Markers Of Mitochondrial Biogenesis Research Articles

Exposure to urban particulate matter (UPM) impairs mitochondrial dynamics in BV2 cells, triggering a mitochondrial biogenesis response.

World Health Organisation data suggest that up to 99% of the global population are exposed to air pollutants above recommended levels. Impacts to health range from increased risk of stroke and cardiovascular disease to chronic respiratory conditions, and air pollution may contribute to over 7 million premature deaths a year. Additionally, mounting evidence suggests that in utero or early life exposure to particulate matter (PM) in ambient air pollution increases the risk of neurodevelopmental impairment with obvious lifelong consequences. Identifying brain-specific cellular targets of PM is vital for determining its long-term consequences. We previously established that microglial-like BV2 cells were particularly sensitive to urban (U)PM-induced damage including reactive oxygen species production, which was abrogated by a mitochondrially targeted antioxidant. Here we extend those studies to find that UPM treatment causes a rapid impairment of mitochondrial function and increased mitochondrial fragmentation. However, there is a subsequent restoration of mitochondrial and therefore cell health occurring concomitantly with upregulated measures of mitochondrial biogenesis and mitochondrial load. Our data highlight that protecting mitochondrial function may represent a valuable mechanism to offset the effects of UPM exposure in the neonatal brain. KEY POINTS: Air pollution represents a growing risk to long-term health especially in early life, and the CNS is emerging a target for airborne particulate matter (PM). We previously showed that microglial-like BV2 cells were vulnerable to urban (U)PM exposure, which impaired cell survival and promoted reactive oxygen species production. Here we find that, following UPM exposure, BV2 mitochondrial membrane potential is rapidly reduced, concomitant with decreased cellular bioenergetics and increased mitochondrial fission. However, markers of mitochondrial biogenesis and mitochondrial mass are subsequently induced, which may represent a cellular mitigation strategy. As mitochondria are more vulnerable in the developing brain, exposure to air pollution may represent a greater risk to lifelong health in this cohort; conversely, promoting mitochondrial integrity may offset these risks.

Mitochondrial Biogenesis and Remodeling Protein Response to Bouts of High-load vs High-volume Resistance Training

Introduction: The effects of higher-load (HL; sets of 5 repetitions at 80% of 1-RM) versus higher-volume (HV; sets of 10 repetitions at 60% of 1-RM) resistance training (RT) on various molecular outcomes has proven to be similar between the two paradigms. However, the mitochondrial response to such training paradigms remains understudied. Therefore, the purpose of this study was to interrogate protein level responses of HL vs HV RT in proteins related to mitochondrial biogenesis and remodeling. We hypothesized that HV RT would have a greater effect on mitochondrial markers of biogenesis and remodeling than HL RT. Methods: Fifteen resistance trained males participated in 6 weeks of unilateral RT (single-leg leg press and single-leg leg extension) where each leg was randomly assigned to undergo either the HL or HV RT. Biopsies of the vastus lateralis were collected from both legs at PRE and POST and western blots analysis was used to assess mitochondrial proteins related to biogenesis and remodeling. The data collected were analyzed using two-way within-subject repeated measures ANOVAs. Results: Our results show no statistically significant effect of RT condition on markers of mitochondrial biogenesis and remodeling. However, there was a main effect of time in markers of both mitochondrial biogenesis and remodeling with MFN1 decreasing (p = 0.007, ƞ2 = 0.234) and PINK1 increasing (p = 0.009, ƞ2 = 0.222) from PRE to POST. Conclusion: HL and HV RT paradigms do not differentially affect the mitochondrial markers assessed, and our hypothesis that HV RT would elicit a greater response in markers of mitochondrial biogenesis and remodeling was not supported. However, our data supports the idea that mitochondrial adaptations can be stimulated regardless of the RT paradigm. This discovery could be advantageous for individuals selecting a mode of RT training that is most likely to result in the greatest exercise adherence as well as provide multiple health benefits. Furthermore, research into RT induced mitochondrial adaptations between sexes remains understudied, thus future investigations into these bioenergetic responses is warranted. Funding for assays and participant compensation was provided through discretionary laboratory funds from MR. Additionally, a portion of CG Vann’s effort was funded through the National Institutes of Health (R01AG054840). 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.

Exogenous erythropoietin increases hematological status, fat oxidation, and aerobic performance in males following prolonged strenuous training.

