Fibroblast growth factor 19 alleviates palmitic acid-induced mitochondrial dysfunction and oxidative stress via the AMPK/PGC-1α pathway in skeletal muscle

NRF2 in age-related musculoskeletal diseases: Role and treatment prospects

The NRF2 pathway is a metabolic- and redox-sensitive signaling axis in which the transcription factor controls the expression of a multitude of genes that enable cells to survive environmental stressors, such as oxidative stress, mainly by inducing the expression of cytoprotective genes. Basal NRF2 levels are maintained under normal physiological conditions, but when exposed to oxidative stress, cells activate the NRF2 pathway, which is crucial for supporting cell survival. Recently, the NRF2 pathway has been found to have novel functions in metabolic regulation and interplay with other signaling pathways, offering novel insights into the treatment of various diseases. Numerous studies have shown that targeting its pathway can effectively investigate the development and progression of age-related musculoskeletal diseases, such as sarcopenia, osteoporosis, osteoarthritis, and intervertebral disc degeneration. Appropriate regulation of the NRF2 pathway flux holds promise as a means to improve musculoskeletal function, thereby providing a new avenue for drug treatment of age-related musculoskeletal diseases in clinical settings. The review summarized an overview of the relationship between NRF2 and cellular processes such as oxidative stress, apoptosis, inflammation, mitochondrial dysfunction, ferroptosis, and autophagy, and explores the potential of targeted NRF2 regulation in the treatment of age-related musculoskeletal diseases.

Luteolin alleviates muscle atrophy, mitochondrial dysfunction and abnormal FNDC5 expression in high fat diet-induced obese rats and palmitic acid-treated C2C12 myotubes

Obesity is associated with a series of skeletal muscle impairments and dysfunctions, which are characterized by metabolic disturbances and muscle atrophy. Luteolin is a phenolic phytochemical with broad pharmacological activities. The present study aimed to evaluate the protective effects of Luteolin on muscle function and explore the potential mechanisms in high-fat diet (HFD)-induced obese rats and palmitic acid (PA)-treated C2C12 myotubes. Male Sprague-Dawley (SD) rats were fed with a control diet or HFD and orally administrated 0.5% sodium carboxymethyl cellulose (vehicle) or Luteolin (25, 50, and 100 mg/kg, respectively) for 12 weeks. The results showed that Luteolin ameliorated HFD-induced body weight gain, glucose intolerance and hyperlipidemia. Luteolin also alleviated muscle atrophy, decreased ectopic lipid deposition and prompted muscle-fiber-type conversion in the skeletal muscle. Meanwhile, we observed an evident improvement in mitochondrial quality control and respiratory capacity, accompanied by reduced oxidative stress. Mechanistic studies indicated that AMPK/SIRT1/PGC-1α signaling pathway plays a key role in the protective effects of Luteolin on skeletal muscle in the obese states, which was further verified by using specific inhibitors of AMPK and SIRT1. Moreover, the mRNA expression levels of markers in brown adipocyte formation were significantly up-regulated post Luteolin supplementation in different adipose depots. Taken together, these results revealed that Luteolin supplementation might be a promising strategy to prevent obesity-induced loss of mass and biological dysfunctions of skeletal muscle.

Multi-omics analysis reveals phenylalanine enhance mitochondrial function and hypoxic endurance via LKB1/AMPK activation

Many studies have focused on the effects of small molecules, such as amino acids, on metabolism under hypoxia. Recent findings have indicated that phenylalanine levels were markedly elevated in adaptation to chronic hypoxia. This raises the possibility that phenylalanine treatment could markedly improve the hypoxic endurance. However, the importance of hypoxia-regulated phenylalanine is still unclear. This study investigates the role of phenylalanine in hypoxia adaptation using a hypoxic zebrafish model and multi-omics analysis. We found that phenylalanine-related metabolic pathways are significantly up-regulated under hypoxia, contributing to enhanced hypoxic endurance. Phenylalanine treatment reduced ROS levels, improved mitochondrial oxygen consumption rate (OCR), and extracellular acidification rate (ECAR) in hypoxic cells. Western blotting revealed increased phenylalanine uptake via L-type amino transporters (LAT1), activating the LKB1/AMPK signaling pathway. This activation up-regulated peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) and the Bcl-2/Bax ratio, while down-regulating uncoupling protein 2 (UCP2), thereby improving mitochondrial function under hypoxia. This is the first comprehensive multi-omics analysis to demonstrate phenylalanine's crucial role in hypoxia adaptation, providing insights for the development of anti-hypoxic drugs.

The role of FGF19 in metabolic regulation: insights from preclinical models to clinical trials

Fibroblast growth factor 19 (FGF19) is a hormone synthesized in enterocytes in response to bile acids. This review explores the pivotal role of FGF19 in metabolism, addressing the urgent global health concern of obesity and its associated pathologies, notably type 2 diabetes. The intriguing inverse correlation between FGF19 and body mass or visceral adiposity, as well as its rapid increase following bariatric surgery, emphasizes its potential as a therapeutic target. This article meticulously examines the impact of FGF19 on metabolism by gathering evidence primarily derived from studies conducted in animal models or cell lines, using both FGF19 treatment and genetic modifications. Overall, these studies demonstrate that FGF19 has antidiabetic and antiobesogenic effects. A thorough examination across metabolic tissues, including the liver, adipose tissue, skeletal muscle, and the central nervous system, is conducted, unraveling the intricate interplay of FGF19 across diverse organs. Moreover, we provide a comprehensive overview of clinical trials involving an FGF19 analog called aldafermin, emphasizing promising results in diseases such as nonalcoholic steatohepatitis and diabetes. Therefore, we aim to foster a deeper understanding of FGF19 role and encourage further exploration of its clinical applications, thereby advancing the field and offering innovative approaches to address the escalating global health challenge of obesity and related metabolic conditions.

Research progress in mechanism of anticancer action of shikonin targeting reactive oxygen species

Excessive buildup of highly reactive molecules can occur due to the generation and dysregulation of reactive oxygen species (ROS) and their associated signaling pathways. ROS have a dual function in cancer development, either leading to DNA mutations that promote the growth and dissemination of cancer cells, or triggering the death of cancer cells. Cancer cells strategically balance their fate by modulating ROS levels, activating pro-cancer signaling pathways, and suppressing antioxidant defenses. Consequently, targeting ROS has emerged as a promising strategy in cancer therapy. Shikonin and its derivatives, along with related drug carriers, can impact several signaling pathways by targeting components involved with oxidative stress to induce processes such as apoptosis, necroptosis, cell cycle arrest, autophagy, as well as modulation of ferroptosis. Moreover, they can increase the responsiveness of drug-resistant cells to chemotherapy drugs, based on the specific characteristics of ROS, as well as the kind and stage of cancer. This research explores the pro-cancer and anti-cancer impacts of ROS, summarize the mechanisms and research achievements of shikonin-targeted ROS in anti-cancer effects and provide suggestions for designing further anti-tumor experiments and undertaking further experimental and practical research.

