Dietary isoflavone daidzein promotes Tfam expression that increases mitochondrial biogenesis in C2C12 muscle cells

The interplay between mitochondria, the gut microbiome and metabolites and their therapeutic potential in primary mitochondrial disease

The various roles of the mitochondria and the microbiome in health and disease have been thoroughly investigated, though they are often examined independently and in the context of chronic disease. However, the mitochondria and microbiome are closely connected, namely, through their evolution, maternal inheritance patterns, overlapping role in many diseases and their importance in the maintenance of human health. The concept known as the "mitochondria-microbiome crosstalk" is the ongoing bidirectional crosstalk between these two entities and warrants further exploration and consideration, especially in the context of primary mitochondrial disease, where mitochondrial dysfunction can be detrimental for clinical manifestation of disease, and the role and composition of the microbiome is rarely investigated. A potential mechanism underlying this crosstalk is the role of metabolites from both the mitochondria and the microbiome. During digestion, gut microbes modulate compounds found in food, which can produce metabolites with various bioactive effects. Similarly, mitochondrial metabolites are produced from substrates that undergo biochemical processes during cellular respiration. This review aims to provide an overview of current literature examining the mitochondria-microbiome crosstalk, the role of commonly studied metabolites serve in signaling and mediating these biochemical pathways, and the impact diet has on both the mitochondria and the microbiome. As a final point, this review highlights the up-to-date implications of the mitochondria-microbiome crosstalk in mitochondrial disease and its potential as a therapeutic tool or target.

Therapeutic Potential of Quercetin as an Antioxidant for Bone-Muscle-Tendon Regeneration and Aging

Quercetin (QC), a naturally occurring bioflavonoid found in various fruits and vegetables, possesses many potential health benefits, primarily attributed to its robust antioxidant properties. The generation of oxidative stress in bone cells is a key modulator of their physiological behavior. Moreover, oxidative stress status influences the pathophysiology of mineralized tissues. Increasing scientific evidence demonstrates that manipulating the redox balance in bone cells might be an effective technique for developing bone disease therapies. The QC antioxidant abilities in skeletal muscle significantly enhance muscle regeneration and reduce muscle atrophy. In addition, QC has been shown to have protective effects against oxidative stress, inflammation, apoptosis, and matrix degradation in tendons, helping to maintain the structural integrity and functionality of tendons. Thus, the antioxidant properties of QC might be crucial for addressing age-related musculoskeletal disorders like osteoporosis, sarcopenia, and tendon-related inflammatory conditions. Understanding how QC influences redox signaling pathways involved in musculoskeletal disorders, including their effect on bone, muscle, and tendon differentiation, might provide insights into the diverse advantages of QC in promoting tissue regeneration and preventing cellular damage. Therefore, this study reviewed the intricate relationship among oxidative stress, inflammation, and tissue repair, affected by the antioxidative abilities of QC, in age-related musculoskeletal tissues to improve the overall health of bones, muscles, and tendons of the skeletal system. Also, reviewing the ongoing clinical trials of QC for musculoskeletal systems is encouraging. Given the positive effect of QC on musculoskeletal health, further scientific investigations and controlled human intervention studies are necessary to explore the therapeutic potential to its optimum strength.

Role of Flavonoids in Modulation of Mitochondria Dynamics during Oxidative Stress

BACKGROUND

Flavonoids are a widespread category of naturally occurring polyphenols distinguished by the flavan nucleus in plant-based foods and beverages, known for their various health benefits. Studies have suggested that consuming 150-500 mg of flavonoids daily is beneficial for health. Recent studies suggest that flavonoids are involved in maintaining mitochondrial activity and preventing impairment of mitochondrial dynamics by oxidative stress.

OBJECTIVE

This review emphasized the significance of studying the impact of flavonoids on mitochondrial dynamics, oxidative stress, and inflammatory response.

METHODS

This review analysed and summarised the findings related to the impact of flavonoids on mitochondria from publicly available search engines namely Pubmed, Scopus, and Web of Science.

DESCRIPTION

Any disruption in mitochondrial dynamics can contribute to cellular dysfunction and diseases, including cancer, cardiac conditions, and neurodegeneration. Flavonoids have been shown to modulate mitochondrial dynamics by regulating protein expression involved in fission and fusion events. Furthermore, flavonoids exhibit potent antioxidant properties by lowering the production of ROS and boosting the performance of antioxidant enzymes. Persistent inflammation is a characteristic of many different disorders. This is because flavonoids also alter the inflammatory response by controlling the expression of numerous cytokines and chemokines involved in the inflammatory process. Flavonoids exhibit an impressive array of significant health effects, making them an effective therapeutic agent for managing various disorders. Further this review summarised available mechanisms underlying flavonoids' actions on mitochondrial dynamics and oxidative stress to recognize the optimal dose and duration of flavonoid intake for therapeutic purposes.

CONCLUSION

This review may provide a solid foundation for developing targeted therapeutic interventions utilizing flavonoids, ultimately benefiting individuals afflicted with various disorders.

