation in both white and brown adipocytes, lowering thermogenesis and blunting fat loss. Emerging evidence suggests that WAT fibrosis is associated with worse weight loss outcomes; indeed, limiting collagen and laminin-α4 deposition mitigates WAT accumulation, enhances browning, and protects against high-fat-diet-induced obesity. Obesity compromises mitochondrial oxidative capacity and lipid oxidation in skeletal muscle, impairing its ability to switch between glucose and lipid metabolism in response to varying nutrient levels and exercise. This dysfunctional phenotype in muscle is exacerbated in the presence of obesity-associated sarcopenia. Additionally, obesity suppresses sarcolipin-induced sarcoplasmic reticulum calcium ATPase (SERCA) activation, resulting in reduced oxidative capacity, diminished energy expenditure, and increased adiposity. In the hypothalamus, obesity and overnutrition impair insulin and leptin signalling. This blunts central satiety signals, favouring a shift in energy balance toward energy conservation and body fat retention. Moreover, both obese animals and humans demonstrate impaired dopaminergic signalling and diminished responses to nutrient intake in the striatum, which tend to persist after weight loss. This may result in enduring inclinations toward overeating and a sedentary lifestyle. Collectively, the tissue adaptations described pose significant challenges to effectively achieving and sustaining weight loss in obesity.

Investigating the thermal sensitivity of key enzymes involved in the energetic metabolism of three insect species.

The metabolic responses of insects to high temperatures have been linked to their mitochondrial substrate oxidation capacity. However, the mechanism behind this mitochondrial flexibility is not well understood. Here, we used three insect species with different thermal tolerances (the honey bee, Apis mellifera; the fruit fly, Drosophila melanogaster; and the potato beetle, Leptinotarsa decemlineata) to characterise the thermal sensitivity of different metabolic enzymes. Specifically, we measured activities of enzymes involved in glycolysis (hexokinase, HK; pyruvate kinase, PK; and lactate dehydrogenase, LDH), pyruvate oxidation and the tricarboxylic acid cycle (pyruvate dehydrogenase, PDH; citrate synthase, CS; malate dehydrogenase, MDH; and aspartate aminotransferase, AAT), the electron transport system (Complex I, CI; Complex II, CII; mitochondrial glycerol-3-phosphate dehydrogenase, mG3PDH; Proline dehydrogenase, ProDH; and Complex IV, CIV) as well as ATP synthase (CV) at 18, 24, 30, 36, 42 and 45˚C. Our results show that at high temperature, all three species have important increased activity of enzymes linked to FADH2 oxidation, specifically CII and mG3PDH. In Drosophila and honey bees, this coincides with an important decrease of PDH and CS activity, respectively, that would limit NADH production. This is in line with the switch from NADH-linked substrates to FADH2-linked substrates previously observed with mitochondrial oxygen consumption. Thus, we demonstrate that even though the three insect species have a different metabolic regulation, a similar response to high temperature involving CII and mG3PDH is observed, denoting the importance of these proteins for thermal tolerance in insects.

Migration increases mitochondrial oxidative capacity without increasing reactive oxygen species emission in a songbird.

Birds remodel their flight muscle metabolism prior to migration to meet the physiological demands of migratory flight, including increases in both oxidative capacity and defence against reactive oxygen species. The degree of plasticity mediated by changes in these mitochondrial properties is poorly understood but may be explained by two non-mutually exclusive hypotheses: variation in mitochondrial quantity or individual mitochondrial function. We tested these hypotheses using yellow-rumped warblers (Setophaga coronata), a Nearctic songbird which biannually migrates two to five thousand kilometres. We predicted higher flight muscle mitochondrial abundance and substrate oxidative capacity and decreased reactive oxygen species emission in migratory warblers captured during autumn migration compared to a short-day photoperiod-induced non-migratory phenotype. We assessed mitochondrial abundance via citrate synthase activity and assessed isolated mitochondrial function using high-resolution fluororespirometry. We found 60% higher tissue citrate synthase activity in the migratory phenotype, indicating higher mitochondrial abundance. We also found 70% higher state 3 respiration (expressed per unit citrate synthase) in mitochondria from migratory warblers when oxidizing palmitoyl-carnitine, but similar H2O2 emission rates between phenotypes. By contrast, non-phosphorylating respiration was higher and H2O2 emission rates were lower in the migratory phenotype. However, flux through electron transport system complexes I-IV, II-IV and IV were similar between phenotypes. In support of our hypotheses, these data suggest that flight muscle mitochondrial abundance and function are seasonally remodeled in migratory songbirds to increase tissue oxidative capacity without increasing reactive oxygen species formation.

