Markers Of Mitochondrial Biogenesis Research Articles

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.

Abstract P373: Nuclear Receptor 4As (NR4A) Expression In Patients With Chronic Kidney Disease

Background: Nuclear Receptor 4As (NR4A1, NR4A2, and NR4A3) play important metabolic, immune, and cardiovascular functions. These receptors also play a role in mitochondrial function. Patients with chronic kidney disease (CKD) have impaired mitochondrial function and biogenesis. Thus, in this study, we hypothesize that NR4As are downregulated in muscles in patients with CKD. Methods: In a cross-sectional study, we performed RNA sequencing in skeletal muscle biopsies from three groups; controls (n=13), patients with CKD 3-5 not yet on hemodialysis (n=13), and patients on maintenance hemodialysis (MHD, n=10). Total RNA was extracted to construct libraries for total RNA sequencing using Illumina NovaSeq 6000 system. Differentially expressed genes were identified with a false discovery rate (FDR) &lt;0.05 and fold change &gt; 2. We focused our analysis on genes involved in mitochondrial biogenesis. Results: Groups were matched by gender, body mass index, and history of diabetes and hypertension. There was no difference in markers of mitochondrial biogenesis between controls and patients with CKD 3-5. We only found a significant decrease in NR4A1 and NR4A3 gene expression in patients on MHD ( Figure 1 ) compared to control (p=0.006 and p= 0.02; NR4A1 and NR4A3, respectively) and to patients with CKD 3-5 (p=8.85E-05 and p=0.005; NR4A1 and NR4A3, respectively). Conclusions: NR4A1 and NR4A3 were downregulated in muscle biopsies from patients on MHD. These findings may explain the reduced mitochondrial content and impaired mitochondrial function in patients with CKD. Further studies should evaluate the benefit of NR4As-targeted therapies to prevent mitochondrial dysfunction in CKD.

Luteolin Ameliorates Hepatic Steatosis and Enhances Mitochondrial Biogenesis via AMPK/PGC-1α Pathway in Western Diet-Fed Mice.

Luteolin (LU), a natural compound, has diverse bioactivities; it alleviates lipid accumulation by enhancing the oxidation of fatty acids in nonalcoholic fatty liver disease (NAFLD). Mitochondrial dysfunction promotes the development of steatosis in NAFLD. However, few studies have focused on the mechanism by which LU affects mitochondrial function in NAFLD. In the present study, we investigated whether LU could ameliorate hepatic steatosis and affect mitochondrial function in Western diet-fed mice. After LU treatment, the indicators of hepatic function and markers of mitochondrial biogenesis were evaluated. The results showed that LU intervention 1) decreased the levels of serum triglyceride, total cholesterol, alanine aminotransferase, and low-density lipoprotein cholesterol; 2) increased the succinate dehydrogenase activity of mitochondrial enzyme; and 3) increased mitochondrial biogenesis by upregulating the AMPK/PGC-1α pathway. Therefore, LU might have the potential to prevent NAFLD.

Effects of Exercise Sequence and Circadian Rhythms on Molecular Mechanisms of Muscle Hypertrophy and Mitochondrial Biogenesis in Obese Rat

PURPOSE: This study aimed to investigate whether endurance and resistance training sequences and circadian rhythms affect muscle hypertrophy and mitochondrial biogenesis-related molecules in obese rats.METHODS: Rats were randomly divided into five groups: the obesity control group (OCG), aerobic-resistance exercise in the morning group (ARMG), resistance-aerobic exercise in the morning group (RAMG), aerobic resistance exercise in the evening group (AREG), and resistance-aerobic exercise in the evening group (RAEG). The exercise groups performed endurance and resistance exercises for 8 weeks according to their circadian rhythms and exercise sequences.RESULTS: We evaluated specific muscle hypertrophy and mitochondrial biogenesis markers in the flexor pollicis longus and soleus muscles using western blot and immunofluorescence techniques. The body weight was significantly decreased in the ARMG, RAMG, AREG, RAEG compared to the OCG after intervention. The soleus muscle fiber cross-sectional area and muscle hypertrophy markers p-Akt and p-mTOR were significantly increased in the AREG group compared with those in the OCG, ARMG, RAMG, and RAEG groups after exercise intervention. Most mitochondrial biogenesis-related markers were significantly increased in the RAMG group than in the other groups after exercise intervention.CONCLUSION: Our findings provide new evidence that muscle hypertrophy might be upregulated by resistance exercise after evening endurance exercise. In addition, morning resistance exercise followed by aerobic exercise, might promote mitochondrial biogenesis.