Daidzein from Dietary Supplement to a Drug Candidate: An Evaluation of Potential

Daidzein (DDZ) is a well-known nutraceutical supplement belonging to the class of isoflavones. It is isolated from various sources such as alfalfa, soybean, and red clover. It demonstrates a broad array of pharmacological/beneficial properties such as cardiovascular exercise, cholesterol reduction, and anticancer, antifibrotic, and antidiabetic effects, which make it effective in treating a wide range of diseases. Its structure and operation are the same as those of human estrogens, which are important in preventing osteoporosis, cancer, and postmenopausal diseases. It is thus a promising candidate for development as a phytopharmaceutical. Addressing safety, efficacy, and physicochemical properties are the primary prerequisites. DDZ is already ingested every day in varying amounts, so there should not be a significant safety risk; however, each indication requires a different dose to be determined. Some clinical trials are already being conducted globally to confirm its safety, efficacy, and therapeutic potential. Furthermore, as a result of its therapeutic influence on health, in order to establish intellectual property, patents are utilized. In light of the vast potential of eugenol, this review presents a detailed data collection on DDZ to substantiate the claim to develop it in the therapeutic category.

Accounting Gut Microbiota as the Mediator of Beneficial Effects of Dietary (Poly)phenols on Skeletal Muscle in Aging

Sarcopenia, the age-related loss of muscle mass and function increasing the risk of disability and adverse outcomes in older people, is substantially influenced by dietary habits. Several studies from animal models of aging and muscle wasting indicate that the intake of specific polyphenol compounds can be associated with myoprotective effects, and improvements in muscle strength and performance. Such findings have also been confirmed in a smaller number of human studies. However, in the gut lumen, dietary polyphenols undergo extensive biotransformation by gut microbiota into a wide range of bioactive compounds, which substantially contribute to bioactivity on skeletal muscle. Thus, the beneficial effects of polyphenols may consistently vary across individuals, depending on the composition and metabolic functionality of gut bacterial communities. The understanding of such variability has recently been improved. For example, resveratrol and urolithin interaction with the microbiota can produce different biological effects according to the microbiota metabotype. In older individuals, the gut microbiota is frequently characterized by dysbiosis, overrepresentation of opportunistic pathogens, and increased inter-individual variability, which may contribute to increasing the variability of biological actions of phenolic compounds at the skeletal muscle level. These interactions should be taken into great consideration for designing effective nutritional strategies to counteract sarcopenia.

Effects of soy protein hydrolysates on antioxidant activity and inhibition of muscle loss

Peptides show biological activity, and are more easily digested than complex proteins. In the present work, we evaluated the effects of soy hydrolysate on skeletal muscle. Soy protein isolate (SPI) was hydrolysed using 2% Alcalase (SPHA) and Flavourzyme (SPHF) at pH 8 for 3 h at 60°C, and at pH 7 for 3 h at 55°C, respectively. Antioxidant properties (total phenolic content and DPPH activity) and inhibition of muscle loss (myogenin, myosin heavy chain [MyHC], creatine kinase, and myostatin) by the SPI hydrolysates in C2C12 cells were compared with those of SPI. Alcalase produced more hydrolysed soy oligopeptides than Flavourzyme. Enzymatic hydrolysis increased the levels of essential amino acids, particularly in SPHF (2,466.85 mg/L) as compared to SPI (56.08 mg/L). The total phenolic contents of hydrolysates increased from 12.02 mg GAE/g in SPI to 22.87 and 18.67 mg GAE/g in SPHA and SPHF, respectively. The IC50 value of DPPH activity decreased four times after hydrolysis (SPI: 124.38, SPHA: 32.18, and SPHF: 30.21 mg/mL). SPHA and SPHF treatments increased the expression levels of both MyHC1 and MyHC3, as well as creatine kinase activity. A significant increase in MyHC3 expression was observed in SPHF at 10 µg/mL. Soy hydrolysates (SPHA: 93.5% and SPHF: 61%) induced a greater decrease in the expression of myostatin, a muscle reduction marker, than SPI (30.4%). In conclusion, soy hydrolysates may inhibit muscle loss, showing particularly better effects when Alcalase is used for hydrolysis.

Dietary Supplements and Natural Products: An Update on Their Clinical Effectiveness and Molecular Mechanisms of Action During Accelerated Biological Aging

Accelerated biological aging, which involves the gradual decline of organ or tissue functions and the distortion of physiological processes, underlies several human diseases. Away from the earlier free radical concept, telomere attrition, cellular senescence, proteostasis loss, mitochondrial dysfunction, stem cell exhaustion, and epigenetic and genomic alterations have emerged as biological hallmarks of aging. Moreover, nutrient-sensing metabolic pathways are critical to an organism's ability to sense and respond to nutrient levels. Pharmaceutical, genetic, and nutritional interventions reverting physiological declines by targeting nutrient-sensing metabolic pathways can promote healthy aging and increase lifespan. On this basis, biological aging hallmarks and nutrient-sensing dependent and independent pathways represent evolving drug targets for many age-linked diseases. Here, we discuss and update the scientific community on contemporary advances in how dietary supplements and natural products beneficially revert accelerated biological aging processes to retrograde human aging and age-dependent human diseases, both from the clinical and preclinical studies point-of-view. Overall, our review suggests that dietary/natural products increase healthspan-rather than lifespan-effectively minimizing the period of frailty at the end of life. However, real-world setting clinical trials and basic studies on dietary supplements and natural products are further required to decisively demonstrate whether dietary/natural products could promote human lifespan.