Skeletal muscle mitochondrial correlates of critical power and W' in healthy active individuals.

The asymptote (critical power; CP) and curvature constant (W') of the hyperbolic power-duration relationship can predict performance within the severe-intensity exercise domain. However, the extent to which these parameters relate to skeletal muscle mitochondrial content and respiratory function is not known. Fifteen males (peak O2 uptake, 52.2±8.7mLkg-1min-1; peak work rate, 366±40W; and gas exchange threshold, 162±41W) performed three to five constant-load tests to task failure for the determination of CP (246±44W) and W' (18.6±4.1kJ). Skeletal muscle biopsies were obtained from the vastus lateralis to determine citrate synthase (CS) activity, as a marker of mitochondrial content, and the ADP-stimulated respiration (P) and maximal electron transfer (E) through mitochondrial complexes (C) I-IV. The CP was positively correlated with CS activity (absolute CP, r=0.881, P<0.001; relative CP, r=0.751, P=0.001). The W' was not correlated with CS activity (P>0.05). Relative CP was positively correlated with mass-corrected CI+IIE (r=0.659, P=0.038), with absolute CP being inversely correlated with CS activity-corrected CIVE (r=-0.701, P=0.024). Relative W' was positively correlated with CS activity-corrected CI+IIP (r=0.713, P=0.021) and the phosphorylation control ratio (r=0.661, P=0.038). There were no further correlations between CP or W' and mitochondrial respiratory variables. These findings support the assertion that skeletal muscle mitochondrial oxidative capacity is positively associated with CP and that this relationship is strongly determined by mitochondrial content.

Role of Cardiorespiratory Fitness and Mitochondrial Oxidative Capacity in Reduced Walk Speed of Older Adults with Diabetes.

Cardiorespiratory fitness and mitochondrial oxidative capacity are associated with reduced walking speed in older adults. The impact of cardiorespiratory fitness and mitochondrial oxidative capacity on walking speed in older adults with diabetes has not been clearly defined. We examined differences in cardiorespiratory fitness and skeletal muscle mitochondrial oxidative capacity between older adults with and without diabetes as well as determine their relative contribution to slower walking speed in older adults with diabetes. Participants with diabetes (n=159) had lower cardiorespiratory fitness and mitochondrial respiration in permeabilized fiber bundles when compared to those without diabetes (n=717), following adjustments for covariates including BMI, chronic comorbid health conditions, and physical activity. 4-m and 400-m walking speeds were slower in those with diabetes. Mitochondrial oxidative capacity alone or combined with cardiorespiratory fitness mediated ∼20-70% of the difference in walk speed between older adults with and without diabetes. Additional adjustments with BMI and co-morbidities further explained the group differences in walk speed. Cardiorespiratory fitness and skeletal muscle mitochondrial oxidative capacity contribute to slower walking speeds in older adults with diabetes.

Inhibition of CISD1 attenuates cisplatin-induced hearing loss in mice via the PI3K and MAPK pathways

Cisplatin is an effective chemotherapeutic drug for different cancers, but it also causes severe and permanent hearing loss. Oxidative stress and mitochondrial dysfunction in cochlear hair cells (HCs) have been shown to be important in the pathogenesis of cisplatin-induced hearing loss (CIHL). CDGSH iron sulfur domain 1 (CISD1, also known as mitoNEET) plays a critical role in mitochondrial oxidative capacity and cellular bioenergetics. Targeting CISD1 may improve mitochondrial function in various diseases. However, the role of CISD1 in cisplatin-induced ototoxicity is unclear. Therefore, this study was performed to assess the role of CISD1 in cisplatin-induced ototoxicity. We found that CISD1 expression was significantly increased after cisplatin treatment in both HEI-OC1 cells and cochlear HCs. Moreover, pharmacological inhibition of CISD1 with NL-1 inhibited cell apoptosis and reduced mitochondrial reactive oxygen species accumulation in HEI-OC1 cells and cochlear explants. Inhibition of CISD1 with small interfering RNA in HEI-OC1 cells had similar protective effects. Furthermore, NL-1 protected against CIHL in adult C57 mice, as evaluated by the auditory brainstem response and immunofluorescent staining. Mechanistically, RNA sequencing revealed that NL-1 attenuated CIHL via the PI3K and MAPK pathways. Most importantly, NL-1 did not interfere with the antitumor efficacy of cisplatin. In conclusion, our study revealed that targeting CISD1 with NL-1 reduced reactive oxygen species accumulation, mitochondrial dysfunction, and apoptosis via the PI3K and MAPK pathways in HEI-OC1 cell lines and mouse cochlear explants in vitro, and it protected against CIHL in adult C57 mice. Our study suggests that CISD1 may serve as a novel target for the prevention of CIHL.

