Mitochondrial Biogenesis Genes Research Articles

Inducible and reversible SOD2 knockdown in mouse skeletal muscle drives impaired pyruvate oxidation and reduced metabolic flexibility

IntroductionSkeletal muscle mitochondrial dysfunction is a key characteristic of aging muscle and contributes to age related diseases such as sarcopenia, frailty, and type 2 diabetes. Mitochondrial oxidative stress has been implicated as a driving factor in these age-related diseases, however whether it is a cause, or a consequence of mitochondrial dysfunction remains to be determined. The development of flexible genetic models is an important tool to test the mechanistic role of mitochondrial oxidative stress on skeletal muscle metabolic dysfunction. We characterize a new model of inducible and reversible mitochondrial redox stress using a tetracycline controlled skeletal muscle specific short hairpin RNA targeted to superoxide dismutase 2 (iSOD2).Methods: iSOD2 KD and control (CON) animals were administered doxycycline for 3- or 12- weeks and followed for up to 24 weeks and mitochondrial respiration and muscle contraction were measured to define the time course of SOD2 KD and muscle functional changes and recovery. ResultsMaximum knockdown of SOD2 protein occurred by 6 weeks and recovered by 24 weeks after DOX treatment. Mitochondrial aconitase activity and maximum mitochondrial respiration declined in KD muscle by 12 weeks and recovered by 24 weeks. There were no significant differences in antioxidant or mitochondrial biogenesis genes between groups. Twelve-week KD showed a small, but significant decrease in muscle fatigue resistance. The primary phenotype was reduced metabolic flexibility characterized by impaired pyruvate driven respiration when other substrates are present. The pyruvate dehydrogenase kinase inhibitor dichloroacetate partially restored pyruvate driven respiration, while the thiol reductant DTT did not. ConclusionWe use a model of inducible and reversible skeletal muscle SOD2 knockdown to demonstrate that elevated matrix superoxide reversibly impairs mitochondrial substrate flexibility characterized by impaired pyruvate oxidation. Despite the bioenergetic effect, the limited change in gene expression suggests that the elevated redox stress in this model is confined to the mitochondrial matrix.

Endurance exercise attenuates Gαq-RNAi induced hereditary obesity and skeletal muscle dysfunction via improving skeletal muscle Srl/MRCC-I pathway in Drosophila

G protein alpha q subunit (Gαq) can binds to the G protein-coupled receptor (GPCR) for signaling and is closely related to lipid metabolism. Endurance exercise is an effective means of combating acquired obesity and its complications, but the mechanisms by which endurance exercise modulates hereditary obesity and its complications are unknown. In this study, we achieved knockdown of Gαq in drosophila adipose tissue and skeletal muscle by constructing the Gαq-UAS-RNAi/Ppl-Gal4 and Gαq-UAS-RNAi/Mef2-GAl4 systems. Drosophila were subjected a three-week endurance exercise intervention, and changes in relevant indicators were detected and observed by RT-PCR, ELISA, oil red staining, immunofluorescence staining, and transmission electron microscopy. The results showed that knockdown of Gαq in both adipose tissue and skeletal muscle induced a significant increase in triglycerides accompanied by a decrease in rapid climbing ability, a decrease in Superoxide Dismutase (SOD) activity level, and a decrease in Mitochondrial respiratory chain complexI (MRCC I) content in Drosophila whole body and skeletal muscle, and down-regulated the expression of the G protein alpha q subunit (Gαq), the skeletal muscle myosin heavy chain expression gene (Mhc), mitochondrial biogenesis gene Spargal(the PGC-1alpha homologue in Drosophila). Endurance exercise significantly improved the triglyceride levels in the whole body and skeletal muscle of drosophila with Gαq knockdown in adipose tissue and skeletal muscle, as well as their ability to climb, increased SOD activity level and MRCCI content level, and up-regulated the expression of Gαq, Mhc, and Spargal(Srl). Thus, the present findings suggest that genetic defects in the Gαq gene in adipose and skeletal muscle tissues induce hereditary obesity and skeletal muscle dysfunction, and that endurance exercise attenuates this hereditary obesity and concomitant skeletal muscle dysfunction in drosophila by improving skeletal muscle fiber contractile proteins, mitochondrial function and function, and antioxidant capacity via mediating the Gαq/Mhc, Gαq/Srl/MRCC-I, and Gαq/SOD pathways.

Alpha-Linolenic Acid Supplementation Improves Testosterone Production in an Aged Breeder Rooster Model: Role of Mitochondrial Modulation and SIRT1 Activation.