Curcuma longa L. Water Extract Enhances Endurance Exercise Capacity by Promoting Intramuscular Mitochondrial Biogenesis in Mice

We investigated the effect of Curcuma longa L. extract on endurance exercise capacity (EEC). EEC is the ability to exercise continuously and recover quickly, even when tired. C. longa contains antioxidants that contribute beneficial effects on the body. We separated groups of nonexercise (CON), exercise control (Ex-CON), branched-chain amino acid (BCAA) intake, and C. longa water extract (CLW) intake (Ex-CLW). EEC increased on the 28th day of BCAA and CLW intake. Both treatment groups exhibited decreased lactate levels with increased levels of nonesterified fatty acids and muscular glycogen compared with the Ex-CON group. Also, the Ex-CLW group possessed higher intramuscular antioxidant enzyme activities (catalase, superoxide dismutase, and glutathione peroxidase) than the Ex-CON group. The expression of PGC-1α, NRF, and Tfam, which are factors related to mitochondrial biogenesis, increased in the Ex-CLW group. Results suggest that CLW intake elevated EEC by increasing intramuscular mitochondrial biogenesis through suppressing the accumulation of fatigue substances and increasing fat consumption, and antioxidant enzyme activity.

Roles of NPAS2 in circadian rhythm and disease

NPAS2, a circadian rhythm gene encoding the neuronal PAS domain protein 2 (NPAS2), has received widespread attention because of its complex functions in cells and diverse roles in disease progression, especially tumorigenesis. NPAS2 binds with DNA at E-box sequences and forms heterodimers with another circadian protein, brain and muscle ARNT-like protein 1 (BMAL1). Nucleotide variations of the NPAS2 gene have been shown to influence the overall survival and risk of death of cancer patients, and differential expression of NPAS2 has been linked to patient outcomes in breast cancer, lung cancer, non-Hodgkin's lymphoma, and other diseases. Here, we review the latest advances in our understanding of NPAS2 with the aim of drawing attention to its potential clinical applications and prospects.

Daidzein alleviates cisplatin-induced muscle atrophy by regulating Glut4/AMPK/FoxO pathway

Cisplatin (DDP) is widely used in cancer treatment, but DDP can cause skeletal muscle atrophy and cachexia. This study explored the effect and mechanism of daidzein (DAI) in reducing DDP-induced skeletal muscle atrophy and cachexia in vivo and in vitro. DAI alleviated the weight, food intake, muscle, adipose tissue, kidney weight and forelimb grip of LLC tumour-bearing mice after DDP treatment, and did not affect the antitumour effect of DDP. DAI can reduce the decrease of the cross-sectional area of skeletal muscle fibre-induced by DDP and prevent the change of fibre type proportion. In skeletal muscle, it can inhibit Glut4/AMPK/FoxO pathway, down-regulate the expression of atrogin1 and MuRF1, and inhibit skeletal muscle protein degradation. In DDP treated C2C12 myotubes, DAI could inhibit Glut4/AMPK/FoxO pathway to reduce myotubes atrophy, while AMPK agonist MK-3903 could reverse the protective effect of DAI. These results suggest that DAI can alleviate DDP-induced skeletal muscle atrophy by downregulating the expression of Atrogin1 and MuRF1 through the regulation of Glut4/AMPK/FoxO pathway.

FNDC5 expression closely correlates with muscle fiber types in porcine longissimus dorsi muscle and regulates myosin heavy chains (MyHCs) mRNA expression in C2C12 cells

BACKGROUND

Irisin (a glycosylated protein) is cleaved from fibronectin type III domain-containing protein 5 (FNDC5), which is expressed mainly in animal muscle tissues and has multiple metabolic regulatory activities. However, their roles in controlling myofiber types in skeletal muscle remain unclear.

METHODOLOGY

Two different commercial hybridized pigs, LJH (a crossed pig containing Chinese native pig genotypes) and DLY (Duroc × Landrace × Yorkshire) were selected to analyze FNDC5 mRNA expression and the mRNA composition of four adult myosin heavy chain (MyHC) isoforms (IIIaIIxIIb) in the longissimus dorsi (LD) muscle. C2C12 myoblasts were cultured to investigate the effects of FNDC5 on the four MyHCs mRNA expressive levels, using small interfering RNA for depletion and a eukaryotic expression vector carrying FNDC5 for overexpression. ZLN005 (a small molecule activator of FNDC5's upstream control gene PGC1α) or recombinant human irisin protein were also used.