This study investigated the effects of EPO on hemoglobin (Hgb) and hematocrit (Hct), time trial (TT) performance, substrate oxidation, and skeletal muscle phenotype throughout 28 days of strenuous exercise. Eight males completed this longitudinal controlled exercise and feeding study using EPO (50 IU/kg body mass) 3×/week for 28 days. Hgb, Hct, and TT performance were assessed PRE and on Days 7, 14, 21, and 27 of EPO. Rested/fasted muscle obtained PRE and POST EPO were analyzed for gene expression, protein signaling, fiber type, and capillarization. Substrate oxidation and glucose turnover were assessed during 90-min of treadmill load carriage (LC; 30% body mass; 55 ± 5% V̇O2peak) exercise using indirect calorimetry, and 6-6-[2H2]-glucose PRE and POST. Hgb and Hct increased, and TT performance improved on Days 21 and 27 compared to PRE (p < 0.05). Energy expenditure, fat oxidation, and metabolic clearance rate during LC increased (p < 0.05) from PRE to POST. Myofiber type, protein markers of mitochondrial biogenesis, and capillarization were unchanged PRE to POST. Transcriptional regulation of mitochondrial activity and fat metabolism increased from PRE to POST (p < 0.05). These data indicate EPO administration during 28 days of strenuous exercise can enhance aerobic performance through improved oxygen carrying capacity, whole-body and skeletal muscle fat metabolism.

Lactate regulates respiratory efficiency and mitochondrial dynamics in primary rat podocytes

Podocytes are crucial for regulating glomerular permeability. They have foot processes that are integral to the renal filtration barrier. Understanding their energy metabolism could shed light on the pathogenesis of filtration barrier injury. Lactate has been increasingly recognized as more than a waste product and has emerged as a significant metabolic fuel and reserve. The recent identification of lactate transporters in podocytes, the expression of which is modulated by glucose levels and lactate, highlights lactate’s relevance. The present study investigated the impact of lactate on podocyte respiratory efficiency and mitochondrial dynamics. We confirmed lactate oxidation in podocytes, suggesting its role in cellular energy production. Under conditions of glucose deprivation or lactate supplementation, a significant shift was seen toward oxidative phosphorylation, reflected by an increase in the oxygen consumption rate/extracellular acidification rate ratio. Notably, lactate dehydrogenase A (LDHA) and lactate dehydrogenase B (LDHB) isoforms, which are involved in lactate conversion to pyruvate, were detected in podocytes for the first time. The presence of lactate led to higher intracellular pyruvate levels, greater LDH activity, and higher LDHB expression. Furthermore, lactate exposure increased mitochondrial DNA-to-nuclear DNA ratios and resulted in upregulation of the mitochondrial biogenesis markers peroxisome proliferator-activated receptor coactivator-1α and transcription factor A mitochondrial, regardless of glucose availability. Changes in mitochondrial size and shape were observed in lactate-exposed podocytes. These findings suggest that lactate is a pivotal energy source for podocytes, especially during energy fluctuations. Understanding lactate’s role in podocyte metabolism could offer insights into renal function and pathologies that involve podocyte injury.

Altered Glycolysis, Mitochondrial Biogenesis, Autophagy and Apoptosis in Peritoneal Endometriosis in Adolescents.

Energy metabolism plays a pivotal role in the pathogenesis of endometriosis. For the initial stages of the disease in adolescents, this aspect remains unexplored. The objective of this paper was to analyze the association of cellular and endosomal profiles of markers of glycolysis, mitochondrial biogenesis, apoptosis, autophagy and estrogen signaling in peritoneal endometriosis (PE) in adolescents. We included 60 girls aged 13-17 years in a case-control study: 45 with laparoscopically confirmed PE (main group) and 15 with paramesonephric cysts (comparison group). Samples of plasma and peritoneal fluid exosomes, endometrioid foci and non-affected peritoneum were tested for estrogen receptor (Erα/β), hexokinase (Hex2), pyruvate dehydrogenase kinase (PDK1), glucose transporter (Glut1), monocarboxylate transporters (MCT1 and MCT2), optic atrophy 1 (OPA1, mitochondrial fusion protein), dynamin-related protein 1 (DRP1, mitochondrial fission protein), Bax, Bcl2, Beclin1, Bnip3, P38 mitogen-activated protein kinase (MAPK), hypoxia-inducible factor 1 (Hif-1α), mitochondrial voltage-dependent anion channel (VDAC) and transforming growth factor (TGFβ) proteins as markers of estrogen signaling, glycolysis rates, mitochondrial biogenesis and damage, apoptosis and autophagy (Western-Blot and PCR). The analysis identified higher levels of molecules associated with proliferation (ERβ), glycolysis (MCT2, PDK1, Glut1, Hex2, TGFβ and Hif-1α), mitochondrial biogenesis (OPA1, DRP1) and autophagy (P38, Beclin1 and Bnip3) and decreased levels of apoptosis markers (Bcl2/Bax) in endometrioid foci compared to non-affected peritoneum and that in the comparison group (p < 0.05). Patients with PE had altered profiles of ERβ in plasma and peritoneal fluid exosomes and higher levels of Glut1, MCT2 and Bnip3 in plasma exosomes (p < 0.05). The results of the differential expression profiles indicate microenvironment modification, mitochondrial biogenesis, estrogen reception activation and glycolytic switch along with apoptosis suppression in peritoneal endometrioid foci already in adolescents.