Aging in males can lead to declines in testosterone production, essential for maintaining male reproductive health. To investigate the effects of dietary supplementation with alpha-linolenic acid (ALA) on testosterone production in aged breeder roosters and understand the underlying molecular mechanisms involved. An in vivo model is established to investigate the effects of dietary ALA supplementation on testosterone production in aged breeder roosters, and the Leydig cell culture is used to identify the potential molecular mechanism. Dietary supplementation with ALA increases in plasma testosterone. Congruently, ALA supplementation enhances the expression of testosterone biosynthesis-related enzymes. ALA supplementation exerts anti-apoptotic effects in testicular mitochondria, as evidenced by a lower expression of pro-apoptotic factors and a higher expression of the anti-apoptotic factor B-cell lymphoma 2 (Bcl-2). Moreover, In Leydig cells, ALA supplementation promotes mitochondrial biogenesis genes. The proposed mechanism is that ALA activates the sirtuin1 (SIRT1)pathway and is supported by higher SIRT1 transcript and protein in Leydig cells. Furthermore, blocking SIRT1 with siRNA reverses ALA's effects on testosterone biosynthesis and mitochondrial function-related genes. These findings indicate that dietary supplementation with ALA can improve testosterone production in aged breeder roosters, possibly by modulation of mitochondrial function via activating the SIRT1 pathway.

Increase in blood derived mitochondrial DNA copy number in strabismus patients

BackgroundAbnormalities in mitochondrial energy homeostasis can lead to various disorders, including ocular motility aberrations. Previous studies have suggested the involvement of mitochondrial aberrations in strabismus etiology. We compared the blood-derived mitochondrial DNA (mtDNA) copy number from comitant strabismus patients with that from age-matched controls, and also compared expression of mitochondrial biogenesis genes in a separate set of extraocular muscle samples from strabismic and control subjects. MethodsBlood samples from 93 strabismic (39 esotropic, 54 exotropic) and 93 control subjectswere analyzed for mtDNA copy number through quantitative polymerase chain reaction. We also examined the expression of 6 genes involved in mitochondrial biogenesis in cDNA obtained from extraocular muscles of a separate group of 26 strabismus patients and 4 healthy controls. ResultsThe mtDNA content was significantly higher in strabismus patients as compared to the control group, both overall (fold change, 1.39; Z = −2.43 [P = 0.01]) and in strabismus subgroups (esotropia: fold change,1.42; Z = 2.59 [P = 0.0096]; exotropia: fold change, 1.41, Z = 3.35 [P = 0.00078]). No significant difference was observed in the expression of the examined biogenesis genes between strabismus and control groups. ConclusionsOur results suggest an association between mtDNA copy number and strabismus; however, further studies are required to elucidate the significance of altered mtDNA in strabismus and its possible significance with regard to the etiology of strabismus.

Aberrant mitochondrial DNA synthesis in macrophages exacerbates inflammation and atherosclerosis

There is a large body of evidence that cellular metabolism governs inflammation, and that inflammation contributes to the progression of atherosclerosis. However, whether mitochondrial DNA synthesis affects macrophage function and atherosclerosis pathology is not fully understood. Here we show, by transcriptomic analyzes of plaque macrophages, spatial single cell transcriptomics of atherosclerotic plaques, and functional experiments, that mitochondrial DNA (mtDNA) synthesis in atherosclerotic plaque macrophages are triggered by vascular cell adhesion molecule 1 (VCAM-1) under inflammatory conditions in both humans and mice. Mechanistically, VCAM-1 activates C/EBPα, which binds to the promoters of key mitochondrial biogenesis genes - Cmpk2 and Pgc1a. Increased CMPK2 and PGC-1α expression triggers mtDNA synthesis, which activates STING-mediated inflammation. Consistently, atherosclerosis and inflammation are less severe in Apoe−/− mice lacking Vcam1 in macrophages. Downregulation of macrophage-specific VCAM-1 in vivo leads to decreased expression of LYZ1 and FCOR, involved in STING signalling. Finally, VCAM-1 expression in human carotid plaque macrophages correlates with necrotic core area, mitochondrial volume, and oxidative damage to DNA. Collectively, our study highlights the importance of macrophage VCAM-1 in inflammation and atherogenesis pathology and proposes a self-acerbating pathway involving increased mtDNA synthesis.

Increased expression of ER stress, inflammasome activation, and mitochondrial biogenesis-related genes in peripheral blood mononuclear cells in major depressive disorder.