RESULTS

In LD muscle, LJH pigs had the higher FNDC5 mRNA level, and MyHC I or IIa proportion than DLY pigs (P <  0.05). For C2C12 cells in vitro, small interfering RNA (si-592) silencing of FNDC5 expression markedly reduced MyHC IIa mRNA levels (P <  0.05), while FNDC5 overexpression significantly increased MyHC IIa mRNA levels (P <  0.05). Exogenous irisin increased the mRNA levels of PGC1α (peroxisome proliferator-activated receptor gamma coactivator 1-alpha), FNDC5, MyHCI, MyHCIIa, NRF1 (nuclear respiratory factor 1), VEGF (vascular endothelial growth factor), and TFAM (mitochondrial transcription factor A,) (P <  0.05), and the enzyme activities of SDH (succinate dehydrogenase), CK (creatine kinase), and MDH (malate dehydrogenase) in C2C12 myotubes (P <  0.05). These results showed that FNDC5 mRNA expression had a significant association with the characteristics of myofiber types in porcine muscle, and participated in regulating MyHCs mRNA expression of C2C12 myogenic differentiation cells in vitro. FNDC5 could be an important factor to control muscle fiber types, which provides a new direction to investigate pork quality via muscle fiber characteristics.

Natural Extracts to Augment Energy Expenditure as a Complementary Approach to Tackle Obesity and Associated Metabolic Alterations

Obesity is the epidemic of the 21st century. In developing countries, the prevalence of obesity continues to rise, and obesity is occurring at younger ages. Obesity and associated metabolic stress disrupt the whole-body physiology. Adipocytes are critical components of the systemic metabolic control, functioning as an endocrine organ. The enlarged adipocytes during obesity recruit macrophages promoting chronic inflammation and insulin resistance. Together with the genetic susceptibility (single nucleotide polymorphisms, SNP) and metabolic alterations at the molecular level, it has been highlighted that key modifiable risk factors, such as those related to lifestyle, contribute to the development of obesity. In this scenario, urgent therapeutic options are needed, including not only pharmacotherapy but also nutrients, bioactive compounds, and natural extracts to reverse the metabolic alterations associated with obesity. Herein, we first summarize the main targetable processes to tackle obesity, including activation of thermogenesis in brown adipose tissue (BAT) and in white adipose tissue (WAT-browning), and the promotion of energy expenditure and/or fatty acid oxidation (FAO) in muscles. Then, we perform a screening of 20 natural extracts (EFSA approved) to determine their potential in the activation of FAO and/or thermogenesis, as well as the increase in respiratory capacity. By means of innovative technologies, such as the study of their effects on cell bioenergetics (Seahorse bioanalyzer), we end up with the selection of four extracts with potential application to ameliorate the deleterious effects of obesity and the chronic associated inflammation.

Precision Nutrition to Activate Thermogenesis as a Complementary Approach to Target Obesity and Associated-Metabolic-Disorders

Simple Summary

Regarding the pandemic of obesity and chronic diseases associated to metabolic alterations that occur nowadays worldwide, here, we review the most recent studies related to bioactive compounds and diet derived ingredients with potential effects to augment the systemic energy expenditure. We specifically focus in two processes: the activation of thermogenesis in adipose tissue and the enhancement of the mitochondrial oxidative phosphorylation capacity in muscles. This may provide relevant information to develop diets and supplements to conduct nutritional intervention studies with the objective to ameliorate the metabolic and chronic inflammation in the course of obesity and related disorders.

Abstract

Obesity is associated to increased incidence and poorer prognosis in multiple cancers, contributing to up to 20% of cancer related deaths. These associations are mainly driven by metabolic and inflammatory changes in the adipose tissue during obesity, which disrupt the physiologic metabolic homeostasis. The association between obesity and hypercholesterolemia, hypertension, cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM) is well known. Importantly, the retrospective analysis of more than 1000 epidemiological studies have also shown the positive correlation between the excess of fatness with the risk of cancer. In addition, more important than weight, it is the dysfunctional adipose tissue the main driver of insulin resistance, metabolic syndrome and all cause of mortality and cancer deaths, which also explains why normal weight individuals may behave as “metabolically unhealthy obese” individuals. Adipocytes also have direct effects on tumor cells through paracrine signaling. Downregulation of adiponectin and upregulation of leptin in serum correlate with markers of chronic inflammation, and crown like structures (CLS) associated to the adipose tissue disfunction. Nevertheless, obesity is a preventable risk factor in cancer. Lifestyle interventions might contribute to reduce the adverse effects of obesity. Thus, Mediterranean diet interventional studies have been shown to reduce to circulation inflammatory factors, insulin sensitivity and cardiovascular function, with durable responses of up to 2 years in obese patients. Mediterranean diet supplemented with extra-virgin olive oil reduced the incidence of breast cancer compared with a control diet. Physical activity is another important lifestyle factor which may also contribute to reduced systemic biomarkers of metabolic syndrome associated to obesity. In this scenario, precision nutrition may provide complementary approaches to target the metabolic inflammation associated to “unhealthy obesity”. Herein, we first describe the different types of adipose tissue -thermogenic active brown adipose tissue (BAT) versus the energy storing white adipose tissue (WAT). We then move on precision nutrition based strategies, by mean of natural extracts derived from plants and/or diet derived ingredients, which may be useful to normalize the metabolic inflammation associated to “unhealthy obesity”. More specifically, we focus on two axis: (1) the activation of thermogenesis in BAT and browning of WAT; (2) and the potential of augmenting the oxidative capacity of muscles to dissipate energy. These strategies may be particularly relevant as complementary approaches to alleviate obesity associated effects on chronic inflammation, immunosuppression, angiogenesis and chemotherapy resistance in cancer. Finally, we summarize main studies where plant derived extracts, mainly, polyphenols and flavonoids, have been applied to increase the energy expenditure.