Influence of the SERCA Activity on Rat’s Soleus Contractile Properties during Functional Unloading

Dysfunction of skeletal muscles and their atrophy during unloading are accompanied by excess calcium accumulation in the myoplasm of muscle fibers. We hypothesized that calcium accumulation may occur, among other reasons, due to inhibition of SERCA activity under muscle unloading. In this case, the use of a SERCA activator will reduce the calcium level in the myoplasm and prevent the consequences of unloading. Male Wistar rats were divided into 3 groups: vivarium control with placebo administration (C, n = 8), 7-day suspension group with placebo administration (7HS, n = 8) and 7-day suspension group with intraperitoneal administration of SERCA CDN1163 activator (50 mg/kg (7HS + CDN), n = 8). One m. soleus of each rat was frozen in liquid nitrogen, the second was tested for functional properties. In the 7HS group, increased soleus fatigue was found in the ex vivo test, a significant increase in mRNA and the number of fast muscle fibers, an increase in the level of calcium-dependent CaMK II phosphorylation and the level of tropomyosin oxidation, as well as a decrease in the content of mitochondrial DNA and protein. All these changes were prevented in the SERCA CDN1163 activator group. Conclusion: 7-day SERCA activator administration does not delay of soleus atrophy, but prevents the development of its fatigue, probably by preventing a decrease in the number of type I fibers and markers of mitochondrial biogenesis.

Local GHR roles in regulation of mitochondrial function through mitochondrial biogenesis during myoblast differentiation

BackgroundMyoblast differentiation requires metabolic reprogramming driven by increased mitochondrial biogenesis and oxidative phosphorylation. The canonical GH-GHR-IGFs axis in liver exhibits a great complexity in response to somatic growth. However, the underlying mechanism of whether local GHR acts as a control valve to regulate mitochondrial function through mitochondrial biogenesis during myoblast differentiation remains unknown.MethodsWe manipulated the GHR expression in chicken primary myoblast to investigate its roles in mitochondrial biogenesis and function during myoblast differentiation.ResultsWe reported that GHR is induced during myoblast differentiation. Local GHR promoted mitochondrial biogenesis during myoblast differentiation, as determined by the fluorescence intensity of Mito-Tracker Green staining and MitoTimer reporter system, the expression of mitochondrial biogenesis markers (PGC1α, NRF1, TFAM) and mtDNA encoded gene (ND1, CYTB, COX1, ATP6), as well as mtDNA content. Consistently, local GHR enhanced mitochondrial function during myoblast differentiation, as determined by the oxygen consumption rate, mitochondrial membrane potential, ATP level and ROS production. We next revealed that the regulation of mitochondrial biogenesis and function by GHR depends on IGF1. In terms of the underlying mechanism, we demonstrated that IGF1 regulates mitochondrial biogenesis via PI3K/AKT/CREB pathway. Additionally, GHR knockdown repressed myoblast differentiation.ConclusionsIn conclusion, our data corroborate that local GHR acts as a control valve to enhance mitochondrial function by promoting mitochondrial biogenesis via IGF1-PI3K/AKT/CREB pathway during myoblast differentiation.2uqMpL47bHNL2ReoTRE-H3Video

Circadian desynchrony disturbs the function of rat spermatozoa

Decreased male fertility is a growing health problem that requires a better understanding of molecular events regulating reproductive competence. Here the effects of circadian desynchrony on the rat spermatozoa functionality were studied. Circadian desynchrony was induced in rats that lived for 2 months under disturbed light conditions designed to mimic shiftwork in humans (two days of constant light, two days of continual dark, and three days of 14:10 h light:dark schedule). Such a condition abolished circadian oscillations in the rats' voluntary activity, followed by a flattened transcriptional pattern of the pituitary gene encoding follicle stimulating hormone subunit (Fshb), and genes important for germ cell maturation (Tnp1 and Prm2) as well as the clock in seminiferous tubules. However, the number of spermatozoa isolated from the epididymis of the rats suffering from circadian desynchrony did not deviate from the controls. Nevertheless, spermatozoa functionality, estimated by motility and progesterone-induced acrosome reaction, was reduced compared to the control. These changes were associated with the altered level of main markers of mitochondrial biogenesis (Pprgc1a/PGC1A, Nrf1/NRF1, Tfam, Cytc), decreased mitochondrial DNA copy number, ATP content, and clock genes (Bmal1/BMAL1, Clock, Cry1/2, and Reverba). The principal-component-analysis (PCA) points to a positive association of the clock and mitochondrial biogenesis-related genes in spermatozoa from rats suffering circadian desynchrony. Altogether, the results show the harmful effect of circadian desynchrony on spermatozoa functionality, targeting energetic homeostasis.