Skeletal muscle adaptations to high-intensity, low-volume concurrent resistance and interval training in recreationally active men and women.

This study compared the structural and cellular skeletal muscle factors underpinning adaptations in maximal strength, power, aerobic capacity, and lean body mass to a 12-week concurrent resistance and interval training program in men and women. Recreationally active women and men completed three training sessions per week consisting of high-intensity, low-volume resistance training followed by interval training performed using a variety upper and lower body exercises representative of military occupational tasks. Pre- and post-training vastus lateralis muscle biopsies were analyzed for changes in muscle fiber type, cross-sectional area, capillarization, and mitochondrial biogenesis marker content. Changes in maximal strength, aerobic capacity, and lean body mass (LBM) were also assessed. Training elicited hypertrophy of type I (12.9%; p = 0.016) and type IIa (12.7%; p = 0.007) muscle fibers in men only. In both sexes, training decreased type IIx fiber expression (1.9%; p = 0.046) and increased total PGC-1α (29.7%, p < 0.001) and citrate synthase (11.0%; p < 0.014) content, but had no effect on COX IV content or muscle capillarization. In both sexes, training increased maximal strength and LBM but not aerobic capacity. The concurrent training program was effective at increasing strength and LBM but not at improving aerobic capacity or skeletal muscle adaptations underpinning aerobic performance.

Effect of CB1 Receptor Deficiency on Mitochondrial Quality Control Pathways in Gastrocnemius Muscle.

This study aims to explore the complex role of cannabinoid type 1 receptor (CB1) signaling in the gastrocnemius muscle, assessing physiological processes in both CB1+/+ and CB1-/- mice. The primary focus is to enhance our understanding of how CB1 contributes to mitochondrial homeostasis. At the tissue level, CB1-/- mice exhibit a substantial miRNA-related alteration in muscle fiber composition, characterized by an enrichment of oxidative fibers. CB1 absence induces a significant increase in the oxidative capacity of muscle, supported by elevated in-gel activity of Complex I and Complex IV of the mitochondrial respiratory chain. The increased oxidative capacity is associated with elevated oxidative stress and impaired antioxidant defense systems. Analysis of mitochondrial biogenesis markers indicates an enhanced capacity for new mitochondria production in CB1-/- mice, possibly adapting to altered muscle fiber composition. Changes in mitochondrial dynamics, mitophagy response, and unfolded protein response (UPR) pathways reveal a dynamic interplay in response to CB1 absence. The interconnected mitochondrial network, influenced by increased fusion and mitochondrial UPR components, underlines the dual role of CB1 in regulating both protein quality control and the generation of new mitochondria. These findings deepen our comprehension of the CB1 impact on muscle physiology, oxidative stress, and MQC processes, highlighting cellular adaptability to CB1-/-. This study paves the way for further exploration of intricate signaling cascades and cross-talk between cellular compartments in the context of CB1 and mitochondrial homeostasis.

Immunohistochemical Analysis of Mitochondrial Dynamics in Different Zones of the Hippocampus during Experimental Modeling of Alzheimer's Disease.

We performed a comparative assessment of the immunohistochemical distribution of markers of mitochondrial fission (Drp-1), mitochondrial fusion (Mfn-2), and mitochondrial biogenesis (PGC-1α) in pyramidal neurons of different zones of the hippocampus in mice with intrahippocampal administration of β-amyloid peptide 25-35. The most pronounced changes in the dynamics associated with a decrease in the amount of the fission marker and an increase in the amount of the fusion marker were observed in the CA3 field on day 38 after peptide administration. In the CA1 field, a significant decrease in the marker of mitochondrial biogenesis PGC-1α was found on day 38, which can indicate a decrease in the intensity of mitochondrial biogenesis. Early mitochondrial changes can play an important role in the pathogenesis of all types of memory impairment in Alzheimer's disease.

