ATGL-catalyzed lipolysis regulates SIRT1 to control PGC-1α/PPAR-α signaling

Inhibition of the expression of TRIM63 alleviates ventilator-induced diaphragmatic dysfunction by modulating the PPARα/PGC-1α pathway

BACKGROUND

Ventilator-induced diaphragmatic dysfunction (VIDD) significantly affects the prognosis of critically ill patients and has attracted considerable attention. Tripartite motif-containing protein 63 (TRIM63) plays a pivotal role in muscle protein degradation and muscle mass regulation. Its overexpression is closely associated with VIDD; however, data on the specific effects of TRIM63 on this pathological process remain insufficient.

OBJECTIVES

The aim of this study is to elucidate the role of TRIM63 in VIDD and to assess the correlation between the TRIM63-peroxisome proliferator activated receptor α (PPARα)/PPAR gamma coactivator (PGC-1α) pathway and mitochondrial function.

METHODS

Specific pathogen-free grade female Wistar rats were divided into four groups: Sham + NS, Sham + MyoMed-205, MV + NS, and MV + MyoMed-205. The inhibitor group received MyoMed-205 to suppress the expression of TRIM63. After the experiment, diaphragmatic contractility, mitochondrial structure and function, oxidative stress levels, autophagy, apoptosis, and the involvement of the PPARα/PGC-1α pathway were evaluated.

RESULTS

Our findings indicated that inhibiting TRIM63 prevented mechanical ventilation (MV)-induced diaphragmatic contractile dysfunction and atrophy. Mechanistically, inhibition of the expression of TRIM63 resulted in significant upregulation of the PPARα and PGC-1α expression levels, improved mitochondrial dynamics, enhanced the mitochondrial membrane potential, and reduced mitophagy and apoptosis. Structurally, inhibition of the expression of TRIM63 ameliorated MV-induced mitochondrial fragmentation, fusion, and fission.

CONCLUSIONS

The upregulated expression of TRIM63 in VIDD exacerbated mitochondrial damage by inhibiting the PPARα/PGC-1α signaling pathway, leading to increased reactive oxygen species, mitophagy, and apoptosis. Inhibition of the expression of TRIM63 enhanced mitochondrial function, decreased mitophagy and apoptosis, and mitigated VIDD. Thus, TRIM63 may serve as a potential target for the prevention and treatment of VIDD.

Autophagy and the peroxisome proliferator-activated receptor signaling pathway: A molecular ballet in lipid metabolism and homeostasis

Lipids, which are indispensable for cellular architecture and energy storage, predominantly consist of triglycerides (TGs), phospholipids, cholesterol, and their derivatives. These hydrophobic entities are housed within dynamic lipid droplets (LDs), which expand and contract in response to nutrient availability. Historically perceived as a cellular waste disposal mechanism, autophagy has now been recognized as a crucial regulator of metabolism. Within this framework, lipophagy, the selective degradation of LDs, plays a fundamental role in maintaining lipid homeostasis. Dysregulated lipid metabolism and autophagy are frequently associated with metabolic disorders such as obesity and atherosclerosis. In this context, peroxisome proliferator-activated receptors (PPARs), particularly PPAR-γ, serve as intracellular lipid sensors and master regulators of gene expression. Their regulatory influence extends to both autophagy and lipid metabolism, indicating a complex interplay between these processes. This review explores the hypothesis that PPARs may directly modulate autophagy within the realm of lipid metabolism, thereby contributing to the pathogenesis of metabolic diseases. By elucidating the underlying molecular mechanisms, we aim to provide a comprehensive understanding of the intricate regulatory network that connects PPARs, autophagy, and lipid homeostasis. The crosstalk between PPARs and other signaling pathways underscores the complexity of their regulatory functions and the potential for therapeutic interventions targeting these pathways. The intricate relationships among PPARs, autophagy, and lipid metabolism represent a pivotal area of research with significant implications for understanding and treating metabolic disorders.