High fat diet feeding induces brain mitochondrial dysfunction in female Ossabaw swine

Study objective: Emerging evidence now suggest reduced mitochondrial function as a key initiator in Alzheimer’s disease (AD)-like pathology increasing the need for models of AD that display mitochondrial dysfunction. Dyslipidemia is a common aliment from overconsumption of a high fat diet (HFD) that increases the risk of AD and may contribute to mitochondrial dysfunction. Rodent studies utilize HFDs to induce brain pathology resembling that of AD. Unsurprisingly, rodent studies are rarely recapitulated in humans, which leads to a very low clinical success rate and highlights the need for more translatable models to study AD-like pathology. Swine seem to share many characteristics of humans and might offer a more translatable model to study HFD induced pathology. Thus, the objective of this study was to determine if HFD feeding in swine could offer a more translatable model to study mitochondrial dysfunction during neurodegeneration. Hypothesis: 6-months of HFD feeding will decrease indices of mitochondrial function and biogenesis in female Ossabaw swine. Methods: To characterize the effects of a HFD on brain mitochondrial health in a highly translatable swine model, high resolution respirometry measurements were taken from isolated brain mitochondria from in female Ossabaw swine fed a HFD for 6-months. Additionally, indices of mitochondrial biogenesis in whole tissue was measured (transcriptional markers of biogenesis and citrate synthase activity). Results: HFD feeding significantly increased body weight (p&lt;0.05) with trending increases in blood glucose (p&lt;0.10). Maximal uncoupled mitochondrial respiration was significantly decreased (p&lt;0.05) with state 3-complex I and state 3 complex I &amp; II trending down in the dorsal hippocampus (DH) after HFD diet feeding (p&lt;0.10). Additionally, state 2 respiration was significantly decreased in the prefrontal cortex (PFC) after HFD feeding (p&lt;0.05). HFD feeding increased transcriptional markers of mitochondrial biogenesis in the DH and PFC (p&lt;0.05), without altering whole homogenate citrate synthase activity in either brain region. Conclusions: These data indicate HFD feeding in Ossabaw pigs could offer a potential model to study pathologies relating to mitochondrial dysfunction during neurodegenerative process. Additionally, the DH was found to be more vulnerable to HFD-induced perturbations, evident by the exacerbated deficits in mitochondrial respiration in this brain region. Finally, these data suggest HFD-induced increase in transcriptional markers of mitochondrial biogenesis may be a compensatory response to HFD-induced mitochondrial respiration deficits. However, citrate synthase activity was not different between groups indicating this upregulation of transcriptional markers was unable to translate to an increase in mitochondrial content in the DH and PFC. The project was supported by the MU Office of Postdoctoral Education Research Grant Program. Additional funding was also generously provided Scott Rector. Images in figure 2 adapted and modified from “Krebs cycle template”, by BioRender.com (2022). Retrieved from https://app.biorender.com/biorender-templates . This work was also supported with resources and the use of facilities at the University of Missouri and Harry S. Truman Memorial Veterans Hospital in Columbia, Missouri. This is the full abstract presented at the American Physiology Summit 2023 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.

Impaired mitochondrial quality control in skeletal muscles from C57 and D2 mdx model of Duchenne Muscular Dystrophy