Inhibitory effects of naringenin on estrogen deficiency-induced obesity via regulation of mitochondrial dynamics and AMPK activation associated with white adipose tissue browning

AimsPost-ovariectomy (OVX) changes in hormones induce obesity and white adipose tissue (WAT) inflammation. Increased energy expenditure via WAT browning is a novel therapeutic strategy for treating obesity. Naringenin (NAR) reduces inflammation and lipogenesis in obesity and attenuates estrogen deficiency-associated metabolic disorders; however, its role in WAT browning remains unclear. Materials and methodsWe investigated NAR ability to inhibit estrogen deficiency-associated obesity in vivo using a rat model and in vitro using 3T3-L1 adipocytes. Key findingsNAR significantly decreased the body weight and WAT mass of rats. O2 consumption, CO2 production, and energy expenditure were significantly lower in the OVX group than in the sham group, but NAR treatment reversed these effects of OVX. NAR treatment markedly improved glucose intolerance and lipid profiles as well as leptin, adiponectin, and irisin levels. NAR upregulated markers of browning and mitochondrial biogenesis in inguinal WAT. Moreover, it enhanced markers of mitochondrial fusion and inhibited fission via activating the AMP-activated protein kinase pathway. Similar results were observed in 3T3-L1 adipocytes. Moreover, NAR-induced mitochondrial biogenesis and fusion were suppressed by dorsomorphin (an AMP-activated protein kinase inhibitor). SignificanceNAR alleviates obesity and metabolic dysfunction through the induction of WAT browning achieved via the modulation of AMP-activated protein kinase-regulated mitochondrial dynamics in WATs. NAR supplementation may therefore represent a potential intervention for preventing postmenopausal adipose tissue dysregulation.

Sucrose-Enriched and Carbohydrate-Free High-Fat Diets Distinctly Affect Substrate Metabolism in Oxidative and Glycolytic Muscles of Rats.

Skeletal muscle substrate preference for fuel is largely influenced by dietary macronutrient availability. The abundance of dietary carbohydrates promotes the utilization of glucose as a substrate for energy production, whereas an abundant dietary fat supply elevates rates of fatty acid (FA) oxidation. The objective of this study was to determine whether an obesogenic, high-fat, sucrose-enriched (HFS) diet or a carbohydrate-free ketogenic diet (KD) exert distinct effects on fat, glucose, and ketone metabolism in oxidative and glycolytic skeletal muscles. Male Wistar rats were fed either a HFS diet or a KD for 16 weeks. Subsequently, the soleus (Sol), extensor digitorum longus (EDL), and epitrochlearis (Epit) muscles were extracted to measure palmitate oxidation, insulin-stimulated glucose metabolism, and markers of mitochondrial biogenesis, ketolytic capacity, and cataplerotic and anaplerotic machinery. Sol, EDL, and Epit muscles from KD-fed rats preserved their ability to elevate glycogen synthesis and lactate production in response to insulin, whereas all muscles from rats fed with the HFS diet displayed blunted responses to insulin. The maintenance of metabolic flexibility with the KD was accompanied by muscle-fiber-type-specific adaptive responses. This was characterized by the Sol muscle in KD-fed rats enhancing mitochondrial biogenesis and ketolytic capacity without elevating its rates of FA oxidation in comparison with that in HFS feeding. Conversely, in the Epit muscle, rates of FA oxidation were increased, whereas the ketolytic capacity was markedly reduced by the KD in comparison with that by HFS feeding. In the EDL muscle, the KD also increased rates of FA oxidation, although it did so without altering its ketolytic capacity when compared to HFS feeding. In conclusion, even though obesogenic and ketogenic diets have elevated contents of fat and alter whole-body substrate partitioning, these two dietary interventions are associated with opposite outcomes with respect to skeletal muscle metabolic flexibility.

Effects of environmental hypoxia on the goldfish skeletal muscle: Focus on oxidative status and mitochondrial dynamics