A subset of major depressive disorder (MDD) is characterized by immune system dysfunction, but the intracellular origin of these immune changes remains unclear. Here we tested the hypothesis that abnormalities in endoplasmic reticulum (ER) stress, inflammasome activity and mitochondrial biogenesis contribute to the development of systemic inflammation in MDD. RT-qPCR was used to measure mRNA expression of key organellar genes from peripheral blood mononuclear cells (PBMCs) isolated from 186 MDD and 67 healthy control (HC) subjects. The comparative CT (2-ΔΔCT) method was applied to quantify mRNA expression using GAPDH as the reference gene. After controlling for age, sex, BMI, and medication status using linear regression models, expression of the inflammasome (NLRC4 and NLRP3) and the ER stress (XBP1u, XBP1s, and ATF4) genes was found to be significantly increased in the MDD versus the HC group. Sensitivity analyses excluding covariates yielded similar results. After excluding outliers, expression of the inflammasome genes was no longer statistically significant but expression of the ER stress genes (XBP1u, XBP1s, and ATF4) remained significant and the mitochondrial biogenesis gene, MFN2, was significantly increased in the MDD group. NLRC4 and MFN2 were positively correlated with serum C-reactive protein concentrations, while ASC trended significant. The altered expression of inflammasome activation, ER stress, and mitochondrial biogenesis pathway components suggest that dysfunction of these organelles may play a role in the pathogenesis of MDD.

Combined Multi-Omics Analysis Reveals the Potential Role of ACADS in Yak Intramuscular Fat Deposition.

The Yak (Bos grunniens) is a special breed of livestock predominantly distributed in the Qinghai-Tibet Plateau of China. Intramuscular fat (IMF) content in beef cattle is a vital indicator of meat quality. In this study, RNA-Seq and Protein-Seq were respectively employed to sequence the transcriptome and proteome of the longissimus dorsi (LD) tissue from 4-year-old yaks with significant differences in IMF content under the same fattening conditions. Five overlapping genes (MYL3, ACADS, L2HGDH, IGFN1, and ENSBGRG00000000-926) were screened using combined analysis. Functional verification tests demonstrated that the key gene ACADS inhibited yak intramuscular preadipocyte (YIMA) differentiation and proliferation, promoted mitochondrial biogenesis gene expression, and increased the mitochondrial membrane potential (MMP). Furthermore, co-transfection experiments further demonstrated that interfering with ACADS reversed the effect of PPARα agonists in promoting lipid differentiation. In conclusion, ACADS potentially inhibits lipid deposition in YIAMs by regulating the PPARα signalling pathway. These findings offer insights into the molecular mechanisms underlying yak meat quality.

Role of mitochondrial dysfunction and biogenesis in fibromyalgia syndrome: Molecular mechanism in central nervous system

A critical role for mitochondrial dysfunction has been shown in the pathogenesis of fibromyalgia. It is a chronic pain syndrome characterized by neuroinflammation and impaired oxidative balance in the central nervous system. Boswellia serrata (BS), a natural polyphenol, is a well-known able to influence the mitochondrial metabolism. The objective of this study was to evaluate the mitochondrial dysfunction and biogenesis in fibromyalgia and their modulation by BS. To induce the model reserpine (1 mg/Kg) was subcutaneously administered for three consecutive days and BS (100 mg/Kg) was given orally for twenty-one days. BS reduced pain like behaviors in reserpine-injected rats and the astrocytes activation in the dorsal horn of the spinal cord and prefrontal cortex that are recognized as key regions associated with the neuropathic pain. Vulnerability to neuroinflammation and impaired neuronal plasticity have been described as consequences of mitochondrial dysfunction. BS administration increased PGC-1α expression in the nucleus of spinal cord and brain tissues, promoting the expression of regulatory genes for mitochondrial biogenesis (NRF-1, Tfam and UCP2) and cellular antioxidant defence mechanisms (catalase, SOD2 and Prdx 3). According with these data BS reduced lipid peroxidation and the GSSG/GSH ratio and increased SOD activity in the same tissues. Our results also showed that BS administration mitigates cytochrome-c leakage by promoting mitochondrial function and supported the movement of PGC-1α protein into the nucleus restoring the quality control of mitochondria. Additionally, BS reduced Drp1 and Fis1, preventing both mitochondrial fission and cell death, and increased the expression of Mfn2 protein, facilitating mitochondrial fusion. Overall, our results showed important mitochondrial dysfunction in central nervous system in fibromyalgia syndrome and the role of BS in restoring mitochondrial dynamics.

Exploring the novel benefits of leucine: Protecting nitrite-induced liver damage in sub-adult grass carp (Ctenopharyngodon idella) through regulating mitochondria quality control