Mitochondrial dysfunction is an early pathological feature of Duchenne muscular dystrophy (DMD) and precedes myopathy. Balanced mitochondrial quality control (e.g., fission, fusion, biogenesis, autophagy, and mitophagy) is essential to maintain the overall mitochondrial health and skeletal muscle function. DBA/2J mdx (D2- mdx) has emerged as a more relevant mouse model of DMD as it more closely mirrors early stage of DMD pathology in humans than the C57BL/10 mdx (C57 -mdx) model. The purpose of this study was to determine whether the expression of proteins responsible for mitochondrial quality control were dysregulated in skeletal muscles from these two mouse models of DMD. We hypothesized that the expression of protein markers of mitochondrial fission and mitophagy would be higher, while markers of mitochondrial fusion would be lower in both models of DMD with greater alterations in D2- mdx mice. 8-10-week-old male C57 -mdx and D2- mdx mice, and their respective wildtype (WT) mice were used in this study. Muscle strength was measured using hang wire test. Gastrocnemius muscles were collected for immunoblot analysis to assess mitochondrial quality control proteins. Hang wire impulse, an indicator of muscle strength, was significantly lower in both models of DMD in comparison to their WT controls (main effect of mdx, P = 0.01). Regarding mitochondrial fission, while there was no difference in protein expression and phosphorylation (Ser 616) of Dynamin-Related Protein 1 (Drp1) between any groups, mitochondrial fission 1 protein (Fis1) was markedly higher in skeletal muscles from both models of DMD when compared to WT controls (main effect of mdx, P=0.0001). Greater expression of Fis1 was observed in D2- mdx than C57- mdx when compared to their respective WT controls (~5.7-fold vs. 3.8-fold). Furthermore, mitochondrial fusion marker Mitofusion 1 (Mfn1) was significantly lower in both models of DMD (main effect of mdx, P=0.029), however, it appears to be mainly driven by the reduction in D2-mdx (mdx x strain interaction, P=0.019). No difference of Mfn1 expression was found in C57-mdx mice. Finally, expression of protein markers of mitochondrial biogenesis (PGC1 a) and autophagy (LC3B) were higher in both models of DMD when compared to their respective WT controls (main effect of mdx, P=0.0001 and P=0.001, respectively). In conclusion, these data suggest that there is dysregulated mitochondrial dynamics towards pro-fission state in skeletal muscle from mdx mice with an exacerbated effect in D2- mdx model, which may contribute to the muscle weakness phenotype associated with DMD This is the full abstract presented at the American Physiology Summit 2023 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.

Increased mitochondrial surface area and cristae density in the skeletal muscle of strength athletes.

Mitochondria are the cellular organelles responsible for resynthesising the majority of ATP. In skeletal muscle, there is an increased ATP turnover during resistance exercise to sustain the energetic demands of muscle contraction. Despite this, little is known regarding the mitochondrial characteristics of chronically strength-trained individuals and any potential pathways regulating the strength-specific mitochondrial remodelling. Here, we investigated the mitochondrial structural characteristics in skeletal muscle of strength athletes and age-matched untrained controls. The mitochondrial pool in strength athletes was characterised by increased mitochondrial cristae density, decreased mitochondrial size, and increased surface-to-volume ratio, despite similar mitochondrial volume density. We also provide a fibre-type and compartment specific assessment of mitochondria morphology in human skeletal muscle, which reveals across groups a compartment-specific influence on mitochondrial morphology that is largely independent of fibre-type. Furthermore, we show that resistance exercise leads to signs of mild mitochondrial stress, without an increase in the number of damaged mitochondria. Using publicly available transcriptomic data we show that acute resistance exercise increases the expression of markers of mitochondrial biogenesis, fission, and mitochondrial unfolded protein responses (UPRmt ). Further, we observed an enrichment of the UPRmt in the basal transcriptome of strength-trained individuals. Together, these findings show that strength athletes possess a unique mitochondrial remodelling, which minimises the space required for mitochondria. We propose that the concurrent activation of markers of mitochondrial biogenesis and mitochondrial remodelling pathways (fission and UPRmt ) with resistance exercise may be partially responsible for the observed mitochondrial phenotype of strength athletes. KEY POINTS: Untrained individuals and strength athletes possess comparable skeletal muscle mitochondrial volume density. In contrast, strength athletes'mitochondria are characterised by increased cristae density, decreased size, and increased surface-to-volume ratio. Type I fibres have an increased number of mitochondrial profiles with minor differences in the mitochondrial morphological characteristics compared to type II fibres. The mitochondrial morphology is distinct across the subcellular compartments in both groups, with subsarcolemmal mitochondria being bigger in size when compared to intermyofibrillar. Acute resistance exercise leads to signs of mild morphological mitochondrial stress accompanied by increased gene expression of markers of mitochondrial biogenesis, fission, and mitochondrial unfolded protein response (UPRmt). Abstract figure legend: Mitochondria are the cellular organelles responsible for resynthesising the majority of ATP. The present study aimed to investigate the mitochondrial structural characteristics of strength athletes when compared to age-matched untrained individuals. Here we show that the mitochondria of strength athletes have an increased mitochondrial cristae density, increased number of profiles, and an increased surface-to-volume ratio; despite similar mitochondrial volumetric density. Furthermore, we show that human type I fibres, when compared to type II fibres, are characterised by an increased number of mitochondrial profiles without differences in their morphological characteristics. Finally, we show that acute resistance exercise leads to mild signs of mitochondrial morphological stress and an increased expression of markers of mitochondrial biogenesis, fission, and mitochondrial unfolded protein response (UPRmt ). This article is protected by copyright. All rights reserved.