PPARα regulates ER-lipid droplet protein Calsyntenin-3β to promote ketogenesis in hepatocytes

Ketogenesis requires fatty acid flux from intracellular (lipid droplets) and extrahepatic (adipose tissue) lipid stores to hepatocyte mitochondria. However, whether interorganelle contact sites regulate this process is unknown. Recent studies have revealed a role for Calsyntenin-3β (CLSTN3β), an endoplasmic reticulum-lipid droplet contact site protein, in the control of lipid utilization in adipose tissue. Here, we show that Clstn3b expression is induced in the liver by the nuclear receptor PPARα in settings of high lipid utilization, including fasting and ketogenic diet feeding. Hepatocyte-specific loss of CLSTN3β in mice impairs ketogenesis independent of changes in PPARα activation. Conversely, hepatic overexpression of CLSTN3β promotes ketogenesis in mice. Mechanistically, CLSTN3β affects LD-mitochondria crosstalk, as evidenced by changes in fatty acid oxidation, lipid-dependent mitochondrial respiration, and the mitochondrial integrated stress response. These findings define a function for CLSTN3β-dependent membrane contacts in hepatic lipid utilization and ketogenesis.

Transcriptional Response to Fasting Studied in the Liver of Mice That Express Phosphorylation Resistant Perilipin 5

Perilipin 5 (PLIN5) is a lipid droplet (LD) protein highly expressed in cells that actively oxidize fatty acids. Previous in vitro studies have revealed that PLIN5 phosphorylation (p-PLIN5) at serine 155 by protein kinase A is critical for transcriptional regulation of PPARa target genes by which PLIN5 adapt cells for fatty acid oxidation. We aim to determine the extent of p-PLIN5 in vivo and the consequence of impaired PLIN5 phosphorylation in the liver by using a whole-body knock-in of phosphorylation-resistant PLIN5 (SA/SA) in mice. Plin5 phosphorylation at S155 was increased in the liver LD fraction of fasted mice compared with that of fed mice by mass spectrometry (P < .05). Quantitative polymerase chain reaction of key lipid metabolism genes did not differ between wild-type and SA/SA liver upon fasting in both young and old males. Young SA/SA female mice showed a small but significant reduction in the expression of Ppara and Cpt1a genes in the liver after overnight fasting. Male SA/SA mice had higher fasting blood glucose (P < .05) without a difference in body weight, serum insulin, or serum lipids. IRS2 was reduced in the liver of fasted male SA/SA mice (P < .05). PLIN5 S155 phosphorylation has a limited impact on the upregulation of hepatic lipid metabolism genes important for fasting response in vivo in females and is largely dispensable in males. Impaired phosphorylation also had little effect on serum lipids or liver triglycerides. However, old SA/SA mice showed decreased IRS2 expression in the liver, which may contribute to glucose intolerance in SA/SA male mice.

Tools to Dissect Lipid Droplet Regulation, Players, and Mechanisms

Spurred by the authors' own recent discovery of reactive metabolite-regulated nexuses involving lipid droplets (LDs), this perspective discusses the latest knowledge and multifaceted approaches toward deconstructing the function of these dynamic organelles, LD-associated localized signaling networks, and protein players. Despite accumulating knowledge surrounding protein families and pathways of conserved importance for LD homeostasis surveillance and maintenance across taxa, much remains to be understood at the molecular level. In particular, metabolic stress-triggered contextual changes in LD-proteins' localized functions, crosstalk with other organelles, and feedback signaling loops and how these are specifically rewired in disease states remain to be illuminated with spatiotemporal precision. We hope this perspective promotes an increased interest in these essential organelles and innovations of new tools and strategies to better understand context-specific LD regulation critical for organismal health.

Deciphering significances of autophagy in the development and metabolism of adipose tissue

The mechanisms of adipose tissue activation and inactivation have been a hot topic of research in the last decade, from which countermeasures have been attempted to be found against obesity as well as other lipid metabolism-related diseases, such as type 2 diabetes mellitus and non-alcoholic fatty liver disease. Autophagy has been shown to be closely related to the regulation of adipocyte activity, which is involved in the whole process including white adipocyte differentiation/maturation and brown or beige adipocyte generation/activation. Dysregulation of autophagy in adipose tissue has been demonstrated to be associated with obesity. On this basis, we summarize the pathways and mechanisms of autophagy involved in the regulation of lipid metabolism and present a review of its pathophysiological roles in lipid metabolism-related diseases, in the hope of providing ideas for the treatment of these diseases.