The skeletal muscle is a highly plastic tissue. Its ability to respond to external stimuli and challenges allows it to face the functional needs of the organism. In the goldfish Carassius auratus, a model of hypoxia resistance, exposure to reduced oxygen is accompanied by an improvement of the swimming performance, relying on a sustained contractile behavior of the skeletal muscle. At the moment, limited information is available on the mechanisms underlying these responses.We here evaluated the effects of short- (4 days) and long- (20 days) term exposure to moderate water hypoxia on the goldfish white skeletal muscle, focusing on oxidative status and mitochondrial dynamics. No differences in lipid peroxidation, measured as 2-thiobarbituric acid-reacting substances (TBARS), and oxidatively modified proteins (OMP) were detected in animals exposed to hypoxia with respect to their normoxic counterparts. Exposure to short-term hypoxia was characterized by an enhanced SOD activity and expression, paralleled by increased levels of Nrf2, a regulator of the antioxidant cell response, and HSP70, a chaperone also acting as a redox sensor. The expression of markers of mitochondrial biogenesis (TFAM) and abundance (VDAC) and of the mtDNA/nDNA ratio was similar under normoxia and under both short- and long-term hypoxia, thus excluding a rearrangement of the mitochondrial apparatus. Only an increase of PGC1α (a transcription factor involved in mitochondrial dynamics) was detected after 20 days of hypoxia. Our results revealed novel aspects of the molecular mechanisms that in the goldfish skeletal muscle may sustain the response to hypoxia, thus contributing to adequate tissue function to organism requirements.

CXXC5 mitigates P. gingivalis-inhibited cementogenesis by influencing mitochondrial biogenesis

BackgroundCementoblasts on the tooth-root surface are responsible for cementum formation (cementogenesis) and sensitive to Porphyromonas gingivalis stimulation. We have previously proved transcription factor CXXC-type zinc finger protein 5 (CXXC5) participates in cementogenesis. Here, we aimed to elucidate the mechanism in which CXXC5 regulates P. gingivalis-inhibited cementogenesis from the perspective of mitochondrial biogenesis.MethodsIn vivo, periapical lesions were induced in mouse mandibular first molars by pulp exposure, and P. gingivalis was applied into the root canals. In vitro, a cementoblast cell line (OCCM-30) was induced cementogenesis and submitted for RNA sequencing. These cells were co-cultured with P. gingivalis and examined for osteogenic ability and mitochondrial biogenesis. Cells with stable CXXC5 overexpression were constructed by lentivirus transduction, and PGC-1α (central inducer of mitochondrial biogenesis) was down-regulated by siRNA transfection.ResultsPeriapical lesions were enlarged, and PGC-1α expression was reduced by P. gingivalis treatment. Upon apical inflammation, Cxxc5 expression decreased with Il-6 upregulation. RNA sequencing showed enhanced expression of osteogenic markers, Cxxc5, and mitochondrial biogenesis markers during cementogenesis. P. gingivalis suppressed osteogenic capacities, mitochondrial biogenesis markers, mitochondrial (mt)DNA copy number, and cellular ATP content of cementoblasts, whereas CXXC5 overexpression rescued these effects. PGC-1α knockdown dramatically impaired cementoblast differentiation, confirming the role of mitochondrial biogenesis on cementogenesis.ConclusionsCXXC5 is a P. gingivalis-sensitive transcription factor that positively regulates cementogenesis by influencing PGC-1α-dependent mitochondrial biogenesis.A5vAuiTS6Tkq1RfziX_nr_Video

All-trans-retinoic acid and valproic acid: A combinatorial approach for the treatment of nephrotic syndrome

Massive proteinuria, oedema, hypoalbuminemia, and hyperlipidemia are the hallmarks of nephrotic syndrome (NS). Recently, epigenetic pathways in renal diseases have been identified. The present work hypothesizes using the combination of two epigenetic drugs all-trans retinoic acid (ATRA) and valproic acid (VPA) as a prospective treatment method to lessen NS-related glomerulosclerosis, fibrosis, and increased renal function parameters along with attenuating inflammation and improving overall mitochondrial health. To induce NS, doxorubicin (8.5 mg/kg, n = 6) was injected intravenously into female Sprague Dawley rats. After 28 days, ATRA and VPA were orally administered to the rats, alone and in combination at a dose of 5 mg/kg (n = 6) and 200 mg/kg (n = 6) in sesame oil and saline, respectively. Prednisolone (3 mg/kg in saline; n = 6) was used as standard. Following 21-daytreatment period, the rats were sacrificed prior to which 24hrs urine samples were obtained. Blood samples were collected and kidneys were extracted for further analyses. Renal function parameters (proteinuria, BUN, albumin, creatinine), levels of tissue reengineering and fibrosis markers (TGF-β, MMP2 activity), cholesterol and triglyceride levels were significantly improved in the ATRA and VPA combination group as compared to positive control group. Histopathological analyses revealed a reduction in inflammation, glomerulosclerosis and fibrosis. The inflammatory markers, namely TNF-α, IL-1β, IL-6, NF-κB, determined by ELISA were downregulated. Mitochondrial biogenesis markers viz. PGC-1α, TFAM, NRF1, Nrf2, PPAR-γ, KEAP-1, analysed by RT-qPCR were upregulated thereby showing a significant improvement in the combination group as compared to positive control and standard group. The study overall contributes to a novel approach to treating NS and our findings will surely drive additional exploratory preclinical and clinical studies.