Role of the gut-muscle axis in mitochondrial function of ageing muscle under different exercise modes

The fundamental role of the gut microbiota through the gut-muscle axis in skeletal muscle ageing is increasingly recognised. Metabolites derived from the intestinal microbiota are essential in maintaining skeletal muscle function and metabolism. The energy produced by mitochondria and moderate levels of reactive oxygen species can contribute to this process. Metabolites can effectively target the mitochondria, slowing the progression of muscle ageing and potentially representing a marker of ageing-related skeletal muscle loss. Moreover, mitochondria can contribute to the immune response, gut microbiota biodiversity, and maintenance of the intestinal barrier function. However, the causal relationship between mitochondrial function and gut microbiota crosstalk remains poorly understood. In addition to elucidating the regulatory pathways of the gut-muscle axis during the ageing process, we focused on the potential role of the "exercise-gut-muscle axis", which represents a pathway under stimulation from different exercise modes to induce mitochondrial adaptations, skeletal muscle metabolism and maintain intestinal barrier function and biodiversity stability. Meanwhile, different exercise modes can induce mitochondrial adaptations and skeletal muscle metabolism and maintain intestinal barrier function and biodiversity. Resistance exercise may promote mitochondrial adaptation, increase the cross-sectional area of skeletal muscle and muscle hypertrophy, and promote muscle fibre and motor unit recruitment. Whereas endurance exercise promotes mitochondrial biogenesis, aerobic capacity, and energy utilisation, activating oxidative metabolism-related pathways to improve skeletal muscle metabolism and function. This review describes the effects of different exercise modes through the gut-muscle axis and how they act through mitochondria in ageing to define the current state of the field and issues requiring resolution.

Sarcopenia and Diabetes: A Detrimental Liaison of Advancing Age

Sarcopenia is an age-related clinical complaint characterized by the progressive deterioration of skeletal muscle mass and strength over time. Type 2 diabetes (T2D) is associated with faster and more relevant skeletal muscle impairment. Both conditions influence each other, leading to negative consequences on glycemic control, cardiovascular risk, general health status, risk of falls, frailty, overall quality of life, and mortality. PubMed/Medline, Scopus, Web of Science, and Google Scholar were searched for research articles, scientific reports, observational studies, clinical trials, narrative and systematic reviews, and meta-analyses to review the evidence on the pathophysiology of di-abetes-induced sarcopenia, its relevance in terms of glucose control and diabetes-related outcomes, and diagnostic and therapeutic challenges. The review comprehensively addresses key elements for the clinical definition and diagnostic criteria of sarcopenia, the pathophysiological correlation be-tween T2D, sarcopenia, and related outcomes, a critical review of the role of antihyperglycemic treatment on skeletal muscle health, and perspectives on the role of specific treatment targeting myokine signaling pathways involved in glucose control and the regulation of skeletal muscle metabolism and trophism. Prompt diagnosis and adequate management, including lifestyle inter-vention, health diet programs, micronutrient supplementation, physical exercise, and pharmaco-logical treatment, are needed to prevent or delay skeletal muscle deterioration in T2D.

Effect of Uncaria tomentosa aqueous extract on the response to palmitate-induced lipotoxicity in cultured skeletal muscle cells

BACKGROUND

Type 2 diabetes mellitus (T2DM) is frequently associated with dyslipidemia, which corresponds to the increase in the triglycerides and fatty acid concentrations in tissues, such as the skeletal muscle. Also, T2DM molecular mechanism involves increasing in reactive oxygen species (ROS) production and oxidative stress. The use of herbal medicines such as Uncaria tomentosa (Ut) has been proposed as an auxiliary treatment for patients with T2DM. In this study, it was evaluated the effect of Ut aqueous extract on cell viability and ROS production, in skeletal myoblasts from C2C12 lineage exposed to the free fatty acid palmitate (PA).

METHODS

Cells were incubated with PA in different concentrations ranging from 10 to 1000 μM, for 24 or 48 h, for cytotoxicity assay. Cell death, DNA fragmentation and ROS production assays were performed in cell cultures incubated with PA for 24 h, in the pre (preventive condition) or post treatment (therapeutic condition) with 250 μg/ml Ut aqueous extract, for 2 or 6 h. Cell death was evaluated by MTT method or flow cytometry. ROS generation was measured by fluorescence spectroscopy using the DCFDA probe.

RESULTS

Cell viability was reduced to approximately 44% after the incubation with PA for 24 h from the concentration of 500 µM. In the incubation of cells with 500 μM PA and Ut extract for 6 h, in both conditions (preventive or therapeutic), it was observed an increase of 27 and 70% in cell viability respectively, in comparison to the cultures incubated with only PA. Also, the incubation of cultures with 500 μM PA, for 24 h, increased 20-fold the ROS formation, while the treatment with Ut extract, for 6 h, both in the preventive or therapeutic conditions, promoted decrease of 21 and 55%, respectively.

CONCLUSION

The Ut extract was efficient in promoting cell protection against PA lipotoxicity and ROS generation, potentially preventing oxidative stress in C2C12 skeletal muscle cells. Since T2DM molecular mechanism involves oxidative stress condition and it is often associated with dyslipidemia and fatty acid accumulation in muscle tissue, these results open perspectives for the use of Ut as an auxiliary strategy for T2DM management.

Muscle-specific overexpression of Atg2 gene and endurance exercise delay age-related deteriorations of skeletal muscle and heart function via activating the AMPK/Sirt1/PGC-1α pathway in male Drosophila

Atg2 is a key gene in autophagy formation and plays an important role in regulating aging progress. Exercise is an important tool to resist oxidative stress in cells and delay muscle aging. However, the relationship between exercise and the muscle Atg2 gene in regulating skeletal muscle aging remains unclear. Here, overexpression or knockdown of muscle Atg2 gene was achieved by constructing the AtgUAS/MhcGal4 system in Drosophila, and these flies were also subjected to an exercise intervention for 2 weeks. The results showed that both overexpression of Atg2 and exercise significantly increased the climbing speed, climbing endurance, cardiac function, and lifespan of aging flies. They also significantly up-regulated the expression of muscle Atg2, AMPK, Sirt1, and PGC-1α genes, and they significantly reduced muscle malondialdehyde and triglyceride. These positive benefits were even more pronounced when the two were combined. However, the effects of Atg2 knockdown on skeletal muscle, heart, and lifespan were reversed compared to its overexpression. Importantly, exercise ameliorated age-related changes induced by Atg2 knockdown. Therefore, current results confirmed that both overexpression of muscle Atg2 and exercise delayed age-related deteriorations of skeletal muscle, the heart function, and lifespan, and exercise could also reverse age-related changes induced by Atg2 knockdown. The molecular mechanism is related to the overexpression of the Atg2 gene and exercise, which increase the activity of the AMPK/Sirt1/PGC-1α pathway, oxidation and antioxidant balance, and lipid metabolism in aging muscle.