Leucine is an essential amino acid for fish. The ability of leucine to resist stress in fish has not been reported. Nitrite is a common pollutant in the aquatic environment. Therefore, we investigated the effects of dietary leucine on growth performance and nitrite-induced liver damage, mitochondrial dysfunction, autophagy, and apoptosis for sub-adult grass carp. A total of 450 grass carp (615.91 ± 1.15 g) were selected and randomly placed into 18 net cages. The leucine contents of the six diets were 2.91, 5.90, 8.92, 11.91, 14.93, and 17.92 g/kg, respectively. After a 9-week feeding trial, the nitrite exposure experiment was set up for 96 h. These results indicated that dietary leucine significantly promoted FW, WG, PWG, and SGR of sub-adult grass carp (P < 0.05). Appropriate levels of dietary leucine (11.91–17.92 g/kg) decreased the activities of serum parameters (glucose, cortisol, and methemoglobin contents, glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, and lactate dehydrogenase), the contents of reactive oxygen species (ROS), nitric oxide (NO) and peroxynitrite (ONOO−). In addition, appropriate levels of dietary leucine (11.91–17.92 g/kg) increased the mRNA levels of mitochondrial biogenesis genes (PGC-1α, Nrf1/2, TFAM), fusion-related genes (Opa1, Mfn1/2) (P < 0.05), and decreased the mRNA levels of caspase 3, caspase 8, caspase 9, fission-related gene (Drp1), mitophagy-related genes (Pink1, Parkin) and autophagy-related genes (Beclin1, Ulk1, Atg5, Atg7, Atg12) (P < 0.05). Appropriate levels of dietary leucine (8.92–17.92 g/kg) also increased the protein levels of AMP-activated protein kinase (AMPK), prostacyclin (p62) and decreased the protein levels of protein light chain 3 (LC3), E3 ubiquitin ligase (Parkin), and Cytochrome c (Cytc). Appropriate levels of leucine (8.92–17.92 g/kg) could promote growth performance and alleviate nitrite-induced mitochondrial dysfunction, autophagy, apoptosis for sub-adult grass carp. Based on quadratic regression analysis of PWG and serum GPT activity, dietary leucine requirements of sub-adult grass carp were recommended to be 12.47 g/kg diet and 12.55 g/kg diet, respectively.

Novel insights into DEHP-induced zebrafish spleen damage: Cellular apoptosis, mitochondrial dysfunction, and innate immunity

DEHP (Di(2-ethylhexyl) phthalate) is the most abundant phthalate component detected in environmental samples as it is widely used in the manufacturing of children's toys, medical devices and furniture. Due to its wide prevalence and propensity to accumulate in the food chain, significant concerns have risen about the safety profile of DEHP. Here, we used a zebrafish model to investigate the toxicity mechanisms of DEHP. Our results indicated that exposure to DEHP altered the ROS content in zebrafish spleen and inhibited the activities of antioxidant enzymes SOD and CAT, detoxification enzyme GSH-Px and induced histopathological damage. In addition, elucidated the mechanism of DEHP significantly promoted apoptosis and caused damage in spleen cells through the bax/bcl-2 pathway. Further genetic testing demonstrated significant alterations in mitochondrial biogenesis, fission, and fusion-related genes and suggested potential mechanistic pathways, including GM10532/m6A/FIS1 axis, the STAT3/POA1 axis, and the NFR1/TFAM axis. Serological and genomic analysis indicated that DEHP exposure activated the C3 complement cascade immune pathway and interfered with innate immune function. IBRv2 analysis proposes that innate immunity may serve as a signal indicator of early toxic responses to DEHP pollutants. This study provided comprehensive cellular and genetic data for DEHP toxicity studies and emphasized the need for future management and remediation of DEHP contamination. It also provides data to specifically support the health risk assessments of DEHP, as well as contributing to broader health and environmental research.

In vitro mitochondrial and myogenic gene expression is influenced by formoterol in human myotubes

BackgroundExercise is an effective treatment for establishing and maintaining skeletal muscle health. The interconnected cascade of gene expression pathways related to myogenesis, mitochondrial homeostasis, and thyroid hormone metabolism are critical to skeletal muscle health. This in vitro study was conducted to investigate the effects of exercise mimetic (formoterol) stimulation on human skeletal muscle cell signaling during myogenesis, and to provide insight on potential targets for future studies exploring therapies for skeletal muscle atrophy. Human myoblasts were cultured and differentiated to evaluate the effects of exercise mimetic stimulation on gene expression during mid and late myogenesis.ResultsWe characterized the expression of 24 genes related to myogenesis, mitochondrial biogenesis, thyroid hormone metabolism, and cellular homeostasis and found that 21 genes were altered in response to formoterol, thus affecting related skeletal muscle pathways. Additionally, formoterol stimulation resulted in a myogenic program that appears to favor prolonged myoblast proliferation and delayed myotube maturation. Robust, yet distinctive effects of exercise mimetic stimulation on gene expression during mid-myogenesis and at terminal differentiation occurred. For instance, MYF5 increased in D6 FORM compared to other groups (p < 0.001) while MYOD and MYOG both decreased expression in the FORM groups compared to CON (p < 0.01). Secondly, mitochondrial biogenesis genes were stimulated following formoterol administration, namely PGC-1α, PGC-1β, and TFAM (p < 0.05). Uniquely in our study, thyroid hormone metabolism related genes were differentially expressed. For instance, DIO2 and DIO3 were both stimulated following formoterol administration (p < 0.05).ConclusionsThe results of our study support the groundwork for establishing further experiments utilizing exercise signaling as a clinical treatment in models targeting dysfunctional skeletal muscle cell growth.