Recovery After High-Intensity Interval Training in Professional Soccer Players: Passive-Active Combination Recovery Technique

Objective: The aim of this study is to investigate which of the passive recovery (PR), active recovery (AR) and passive-active combination recovery (PAR) techniques applied after the end of high-intensity interval training (HIIT) was more effective in professional super league soccer players. Method: 28 trained professional male soccer players (age: 24.79±2.75 years, height: 180.50±5.81 cm, weight: 74.18±5.47 kg) from the Türkiye Super League team participated in this study voluntarily. Before the study, participants were assigned to 3 groups according to heart rate (HR) and lactic acid (La) levels. Each HIIT load intensity was determined according to the Karvonen method. HIIT sessions were performed for 5 repetitions of 2 minutes (1 set = 5x2 minutes) and a 30-second rest was given between repetitions. At the end of the set, a 2-minute recovery period was applied. Three different recovery techniques, PR, AR and PAR, were applied alternately to each group at the end of the HIIT programs. Participants' HR and La values were taken at the end of HIIT and recovery techniques. Differences between the obtained data were determined by repeated measures one-way ANOVA and multiple comparison tests. P&lt;0.05 level was considered significant in all tests. Results: Although there was no significant difference in La levels between groups (p&gt;0.05), significant differences were observed between HR and loading intensities (p&lt;0.05). According to the results of multiple comparisons, the recoveries in HR and La levels were found to be significant in favor of the PAT group (p&lt;0.05). Discussion: It can be thought that football players increase the mitochondrial biogenesis, oxidative and lipid oxidation capacities of skeletal muscles due to adaptations to HIIT and similar heavy workouts. Depending on these developments in the athletes' condition, it can be said that all three recovery techniques affect the decrease of HR and La in the two-minute period. Conclusion: PR and PAR techniques were effective in reducing HR levels. AR and PAR techniques were effective in reducing La levels. Therefore, it can be said that the PAR technique is more effective in reducing both HR and La levels together. 

Pennogenin 3-O-β-Chacotrioside Attenuates Hypertrophied Lipid Accumulation by Enhancing Mitochondrial Oxidative Capacity.

Excessive lipid accumulation in adipocytes is a primary contributor to the development of metabolic disorders, including obesity. The consumption of bioactive compounds derived from natural sources has been recognized as being safe and effective in preventing and alleviating obesity. Therefore, we aimed to explore the antilipidemic effects of pennogenin 3-O-β-chacotrioside (P3C), a steroid glycoside, on hypertrophied 3T3-L1 adipocytes. Oil Red O and Nile red staining demonstrated a P3C-induced reduction in lipid droplet accumulation. Additionally, the increased expression of adipogenic and lipogenic factors, including PPARγ and C/EBPα, during the differentiation process was significantly decreased by P3C treatment at both the protein and mRNA levels. Furthermore, P3C treatment upregulated the expression of fatty acid oxidation-related genes such as PGC1α and CPT1a. Moreover, mitochondrial respiration and ATP generation increased following P3C treatment, as determined using the Seahorse XF analyzer. P3C treatment also increased the protein expression of mitochondrial oxidative phosphorylation in hypertrophied adipocytes. Our findings suggest that P3C could serve as a natural lipid-lowering agent, reducing lipogenesis and enhancing mitochondrial oxidative capacity. Therefore, P3C may be a promising candidate as a therapeutic agent for obesity-related diseases.

Effects of short-term exercise and endurance training on skeletal muscle mitochondria damage induced by particular matter, atmospherically relevant artificial PM2.5.