Mitochondrial dysfunction: roles in skeletal muscle atrophy

Mitochondria play important roles in maintaining cellular homeostasis and skeletal muscle health, and damage to mitochondria can lead to a series of pathophysiological changes. Mitochondrial dysfunction can lead to skeletal muscle atrophy, and its molecular mechanism leading to skeletal muscle atrophy is complex. Understanding the pathogenesis of mitochondrial dysfunction is useful for the prevention and treatment of skeletal muscle atrophy, and finding drugs and methods to target and modulate mitochondrial function are urgent tasks in the prevention and treatment of skeletal muscle atrophy. In this review, we first discussed the roles of normal mitochondria in skeletal muscle. Importantly, we described the effect of mitochondrial dysfunction on skeletal muscle atrophy and the molecular mechanisms involved. Furthermore, the regulatory roles of different signaling pathways (AMPK-SIRT1-PGC-1α, IGF-1-PI3K-Akt-mTOR, FoxOs, JAK-STAT3, TGF-β-Smad2/3 and NF-κB pathways, etc.) and the roles of mitochondrial factors were investigated in mitochondrial dysfunction. Next, we analyzed the manifestations of mitochondrial dysfunction in muscle atrophy caused by different diseases. Finally, we summarized the preventive and therapeutic effects of targeted regulation of mitochondrial function on skeletal muscle atrophy, including drug therapy, exercise and diet, gene therapy, stem cell therapy and physical therapy. This review is of great significance for the holistic understanding of the important role of mitochondria in skeletal muscle, which is helpful for researchers to further understanding the molecular regulatory mechanism of skeletal muscle atrophy, and has an important inspiring role for the development of therapeutic strategies for muscle atrophy targeting mitochondria in the future.

Effects and mechanism of perinatal nonylphenol exposure on cardiac function and myocardial mitochondria in neonatal rats

BACKGROUND

Nonylphenol (NP) is a common environmental endocrine disruptor that is associated with the development of cardiovascular disease. However, the toxic effect of NP on mitochondria in the heart of offspring to exposed individuals remains exclusive.

OBJECTIVE

To investigate whether perinatal NP exposure causes mitochondrial damage in the hearts of offspring of exposed individuals and determine its mechanism of action through both animal and cell experiments.

METHODS AND RESULTS

For the in vivo experiment, pregnant rats were randomly divided into four groups: the control group (corn oil, C), low dose group (2.5 mg/kg/day, L-NP group), medium dose group (50 mg/kg/day, M-NP group), and high dose group (100 mg/kg/day, H-NP group), with 12 rats in each group. The NP concentration in the hearts of offspring at PND21 and PND90 increased with the increase of the NP dose. Perinatal NP exposure induced a gradual increase in systolic blood pressure in offspring at PND90. In the H-NP group, there was a high degree of inflammatory cell infiltration, myofibril breaks, inconspicuous or absent nuclei, and pink collagen deposition. At PND90, the membrane integrity of mitochondria in the H-NP group was disrupted, the cristae disorder was aggravated, and there was internal lysis with vacuolation. Compared to the control group, the mitochondrial membrane potential of offspring at PND21 and PND90 was decreased in each of the NP exposure groups. NP exposure decreased the activity of mitochondrial respiratory enzyme complex I (CI) and increased the activity of mitochondrial respiratory enzyme complex IV (CIV) in the offspring. At PND21 and PND90, the mRNA and protein expression levels of cardiac mitochondrial PGC-1α, NRF-1, and TFAM decreased with increasing NP dose in a dose-dependent manner. In the in vitro experiment, H9C2 cells were divided into the following four groups: the blank group, RSV group (15 μg/ml), RSV + NP group (15 μg/ml RSV + 120 mmol/L NP), and NP group (120 mmol/L). With increasing NP concentration, the cell survival rate gradually decreased. Compared to the control, the membrane potential was significantly decreased in the NP group; the protein expression levels of SIRT1, PGC-1α, NRF-1, and TFAM in the NP group were significantly lower.

CONCLUSION

Perinatal NP exposure caused mitochondrial damage and dysfunction in the offspring of exposed individuals in a dose-dependent manner. This toxic effect may be related to NP-induced mitochondrial pathology in the offspring and the inhibition of both gene and protein expression involved in the PGC-1α/NRF-1/TFAM mitochondrial biogenesis signaling pathway following NP exposure.

The roles of hepatokine and osteokine in liver-bone crosstalk: Advance in basic and clinical aspects

Both the liver and bone are important secretory organs in the endocrine system. By secreting organ factors (hepatokines), the liver regulates the activity of other organs. Similarly, bone-derived factors, osteokines, are created during bone metabolism and act in an endocrine manner. Generally, the dysregulation of hepatokines is frequently accompanied by changes in bone mass, and osteokines can also disrupt liver metabolism. The crosstalk between the liver and bone, particularly the function and mechanism of hepatokines and osteokines, has increasingly gained notoriety as a topic of interest in recent years. Here, based on preclinical and clinical evidence, we summarize the potential roles of hepatokines and osteokines in liver-bone interaction, discuss the current shortcomings and contradictions, and make recommendations for future research.

Ursolic Acid Ameliorates Myocardial Ischaemia/Reperfusion Injury by Improving Mitochondrial Function via Immunoproteasome-PP2A-AMPK Signalling

Cardiac ischaemia/reperfusion (I/R) injury causes cardiomyocyte apoptosis and mitochondrial dysfunction. Ursolic acid (UA), as a pentacyclic triterpenoid carboxylic acid, exerts several bioactivities in animal models of different diseases, but the preventive role of UA in I/R-induced myocardial dysfunction remains largely unknown. Male wild-type mice were pre-administered with UA at a dosage of 80 mg/kg i.p. and then subjected to cardiac I/R injury for 24 h. Cardiac function and pathological changes were examined by echocardiography and histological staining. The protein and mRNA levels of the genes were determined using qPCR and immunoblotting analysis. Our results revealed that UA administration in mice significantly attenuated the I/R-induced decline in cardiac function, infarct size, myocyte apoptosis, and oxidative stress. Mechanistically, UA increased three immunoproteasome catalytic subunit expressions and activities, which promoted ubiquitinated PP2A degradation and activated AMPK-PGC1α signalling, leading to improved mitochondrial biosynthesis and dynamic balance. In vitro experiments confirmed that UA treatment prevented hypoxia/reperfusion (H/R)-induced cardiomyocyte apoptosis and mitochondrial dysfunction through activation of AMPK signalling. In summary, our findings identify UA as a new activator of the immunoproteasome that exerts a protective role in I/R-induced myocardial dysfunction and suggest that UA supplementation could be beneficial for the prevention of cardiac ischaemic disease.