Rutin and Gallic Acid Regulates Mitochondrial Functions via the SIRT1 Pathway in C2C12 Myotubes

Mitochondria are highly dynamic organelles, balancing synthesis and degradation in response to increases in mitochondrial turnover (i.e., biogenesis, fusion, fission, and mitophagy) and function. The aim of this study was to investigate the role of polyphenols in the regulation of mitochondrial functions and dynamics in C2C12 myotubes and their molecular mechanisms. Our results indicate that gallic acid and rutin are the most potential polyphenol compounds in response to 15 phenolic acids and 5 flavonoids. Gallic acid and rutin were associated with a significantly greater mitochondrial DNA (cytochrome b and COX-II), mitochondrial enzymatic activities (including citrate synthase and cytochrome c oxidase), and intracellular ATP levels in C2C12 myotubes. Moreover, gallic acid and rutin significantly increased the gene expressions of mitochondrial turnover in C2C12 myotubes. Our findings indicated that gallic acid and rutin may have a beneficial effect on mitochondrial dynamics via regulation of the SIRT1-associated pathway in C2C12 myotubes.

The Role of Isoflavones in Type 2 Diabetes Prevention and Treatment-A Narrative Review

Given the growing number of type 2 diabetic individuals and the substantial social and financial costs associated with diabetes management, every effort should be made to improve its prevention and treatment methods. There is an ongoing search for natural dietary compounds that could be used for this purpose. This narrative review focuses on the therapeutic potential of isoflavones in diabetes prevention and treatment. This review summarizes (i) the molecular mechanisms of isoflavones action that are critical to their anti-diabetic properties; (ii) preclinical (in vitro and in vivo) studies evaluating the influence of isoflavones on the function of key organs involved in the pathogenesis of diabetes; and (iii) epidemiological studies and clinical trials that assessed the effectiveness of isoflavones in the prevention and treatment of type 2 diabetes in humans. Apart from discussing the effects of isoflavones on the function of organs “classically” associated with the pathogenesis of diabetes (pancreas, liver, muscles, and adipose tissue), the impact of these compounds on other organs that contribute to the glucose homeostasis (gastrointestinal tract, kidneys, and brain) is also reviewed.

Flavonoids: nutraceutical potential for counteracting muscle atrophy

Skeletal muscle plays a vital role in the conversion of chemical energy into physical force. Muscle atrophy, characterized by a reduction in muscle mass, is a symptom of chronic disease (cachexia), aging (sarcopenia), and muscle disuse (inactivity). To date, several trials have been conducted to prevent and inhibit muscle atrophy development; however, few interventions are currently available for muscle atrophy. Recently, food ingredients, plant extracts, and phytochemicals have received attention as treatment sources to prevent muscle wasting. Flavonoids are bioactive polyphenol compounds found in foods and plants. They possess diverse biological activities, including anti-obesity, anti-diabetes, anti-cancer, anti-oxidation, and anti-inflammation. The effects of flavonoids on muscle atrophy have been investigated by monitoring molecular mechanisms involved in protein turnover, mitochondrial activity, and myogenesis. This review summarizes the reported effects of flavonoids on sarcopenia, cachexia, and disuse muscle atrophy, thus, providing an insight into the understanding of the associated molecular mechanisms.

Rice Bran Phenolic Extract Confers Protective Effects against Alcoholic Liver Disease in Mice by Alleviating Mitochondrial Dysfunction via the PGC-1α-TFAM Pathway Mediated by microRNA-494-3p

The initiation and development of alcoholic liver disease (ALD) is mediated, at least partly, by mitochondria dysfunction, which is regulated by PPARγ coactivator-1α (PGC-1α) via mitochondria transcription factor A (TFAM). Then, PGC-1α expression was regulated by several microRNAs. This research investigated the hepatoprotective effects of the rice bran phenolic extract (RBPE) on mice fed with an ethanol-containing diet via the microRNAs-PGC-1α-TFAM signal pathway. RBPE treatment protected against alcoholic liver injury, as indicated by decreased serum aminotransferase activities and hepatic triglyceride accumulation, together with alleviated oxidative stress in serum and the liver. RBPE treatment alleviated ethanol-induced mitochondrial dysfunction through altering the membrane potential, mtDNA content, and respiratory chain complex enzyme activities in mitochondria, resulting in increased hepatic ATP production. Decreased cytoplasmic cytochrome c contents, caspase-3 activity, and Bax/Bcl-2 ratio were detected in the liver of RBPE-treated mice, indicating that the RBPE might inhibit ethanol-induced hepatocellular apoptosis. Furthermore, ethanol-induced decreases in the mRNA and protein expression of PGC-1α and TFAM were remarkably alleviated in RBPE-treated mice. RBPE treatment to ethanol-fed mice could also downregulate the expression of microRNA-494-3p, which regulates PGC-1α expression directly. Therefore, the RBPE might exert protection against ALD by alleviating mitochondrial dysfunction and the resulting hepatocyte apoptosis via the PGC-1α-TFAM signal pathway mediated by microRNA-494-3p.