Церебропротекторное действие нового аналога халкона при экспериментальной черепно-мозговой травме. Фокус на митохондриальный биогенез и нейровоспаление

INTRODUCTION: Currently, the treatment of traumatic brain injuries requires a comprehensive approach which includes, among other things, the use of drugs possessing cerebroprotective activity. As a rule, the action of cerebral protectors is concentrated on separate pathophysiological mechanisms of brain damage, for example, the mitochondrial dysfunction. AIM: To study the effect of a new chalcone analogue on changes in the processes of mitochondrial biogenesis and neuroinflammation in rats with experimental traumatic brain injury. MATERIALS AND METHODS: In the work, rats of Wistar line were used in whom a traumatic brain injury was modeled by a single exposure of the parietal region of the skull to a freely falling weight. The studied compound and the comparison drug, choline alfoscerate, were introduced orally within 7 days after injury, at doses of 50 mg/kg and 150 mg/kg, respectively. The behavioral reactions of the animals were evaluated in the ‘open field’ test. The intensity of neuroinflammation was determined by changes in the concentrations of IL-1β, IL-6 and TNF-α in the brain tissue. The markers of mitochondrial biogenesis were changes in the activity of succinate dehydrogenase and cytochrome c oxidase. RESULTS: In the course of the work, it was found that the use of a new chalcone analogue in conditions of experimental traumatic brain injury facilitates an increase in locomotor and exploratory activity in rats, as well as reduces the level of anxiety. With the introduction of the studied compound, a decrease in the intensity of neuroinflammation reactions was observed, as evidenced by a decrease in the content of IL-1β by 58.8% (p &lt; 0.05), IL-6 by 55.0% (p &lt; 0.05) and TNF-α by 50.7% (p &lt; 0.05) compared with untreated animals. The activity of succinate dehydrogenase and cytochrome c oxidase increased by 63.6% (p &lt; 0.05) and 27.6% (p &lt; 0.05), respectively, when using the studied chalcone analogue. To note, the activity of enzymatic markers of mitochondrial biogenesis in rats treated with chalcone analogue was higher than in animals who were introduced choline alfoscerate. CONCLUSIONS: The study showed for prospects of further investigation of a new chalcone analogues as a complex cerebroprotective agent for treatment of sequelae of a traumatic brain injury.

Western diet-induced obesity results in brain mitochondrial dysfunction in female Ossabaw swine.

Diet-induced obesity is implicated in the development of a variety of neurodegenerative disorders. Concurrently, the loss of mitochondrial Complex I protein or function is emerging as a key phenotype across an array of neurodegenerative disorders. Therefore, the objective of this study was to determine if Western diet (WD) feeding in swine [carbohydrate = 40.8% kCal (17.8% of total calories from high fructose corn syrup), protein = 16.2% kcal, fat = 42.9% kCal, and 2% cholesterol] would result in Complex I syndrome pathology. To characterize the effects of WD-induced obesity on brain mitochondria in swine, high resolution respirometry measurements from isolated brain mitochondria, oxidative phosphorylation Complex expression, and indices of oxidative stress and mitochondrial biogenesis were assessed in female Ossabaw swine fed a WD for 6-months. In line with Complex I syndrome, WD feeding severely reduced State 3 Complex I, State 3 Complex I and II, and uncoupled mitochondrial respiration in the hippocampus and prefrontal cortex (PFC). State 3 Complex I mitochondrial respiration in the PFC inversely correlated with serum total cholesterol. WD feeding also significantly reduced protein expression of oxidative phosphorylation Complexes I-V in the PFC. WD feeding significantly increased markers of antioxidant defense and mitochondrial biogenesis in the hippocampi and PFC. These data suggest WD-induced obesity may contribute to Complex I syndrome pathology by increasing oxidative stress, decreasing oxidative phosphorylation Complex protein expression, and reducing brain mitochondrial respiration. Furthermore, these findings provide mechanistic insight into the clinical link between obesity and mitochondrial Complex I related neurodegenerative disorders.

Betanin from Beetroot (Beta vulgaris L.) Regulates Lipid Metabolism and Promotes Fat Browning in 3T3-L1 Adipocytes.