Sleeve Gastrectomy-Induced Weight Loss Increases Insulin Clearance in Obese Mice

Sleeve gastrectomy (SG) successfully recovers metabolic homeostasis in obese humans and rodents while also resulting in the normalization of insulin sensitivity and insulinemia. Reduced insulin levels have been attributed to lower insulin secretion and increased insulin clearance in individuals submitted to SG. Insulin degradation mainly occurs in the liver in a process controlled, at least in part, by the insulin-degrading enzyme (IDE). However, research has yet to explore whether liver IDE expression or activity is altered after SG surgery. In this study, C57BL/6 mice were fed a chow (CTL) or high-fat diet (HFD) for 10 weeks. Afterward, the HFD mice were randomly assigned to two groups: sham-surgical (HFD-SHAM) and SG-surgical (HFD-SG). Here, we confirmed that SG improves glucose-insulin homeostasis in obese mice. Additionally, SG reduced insulinemia by reducing insulin secretion, assessed by the analysis of plasmatic C-peptide content, and increasing insulin clearance, which was evaluated through the calculation of the plasmatic C-peptide:insulin ratio. Although no changes in hepatic IDE activity were observed, IDE expression was higher in the liver of HFD-SG compared with HFD-SHAM mice. These results indicate that SG may be helpful to counteract obesity-induced hyperinsulinemia by increasing insulin clearance, likely through enhanced liver IDE expression.

Role of the Gut Microbiome in Skeletal Muscle Physiology and Pathophysiology

PURPOSE OF REVIEW

This review aims to summarize the recent findings about the contribution of the gut microbiome to muscle pathophysiology and discuss molecular pathways that may be involved in such process. Related findings in the context of cancer cachexia are outlined.

RECENT FINDINGS

Many bacterial metabolites have been reported to exert a beneficial or detrimental impact on muscle physiology. Most of the evidence concentrates on short-chain fatty acids (SCFAs), with an emerging role for bile acids, bacterial amino acid metabolites (bAAms), and bacterial polyphenol metabolites. Other molecular players worth considering include cytokines, hormones, lipopolysaccharides, and quorum sensing molecules. The current literature clearly establishes the ability for the gut microbiome to modulate muscle function and mass. The understanding of the mechanisms underlying this gut-muscle axis may lead to the delivery of novel therapeutic tools to tackle muscle wasting in cancer cachexia, chronic kidney disease, liver fibrosis, and age-related sarcopenia.

The Whole-transcriptome Landscape of Diabetes-related Sarcopenia Reveals the Specific Function of Novel lncRNA Gm20743

While the exact mechanism remains unclear, type 2 diabetes mellitus increases the risk of sarcopenia which is characterized by decreased muscle mass, strength, and function. Whole-transcriptome RNA sequencing and informatics were performed on the diabetes-induced sarcopenia model of db/db mice. To determine the specific function of lncRNA Gm20743, the detection of Mito-Sox, reactive oxygen species, Ethynyl-2′-deoxyuridine, and myosin heavy chain was performed in overexpressed and knockdown-Gm20743 C2C12 cells. RNA-seq data and informatics revealed the key lncRNA-mRNA interactions and indicated a potential regulatory role of lncRNAs. We characterized three core candidate lncRNAs Gm20743, Gm35438, 1700047G03Rik, and their potential function. Furthermore, the results suggested lncRNA Gm20743 may be involved in regulating mitochondrial function, oxidative stress, cell proliferation, and myotube differentiation in skeletal muscle cells. These findings significantly improve our understanding of lncRNAs that may mediate muscle mass, strength, and function in diabetes and represent potential therapeutic targets for diabetes-induced sarcopenia.

The role of lncRNA Gm20743 in the development of diabetic sarcopenia is explored using a mouse model.

ISG15 deficiency features a complex cellular phenotype that responds to treatment with itaconate and derivatives

Background

Congenital ISG15 deficiency is a rare autoinflammatory disorder that is driven by chronically elevated systemic interferon levels and predominantly affects central nervous system and skin.

Methods and results

We have developed induced pluripotent stem cell‐derived macrophages and endothelial cells as a model to study the cellular phenotype of ISG15 deficiency and identify novel treatments. ISG15^–/– macrophages exhibited the expected hyperinflammatory responses, but normal phagocytic function. In addition, they displayed a multifaceted pathological phenotype featuring increased apoptosis/pyroptosis, oxidative stress, glycolysis, and acylcarnitine levels, but decreased glutamine uptake, BCAT1 expression, branched chain amino acid catabolism, oxidative phosphorylation, β‐oxidation, and NAD(P)H‐dependent oxidoreductase activity. Furthermore, expression of genes involved in mitochondrial biogenesis and respiratory chain complexes II–V was diminished in ISG15^–/– cells. Defective mitochondrial respiration was restored by transduction with wild‐type ISG15, but only partially by a conjugation‐deficient variant, suggesting that some ISG15 functions in mitochondrial respiration require ISGylation to cellular targets. Treatment with itaconate, dimethyl‐itaconate, 4‐octyl‐itaconate, and the JAK1/2 inhibitor ruxolitinib ameliorated increased inflammation, propensity for cell death, and oxidative stress. Furthermore, the treatments greatly improved mitochondria‐related gene expression, BCAT1 levels, redox balance, and intracellular and extracellular ATP levels. However, efficacy differed among the compounds according to read‐out and cell type, suggesting that their effects on cellular targets are not identical. Indeed, only itaconates increased expression of anti‐oxidant genes NFE2L2, HMOX1, and GPX7, and dimethyl‐itaconate improved redox balance the most. Even though itaconate treatments normalized the elevated expression of interferon‐stimulated genes, ISG15^–/– macrophages maintained their reduced susceptibility to influenza virus infection.

Conclusions

These findings expand the cellular phenotype of human ISG15 deficiency and reveal the importance of ISG15 for regulating oxidative stress, branched chain amino acid metabolism, and mitochondrial function in humans. The results validate ruxolitinib as treatment for ISG15 deficiency and suggest itaconate‐based medications as additional therapeutics for this rare disorder.

Enterohepatic and non-canonical roles of farnesoid X receptor in controlling lipid and glucose metabolism

Farnesoid X receptor (FXR) is a nuclear receptor that transcriptionally regulates bile acid homeostasis along with nutrient metabolism. In addition to the gastrointestinal (GI) tract, FXR expression has been widely noted in kidney, adrenal gland, pancreas, adipose, skeletal muscle, heart, and brain. Except for the liver and gut, the relevance of FXR signaling in metabolism in other tissues remains poorly understood. This review examines the classical and non-canonical tissue-specific roles of FXR in regulating, lipids, and glucose homeostasis under normal and diseased states. FXR activation has been reported to be protective against cholestasis, nonalcoholic fatty liver disease (NAFLD), nonalcoholic steatohepatitis (NASH), type 2 diabetes, cardiovascular and kidney diseases. Several ongoing clinical trials are investigating FXR ligands as a therapeutic target for primary biliary cholangitis (PBC) and NASH, which substantiate the significance of FXR signaling in modulating metabolic processes. This review highlights that FXR ligands, albeit an attractive therapeutic target for treating metabolic diseases, tissue-specific modulation of FXR may be the key to overcoming some of the adverse clinical effects.