Mitochondrial HMG-Box Containing Proteins: From Biochemical Properties to the Roles in Human Diseases

Mitochondrial DNA (mtDNA) molecules are packaged into compact nucleo-protein structures called mitochondrial nucleoids (mt-nucleoids). Their compaction is mediated in part by high-mobility group (HMG)-box containing proteins (mtHMG proteins), whose additional roles include the protection of mtDNA against damage, the regulation of gene expression and the segregation of mtDNA into daughter organelles. The molecular mechanisms underlying these functions have been identified through extensive biochemical, genetic, and structural studies, particularly on yeast (Abf2) and mammalian mitochondrial transcription factor A (TFAM) mtHMG proteins. The aim of this paper is to provide a comprehensive overview of the biochemical properties of mtHMG proteins, the structural basis of their interaction with DNA, their roles in various mtDNA transactions, and the evolutionary trajectories leading to their rapid diversification. We also describe how defects in the maintenance of mtDNA in cells with dysfunctional mtHMG proteins lead to different pathologies at the cellular and organismal level.

Flavonoids and Mitochondria: Activation of Cytoprotective Pathways?

A large number of diverse mechanisms that lead to cytoprotection have been described to date. Perhaps, not surprisingly, the role of mitochondria in these phenomena is notable. In addition to being metabolic centers, due to their role in cell catabolism, ATP synthesis, and biosynthesis these organelles are triggers and/or end-effectors of a large number of signaling pathways. Their role in the regulation of the intrinsic apoptotic pathway, calcium homeostasis, and reactive oxygen species signaling is well documented. In this review, we aim to characterize the prospects of influencing cytoprotective mitochondrial signaling routes by natural substances of plant origin, namely, flavonoids (e.g., flavanones, flavones, flavonols, flavan-3-ols, anthocyanidins, and isoflavones). Flavonoids are a family of widely distributed plant secondary metabolites known for their beneficial effects on human health and are widely applied in traditional medicine. Their pharmacological characteristics include antioxidative, anticarcinogenic, anti-inflammatory, antibacterial, and antidiabetic properties. Here, we focus on presenting mitochondria-mediated cytoprotection against various insults. Thus, the role of flavonoids as antioxidants and modulators of antioxidant cellular response, apoptosis, mitochondrial biogenesis, autophagy, and fission and fusion is reported. Finally, an emerging field of flavonoid-mediated changes in the activity of mitochondrial ion channels and their role in cytoprotection is outlined.

Polyphenols as Caloric Restriction Mimetics Regulating Mitochondrial Biogenesis and Mitophagy

The tight coordination between mitochondrial biogenesis and mitophagy can be dysregulated during aging, critically influencing whole-body metabolism, health, and lifespan. To date, caloric restriction (CR) appears to be the most effective intervention strategy to improve mitochondrial turnover in aging organisms. The development of pharmacological mimetics of CR has gained attention as an attractive and potentially feasible approach to mimic the CR phenotype. Polyphenols, ubiquitously present in fruits and vegetables, have emerged as well-tolerated CR mimetics that target mitochondrial turnover. Here, we discuss the molecular mechanisms that orchestrate mitochondrial biogenesis and mitophagy, and we summarize the current knowledge of how CR promotes mitochondrial maintenance and to what extent different polyphenols may mimic CR and coordinate mitochondrial biogenesis and clearance.

Daidzein promotes the expression of oxidative phosphorylation- and fatty acid oxidation-related genes via an estrogen-related receptor α pathway to decrease lipid accumulation in muscle cells

Estrogen-related receptor (ERR)α regulates genes involved in fatty acid oxidation (FAO) and oxidative phosphorylation (OXPHOS) in muscle. The soy isoflavone daidzein was reported to be a putative ERRα activator, but little is known about its effects on gene expression and FA metabolism. This study aimed to clarify whether daidzein affects FAO- and OXPHOS-related genes thereby modulating intracellular FA metabolism in muscle cells. For this purpose, we used the C2C12 murine muscle cell line. ERRα-expressing C2C12 myotubes were treated with 50 μM daidzein, and gene expression was examined. The expression of FAO genes such as pyruvate dehydrogenase kinase 4 (Pdk4) and acyl-coenzyme A dehydrogenase (Acadm) and that of OXPHOS genes such as ATP synthase F1 subunit beta (Atp5b) and cytochrome c (Cycs) was significantly increased by daidzein, and these effects were partially blocked by an ERRα inhibitor. Using a reporter assay, we showed that daidzein enhanced the promoter activity of these genes and that ERRα responsive elements in the promoter region were necessary for the action of daidzein. Finally, daidzein significantly decreased lipid accumulation in C2C12 myotubes associated with increased oxygen consumption. In conclusion, daidzein decreases lipid deposition in muscle cells by regulating the expression of genes related to FAO and OXPHOS via an ERRα-associated pathway at least in part. These results suggest that daidzein would be a beneficial tool to protect against various diseases caused by muscle lipotoxicity.