Fat browning, which converts white adipose tissue to brown, has attracted attention as a promising strategy for the treatment of obesity. Betanin (BT) has been reported to have potential anti-obesity activity. 3T3-L1 cells were differentiated for 7 days during BT treatment. The BT concentration range for the study was determined using an MTT assay, and lipid accumulation was evaluated by Oil-Red-O staining. The expression of protein level was analyzed by Western blot. Immunofluorescence images were performed with confocal microscopy to visually show the amount and location of thermogenesis factor uncoupling protein1 (UCP1) and mitochondria. qRT-PCR was performed to evaluate mRNA expression. BT inhibited lipid accumulation and increased the expression of UCP1, peroxisome-proliferator-activated receptor gamma (PPARγ), and PPARγ coactivator-1 alpha (PGC-1α). In addition, the increases in beige adipocyte-specific markers were observed, supporting BT-mediated browning of the fat tissue. The UCP1 was localized in the inner membrane of the mitochondria, and its expression was associated with mitochondrial activation. Consistent with this, the mRNA expression of mitochondrial biogenesis markers increased in 3T3-L1 cells after BT treatment. Immunofluorescence staining also indicated an increased number of mitochondria and UCP1, respectively. Moreover, BT inhibited lipogenesis and enhanced lipolysis and fatty acid oxidation. This mechanism has been suggested to be mediated by an adenosine monophosphate-activated protein kinase (AMPK) pathway. BT induces fat browning and regulates lipid metabolism via the AMPK-mediated pathway in 3T3-L1 cells, suggesting that BT can be a promising candidate for controlling obesity.

Tom70-regulated mitochondrial biogenesis via TFAM improves hypoxia-induced dysfunction of pulmonary vascular endothelial cells and alleviates hypoxic pulmonary hypertension

BackgroundHypoxic pulmonary hypertension (HPH) is a common type of pulmonary hypertension and characterized by pulmonary vascular remodeling and constriction. A large number of studies have shown that pulmonary vascular endothelial cells (PVECs) dysfunction plays an important role in the initiation and development stages of HPH, but the mechanism of PVECs dysfunction after hypoxia remains unclear. In this study, we explored the exact mechanism of PVECs dysfunction after hypoxia.MethodsIn vitro, we used primary cultured PVECs hypoxia model to mimic HPH injury. We detected the expressions of mitochondrial biogenesis markers, mitochondrial transcription factor A (TFAM) level inside mitochondria, mitochondrial quantity and function, and the components expressions of translocase of outer mitochondrial membrane (TOM) at 24 h after hypoxia. To explore the effects of Tom70 on mitochondrial biogenesis and functions of PVECs after hypoxia, Tom70 overexpression adenovirus was constructed, and the expressions of mitochondrial biogenesis markers, TFAM level inside mitochondria, mitochondrial quantity and function, and the functions of PVECs were detected. And in vivo, we used cre-dependent overexpression adenovirus of Tom70 in the Cdh5-CreERT2 mouse model of HPH to verify the role of upregulating PVECs Tom70 in improving HPH.ResultsHypoxia obviously increased the expressions of mitochondrial biogenesis markers for PGC-1α, NRF-1 and TFAM, but reduced the content of TFAM in mitochondria and the quantity and functions of mitochondria. In addition, only Tom70 expression among the TOM components was significantly decreased after hypoxia, and up-regulation of Tom70 significantly increased the content of TFAM in mitochondria of PVECs by transporting TFAM into mitochondria after hypoxia, enhanced the quantity and functions of mitochondria, improved the functions of PVECs, and ultimately alleviated HPH.ConclusionThe findings of present study demonstrated that hypoxia induced the decreased expression of Tom70 in PVECs, reduced the mitochondrial biogenesis-associated TFAM protein transporting into mitochondria, inhibited mitochondrial biogenesis, caused PVECs injury, and prompted the formation of HPH. However, up-regulation of Tom70 abolished the hypoxia-induced injurious effects on PVECs and alleviated HPH.

Mitochondrial Dysfunction and Decreased Cytochrome c in Cell and Animal Models of Machado-Joseph Disease.

Mitochondrial dysfunction has been described in many neurodegenerative disorders; however, there is less information regarding mitochondrial deficits in Machado-Joseph disease (MJD), a polyglutamine (polyQ) disorder caused by CAG repeat expansion in the ATXN3 gene. In the present study, we characterized the changes in mitochondrial function and biogenesis markers in two MJD models, CMVMJD135 (MJD135) transgenic mice at a fully established phenotype stage and tetracycline-regulated PC6-3 Q108 cell line expressing mutant ataxin-3 (mATXN3). We detected mATXN3 in the mitochondrial fractions of PC6-3 Q108 cells, suggesting the interaction of expanded ATXN3 with the organelle. Interestingly, in both the cerebella of the MJD135 mouse model and in PC6-3 Q108 cells, we found decreased mitochondrial respiration, ATP production and mitochondrial membrane potential, strongly suggesting mitochondrial dysfunction in MJD. Also, in PC6-3 Q108 cells, an additional enhanced glycolytic flux was observed. Supporting the functional deficits observed in MJD mitochondria, MJD135 mouse cerebellum and PC6-3 Q108 cells showed reduced cytochrome c mRNA and protein levels. Overall, our findings show compromised mitochondrial function associated with decreased cytochrome c levels in both cell and animal models of MJD.