Mechanisms Involved in Gut Microbiota Regulation of Skeletal Muscle

Skeletal muscle is one of the largest organs in the body and is essential for maintaining quality of life. Loss of skeletal muscle mass and function can lead to a range of adverse consequences. The gut microbiota can interact with skeletal muscle by regulating a variety of processes that affect host physiology, including inflammatory immunity, protein anabolism, energy, lipids, neuromuscular connectivity, oxidative stress, mitochondrial function, and endocrine and insulin resistance. It is proposed that the gut microbiota plays a role in the direction of skeletal muscle mass and work. Even though the notion of the gut microbiota-muscle axis (gut-muscle axis) has been postulated, its causal link is still unknown. The impact of the gut microbiota on skeletal muscle function and quality is described in detail in this review.

Endocrine Fibroblast Growth Factors in Relation to Stress Signaling

Fibroblast growth factors (FGFs) play important roles in various growth signaling processes, including proliferation, development, and differentiation. Endocrine FGFs, i.e., atypical FGFs, including FGF15/19, FGF21, and FGF23, function as endocrine hormones that regulate energy metabolism. Nutritional status is known to regulate the expression of endocrine FGFs through nuclear hormone receptors. The increased expression of endocrine FGFs regulates energy metabolism processes, such as fatty acid metabolism and glucose metabolism. Recently, a relationship was found between the FGF19 subfamily and stress signaling during stresses such as endoplasmic reticulum stress and oxidative stress. This review focuses on endocrine FGFs and the recent progress in FGF studies in relation to stress signaling. In addition, the relevance of the stress-FGF pathway to disease and human health is discussed.

Ileal FXR-FGF15/19 signaling activation improves skeletal muscle loss in aged mice

Sarcopenia is the age-related decrease in skeletal muscle mass, and current therapies for this disease are ineffective. We previously showed that ileal farnesoid X receptor (FXR)-fibroblast growth factor 15/19 (FGF15/19) signaling acts as a regulator of gut microbiota to mediate host skeletal muscle. However, the therapeutic potential of this pathway for sarcopenia is unknown. This study showed that ileal FXR-FGF15/19 signaling was downregulated in older men and aged male mice due to changes in the gut microbiota and microbial bile acid metabolism during aging. In addition, the intestine-specific FXR agonist fexaramine increased skeletal muscle mass and improve muscle performance in aged mice. Ileal FXR activation increased skeletal muscle protein synthesis in a FGF15/19-dependent way, indicating that ileal FXR-FGF15/19 signaling is a potential therapeutic target for sarcopenia.

Forkhead-box C1 attenuates high glucose-induced trophoblast cell injury during gestational diabetes mellitus via activating adenosine monophosphate-activated protein kinase through regulating fibroblast growth factor 19

Gestational diabetes mellitus (GDM) is a complication developed during pregnancy and recover after childbirth. The purpose of this study was to investigate the protective role of FOXC1 during GDM and the underlying mechanism. FOXC1 was downregulated in GDM placental tissues and HG-treated HTR-8/SVneo cells. Overexpression of FOXC1 prevented HG-induced inhibition of cell proliferation, migration and invasion. FOXC1 suppressed HG-induced cell apoptosis in HTR-8/SVneo cells. The apoptosis-related proteins: cleaved caspase-3, cleaved caspase-9 and BAX, were also downregulated by FOXC1 overexpression. FOXC1 increased glucose uptake and improved insulin sensitivity. The expression of FOXC1 was positively correlated with FGF19 expression. FOXC1 regulated the expression of FGF19 and phosphorylation of AMPK. Inhibition of FGF19 attenuated the biological functions of FOXC1 through inactivation of AMPK. In conclusion, this study demonstrates that FOXC1 attenuates HG-induced trophoblast cell injury through upregulating FGF19 to activate the AMPK signaling pathway during GDM, suggesting that FOXC1 is a potential therapeutic target for drug discovery in the future.

FGF19 protects against obesity-induced bone loss by promoting osteogenic differentiation

Human fibroblast growth factor 19 (FGF19) has become a potential therapeutic target for metabolic-related diseases. However, the effects of FGF19 on obesity-induced bone loss have not been completely elucidated. The aim of this study was to investigate the protective effects of FGF19 in high-fat diet (HFD)-fed obese mice and palmitic acid (PA)-treated osteoblasts and to further explore its underlying mechanisms. In vivo, we found that FGF19 alleviated the decreased bone mineral density (BMD) induced by HFD. Micro-CT analysis of femur samples and histological analysis indicated that FGF19 alleviated HFD-induced loss of bone trabeculae and damage to the bone trabecular structure. In vitro, the results suggested that FGF19 ameliorated the PA-induced decline in osteoblast proliferation, increased cell death and impaired cell morphology. Additionally, FGF19 protected against the decline in activation of alkaline phosphatase (ALP) and protein expression of Collagen-1, Runx-2, and osteopontin (OPN) induced by PA. Furthermore, FGF19 might enhance osteogenic differentiation via the Wnt/β-catenin pathway and inhibit osteoclastogenesis by regulating the osteoprotegerin (OPG)/receptor activator of NF-κB ligand (RANKL) axis, thus attenuating the negative effect of PA in osteoblasts. In conclusion, our results suggested that FGF19 might promote osteogenic differentiation partially through activation of the Wnt/β-catenin pathway and alleviate obesity-induced bone loss.

Depletion of gut microbiota induces skeletal muscle atrophy by FXR-FGF15/19 signalling

Background: Recent evidence indicates that host-gut microbiota crosstalk has nonnegligible effects on host skeletal muscle, yet gut microbiota-regulating mechanisms remain obscure.Methods: C57BL/6 mice were treated with a cocktail of antibiotics (Abx) to depress gut microbiota for 4 weeks. The profiles of gut microbiota and microbial bile acids were measured by 16S rRNA sequencing and ultra-performance liquid chromatography (UPLC), respectively. We performed qPCR, western blot and ELISA assays in different tissue samples to evaluate FXR-FGF15/19 signaling.Results: Abx treatment induced skeletal muscle atrophy in mice. These effects were associated with microbial dysbiosis and aberrant bile acid (BA) metabolism in intestine. Ileal farnesoid X receptor (FXR)-fibroblast growth factor 15 (FGF15) signaling was inhibited in response to microbial BA disturbance. Mechanistically, circulating FGF15 was decreased, which downregulated skeletal muscle protein synthesis through the extracellular-signal-regulated protein kinase 1/2 (ERK1/2) signaling pathway. Treating Abx mice with FGF19 (human FGF15 ortholog) partly reversed skeletal muscle loss.Conclusions: These findings indicate that the BA-FXR-FGF15/19 axis acts as a regulator of gut microbiota to mediate host skeletal muscle.