This study aimed to investigate the potential of short-term aerobic exercise to mitigate skeletal muscle mitochondrial damage following ambient PM2.5 exposure, and how 12 weeks of endurance training can enhance aerobic fitness to protect against such damage. Twenty-four male C57BL/6 J mice were split into sedentary (SED, n = 12) and endurance training (ETR, n = 12) groups. The ETR group underwent 12 weeks of training (10-15 m/min, 60 min/day, 4 times/week), confirmed by an Endurance Exercise Capacity (EEC) test. Post-initial training, the SED group was further divided into SSED (SED and sedentary, n = 6) and SPE (SED and PM2.5 + Exercise, n = 6). Similarly, the ETR group was divided into EEX (ETR and Exercise, n = 6) and EPE (ETR and PM2.5 + Exercise, n = 6). These groups underwent 1 week of atmospherically relevant artificial PM2.5 exposure and treadmill running (3 times/week). Following treatments, an EEC test was conducted, and mice were sacrificed for blood and skeletal muscle extraction. Blood samples were analyzed for oxidative stress indicators, while skeletal muscles were assessed for mitochondrial oxidative metabolism, antioxidant capacity, and mitochondrial damage using western blot and transmission electron microscopy (TEM). After 12 weeks of endurance training, the EEC significantly increased (p < 0.000) in the ETR group compared to the SED group. Following a one-week comparison among the four groups with atmospherically relevant artificial PM2.5 exposure and exercise treatment post-endurance training, the EEX group showed improvements in EEC, oxidative metabolism, mitochondrial dynamics, and antioxidant functions. Conversely, these factors decreased in the EPE group compared to the EEX. Additionally, within the SPE group, exercise effects were evident in HK2, LDH, SOD2, and GPX4, while no impact of short-term exercise was observed in all other factors. TEM images revealed no evidence of mitochondrial damage in both the SED and EEX groups, while the majority of mitochondria were damaged in the SPE group. The EPE group also exhibited damaged mitochondria, although significantly less than the SPE group. Atmospherically relevant artificial PM2.5 exposure can elevate oxidative stress, potentially disrupting the benefits of short-term endurance exercise and leading to mitochondrial damage. Nonetheless, increased aerobic fitness through endurance training can mitigate PM2.5-induced mitochondrial damage.

High-dose atorvastatin therapy progressively decreases skeletal muscle mitochondrial respiratory capacity in humans.

BACKGROUNDWhile the benefits of statin therapy on atherosclerotic cardiovascular disease are clear, patients often experience mild to moderate skeletal myopathic symptoms, the mechanism for which is unknown. This study investigated the potential effect of high-dose atorvastatin therapy on skeletal muscle mitochondrial function and whole-body aerobic capacity in humans.METHODSEight overweight (BMI, 31.9 ± 2.0) but otherwise healthy sedentary adults (4 females, 4 males) were studied before (day 0) and 14, 28, and 56 days after initiating atorvastatin (80 mg/d) therapy.RESULTSMaximal ADP-stimulated respiration, measured in permeabilized fiber bundles from muscle biopsies taken at each time point, declined gradually over the course of atorvastatin treatment, resulting in > 30% loss of skeletal muscle mitochondrial oxidative phosphorylation capacity by day 56. Indices of in vivo muscle oxidative capacity (via near-infrared spectroscopy) decreased by 23% to 45%. In whole muscle homogenates from day 0 biopsies, atorvastatin inhibited complex III activity at midmicromolar concentrations, whereas complex IV activity was inhibited at low nanomolar concentrations.CONCLUSIONThese findings demonstrate that high-dose atorvastatin treatment elicits a striking progressive decline in skeletal muscle mitochondrial respiratory capacity, highlighting the need for longer-term dose-response studies in different patient populations to thoroughly define the effect of statin therapy on skeletal muscle health.FUNDINGNIH R01 AR071263.

Mitochondrial transplantation: new challenges for cancer

This review discusses the uniqueness of mitochondria providing normal cellular functions and at the same time involved in many pathological conditions, and also analyzes the scientific literature to clarify the effectiveness of mitochondrial transplantation in cancer treatment. Being important and semi-autonomous organelles in cells, they are able to adapt their functions to the needs of the corresponding organ. The ability of mitochondria to reprogram is important for all cell types that can switch between resting and proliferation. At the same time, tumor mitochondria undergo adaptive changes to accelerate the reproduction of tumor cells in an acidic and hypoxic microenvironment. According to emerging data, mitochondria can go beyond the boundaries of cells and move between the cells of the body. Intercellular transfer of mitochondria occurs naturally in humans as a normal mechanism for repairing damaged cells. The revealed physiological mitochondrial transfer has become the basis for a modern form of mitochondrial transplantation, including autologous (isogenic), allogeneic, and even xenogenic transplantation. Currently, exogenous healthy mitochondria are used in treatment of several carcinomas, including breast cancer, pancreatic cancer, and glioma. Investigation of the functional activity of healthy mitochondria demonstrated and confirmed the fact that female mitochondria are more efficient in suppressing tumor cell proliferation than male mitochondria. However, tissue-specific sex differences in mitochondrial morphology and oxidative capacity were described, and few studies showed functional sex differences in mitochondria during therapy. The reviewed studies report that mitochondrial transplantation can be specifically targeted to a tumor, providing evidence for changes in tumor function after mitochondrial administration. Thus, the appearance of the most interesting data on the unique functions of mitochondria indicates the obvious need for mitochondrial transplantation.