Upregulation of Mitochondrial Transcription Factor A Promotes the Repairment of Renal Tubular Epithelial Cells in Sepsis by Inhibiting Reactive Oxygen Species-Mediated Toll-Like Receptor 4/p38MAPK Signaling

BACKGROUND

Mitochondrial transcription factor A (TFAM) plays multiple pathophysiologic roles in mitochondrial DNA (mtDNA) maintenance. However, the role of TFAM in sepsis-induced acute kidney injury (AKI) remains largely unknown.

METHODS

Lipopolysaccharide (LPS) treatment of HK-2 cells mimics the in vitro model of AKI inflammation. pcDNA3.1 plasmid was used to construct pcDNA3.1-TFAM. sh-TFAM-543, sh-TFAM-717, sh-TFAM-765, sh-TFAM-904 and pcDNA3.1-TFAM were transfected into HK-2 cells using Lipofectamine 2000. MtDNA transcriptional levels were detected by quantitative real-time polymerase chain reaction (qRT-PCR). 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay was performed to assess the cell viability. Changes in reactive oxygen species (ROS) and mitochondrial membrane potential in HK-2 cells were detected using the corresponding kits. Immunofluorescence experiment was used to investigate the displacement of TFAM. mRNA and protein expression levels of TFAM and its related genes were measured by qRT-PCR and western blot respectively. Mice in sepsis were administered cecal ligation and puncture surgery.

RESULTS

LPS treatment was a non-lethal influencing factor, leading to the upregulation of ROS levels and downregulation of mtDNA copy number and NADH dehydrogenase subunit-1 (ND1) expression, and caused damage to the mitochondria. As the LPS treatment time increased, TFAM was displaced from the periphery of the nucleus to cytoplasm. TFAM reduced ROS and P38MAPK levels by inhibiting toll-like receptor 4 (TLR4) expression, ultimately inhibiting inflammation and repairing mtDNA.

CONCLUSIONS

Our results indicate that TFAM repairs mtDNA by blocking the TLR4/ROS/P38MAPK signaling pathway in inflammatory cells, thereby repairing septic tubular epithelial cells, and TFAM may serve as a new target for sepsis therapy.

Effect of saffron (Crocus sativus L.) and endurance training on mitochondrial biogenesis, endurance capacity, inflammation, antioxidant, and metabolic biomarkers in Wistar rats

We aimed to evaluate the effect of saffron (Crocus Sativus L.) treatment on endurance capacity, mitochondrial biogenesis, inflammation, antioxidant, and metabolic biomarkers in Wistar rats. Forty male rats were allocated equally into four groups: Saffron, Exercise and Saffron, Exercise and Placebo, and Placebo. Endurance training was accomplished on a specified rodent motor-driven treadmill. Running to fatigue test and also metabolic and molecular indices were measured after eight weeks of intervention. mtDNA copy number and NRF-1 gene expression increased significantly in the Ex + S group compared to the exercised and control group (p < 0.05). Endurance capacity time increased in the Ex + S group compared to the Ex group (p < 0.05). Malondialdehyde, CPK, AST, and IL-6 decreased and antioxidant parameters including Glutathione peroxidase and Glutathione increased in the Ex + S group compared to exercised rats (p < 0.01). Saffron enhanced mitochondrial biogenesis, decreased oxidative stress, inflammation, and modulated metabolic biomarkers in exercised rats. PRACTICAL APPLICATIONS: The influence of potential nutrient factors on exercise performance has reached much attention in recent years. Athletes require an appropriate sport supplement to reimburse their fatigue and improve their resilience. Saffron (Crocus Sativus L.) is a well-known spice in the food trade which is quite popular around the world by giving a desirable taste to food. In an experimental study, we showed that saffron extract treatment during endurance training could improve endurance capacity by modulating several metabolic and genomic factors. Therefore, by relying on the results of this study and the positive effects of saffron published in previous studies, saffron could be added to sport beverages and supplements to enhance an athlete's performance.