Vanadium Induces Oxidative Stress and Mitochondrial Quality Control Disorder in the Heart of Ducks

Vanadium (V) is an ultra-trace element presenting in humans and animals, but excessive V can cause toxic effects. Mitochondrial quality control (MQC) is an essential process for maintaining mitochondrial functions, but the relationship between V toxicity and MQC is unclear. To investigate the effects of excessive V on oxidative stress and MQC in duck hearts, 72 ducks were randomly divided into two groups, including the control group and the V group (30 mg of V/kg dry matter). The cardiac tissues were collected for the histomorphology observation and oxidative stress status evaluation at 22 and 44 days. In addition, the mRNA and protein levels of MQC-related factors were also analyzed. The results showed that excessive V could trigger vacuolar degeneration, granular degeneration, as well as mitochondrial vacuolization and swelling in myocardial cells. In addition, CAT activity was elevated in two time points, while T-SOD activity was increased in 22 days but decreased in 44 days after V treatment. Meanwhile, excessive V intake could also increase the number of Drp1 puncta, the mRNA levels of mitochondrial fission–related factors (Drp1and MFF), and protein (MFF) level, but decrease the number of Parkin puncta and the mitochondrial biogenesis (PGC-1α, NRF-1, and TFAM), mitochondrial fusion (OPA1, Mfn1, and Mfn2), and mitophagy (Parkin, PINK1, P62, and LC3B) related mRNA levels and protein (PGC-1α, Mfn1, Mfn2, PINK1) levels. Collectively, our results suggested that excessive V could induce oxidative stress and MQC disorder in the heart of ducks.

Pathogenic mitochondrial dysfunction and metabolic abnormalities

Herein we trace links between biochemical pathways, pathogenesis, and metabolic diseases to set the stage for new therapeutic advances. Cellular and acellular microorganisms including bacteria and viruses are primary pathogenic drivers that cause disease. Missing from this statement are subcellular compartments, importantly mitochondria, which can be pathogenic by themselves, also serving as key metabolic disease intermediaries. The breakdown of food molecules provides chemical energy to power cellular processes, with mitochondria as powerhouses and ATP as the principal energy carrying molecule. Most animal cell ATP is produced by mitochondrial synthase; its central role in metabolism has been known for >80 years. Metabolic disorders involving many organ systems are prevalent in all age groups. Progressive pathogenic mitochondrial dysfunction is a hallmark of genetic mitochondrial diseases, the most common phenotypic expression of inherited metabolic disorders. Confluent genetic, metabolic, and mitochondrial axes surface in diabetes, heart failure, neurodegenerative disease, and even in the ongoing coronavirus pandemic.

Dapagliflozin attenuates steatosis in livers of high-fat diet-induced mice and oleic acid-treated L02 cells via regulating AMPK/mTOR pathway

Dapagliflozin (DAPA), a kind of sodium-glucose cotransporter 2(SGLT2) inhibitor is used to treat diabetes mellitus by inhibiting urine glucose reuptake. Recent clinical outcomes indicate that SGLT2 inhibitors may exert pharmacological activities against non-alcoholic fatty liver diseases. Nonetheless, the underlying molecular mechanisms are still poorly elucidated. In this study, we investigated the potential anti-fatty liver effects of DAPA in vivo and in vitro and assayed their underlying mechanisms. Male NIH (National Institutes of Health) mice were fed with a high-fat diet (HFD) and then treated with DAPA by gavage for 4 weeks. In the following experiments, L02 cells were treated with oleic acid (OA) and different concentrations of DAPA to assess lipid metabolism. Our results revealed that DAPA administration could remarkably suppress excessive fat accumulation in the liver tissues of HFD-fed mice and OA-treated L02 cells. Importantly, DAPA could downregulate the expression levels of proteins related to lipid synthesis and upregulate the expression levels of genes associated with fatty acid oxidation in vitro and in vivo. We also found that DAPA intervention could activate adenosine monophosphate-activated protein kinase (AMPK) phosphorylation but inhibit mammalian target of rapamycin (mTOR) phosphorylation in vitro and in vivo. AMPK activation might be mediated by increasing liver kinase B1 activity and decreasing ATP level. Furthermore, these ameliorative effects were completely eliminated by an AMPK inhibitor, compound C. This study suggested that DAPA might remarkably ameliorate hepatic steatosis mediated through the AMPK/mTOR pathway and thus could be a potential drug candidate for the treatment of fatty liver diseases.

The Saga of Endocrine FGFs

Fibroblast growth factors (FGFs) are cell-signaling proteins with diverse functions in cell development, repair, and metabolism. The human FGF family consists of 22 structurally related members, which can be classified into three separate groups based on their action of mechanisms, namely: intracrine, paracrine/autocrine, and endocrine FGF subfamilies. FGF19, FGF21, and FGF23 belong to the hormone-like/endocrine FGF subfamily. These endocrine FGFs are mainly associated with the regulation of cell metabolic activities such as homeostasis of lipids, glucose, energy, bile acids, and minerals (phosphate/active vitamin D). Endocrine FGFs function through a unique protein family called klotho. Two members of this family, α-klotho, or β-klotho, act as main cofactors which can scaffold to tether FGF19/21/23 to their receptor(s) (FGFRs) to form an active complex. There are ongoing studies pertaining to the structure and mechanism of these individual ternary complexes. These studies aim to provide potential insights into the physiological and pathophysiological roles and therapeutic strategies for metabolic diseases. Herein, we provide a comprehensive review of the history, structure–function relationship(s), downstream signaling, physiological roles, and future perspectives on endocrine FGFs.

Potential of Telomerase in Age-Related Macular Degeneration-Involvement of Senescence, DNA Damage Response and Autophagy and a Key Role of PGC-1α

Age-related macular degeneration (AMD), the main cause of vision loss in the elderly, is associated with oxidation in the retina cells promoting telomere attrition. Activation of telomerase was reported to improve macular functions in AMD patients. The catalytic subunit of human telomerase (hTERT) may directly interact with proteins important for senescence, DNA damage response, and autophagy, which are impaired in AMD. hTERT interaction with mTORC1 (mTOR (mechanistic target of rapamycin) complex 1) and PINK1 (PTEN-induced kinase 1) activates macroautophagy and mitophagy, respectively, and removes cellular debris accumulated over AMD progression. Ectopic expression of telomerase in retinal pigment epithelium (RPE) cells lengthened telomeres, reduced senescence, and extended their lifespan. These effects provide evidence for the potential of telomerase in AMD therapy. Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) may be involved in AMD pathogenesis through decreasing oxidative stress and senescence, regulation of vascular endothelial growth factor (VEGF), and improving autophagy. PGC-1α and TERT form an inhibitory positive feedback loop. In conclusion, telomerase activation and its ectopic expression in RPE cells, as well as controlled clinical trials on the effects of telomerase activation in AMD patients, are justified and should be assisted by PGC-1α modulators to increase the therapeutic potential of telomerase in AMD.