Evolved changes in phenotype across skeletal muscles in deer mice native to high altitude.

The cold and hypoxic conditions at high altitude necessitate high metabolic O2 demands to support thermogenesis while hypoxia reduces O2 availability. Skeletal muscles play key roles in thermogenesis, but our appreciation of muscle plasticity and adaptation at high altitude has been hindered by past emphasis on only a small number of muscles. We examined this issue in deer mice (Peromyscus maniculatus). Mice derived from both high-altitude and low-altitude populations were born and raised in captivity and then acclimated as adults to normoxia or hypobaric hypoxia (12 kPa O2 for 6-8 wk). Maximal activities of citrate synthase (CS), cytochrome c oxidase (COX), β-hydroxyacyl-CoA dehydrogenase (HOAD), hexokinase (HK), pyruvate kinase (PK), and lactate dehydrogenase (LDH) were measured in 20 muscles involved in shivering, locomotion, body posture, ventilation, and mastication. Principal components analysis revealed an overall difference in muscle phenotype between populations but no effect of hypoxia acclimation. High-altitude mice had greater activities of mitochondrial enzymes and/or lower activities of PK or LDH across many (but not all) respiratory, limb, core and mastication muscles compared with low-altitude mice. In contrast, chronic hypoxia had very few effects across muscles. Further examination of CS in the gastrocnemius showed that population differences in enzyme activity stemmed from differences in protein abundance and mRNA expression but not from population differences in CS amino acid sequence. Overall, our results suggest that evolved increases in oxidative capacity across many skeletal muscles, at least partially driven by differences in transcriptional regulation, may contribute to high-altitude adaptation in deer mice.NEW & NOTEWORTHY Most previous studies of muscle plasticity and adaptation in high-altitude environments have focused on a very limited number of skeletal muscles. Comparing high-altitude versus low-altitude populations of deer mice, we show that a large number of muscles involved in shivering, locomotion, body posture, ventilation, and mastication exhibit greater mitochondrial enzyme activities in the high-altitude population. Therefore, evolved increases in mitochondrial oxidative capacity across skeletal muscles contribute to high-altitude adaptation.

Effects of chronic alcohol intoxication on aerobic exercise-induced adaptations in female mice.

Chronic alcohol intoxication decreases muscle strength/function and causes mitochondrial dysfunction. Aerobic exercise training improves mitochondrial oxidative capacity and increases muscle mass and strength. Presently, the impact of chronic alcohol on aerobic exercise-induced adaptations was investigated. Female C57BL/6Hsd mice were randomly assigned to one of four groups: control sedentary (CON SED; n = 26), alcohol sedentary (ETOH SED; n = 27), control exercise (CON EX; n = 28), and alcohol exercise (ETOH EX; n = 25). Exercise mice had running wheel access for 2 h a day, 7 days a week. All mice were fed either control or an alcohol-containing liquid diet. Grip strength testing and EchoMRI were performed before and after the interventions. After 6 wk, hindlimb muscles were collected for molecular analyses. A subset of mice performed a treadmill run to fatigue (RTF), then abstained from alcohol for 2 wk and repeated the RTF. Alcohol decreased lean mass and forelimb grip strength compared with control-fed mice. Alcohol blunted the exercise-induced increase in muscle mass (plantaris and soleus), type IIa fiber percentage in the plantaris, and run time to fatigue. Mitochondrial markers (Citrate synthase activity and Complex I-IV, COXIV and Cytochrome C protein expression) were increased with exercise regardless of ETOH in the gastrocnemius but not tibialis anterior muscle. Two weeks of alcohol abstinence improved RTF time in ETOH EX but not in ETOH SED. These data suggest that alcohol impairs some exercise-induced adaptations in skeletal muscle, but not all were negatively affected, indicating that exercise may be a beneficial behavior even while consuming alcohol.NEW & NOTEWORTHY Alcohol consumption during an aerobic exercise training period prevented training-induced increases in run to fatigue time and grip strength. Cessation of alcohol allowed for recovery of endurance performance within 2 wk. The worsened exercise performance after alcohol was unrelated to impairments in markers of mitochondrial health. Therefore, some adaptations to exercise training are impaired with alcohol use (endurance performance, muscle growth, and strength), while others remain mostly unaffected (mitochondrial health).