Intracellular Iron Controls HSC Metabolism By Affecting Mitochondrial Fitness

Iron is an important source of reactive oxygen species (ROS) within the cell and recent evidence highlighted its role in regulating HSC self-renewal and differentiation. However, whether and how iron influences HSC metabolism is still undetermined. Cellular metabolism is a key regulator of HSC maintenance and HSCs adapt their metabolic state to their function. Quiescent HSCs have low energy requirements and depend on anaerobic glycolysis, whereas active HSCs require high energy for proliferation and differentiation thus enhancing oxidative phosphorylation (OXPHOS), glycolysis and fatty acid oxidation (FAO). To explore which metabolic pathways are triggered by intracellular iron levels, we took advantage of the thalassemic Hbb th3/+mice ( th3), characterized by chronic iron overload (IO). We previously demonstrated an impaired function of th3 HSCs due to persistence into altered BM niche ( Aprile et al., 2020). Th3 HSCs showed higher levels of intracellular free reactive iron (1.7±0.2 calcein MFI fold to wt, p&amp;lt;0.0001) and interestingly iron specifically accumulated in the mitochondria. As a result, mitochondria are impaired, with low mass and activity, as assessed by decreased mitochondrial membrane potential ( th3 1068±167 vs. wt 3215±686 MFI TMRE, p&amp;lt;0.05). These data, together with a reduced expression of mitochondrial biogenesis and mitophagy genes, indicate an accumulation of damaged mitochondria. To demonstrate a direct effect of iron on mitochondrial fitness in HSCs, we treated wt mice with iron dextran. Consistently, IO wt HSCs showed reduced mitochondrial activity following intracellular iron accumulation. Since mitochondria are the major site of cellular ATP production mostly through OXPHOS, we measured the metabolic state of HSCs in ß-thalassemia. ATP levels in sorted th3 HSCs was halved than the one in wt mice ( th3 3.7±0.3 vs. wt 9.8±2.6 ATP nM, p&amp;lt;0.01). Inhibition of OXPHOS by oligomycin lowered the ATP content in wt cells with a minor effect in th3 HSCs, thus indicating a reduced OXPHOS-dependent metabolism, despite their active cycling profile. Since mitochondria are damaged and OXPHOS and glycolysis are the two main metabolic pathways involved in cellular ATP generation, we hypothesized increased glycolytic dependency to compensate for reduced OXPHOS in th3 HSCs. Indeed, in these cells we observed a positive enrichment of glycolytic genes, such as Tpi1, Gapdh and Pklr, and a 1.4-fold higher glucose uptake ( th3 2401±85 vs. wt 1639±163 MFI 2NBDG, p&amp;lt;0.05). In vivo administration of the iron chelator DFO normalized intracellular iron content and rescued mitochondrial dysfunction in th3 mice, indicating the reversibility of mitochondrial defects. Moreover, HSCs from DFO-treated mice showed reduced glucose uptake, thus demonstrating that IO causes mitochondrial defects and metabolic adaptations of HSCs. Excess iron is expected to give rise to ROS and, consistently, th3 HSCs displayed high mitochondrial ROS (mtROS) levels ( th3 5205±459 vs. wt 2507±756 MFI MitoSOX, p&amp;lt;0.01). I n vivo reduction of mtROS by MitoQ administration restored mitochondrial activity and decreased glucose uptake. Remarkably, MitoQ rescued the quiescence and self-renewal ability of th3 HSCs, as shown by superior chimerism in secondary transplantation of HSCs from MitoQ-treated th3 donors in lethally irradiated recipients ( th3 HSC+MitoQ 81.7±1.6 vs. untreated th3 HSC 34.9±14.6 vs. % of chimerism, p&amp;lt;0.05), thus indicating that IO-derived ROS impair HSC function by affecting mitochondrial fitness and bioenergetics. Preliminary results confirmed intracellular IO and mitochondrial defects also in HSCs from Townes mice, a model of sickle cell anemia characterized by IO. Collectively, our study revealed that increased intracellular iron and ROS levels alter HSC metabolic programs by inducing mitochondrial dysfunction. Since mitochondria are defective, IO HSCs are unable to produce appropriate levels of ATP through OXPHOS and rely on glycolysis, despite their active cycling activity. Finally, the rescue of mitochondrial activity can restore the functional defects of th3 HSCs.

Handelin alleviates cachexia- and aging-induced skeletal muscle atrophy by improving protein homeostasis and inhibiting inflammation.