HuR stabilizes TFAM mRNA in an ATM/p38-dependent manner in ionizing irradiated cancer cells

Mitochondrial transcription factor A (TFAM) plays key roles in transcription and maintenance of mtDNA. It has been reported that TFAM could promote the proliferation and tumorigenesis of cells under stressed conditions. Previous evidence showed ionizing radiation stimulated the expression of TFAM, the replication of mtDNA, and the activity of mtDNA‐encoded cytochrome C oxidase. However, little is known about the mechanism of TFAM regulation in irradiated cells. In this article, we explored the role of mRNA stability in regulating TFAM expression in irradiated cancer cells. Our results showed that radiation stimulated the levels of TFAM mRNA and protein. RNA‐binding protein HuR associated and stabilized TFAM mRNA to facilitate the expression of TFAM, which was enhanced by radiation. Furthermore, radiation‐activated ataxia‐telangiectasia mutated kinase/p38 signaling positively contributed to the nucleus to cytosol translocation of HuR, its binding and stabilization of TFAM mRNA, without affecting the transcription and the stability of TFAM. Our current work proposed a new mechanism of DNA damage response‐regulated mitochondrial function variations, and indicated that TFAM might be a potential target for increasing the sensitization of cancer cells to radiotherapy.

Mitochondrial pathways to cardiac recovery: TFAM

Mitochondrial dysfunction underlines a multitude of pathologies; however, studies are scarce that rescue the mitochondria for cellular resuscitation. Exploration into the protective role of mitochondrial transcription factor A (TFAM) and its mitochondrial functions respective to cardiomyocyte death are in need of further investigation. TFAM is a gene regulator that acts to mitigate calcium mishandling and ROS production by wrapping around mitochondrial DNA (mtDNA) complexes. TFAM's regulatory functions over serca2a, NFAT, and Lon protease contribute to cardiomyocyte stability. Calcium- and ROS-dependent proteases, calpains, and matrix metalloproteinases (MMPs) are abundantly found upregulated in the failing heart. TFAM's regulatory role over ROS production and calcium mishandling leads to further investigation into the cardioprotective role of exogenous TFAM. In an effort to restabilize physiological and contractile activity of cardiomyocytes in HF models, we propose that TFAM-packed exosomes (TFAM-PE) will act therapeutically by mitigating mitochondrial dysfunction. Notably, this is the first mention of exosomal delivery of transcription factors in the literature. Here we elucidate the role of TFAM in mitochondrial rescue and focus on its therapeutic potential.

Effect of polyphenols from coffee and grape on gene expression in myoblasts

Coffee and grape contain various bioactive compounds like polyphenols that may exert beneficial effects, especially antioxidant activity, on human health upon consumption. However, the molecular mechanisms through which these effects are achieved are not fully elucidated. Thus, in the present study in order to investigate these mechanisms, a whole genome expression DNA microarray analysis was carried out in myoblasts treated with polyphenols of coffee and grape pomace at concentrations that improved the redox status. Grape was composed of catechin, epicatechin, cyanidin, malvidin, delphinidin, petunidin, myrtillin, kuromanin, oenin, peonidin, quercetin, gallic acid and caftaric acid as LC-MS revealed, with a total polyphenolic content (TPC) of 648 mg of gallic acid equivalents/g of dry matter. Coffee had a TPC of 42.61 mg GAE/g coffee and was composed of 3-chlorogenic acid (16.61 mg/g), 4- and 5-chlorogenic acids (13.62 mg/g), as UHPLC-HRMS revealed. According to the results, grape polyphenols altered mainly the expression of cytoskeleton and differentiation-associated genes, while coffee compounds had a more profound effect, on the expression levels of many metabolic and antioxidant genes possibly through the nuclear factor (erythroid-derived 2) like-2 (Nrf2) pathway.

Molecular mechanisms and therapeutic interventions in sarcopenia

Sarcopenia is the degenerative loss of muscle mass and function with aging. Recently sarcopenia was recognized as a clinical disease by the International Classification of Disease, 10th revision, Clinical Modification. An imbalance between protein synthesis and degradation causes a gradual loss of muscle mass, resulting in a decline of muscle function as a progress of sarcopenia. Many mechanisms involved in the onset of sarcopenia include age-related factors as well as activity-, disease-, and nutrition-related factors. The stage of sarcopenia reflecting the severity of conditions assists clinical management of sarcopenia. It is important that systemic descriptions of the disease conditions include age, sex, and other environmental risk factors as well as levels of physical function. To develop a new therapeutic intervention needed is the detailed understanding of molecular and cellular mechanisms by which apoptosis, autophagy, atrophy, and hypertrophy occur in the muscle stem cells, myotubes, and/or neuromuscular junction. The new strategy to managing sarcopenia will be signal-modulating small molecules, natural compounds, repurposing of old drugs, and muscle-specific microRNAs.

Development of Therapeutics That Induce Mitochondrial Biogenesis for the Treatment of Acute and Chronic Degenerative Diseases

Mitochondria have various roles in cellular metabolism and homeostasis. Because mitochondrial dysfunction is associated with many acute and chronic degenerative diseases, mitochondrial biogenesis (MB) is a therapeutic target for treating such diseases. Here, we review the role of mitochondrial dysfunction in acute and chronic degenerative diseases and the cellular signaling pathways by which MB is induced. We then review existing work describing the development and application of drugs that induce MB in vitro and in vivo. In particular, we discuss natural products and modulators of transcription factors, kinases, cyclic nucleotides, and G protein-coupled receptors.