Palmitic Acid, but Not Lauric Acid, Induces Metabolic Inflammation, Mitochondrial Fragmentation, and a Drop in Mitochondrial Membrane Potential in Human Primary Myotubes

The chain length of saturated fatty acids may dictate their impact on inflammation and mitochondrial dysfunction, two pivotal players in the pathogenesis of insulin resistance. However, these paradigms have only been investigated in animal models and cell lines so far. Thus, the aim of this study was to compare the effect of palmitic (PA) (16:0) and lauric (LA) (12:0) acid on human primary myotubes mitochondrial health and metabolic inflammation. Human primary myotubes were challenged with either PA or LA (500 μM). After 24 h, the expression of interleukin 6 (IL-6) was assessed by quantitative polymerase chain reaction (PCR), whereas Western blot was used to quantify the abundance of the inhibitor of nuclear factor κB (IκBα), electron transport chain complex proteins and mitofusin-2 (MFN-2). Mitochondrial membrane potential and dynamics were evaluated using tetraethylbenzimidazolylcarbocyanine iodide (JC-1) and immunocytochemistry, respectively. PA, contrarily to LA, triggered an inflammatory response marked by the upregulation of IL-6 mRNA (11-fold; P < 0.01) and a decrease in IκBα (32%; P < 0.05). Furthermore, whereas PA and LA did not differently modulate the levels of mitochondrial electron transport chain complex proteins, PA induced mitochondrial fragmentation (37%; P < 0.001), decreased MFN-2 (38%; P < 0.05), and caused a drop in mitochondrial membrane potential (11%; P < 0.01) compared to control, with this effect being absent in LA-treated cells. Thus, LA, as opposed to PA, did not trigger pathogenetic mechanisms proposed to be linked with insulin resistance and therefore represents a healthier saturated fatty acid choice to potentially preserve skeletal muscle metabolic health.

Qiangji Jianli Decoction Alleviates Hydrogen Peroxide-Induced Mitochondrial Dysfunction via Regulating Mitochondrial Dynamics and Biogenesis in L6 Myoblasts

Oxidative stress can cause the excessive generation of reactive oxygen species (ROS) and has various adverse effects on muscular mitochondria. Qiangji Jianli decoction (QJJLD) is an effective traditional Chinese medicine (TCM) that is widely applied to improve muscle weakness, and it has active constituents that prevent mitochondrial dysfunction. To investigate the protective mechanism of QJJLD against hydrogen peroxide- (H2O2-) mediated mitochondrial dysfunction in L6 myoblasts. Cell viability was determined with MTT assay. Mitochondrial ultrastructure was detected by transmission electron microscope (TEM). ROS and mitochondrial membrane potential (MMP) were analyzed by fluorescence microscope and flow cytometry. The superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activity, and malondialdehyde (MDA) level were determined by WST-1, TBA, and DTNB methods, respectively. The mRNA and protein levels were measured by quantitative real-time PCR (qRT-PCR) and Western blot. The cell viability was decreased, and the cellular ROS level was increased when L6 myoblasts were exposed to H2O2. After treatment with QJJLD-containing serum, the SOD and GSH-Px activities were increased. MDA level was decreased concurrently. ROS level was decreased while respiratory chain complex activity and ATP content were increased in L6 myoblasts. MMP loss was attenuated. Mitochondrial ultrastructure was also improved. Simultaneously, the protein expressions of p-AMPK, PGC-1α, NRF1, and TFAM were upregulated. The mRNA and protein expressions of Mfn1/2 and Opa1 were also upregulated while Drp1 and Fis1 were downregulated. These results suggest that QJJLD may alleviate mitochondrial dysfunction through the regulation of mitochondrial dynamics and biogenesis, the inhibition of ROS generation, and the promotion of mitochondrial energy metabolism.

FGF19 protects skeletal muscle against obesity-induced muscle atrophy, metabolic derangement and abnormal irisin levels via the AMPK/SIRT-1/PGC-α pathway

Obesity is associated with biological dysfunction in skeletal muscle. As a condition of obesity accompanied by muscle mass loss and physical dysfunction, sarcopenic obesity (SO) has become a novel public health problem. Human fibroblast growth factor 19 (FGF19) plays a therapeutic role in metabolic diseases. However, the protective effects of FGF19 on skeletal muscle in obesity and SO are still not completely understood. Our results showed that FGF19 administration improved muscle loss and grip strength in young and aged mice fed a high‐fat diet (HFD). Increases in muscle atrophy markers (FOXO‐3, Atrogin‐1, MuRF‐1) were abrogated by FGF19 in palmitic acid (PA)‐treated C2C12 myotubes and in the skeletal muscle of HFD‐fed mice. FGF19 not only reduced HFD‐induced body weight gain, excessive lipid accumulation and hyperlipidaemia but also promoted energy expenditure (PGC‐1α, UCP‐1, PPAR‐γ) in brown adipose tissue (BAT). FGF19 treatment restored PA‐ and HFD‐induced hyperglycaemia, impaired glucose tolerance and insulin resistance (IRS‐1, GLUT‐4) and mitigated the PA‐ and HFD‐induced decrease in FNDC‐5/irisin expression. However, these beneficial effects of FGF19 on skeletal muscle were abolished by inhibiting AMPK, SIRT‐1 and PGC‐1α expression. Taken together, this study suggests that FGF19 protects skeletal muscle against obesity‐induced muscle atrophy, metabolic derangement and abnormal irisin secretion partially through the AMPK/SIRT‐1/PGC‐α signalling pathway, which might be a potential therapeutic target for obesity and SO.

Empagliflozin prevents from early cardiac injury post myocardial infarction in non-diabetic mice

OBJECTIVES

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have been confirmed to reduce the rate of rehospitalization for heart failure and cardiovascular death in diabetic patients. The aim of our study was to investigate the cardioprotective role of SGLT2 inhibitors in early myocardial infarction (MI) of non-diabetic mice.

METHODS

C57BL/6 mice underwent left artery coronary artery descending (LAD) ligation to induce MI. Following the surgery, animals were randomized to receive saline or empagliflozin. Empagliflozin (EMPA) was administrated at 10 mg/kg per day by oral gavage for 2 weeks. Echocardiography, histological staining and qualitative RT-PCR were performed to assess the cardiac remodeling post MI. In vitro experiments were performed to evaluate the effect of empagliflozin on apoptosis, oxidative stress and mitochondrial membrane potential of cardiomyocyte subjected to hypoxic treatment.