Mitochondrial DNA Copy Number Drives the Penetrance of Acute Intermittent Porphyria.

No published study has investigated the mitochondrial count in patients suffering from acute intermittent porphyria (AIP). In order to determine whether mitochondrial content can influence the pathogenesis of porphyria, we measured the mitochondrial DNA (mtDNA) copy number in the peripheral blood cells of 34 patients and 37 healthy individuals. We found that all AIP patients had a low number of mitochondria, likely as a result of a protective mechanism against an inherited heme synthesis deficiency. Furthermore, we identified a close correlation between disease penetrance and decreases in the mitochondrial content and serum levels of PERM1, a marker of mitochondrial biogenesis. In a healthy individual, mitochondrial count is usually modulated to fit its ability to respond to various environmental stressors and bioenergetic demands. In AIP patients, coincidentally, the phenotype only manifests in response to endogenous and exogenous triggers factors. Therefore, these new findings suggest that a deficiency in mitochondrial proliferation could affect the individual responsiveness to stimuli, providing a new explanation for the variability in the clinical manifestations of porphyria. However, the metabolic and/or genetic factors responsible for this impairment remain to be identified. In conclusion, both mtDNA copy number per cell and mitochondrial biogenesis seem to play a role in either inhibiting or promoting disease expression. They could serve as two novel biomarkers for porphyria.

Structural and functional impairments of skeletal muscle in patients with postacute sequelae of SARS-CoV-2 infection.

Following acute coronavirus disease 2019 (COVID-19), a substantial proportion of patients showed symptoms and sequelae for several months, namely the postacute sequelae of COVID-19 (PASC) syndrome. Major phenomena are exercise intolerance, muscle weakness, and fatigue. We aimed to investigate the physiopathology of exercise intolerance in patients with PASC syndrome by structural and functional analyses of skeletal muscle. At least 3 mo after infection, nonhospitalized patients with PASC (n = 11, age: 54 ± 11 yr; PASC) and patients without long-term symptoms (n = 12, age: 49 ± 9 yr; CTRL) visited the laboratory on four nonconsecutive days. Spirometry, lung diffusion capacity, and quality of life were assessed at rest. A cardiopulmonary incremental exercise test was performed. Oxygen consumption (V̇o2) kinetics were determined by moderate-intensity exercises. Muscle oxidative capacity (k) was assessed by near-infrared spectroscopy. Histochemical analysis, O2 flux (JO2) by high-resolution respirometry, and quantification of key molecular markers of mitochondrial biogenesis and dynamics were performed in vastus lateralis biopsies. Pulmonary and cardiac functions were within normal range in all patients. V̇o2peak was lower in PASC than CTRL (24.7 ± 5.0 vs. 32.9 ± 7.4 mL·min-1·kg-1, respectively, P < 0.05). V̇o2 kinetics was slower in PASC than CTRL (41 ± 12 vs. 30 ± 9 s-1, P < 0.05). k was lower in PASC than CTRL (1.54 ± 0.49 vs. 2.07 ± 0.51 min-1, P < 0.05). Citrate synthase, peroxisome proliferator-activated receptor-γ coactivator (PGC)1α, and JO2 for mitochondrial complex II were significantly lower in PASC vs. CTRL (all P values <0.05). In our cohort of patients with PASC, we showed limited exercise tolerance mainly due to "peripheral" determinants. Substantial reductions were observed for biomarkers of mitochondrial function, content, and biogenesis. PASC syndrome, therefore, appears to negatively impact skeletal muscle function, although the disease is a heterogeneous condition.NEW & NOTEWORTHY Several months after mild acute SARS-CoV-2 infection, a substantial proportion of patients present persisting, and often debilitating, symptoms and sequelae. These patients show reduced quality of life due to exercise intolerance, muscle weakness, and fatigue. The present study supports the hypothesis that "peripheral" impairments at skeletal muscle level, namely, reduced mitochondrial function and markers of mitochondrial biogenesis, are major determinants of exercise intolerance and fatigue, "central" phenomena at respiratory, and cardiac level being less relevant.