Accumulation of high-energy phosphates blocks the expression of mitochondrial biogenesis markers and slow-type myosin in soleus muscle under 24 hours of rat hindlimb suspension

Under the initial stage of muscle mechanical unloading, the skeletal muscle undergo accumulation of high-energy phosphates followed by AMP-dependent proteinkinase (AMPK) inactivation. Since AMPK is known to activate mitochondrial biogenesis, it cannot be excluded that AMPK inactivation results in oxidative potential decrease at the later stages of muscle unloading. We decided to test the role of the accumulation of high-energy phosphates in skeletal muscle fibers in the inactivation of mitochondrial biogenesis regulators at an early stage of muscle unloading. To reduce the ATP/ADP ratio, we used beta-guanidine propionic acid, and the obtained data indicating that already during the first day of simulated microgravity, the accumulation of high-energy phosphates can reduce the expression level of mRNA of the key regulator of mitochondrial biogenesis PGC-1α, the transcription factor TFAM, as well as the mitochondrial fusion regulator - mitofusin-1. A number of other parameters of mitochondrial signaling were not subject to changes at this time-point. Thus, we demonstrated the role of the ATP/ADP ratio in the inactivation of several regulators of mitochondrial biogenesis in the postural soleus muscle at an early stage of functional unloading.

Abstract 1653: Heme sequestration modulates the tumor immune microenvironment in KRAS mutation/LKB1 inactivation non-small cell lung cancer

Abstract Non-small cell lung cancer (NSCLC) accounts for approximately 85% of all lung cancers. KRAS mutations and LKB1 inactivation commonly occur in NSCLC and are associated with poor prognosis. Several studies enunciate the role of the immune system in lung cancer progression through cancer cells' ability to escape immune surveillance. Therefore, understanding NSCLC progression requires the examination of the molecular mechanisms behind this process. The importance of oxidative phosphorylation (OXPHOS) and mitochondrial metabolism in lung cancer has been continuously emphasized; OXPHOS and mitochondrial biogenesis markers predict low survival in NSCLC patients. Additionally, heme is an essential molecule in the OXPHOS pathway, and previous studies have shown that heme sequestration using heme sequestering protein 2 (HeSP2) arrests tumor progression. HeSP2 can potentially normalize the tumor immune microenvironment (TIME) via multiple mechanisms including the normalization of vessels which may promote immune cell infiltration, the reduction of hypoxia which may promote antitumor immune function, and the reduction of heme levels which potentially decreases the production of immunosuppressive enzymes requiring heme as a cofactor. In this study, control and HeSP2-treated tumors generated from a genetically engineered mouse model LSL-KrasG12D LKB1-/- (LSL-KRASG12D; LKBloxP/loxP; LSL-Luciferase (KLLuc) infected with AdenoCre virus and sacrificed at 10 months were used for immunohistochemical analysis. We examined immune markers under HeSP2 treatment to determine the immune system response to heme targeting and its effects on tumor progression. Results demonstrated that HeSP2 can modulate the tumor immune microenvironment increasing the levels of immune markers, which suggests that heme targeting can potentiate immunotherapy efficacy in lung cancer treatment. Citation Format: Maria del Carmen Chacon Castro, Eranda Berisha, Narges Salamat, Li Zhang. Heme sequestration modulates the tumor immune microenvironment in KRAS mutation/LKB1 inactivation non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1653.

Swimming in cold water upregulates genes involved in thermogenesis and the browning of white adipose tissues.