Crosstalk between SIRT1/Nrf2 signaling and NLRP3 inflammasome/pyroptosis as a mechanistic approach for the neuroprotective effect of linagliptin in Parkinson's disease

In recent years, special attention has been paid to highlighting the antiparkinsonian effect of linagliptin. However, the mechanism of its action has not yet been well investigated. The present study aimed to verify the neuroprotective effect of linagliptin in the rotenone model of Parkinson's disease (PD) and further explore its potential molecular mechanisms. Rats were intoxicated with rotenone (2 mg/kg/day; sc) and treated with linagliptin (10  mg/kg/day; po) for 14 consecutive days. The present finding showed that linagliptin ameliorated the histopathological changes of rotenone on substantia nigra and striata. Linagliptin decreased α-synuclein immunoreactivity along with an increase in tyrosine hydroxylase immunoreactivity and striatal dopamine content. This was reflected in the marked improvement of the behavior and motor deficits in rotenone-intoxicated rats. On the molecular level, linagliptin upregulated sirtuin 1 (SIRT1)/ nuclear factor erythroid 2-related factor 2 (Nrf2) signaling, reduced ionized calcium-binding adaptor molecule 1 (Iba1) protein expression, restored glutathione (GSH) content, and elevated heme oxygenase-1 (HO-1) level in rats with rotenone intoxication. Moreover, linagliptin inhibited NOD-like receptor protein 3 (NLRP3)/caspase-1/interleukin-1β (IL-1β) cascade with subsequent reduction in gasdermin D (GSDMD) expression. Therefore, the present study reveals the ability of linagliptin, through the activation of SIRT1/Nrf2 signaling, to suppress NLRP3 inflammasome-mediated pyroptosis and protect against rotenone-induced parkinsonism.

DFCP1 is a regulator of starvation-driven ATGL-mediated lipid droplet lipolysis

Lipid droplets (LDs) are transient lipid storage organelles that can be readily tapped to resupply cells with energy or lipid building blocks, and therefore play a central role in cellular metabolism. Double FYVE Domain Containing Protein 1 (DFCP1/ZFYVE1) has emerged as a key regulator of LD metabolism, where the nucleotide-dependent accumulation of DFCP1 on LDs influences their size, number, and dynamics. Here we show that DFCP1 regulates lipid metabolism by directly modulating the activity of Adipose Triglyceride Lipase (ATGL/PNPLA2), the rate-limiting lipase driving the catabolism of LDs. We show through pharmacological inhibition of key enzymes associated with LD metabolism that DFCP1 specifically regulates lipolysis and, to a lesser extent, lipophagy. Consistent with this observation, DFCP1 interacts with and recruits ATGL to LDs in starved cells, irrespective of other known regulatory factors of ATGL. We further establish that this interaction prevents dynamic disassociation of ATGL from LDs and thereby impedes the rate of LD lipolysis. Collectively, our findings indicate that DFCP1 is a nutrient-sensitive regulator of LD catabolism.

Lipid droplets as cell fate determinants in skeletal muscle

Lipid droplets (LDs) are dynamic organelles that communicate with other cellular components to orchestrate energetic homeostasis and signal transduction. In skeletal muscle, the presence and importance of LDs have been widely studied in myofibers of both rodents and humans under physiological conditions and in metabolic disorders. However, the role of LDs in myogenic stem cells has only recently begun to be unveiled. In this review we briefly summarize the process of LD biogenesis and degradation in the most prevalent model. We then review recent knowledge on LDs in skeletal muscle and muscle stem cells. We further introduce advanced methodologies for LD imaging and mass spectrometry that have propelled our understanding of the dynamics and heterogeneity of LDs.

Exercise-regulated lipolysis: Its role and mechanism in health and diseases

Exercise has received considerable attention because of its importance not just in regulating physiological function, but also in ameliorating multiple pathological processes. Among these processes, lipolysis may play an important role in exercise-induced benefits. It is generally accepted that active lipolysis contributes to breakdown of fats, leading to the release of free fatty acids (FFAs) that serve as an energy source for muscles and other tissues during exercise. However, the significance of lipolysis in the context of exercise has not been fully understood. This review comprehensively outlines the potential regulatory mechanisms by which exercise stimulates lipolysis. The potential roles of exercise-mediated lipolysis in various physiological and pathological processes are also summarized. Additionally, we also discussed the potential non-classical effects of key lipolytic effectors induced by exercise. This will enhance our understanding of how exercise improves lipolytic function to bring about beneficial effects, offering new insights into potential therapeutic avenues for promoting health and alleviating diseases.