Handelin is a bioactive compound from Chrysanthemum indicum L. that improves motor function and muscle integrity during aging in Caenorhabditis elegans. This study aimed to further evaluate the protective effects and molecular mechanisms of handelin in a mouse muscle atrophy model induced by cachexia and aging. A tumour necrosis factor (TNF)-α-induced atrophy model was used to examine handelin activity in cultured C2C12 myotubes in vitro. Lipopolysaccharide (LPS)-treated 8-week-old model mice and 23-month-old (aged) mice were used to examine the therapeutic effects of handelin on cachexia- and aging-induced muscle atrophy, respectively, in vivo. Protein and mRNA expressions were analysed by Western blotting, ELISA and quantitative PCR, respectively. Skeletal muscle mass was measured by histological analysis. Handelin treatment resulted in an upregulation of protein levels of early (MyoD and myogenin) and late (myosin heavy chain, MyHC) differentiation markers in C2C12 myotubes (P<0.05), and enhanced mitochondrial respiratory (P<0.05). In TNF-α-induced myotube atrophy model, handelin maintained MyHC protein levels, increased insulin-like growth factor (Igf1) mRNA expression and phosphorylated protein kinase B protein levels (P<0.05). Handelin also reduced atrogin-1 expression, inhibited nuclear factor-κB activation and reduced mRNA levels of interleukin (Il)6, Il1b and chemokine ligand 1 (Cxcl1) (P<0.05). In LPS-treated mice, handelin increased body weight (P<0.05), the weight (P<0.01) and cross-sectional area (CSA) of the soleus muscle (P<0.0001) and improved motor function (P<0.05). In aged mice, handelin slightly increased the weight of the tibialis anterior muscle (P=0.06) and CSA of the tibialis anterior and gastrocnemius muscles (P<0.0001). In the tibialis anterior muscle of aged mice, handelin upregulated mRNA levels of Igf1 (P<0.01), anti-inflammatory cytokine Il10 (P<0.01), mitochondrial biogenesis genes (P<0.05) and antioxidant-related enzymes (P<0.05) and strengthened Sod and Cat enzyme activity (P<0.05). Handelin also reduced lipid peroxidation and protein carbonylation, downregulated mRNA levels of Fbxo32, Mstn, Cxcl1, Il1b and Tnf (P<0.05), and decreased IL-1β levels in serum (P<0.05). Knockdown of Hsp70 or using an Hsp70 inhibitor abolished the ameliorating effects of handelin on myotube atrophy. Handelin ameliorated cachexia- and aging-induced skeletal muscle atrophy in vitro and in vivo, by maintaining homeostasis of protein synthesis and degradation, possibly by inhibiting inflammation. Handelin is a potentially promising drug candidate for the treatment of muscle wasting.

Rationale and protocol of a double-blind, randomized, placebo-controlled trial to test the efficacy, safety, and tolerability of dimethyl fumarate in Friedreich Ataxia (DMF-FA-201).

Friedreich Ataxia (FRDA) is an autosomal recessive neurodegenerative disorder that causes gait and limb ataxia, dysarthria, and impaired vibratory sense, with cardiomyopathy being the predominant cause of death. There is no approved therapy, which results in the use of symptomatic treatments and the chronic support of physiotherapy. Dimethyl fumarate (DMF) is a fumaric acid ester used for the treatment of psoriasis and Multiple Sclerosis (MS). It induces Nrf2 in vitro and in vivo, and it increases frataxin in FRDA patient lymphoblasts, in mouse models, and in MS treated patients. The aim of our study is to investigate if DMF can increase the expression of the FXN gene and frataxin protein and ameliorate in-vivo detectable measures of mitochondrial dysfunction in FRDA. The study is composed of a screening visit and two sequential 12-week phases: a core phase and an extension phase. During the first phase (core), patients will be randomly assigned to either the DMF or a placebo group in a 1:1 ratio. During the first week, patients will receive a total daily dose of 240 mg of DMF or placebo; from the second week of treatment, the dose will be increased to two 120 mg tablets BID for a total daily dose of 480 mg. During the second phase (extension), all patients will be treated with DMF. EudraCT number 2021-006274-23. The primary endpoint will be a change in FXN gene expression level after 12 weeks of treatment. Secondary endpoints will be frataxin protein level, cardiopulmonary exercise test outputs, echocardiographic measures, Nrf2 pathway and mitochondrial biogenesis gene expression, safety, clinical scales, and quality of life scales. This is the first study aimed at exploring the ability of DMF, an already available treatment for MS and psoriasis, to correct the biological deficits of FRDA and potentially improve mitochondrial respiration in-vivo.

Glial Activation, Mitochondrial Imbalance, and Akt/mTOR Signaling May Be Potential Mechanisms of Cognitive Impairment in Heart Failure Mice.