The purpose of this study was to investigate whether there is an interacting effect of six weeks of swimming in cold water on the gene expression of browning markers in adipose tissue in rodents. Twenty male Wistar rats were randomly divided into four groups: Control (C, 25 °C), Cold Exposure (CE, 4 °C), Swimming in tepid Water (STW, 30 °C), and Swimming in Cold Water (SCW, 15 °C). The swimming included 2-3 min intervals, 1 min rest, until exhaustion, three days a week for six weeks, with 3 to 6% of bodyweight overload. Rats from CE were exposed to cold for 2 h per day, five days per week. After the experimental protocol, interscapular brown (BAT) and inguinal subcutaneous white (WAT) fat tissues were excised, weighed, and processed for beiging and mitochondrial biogenesis markers gene expression. The experimental protocols resulted in an apparent increase in the number of brown adipocytes (per mm2) in the adipose deposits compared to the C group; substantial changes were observed in the SCW group. Compared to other groups, cold exposure alone increased significantly serum norepinephrine, and also β2-adrenergic receptor expression was upregulated in the adipocytes compared to the C group. The STW group increased the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ) coactivator-1 alpha (PGC-1α), β2-adrenergic receptor, and CCAAT/enhancer-binding proteins-α(c/EBP-α) in WAT in comparison with the C group(p < 0.05). In both adipocytes, the SCW intervention significantly upregulated the expression of PGC-1α, PPAR-γ, and c/EBP-α genes in comparison with the C and CE groups. In addition, the expression of TFAM and UCP1 was upregulated substantially in the SCW group compared to other groups. Our data demonstrate that swim training and cold exposure present additive effects in the expression of genes involved in the beiging process and mitochondrial biogenesis markers in BAT and WAT. In addition, it seems that the upregulation of these genes is related to the activation of β2-adrenergic receptors.

Liraglutide demonstrates a therapeutic effect on mitochondrial dysfunction in human SGBS adipocytes in vitro

AimsLiraglutide (LG), a glucagon-like peptide-1 receptor (GLP-1R) agonist, has been shown to improve white adipose tissue mitochondrial metabolism in mice but not in human adipocytes. Therefore, we explored whether LG has therapeutic efficacy in mitochondrial dysfunction in human adipocytes in vitro. MethodsWe tested the effects of short-term (ST-LG: 24 h) and long-term (LT-LG: D0-15 days) treatments in human SGBS adipocytes on mitochondrial respiration, mRNA and protein expression. GLP-1R inhibition was investigated by the co-treatment of GLP-1R inhibitor, exendin 9–39 (Ex9-39) and ST-LG treatment. We also explored the ability of ST-LG to alleviate mitochondrial dysfunction induced by tumor necrosis factor-alpha (TNFα). ResultsLT-LG treatment induced the formation of smaller lipid droplets and increased the expression of genes related to lipolysis. Both ST-LG and LT-LG treatments promoted mitochondrial respiration. Additionally, LT-LG treatment increased the expression of a brown adipocyte marker, uncoupling protein 1 (UCP-1), and the markers of mitochondrial biogenesis. Interestingly, ST-LG rescued TNFα-induced defects in mitochondrial energy metabolism and inflammation in SGBS adipocytes. ConclusionLG stimulates mitochondrial respiration and biogenesis in human adipocytes, potentially via UCP-1-mediated adipocyte browning. Importantly, our study demonstrates for the first time that LG has a therapeutic potential on mitochondrial activity in human adipocytes.

Mitochondrial Complex Abundance, Mitophagy Proteins, and Physical Performance in People With and Without Peripheral Artery Disease.

Background Mitochondrial abnormalities exist in gastrocnemius muscle of people with peripheral artery disease (PAD). Whether abnormalities in mitochondrial biogenesis and autophagy are associated with greater ischemia or walking impairment in PAD is unknown. Methods and Results Protein markers of mitochondrial biogenesis and autophagy and the abundance of mitochondrial electron transport chain complexes were quantified in gastrocnemius muscle biopsies from people with and without PAD. Their 6-minute walk distance and 4-m gait speed were measured. Sixty-seven participants (mean age 65.0 years [±6.8], 16 [23.9%] women, 48 [71.6%] Black) were enrolled, including 15 with moderate to severe PAD (ankle brachial index [ABI] <0.60), 29 with mild PAD (ABI 0.60-0.90), and 23 without PAD (ABI 1.00-1.40). Abundance of all electron transport chain complexes was significantly higher in participants with lower ABI (eg, complex I: 0.66, 0.45, 0.48 arbitrary units [AU], respectively, P trend=0.043). Lower ABI values were associated with a higher LC3A/B II-to-LC3A/B I (microtubule-associated protein 1A/1B-light chain 3) ratio (2.54, 2.31, 2.15 AU, respectively, P trend=0.017) and reduced abundance of the autophagy receptor p62 (0.71, 0.69, 0.80 AU, respectively, P trend=0.033). The abundance of each electron transport chain complex was positively and significantly associated with 6-minute walk distance and 4-m gait speed at usual and fast pace only among participants without PAD (eg, complex I: r=0.541, P=0.008; r=0.477, P=0.021; r=0.628, P=0.001, respectively). Conclusions These results suggest that accumulation of electron transport chain complexes in gastrocnemius muscle of people with PAD may be because of impaired mitophagy in the setting of ischemia. Findings are descriptive, and further study in larger sample sizes is needed.