Exploring the links of skeletal muscle mitochondrial oxidative capacity, physical functionality, and mental well-being of cancer survivors

Physical impairments following cancer treatment have been linked with the toxic effects of these treatments on muscle mass and strength, through their deleterious effects on skeletal muscle mitochondrial oxidative capacity. Accordingly, we designed the present study to explore relationships of skeletal muscle mitochondrial oxidative capacity with physical performance and perceived cancer-related psychosocial experiences of cancer survivors. We assessed skeletal muscle mitochondrial oxidative capacity using in vivo phosphorus-31 magnetic resonance spectroscopy (31P MRS), measuring the postexercise phosphocreatine resynthesis time constant, τPCr, in 11 post-chemotherapy participants aged 34–70 years. During the MRS procedure, participants performed rapid ballistic knee extension exercise to deplete phosphocreatine (PCr); hence, measuring the primary study outcome, which was the recovery rate of PCr (τPCr). Patient-reported outcomes of psychosocial symptoms and well-being were assessed using the Patient-Reported Outcomes Measurement Information System and the 36-Item Short Form health survey (SF-36). Rapid bioenergetic recovery, reflected through a smaller value of τPCr was associated with worse depression (rho ρ = − 0.69, p = 0.018, and Cohen’s d = − 1.104), anxiety (ρ = − 0.61, p = .046, d = − 0.677), and overall mental health (ρ = 0.74, p = 0.010, d = 2.198) scores, but better resilience (ρ = 0.65, p = 0.029), and coping-self efficacy (ρ = 0.63, p = 0.04) scores. This is the first study to link skeletal muscle mitochondrial oxidative capacity with subjective reports of cancer-related behavioral toxicities. Further investigations are warranted to confirm these findings probing into the role of disease status and personal attributes in these preliminary results.

Marine fungus Aspergillus c1. sp metabolite activates the HSF1/PGC-1α axis, inducing a thermogenic program for treating obesity

Background and aims: Obesity is one of the most prevalent diseases worldwide with less ideal approved agents in clinic. Activating the HSF1/PGC-1α axis in adipose tissues has been reported to induce thermogenesis in mice, which presents a promising therapeutic avenue for obesity treatment. The present study aimed to identified novel natural HSF1 activator and evaluated the therapeutic effects of the newly discovered compound on obesity-associated metabolic disorders and the molecular mechanisms of these effects.Methods: Our previous reported HSF1/PGC-1α activator screening system was used to identify novel natural HSF1 activator. The PGC-1α luciferase activity, immunoblot, protein nuclear-translocation, immunofluorescence, chromatin immunoprecipitation assays were used to evaluate the activity of compound HN-001 in activating HSF1. The experiments of mitochondrial number measurement, TG assay and imaging, cellular metabolic assay, gene assays, and CRISPR/Cas 9 were applied for investigating the metabolic effect of HN-001 in C3H10-T1/2 adipocytes. The in vivo anti-obesity efficacies and beneficial metabolic effects of HN-001 were evaluated by performing body and fat mass quantification, plasma chemical analysis, GTT, ITT, cold tolerance test, thermogenesis analysis.Results: HN-001 dose- and time-dependently activated HSF1 and induced HSF1 nuclear translocation, resulting in an enhancement in binding with the gene Pgc-1α. This improvement induced activation of adipose thermogenesis and enhancement of mitochondrial oxidation capacity, thus inhibiting adipocyte maturation. Deletion of HSF1 in adipocytes impaired mitochondrial oxidation and abolished the above beneficial metabolic effects of HN-001, including adipocyte browning induction, improvements in mitogenesis and oxidation capacity, and lipid-lowering ability. In mice, HN-001 treatment efficiently alleviated diet-induced obesity and metabolic disorders. These changes were associated with increased body temperature in mice and activation of the HSF1/PGC-1α axis in adipose tissues. UCP1 expression and mitochondrial biogenesis were increased in both white and brown adipose tissues of HN-001-treated mice.Conclusion: These data indicate that HN-001 may have therapeutic potential for obesity-related metabolic diseases by increasing the capacity of energy expenditure in adipose tissues through a mechanism involving the HSF1/PGC-1α axis, which shed new light on the development of novel anti-obesity agents derived from marine sources.