Heart failure (HF) is a major health burden worldwide, with approximately half of HF patients having a comorbid cognitive impairment (CI). However, it is still unclear how CI develops in patients with HF. In the present study, a mice model of heart failure was established by ligating the left anterior descending coronary artery. Echocardiography 1month later confirmed the decline in ejection fraction and ventricular remodeling. Cognitive function was examined by the Pavlovian fear conditioning and the Morris water maze. HF group cued fear memory, spatial memory, and learning impairment, accompanied by activation of glial cells (astrocytes, microglia, and oligodendrocytes) in the hippocampus. In addition, the mitochondrial biogenesis genes TFAM and SIRT1 decreased, and the fission gene DRP1 increased in the hippocampus. Damaged mitochondria release excessive ROS, and the ability to produce ATP decreases. Damaged swollen mitochondria with altered morphology and aberrant inner-membrane crista were observed under a transmission electron microscope. Finally, Akt/mTOR signaling was upregulated in the hippocampus of heart failure mice. These findings suggest that activation of Akt/mTOR signaling, glial activation, and mitochondrial dynamics imbalance could trigger cognitive impairment in the pathological process of heart failure mice.

Abstract P3189: Vcam-1-mediated Mitochondrial Biogenesis In Macrophages Exacerbates Inflammation And Atherosclerosis

Atherosclerotic cardiovascular disease is a leading cause of adult mortality worldwide. Macrophages play a key role in atherogenesis by sustaining the local inflammatory response, facilitating accumulation of immune cells in atheromas that contribute to plaque development. Mitochondrial metabolism plays a key role in governing inflammatory gene expression in macrophages. Yet, the role of mitochondrial biogenesis and mitochondrial DNA synthesis in regulating macrophage inflammation is not known. Vascular cell adhesion protein 1 (VCAM-1) expressed by endothelial cells mediates monocyte adhesion and extravasation in developing atherosclerotic plaques. We observed increased VCAM-1 expression in human and murine plaque macrophages. However, the function of this cell adhesion molecule expressed by macrophages is not known. Here, we evaluated if and how myeloid-VCAM-1 drive mitochondrial biogenesis, inflammation, and atherosclerosis pathology. Increased VCAM-1 expression in plaque macrophages correlated with oxidative DNA damage and mitochondrial volume. To understand the role of myeloid-Vcam1 in atherogenesis, we generated Apoe -/- LyzM cre/+ VCAM-1 fl/fl mice. Consistently, Apoe -/- mice lacking Vcam1 in macrophages exhibited reduced atherosclerosis severity and inflammation. Vcam1-deficient macrophages exhibited decreased inflammation, oxidative phosphorylation, mitochondrial biogenesis, and mitochondrial DNA synthesis genes, including Cmpk2. Cmpk2 deletion in macrophages after oxidized LDL treatment reduced inflammatory mediators that aggravate atherosclerosis. RNA sequencing analysis of Vcam-1 -deficient plaque macrophages and analysis of macrophages lacking Cmpk2 identified Fcor and Lyz1 as the target genes of Vcam1 and Cmpk2 . Interestingly, atherosclerotic plaque macrophages deficient of Sting , which mediates inflammatory signaling in response to oxidized mitochondrial DNA, had increased levels of Fcor and Lyz1 . Our data suggest that VCAM-1 in macrophages signals via CMPK2 and POLG to promote mitochondrial biogenesis, oxidation, and fragmentation, mediating atherogenesis.

Prospective epigenome and transcriptome analyses of cord and peripheral blood from preterm infants at risk of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a prevalent chronic lung disease of prematurity with limited treatment options. To uncover biomarkers of BPD risk, this study investigated epigenetic and transcriptomic signatures of prematurity at birth and during the neonatal period at day 14 and 28. Peripheral blood DNAs from preterm infants were applied to methylation arrays and cell-type composition was estimated by deconvolution. Covariate-adjusted robust linear regression elucidated BPD- and prolonged oxygen (≥ 14 days) exposure-associated CpGs. RNAs from cord and peripheral blood were sequenced, and differentially expressed genes (DEGs) for BPD or oxygen exposure were determined. Estimated neutrophil–lymphocyte ratios in peripheral blood at day 14 in BPD infants were significantly higher than nonBPD infants, suggesting an heightened inflammatory response in developing BPD. BPD-DEGs in cord blood indicated lymphopoiesis inhibition, altered Th1/Th2 responses, DNA damage, and organ degeneration. On day 14, BPD-associated CpGs were highly enriched in neutrophil activation, infection, and CD4 + T cell quantity, and BPD-DEGs were involved in DNA damage, cellular senescence, T cell homeostasis, and hyper-cytokinesis. On day 28, BPD-associated CpGs along with BPD-DEGs were enriched for phagocytosis, neurological disorder, and nucleotide metabolism. Oxygen supplementation markedly downregulated mitochondrial biogenesis genes and altered CpGs annotated to developmental genes. Prematurity-altered DNA methylation could cause abnormal lymphopoiesis, cellular assembly and cell cycle progression to increase BPD risk. Similar pathways between epigenome and transcriptome networks suggest coordination of the two in dysregulating leukopoiesis, adaptive immunity, and innate immunity. The results provide molecular insights into biomarkers for early detection and prevention of BPD.