Microbiota Mediate Enhanced Exercise Capacity Induced by Exercise Training.

We investigated the effects of gut microbes, and the mechanisms mediating the enhanced exercise performance induced by exercise training, i.e., skeletal muscle blood flow, and mitochondrial biogenesis and oxidative function in male mice. All mice received a graded exercise test before (PRE) and after exercise training via forced treadmill running at 60% to 70% of maximal running capacity 5 d·wk -1 for 5 wk (POST). To examine the role of the gut microbes, the graded exercise was repeated after 7 d of access to antibiotic (ABX)-treated water, used to eliminate gut microbes. Peripheral blood flow, mitochondrial oxidative capacity, and markers of mitochondrial biogenesis were collected at each time point. Exercise training led to increases of 60% ± 13% in maximal running distance and 63% ± 11% work to exhaustion ( P < 0.001). These increases were abolished after ABX ( P < 0.001). Exercise training increased hindlimb blood flow and markers of mitochondrial biogenesis and oxidative function, including AMP-activated protein kinase, sirtuin-1, PGC-1α citrate synthase, complex IV, and nitric oxide, all of which were also abolished by ABX treatment. Our results support the concept that gut microbiota mediate enhanced exercise capacity after exercise training and the mechanisms responsible, i.e., hindlimb blood flow, mitochondrial biogenesis, and metabolic profile. Finally, results of this study emphasize the need to fully examine the impact of prescribing ABX to athletes during their training regimens and how this may affect their performance.

The Extracellular Matrix Vitalizer RATM Increased Skin Elasticity by Modulating Mitochondrial Function in Aged Animal Skin

Oxidative stress-induced cellular senescence and mitochondrial dysfunction result in skin aging by increasing ECM levels-degrading proteins such as MMPs, and decreasing collagen synthesis. MMPs also destroy the basement membrane, which is involved in skin elasticity. The extracellular matrix vitalizer RATM (RA) contains various antioxidants and sodium hyaluronate, which lead to skin rejuvenation. We evaluated whether RA decreases oxidative stress and mitochondrial dysfunction, eventually increasing skin elasticity in aged animals. Oxidative stress was assessed by assaying NADPH oxidase activity, which is involved in ROS generation, and the expression of SOD, which removes ROS. NADPH oxidase activity was increased in aged skin and decreased by RA injection. SOD expression was decreased in aged skin and increased by RA injection. Damage to mitochondrial DNA and mitochondrial fusion markers was increased in aged skin and decreased by RA. The levels of mitochondrial biogenesis markers and fission markers were decreased in aged skin and increased by RA. The levels of NF-κB/AP-1 and MMP1/2/3/9 were increased in aged skin and decreased by RA. The levels of TGF-β, CTGF, and collagen I/III were decreased in aged skin and increased by RA. The expression of laminin and nidogen and basement membrane density were decreased in aged skin and increased by RA. RA increased collagen fiber accumulation and elasticity in aged skin. In conclusion, RA improves skin rejuvenation by decreasing oxidative stress and mitochondrial dysfunction in aged skin.

High dietary lipid level promotes low salinity adaptation in the marine euryhaline crab (Scylla paramamosain).