A systematic review of the relationship between muscle oxygen dynamics and energy rich phosphates. Can NIRS help?

BackgroundPhosphocreatine dynamics provide the gold standard evaluation of in-vivo mitochondrial function and is tightly coupled with oxygen availability. Low mitochondrial oxidative capacity has been associated with health issues and low exercise performance.MethodsTo evaluate the relationship between near-infrared spectroscopy-based muscle oxygen dynamics and magnetic resonance spectroscopy-based energy-rich phosphates, a systematic review of the literature related to muscle oxygen dynamics and energy-rich phosphates was conducted. PRISMA guidelines were followed to perform a comprehensive and systematic search of four databases on 02-11-2021 (PubMed, MEDLINE, Scopus and Web of Science). Beforehand pre-registration with the Open Science Framework was performed. Studies had to include healthy humans aged 18–55, measures related to NIRS-based muscle oxygen measures in combination with energy-rich phosphates. Exclusion criteria were clinical populations, laboratory animals, acutely injured subjects, data that only assessed oxygen dynamics or energy-rich phosphates, or grey literature. The Effective Public Health Practice Project Quality Assessment Tool was used to assess methodological quality, and data extraction was presented in a table.ResultsOut of 1483 records, 28 were eligible. All included studies were rated moderate. The studies suggest muscle oxygen dynamics could indicate energy-rich phosphates under appropriate protocol settings.ConclusionArterial occlusion and exercise intensity might be important factors to control if NIRS application should be used to examine energetics. However, more research needs to be conducted without arterial occlusion and with high-intensity exercises to support the applicability of NIRS and provide an agreement level in the concurrent course of muscle oxygen kinetics and muscle energetics.Trial registrationhttps://osf.io/py32n/.Key points1. NIRS derived measures of muscle oxygenation agree with gold-standard measures of high energy phosphates when assessed in an appropriate protocol setting.2. At rest when applying the AO protocol, in the absence of muscle activity, an initial disjunction between the NIRS signal and high energy phosphates can been seen, suggesting a cascading relationship.3. During exercise and recovery a disruption of oxygen delivery is required to provide the appropriate setting for evaluation through either an AO protocol or high intensity contractions.

Neuroprotective Effect of Solid Lipid Nanoparticles Loaded with Lepidium sativum (L.) Seed Bioactive Components Enhance Bioavailability and Wnt/β-Catenin/Camk-II Signaling Cascade in SH-SY5Y Neuroblastoma Cells.

The primary pathological hallmark of Alzheimer's disease (AD) is the formation and accumulation of neurofibrillary tangles and plaques, which result from the aggregation of amyloid-β (Aβ) induced by oxidative stress. The effectiveness of Alzheimer's disease (AD) therapeutics significantly hinges on the drug's bioavailability and its ability to penetrate neuronal cells. The current investigation was designed as a first attempt to examine bio-fabricated Lepidium sativum (LS) seed-extract-loaded solid lipid nanoparticles (SLNps) to increase bioavailability and bioefficacy for the prevention of undifferentiated SH-SY5Y neuronal cells from oxidative stress induced by H2O2 and amyloid-β peptide (Aβ,1-42). The SLNps were fabricated using LS extract as a water phase and hyaluronic acid and chia seed fatty acids as a lipid phase, then confirmed and characterized using UV, Zeta size, and SEM methods. The biological safety of synthesized LS-SLNps has been determined using MTT assay and PI staining (nuclear damage) in hMSCs. LS-SLNp-pretreated neuronal cells were induced with oxidative stress and 2 µM of beta-amyloid (Aβ,1-42) fibrils; furthermore, the neuroprotective potential of LS-SLNps was determined through the quenching of oxidative stress, enhancing mitochondrial oxidative capacity, and immunoregulatory potential. Observations found that cells treated with both H2O2 and beta-amyloid (Aβ,1-42) fibrils showed decreased neuronal cell growth, nuclear damage, and mitochondrial membrane potential due to oxidative stress. However, SH-SY5Y cells pretreated with LS-SLNps for 24 h showed an increase in cell proliferation with uniform morphology and increased mitochondrial membrane potential compared to cells pretreated with LS alone. Gene expression analysis found that LS-SLNps increased the expression of Wnt 3a and 5a, which stimulated the canonical, β-catenin, and non-canonical Camk-II expressions of nerve cell growth factors, confirming the molecular-level reversal of neurodegenerative diseases.