Serum of COVID-19 patients changes neuroinflammation and mitochondrial homeostasis markers in hippocampus of aged rats.

Patients affected by COVID-19 present mostly with respiratory symptoms but acute neurological symptoms are also commonly observed. Furthermore, a considerable number of individuals develop persistent and often remitting symptoms months after infection, characterizing the condition called long-COVID. Since the pathophysiology of acute and persistent neurological manifestations is not fully established, we evaluated the expression of different genes in hippocampal slices of aged rats exposed to the serum of a post-COVID (sPC) individual and to the serum of patients infected by SARS-CoV-2 [Zeta (sZeta) and Gamma (sGamma) variants]. The expression of proteins related to inflammatory process, redox homeostasis, mitochondrial quality control and glial reactivity was determined. Our data show that the exposure to sPC, sZeta and sGamma differentially altered the mRNA levels of most inflammatory proteins and reduced those of antioxidant response markers in rat hippocampus. Furthermore, a decrease in the expression of mitochondrial biogenesis genes was induced by all serum samples, whereas a reduction in mitochondrial dynamics was only caused by sPC. Regarding the glial reactivity, S100B expression was modified by sPC and sZeta. These findings demonstrate that changes in the inflammatory response and a reduction of mitochondrial biogenesis and dynamics may contribute to the neurological damage observed in COVID-19 patients.

Interleukin-6 Drives Mitochondrial Dysregulation and Accelerates Physical Decline: Insights From an Inducible Humanized IL-6 Knock-In Mouse Model.

Chronic activation of inflammatory pathways (CI) and mitochondrial dysfunction are independently linked to age-related functional decline and early mortality. Interleukin 6 (IL-6) is among the most consistently elevated chronic activation of inflammatory pathways markers, but whether IL-6 plays a causative role in this mitochondrial dysfunction and physical deterioration remains unclear. To characterize the role of IL-6 in age-related mitochondrial dysregulation and physical decline, we have developed an inducible human IL-6 (hIL-6) knock-in mouse (TetO-hIL-6mitoQC) that also contains a mitochondrial-quality control reporter. Six weeks of hIL-6 induction resulted in upregulation of proinflammatory markers, cell proliferation and metabolic pathways, and dysregulated energy utilization. Decreased grip strength, increased falls off the treadmill, and increased frailty index were also observed. Further characterization of skeletal muscles postinduction revealed an increase in mitophagy, downregulation of mitochondrial biogenesis genes, and an overall decrease in total mitochondrial numbers. This study highlights the contribution of IL-6 to mitochondrial dysregulation and supports a causal role of hIL-6 in physical decline and frailty.

Tissue heterogeneity of mitochondrial activity, biogenesis and mitochondrial protein gene expression in buffalo.

Cellular metabolism is most invariant process, occurring in all living organisms, which involves mitochondrial proteins from both nuclear and mitochondrial genomes. The mitochondrial DNA (mtDNA) copy number, protein-coding genes (mtPCGs) expression, and activity vary between various tissues to fulfill specific energy demands across the tissues. In present study, we investigated the OXPHOS complexes and citrate synthase activity in isolated mitochondria from various tissues of freshly slaughtered buffaloes (n = 3). Further, the evaluation of tissue-specific diversity based on the quantification of mtDNA copy numbers was performed and also comprised an expression study of 13 mtPCGs. We found that the functional activity of individual OXPHOS complex I was significantly higher in the liver compared to muscle and brain. Additionally, OXPHOS complex III and V activities was observed significantly higher levels in liver compared to heart, ovary, and brain. Similarly, CS-specific activity differs between tissues, with the ovary, kidney, and liver having significantly greater. Furthermore, we revealed the mtDNA copy number was strictly tissue-specific, with muscle and brain tissues exhibiting the highest levels. Among 13 PCGs expression analyses, mRNA abundances in all genes were differentially expressed among the different tissue. Overall, our results indicate the existence of a tissue-specific variation in mitochondrial activity, bioenergetics, and mtPCGs expression among various types of buffalo tissues. This study serves as a critical first stage in gathering vital comparable data about the physiological function of mitochondria in energy metabolism in distinct tissues, laying the groundwork for future mitochondrial based diagnosis and research.