The physiological processes involved in adaptation to osmotic pressure in euryhaline crustaceans are highly energy demanding, but the effects of dietary lipids (fat) on low salinity adaptations have not been well evaluated. In the present study, a total of 120 mud crabs (Scylla paramamosain, BW=17.87±1.49g) were fed control and high-fat (HF) diets, at both medium salinity (23‰) and low salinity (4‰) for 6wk, and each treatment had 3 replicates with each replicate containing 10 crabs. The results indicated that a HF diet significantly mitigated the reduction in survival rate, percent weight gain and feed efficiency induced by low salinity (P<0.05). Low salinity lowered lipogenesis and activated lipolysis resulting in lipid depletion in the hepatopancreas of mud crabs (P<0.05). Thus, HF diets enhanced the process of lipolysis to supply more energy. In the gills, low salinity and the HF diet increased the levels of mitochondrial biogenesis markers, the activity of mitochondrial complexes, and the expression levels of genes related to energy metabolism (P<0.05). Consequently, the positive effects of the HF diet on energy metabolism in mud crabs at low salinity promoted osmotic pressure regulation. Specifically, significantly higher haemolymph osmotic pressure and inorganic ion content, as well as higher osmotic pressure regulatory enzyme activity in gills, and gene and protein expression levels of NaK-ATPase were observed in crabs fed the HF diet at low salinity (P<0.05). In summary, high dietary lipid levels improved energy provision to facilitate mitochondrial biogenesis, which increased ATP provision for osmotic pressure regulation of mud crabs. This study also illustrates the importance of dietary lipid nutrition supplementation for low salinity adaptations in mud crabs.

Mitochondrial dysfunction in a rat model and the related risk of metabolic disorders.

To explore whether kidney deficiency (KYD) is prone to metabolic disorders may be linked to impaired mitochondrial function in thermogenesis and metabolic tissues. A rat model of KYD was used, which was established using Sprague Dawley rat dams with warm preference subjected to herbal treatment that can improve kidney . The human relevance was confirmed by reduced serum corticosterone levels, and increased preference for warm location. KYD Rats were underdeveloped. Adenosine-triphosphate (ATP) production was reduced in the brown fat, but increased in the muscle. However, oxidative phosphorylated complexes to generate ATP and mitochondrial biogenesis marker were reduced in both tissues. When the second insult of high-fat diet (HFD) was introduced, KYD rats gained less weight yet developed more severe lipid and glucose metabolic disorders. This may be driven by disregulated liver gluconeogenesis marker forkhead box protein O1 and lipid metabolic regulator cholesterol 7 alpha-hydroxylase. KYD rats exhibited reduced mito-chondrial function in the brown fat, but were partially compensated by skeletal muscle, associated with the phenotype of warm preference and metabolic disorder, which was further exacerbated by additional HFD consumption. Future studies can focus on treatment targetting mitochondria function to reverse this phenotype.

Acute resistance exercise training does not augment mitochondrial remodelling in master athletes or untrained older adults.

Background: Ageing is associated with alterations to skeletal muscle oxidative metabolism that may be influenced by physical activity status, although the mechanisms underlying these changes have not been unraveled. Similarly, the effect of resistance exercise training (RET) on skeletal muscle mitochondrial regulation is unclear. Methods: Seven endurance-trained masters athletes ([MA], 74 ± 3years) and seven untrained older adults ([OC]. 69 ± 6years) completed a single session of knee extension RET (6 x 12 repetitions, 75% 1-RM, 120-s intra-set recovery). Vastus lateralis muscle biopsies were collected pre-RET, 1h post-RET, and 48h post-RET. Skeletal muscle biopsies were analyzed for citrate synthase (CS) enzyme activity, mitochondrial content, and markers of mitochondrial quality control via immunoblotting. Results: Pre-RET CS activity and protein content were ∼45% (p < .001) and ∼74% greater in MA compared with OC (p = .006). There was a significant reduction (∼18%) in CS activity 48h post-RET (p < .05) in OC, but not MA. Pre-RET abundance of individual and combined mitochondrial electron transport chain (ETC) complexes I-V were significantly greater in MA compared with OC, as were markers of mitochondrial fission and fusion dynamics (p-DRP-1Ser616, p-MFFSer146, OPA-1 & FIS-1, p < .05 for all). Moreover, MA displayed greater expression of p-AMPKThr172, PGC1α, TFAM, and SIRT-3 (p < .05 for all). Notably, RET did not alter the expression of any marker of mitochondrial content, biogenesis, or quality control in both OC and MA. Conclusion: The present data suggest that long-term aerobic exercise training supports superior skeletal muscle mitochondrial density and protein content into later life, which may be regulated by greater mitochondrial quality control mechanisms and supported via superior fission-fusion dynamics. However, a single session of RET is unable to induce mitochondrial remodelling in the acute (1h post-RET) and delayed (48h post-RET) recovery period in OC and MA.