RESULTS

Compared with MI group, the empagliflozin treatment group showed improved cardiac function, reduced infarct size and interstitial fibrosis. Empagliflozin also inhibited cardiomyocyte apoptosis by alleviating oxidative stress and restoring mitochondrial membrane potential. Immunoblotting analysis revealed activated AMP-activated protein kinase (AMPK) signaling may mediated the cardioprotective role of empagliflozin.

CONCLUSIONS

In summary, empagliflozin could inhibit cardiomyocyte apoptosis and improve cardiac remodeling early MI, which provided insights into the benefic effect of empagliflozin on MI patients without diabetes.

Heat shock protein 22 modulates NRF1/TFAM-dependent mitochondrial biogenesis and DRP1-sparked mitochondrial apoptosis through AMPK-PGC1α signaling pathway to alleviate the early brain injury of subarachnoid hemorrhage in rats

Mitochondrial dysfunction has been widely accepted as a detrimental factor in subarachnoid hemorrhage (SAH)-induced early brain injury (EBI), which is eminently related to poor neurologic function outcome. Previous studies have revealed that enhancement of heat shock protein 22 (hsp22) under conditions of stress is a friendly mediator of mitochondrial homeostasis, oxidative stress and apoptosis, thus accelerating neurological recovery. However, no study has confirmed whether hsp22 attenuates mitochondrial stress and apoptosis in the setting of SAH-induced EBI. Our results indicated that endogenous hsp22, p-AMPK/AMPK, PGC1α, TFAM, Nrf1 and Drp1 were significantly upregulated in cortical neurons in response to SAH, accompanied by neurologic impairment, brain edema, neuronal degeneration, lower level of mtDNA and ATP, mitochondria-cytosol translocation of cytochrome c, oxidative injury and caspase 3-involved mitochondrial apoptosis. However, exogenous hsp22 maintained neurological function, reduced brain edema, improved oxidative stress and mitochondrial apoptosis, these effects were highly dependent on PGC1α-related mitochondrial biogenesis/fission, as evidenced by co-application of PGC1α siRNA. Furthermore, we demonstrated that blockade of AMPK with dorsomorphin also compromised the neuroprotective actions of hsp22, along with the alterations of PGC1α and its associated pathway molecules. These data revealed that hsp22 exerted neuroprotective effects by salvaging mitochondrial function in an AMPK-PGC1α dependent manner, which modulates TFAM/Nrf1-induced mitochondrial biogenesis with positive feedback and DRP1-triggered mitochondrial apoptosis with negative feedback, further reducing oxidative stress and brain injury. Boosting the biogenesis and repressing excessive fission of mitochondria by hsp22 may be an efficient treatment to relieve SAH-elicited EBI.

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Hsp22 is notably upregulated in neurons at 24 h after SAH.

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Hsp22 boosts the NRF1/TFAM-dependent mitochondrial biogenesis.

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Hsp22 represses DRP1-sparked mitochondrial apoptosis.

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AMPK-PGC1α pathway is involved in hsp22-mediated neuroprotection after SAH.

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Modulation of mitochondrial biogenesis and fission may be efficient for treating SAH.

Novel therapies targeting hypoxia mechanism to treat pancreatic cancer

Pancreatic cancer (PC) is one of the deadliest malignancies. The high mortality rate of PC largely results from delayed diagnosis and early metastasis. Therefore, identifying novel treatment targets for patients with PC is urgently required to improve survival rates. A major barrier to successful treatment of PC is the presence of a hypoxic tumor microenvironment, which is associated with poor prognosis, treatment resistance, increased invasion and metastasis. Recent studies have identified a number of novel molecules and pathways in PC cells that promote cancer cells progression under hypoxic conditions, which may provide new therapy strategies to inhibit the development and metastasis of PC. This review summarizes the latest research of hypoxia in PC and provides an overview of how the current therapies have the capacity to overcome hypoxia and improve PC patient treatment. These findings will eventually provide guidance for future PC management and clinical trials and hopefully improve the survival of patients with PC.

MicroRNA-9-3p Aggravates Cerebral Ischemia/Reperfusion Injury by Targeting Fibroblast Growth Factor 19 (FGF19) to Inactivate GSK-3β/Nrf2/ARE Signaling

PURPOSE

MicroRNAs (miRNAs) are emerging as essential regulators in the development of cerebral ischemia/reperfusion (I/R) injury. This study aimed to explore the regulation of miR-9-3p on FGF19-GSK-3β/Nrf2/ARE signaling in cerebral I/R injury.

MATERIALS AND METHODS

A mouse model with I/R injury was constructed by middle cerebral artery occlusion (MCAO) and an HT22 cell model was established by oxygen-glucose deprivation/reperfusion (OGD/R). The expression of miR-9-3p was detected by RT-qPCR. Protein expression of fibroblast growth factor 19 (FGF19), cleaved caspase-3, and GSK-3β signaling-related proteins (p-GSK-3β and Nrf2) were detected by Western blot. Cell viability was assessed by MTT assay. Oxidative stress was detected by commercial kits. The target of miR-9-3p was predicted by TargetScan and confirmed by luciferase reporter assay. The effects of miR-9-3p on GSK-3β/Nrf2/ARE signaling were assessed by rescue experiments.

RESULTS

MiR-9-3p was significantly upregulated in brain tissues of MCAO/R-treated mice and OGD/R-treated HT22 cells. Downregulation of miR-9-3p attenuated infarct volume and neurological outcomes of MCAO/R-treated mice in vivo and OGD/R-induced cell injury and oxidative stress in vitro, while overexpression of miR-9-3p showed the opposite effects. MiR-9-3p directly bound to the 3'-untranslated region of FGF19 and negatively regulated its expression. Inhibition of miR-9-3p enhanced GSK-3β/Nrf2/ARE signaling-mediated antioxidant response, while this effect was partially eliminated by FGF19 or Nrf2 silencing.

CONCLUSION

Our study suggests that inhibition of miR-9-3p protects against cerebral I/R injury through activating GSK-3β/Nrf2/ARE signaling-mediated antioxidant responses by targeting FGF19, providing a potential therapeutic target for ischemic stroke.

Relationship Between Fibroblast Growth Factor 19 and Diabetic Retinopathy in Patients with Type 2 Diabetes Mellitus

AIM

This study aimed to evaluate whether fibroblast growth factor 19 (FGF19) is associated with the risk of diabetic retinopathy in patients with type 2 diabetes mellitus (T2DM).

METHODS

A total of 357 patients with T2DM were investigated in this cross-sectional study. Logistic regression analysis was performed to assess the association between FGF19 level and diabetic retinopathy.

RESULTS

Serum FGF19 level was significantly lower in patients with diabetic retinopathy in those without diabetic retinopathy. The multivariable analysis revealed a significant association between serum FGF19 level and diabetic retinopathy (odds ratio for every 1 standard deviation increase in logarithmic value = 0.69, 95% confidence interval 0.51-0.94, p = 0.019).

CONCLUSION

Serum FGF19 level was negatively associated with diabetic retinopathy in patients with T2DM.