The mitochondrial genome-encoded peptide MOTS-c interacts with Bcl-2 to alleviate nonalcoholic steatohepatitis progression

Nonalcoholic steatohepatitis (NASH) is a metabolism-associated fatty liver disease with accumulated mitochondrial stress, and targeting mitochondrial function is a potential therapy. The mitochondrial genome-encoded bioactive peptide MOTS-c plays broad physiological roles, but its effectiveness and direct targets in NASH treatment are still unclear. Here, we show that long-term preventive and short-term therapeutic effects of MOTS-c treatments alleviate NASH-diet-induced liver steatosis, cellular apoptosis, inflammation, and fibrosis. Mitochondrial oxidative capacity and metabolites profiling analysis show that MOTS-c significantly reverses NASH-induced mitochondrial metabolic deficiency. Moreover, we identify that MOTS-c directly interacts with the BH3 domain of antiapoptotic B cell lymphoma-2 (Bcl-2), increases Bcl-2 protein stability, and suppresses Bcl-2 ubiquitination. By using a Bcl-2 inhibitor or adeno-associated virus (AAV)-mediated Bcl-2 knockdown, we further confirm that MOTS-c improves NASH-induced mitochondrial dysfunction, inflammation, and fibrosis, which are dependent on Bcl-2 function. Therefore, our findings show that MOTS-c is a potential therapeutic agent to inhibit the progression of NASH.

Sirtuin3 ensures the metabolic plasticity of neurotransmission during glucose deprivation.

Neurotransmission is an energetically expensive process that underlies cognition. During intense electrical activity or dietary restrictions, the glucose level in the brain plummets, forcing neurons to utilize alternative fuels. However, the molecular mechanisms of neuronal metabolic plasticity remain poorly understood. Here, we demonstrate that glucose-deprived neurons activate the CREB and PGC1α transcriptional program, which induces expression of the mitochondrial deacetylase Sirtuin 3 (Sirt3) both in vitro and in vivo. We show that Sirt3 localizes to axonal mitochondria and stimulates mitochondrial oxidative capacity in hippocampal nerve terminals. Sirt3 plays an essential role in sustaining synaptic transmission in the absence of glucose by providing metabolic support for the retrieval of synaptic vesicles after release. These results demonstrate that the transcriptional induction of Sirt3 facilitates the metabolic plasticity of synaptic transmission.

Abstract 16878: Exercise Intolerance in Heart Failure With Preserved Ejection Fraction is More Closely Related to Energetic Decline During Exercise Than to Mitochondrial Oxidative Capacity in Recovery

Introduction: Heart failure (HF) with preserved ejection fraction (HFpEF) is associated with severe exercise intolerance (EI) and exertional fatigue. Impaired skeletal muscle high-energy phosphate metabolism has been reported in HFpEF patients and postulated as a potential contributor to EI. However, whether EI is more closely related to rapid energetic decline during exercise, or reduced mitochondrial oxidative capacity remains unknown. Hypothesis: We hypothesized that six-minute walk distance (6MWD) is more closely related to the rate of skeletal muscle energetic decline during exercise than mitochondrial oxidative capacity in HFpEF. Methods: Calf muscle energetics were measured by phosphorus magnetic resonance spectroscopy ( 31 PMRS). The rate of phosphocreatine (PCr) decline normalized to work performed during graded plantar flexion exercise to volitional fatigue and the time for PCr post-exercise recovery, an established metric inversely related to mitochondrial oxidative capacity, were measured in 64 HFpEF patients (age: 65 ± 11 years; 53% women). Results: The mean rate of PCr decline, PCr recovery time, and 6MWD were 52 ± 108 μmol/g wet weight/KJ, 80 ± 45 seconds, and 296 ± 109 meters, respectively. The 6MWD was inversely related to the rate of PCr decline (r = -0.46; P = 0.0002; Figure, A ) but not significantly related to the PCr recovery time (r = -0.06; P = 0.66; Figure, B ), as determined by Pearson’s correlation coefficients. Conclusions: EI, as measured by 6MWD, in HFpEF patients is closely associated with impaired skeletal muscle metabolism, specifically rapid skeletal muscle PCr decline during exercise rather than mitochondrial oxidative capacity. This suggests that impaired glycolytic metabolism and substrate delivery may contribute metabolically to EI in HFpEF patients.