Fisetin Ameliorates Hepatocyte Lipid Droplet Accumulation via Targeting the Rhythmic Protein BMAL1 to Regulate Cell Death-Inducing DNA Fragmentation Factor-α-like Effector C-Mediated Lipid Droplet Fusion

High fat diet (HFD) induces the enlargement and accumulation of lipid droplets (LDs) in hepatocytes, thereby influencing the homeostasis of lipid metabolism. Cell death-inducing DNA fragmentation factor-α-like effector C (CIDEC), a surface protein of LDs, facilitates their fusion and growth, transforming small LDs into larger ones. Lipophagy, a selective form of autophagy, primarily targets small LDs for degradation. Fisetin (FIS), a natural dietary flavonoid present in various fruits and vegetables, has an unclear mechanism for reducing LD accumulation. In this study, we observed that FIS significantly ameliorated HFD-induced lipid accumulation in the hepatocytes of C57BL/6 mice. In further mechanistic studies, we revealed that FFA enhanced the expression of CIDEC, which promoted the fusion of LDs and caused them to become larger. The enlarged LDs could not be degraded by autophagy, which ultimately led to accumulation of LDs. Conversely, FIS alleviated LD accumulation by inhibiting CIDEC-mediated fusion, resulting in smaller LDs that facilitated lipophagy. Additionally, studies indicated that the dysfunction of circadian rhythms is closely related to lipid metabolism. In our study, we showed that HFD and FFA disrupted circadian rhythm in C57BL/6 mouse hepatocytes and AML12 cells, while FIS modified the rhythm disturbances and increased protein expression of the core clocks BMAL1 and CLOCK. We silenced the BMAL1 protein and revealed that si-BMAL1 upregulated CIDEC proteins. These data suggested that FIS might inhibit CIDEC-mediated LD fusion and enhance hepatocyte lipophagy by promoting the expression of rhythm protein BMAL1, thereby alleviating LD accumulation in C57BL/6 and AML12 cells caused by the HFD and FFA. The present study provided novel insights and potential targets for utilizing functional food factors to mitigate the accumulation of LD in hepatocytes.

Perilipin 5 Phosphorylation is Dispensable for Upregulation of Hepatic Lipid Metabolism Genes upon Fasting but Required for Insulin Receptor Substrate 2 Expression in Male Mice

Objective

Perilipin 5 (PLIN5) is a lipid droplet protein highly expressed in cells that actively oxidize fatty acids. Previous in vitro studies have revealed that PLIN5 phosphorylation (p-PLIN5) at serine 155 by PKA is critical for transcriptional regulation of PPARa target genes by which PLIN5 adapt cells for fatty acid oxidation. We aim to determine the extent of p-PLIN5 in vivo and the consequence of impaired PLIN5 phosphorylation in the liver by using a whole-body knock-in of phosphorylation resistant PLIN5 (SA/SA) in mice.

Methods

We measured PLIN5 and p-PLIN5 with mass spectrometry and Phos-tag gels. We assessed serum chemistry in WT and SA/SA mice upon fasting. RNA sequencing and qPCR compared the gene expression in the liver of SA/SA and WT mice after overnight fast.

Results

Plin5 phosphorylation at S155 was increased in the liver LD fraction of fasted mice compared with that of fed mice by mass spectrometry (p<0.05). qPCR of key lipid metabolism genes did not differ between WT and SA/SA liver upon fasting. Male SA/SA mice had a higher fasting blood glucose (p<0.05) without a difference in body weight, serum insulin, or serum lipids. IRS2 was reduced in the liver of fasted male SA/SA mice (p<0.05).

Conclusion

PLIN5 S155 phosphorylation is dispensable for the upregulation of lipid metabolism genes important for fasting response in vivo. Impaired phosphorylation also had little effect on serum lipids or liver TG. However, SA/SA mice showed decreased IRS2 expression in the liver, which may contribute to glucose intolerance in SA/SA male mice.

Boosting Health Benefits in Vegetables: A Novel Ultraviolet B (UVB) Device for Rapid At-Home Enhancement of Phytochemicals and Bioactivity

The consumption of vegetables is essential for reducing the risk of noncommunicable diseases, yet global intake falls short of recommended levels. Enhancing the nutraceutical content of vegetables through postharvest abiotic stress, such as ultraviolet B (UVB) radiation, offers a promising solution to increase health benefits. This study developed a user-friendly, at-home UVB device designed to increase the phytochemical content in common vegetables like carrots, lettuce, and broccoli. The device applies UVB radiation (305-315 nm) to fresh-cut vegetables, optimizing exposure time and intensity to maximize nutraceutical enrichment. The results demonstrated that UVB exposure increased the phenolic content by 44% in carrots, 58% in broccoli, and 10% in lettuce, with chlorogenic acid levels rising by 367% in lettuce, 547% in broccoli, and 43% in carrots after 48 h of storage. UVB treatment also enhanced antioxidant activity by up to 41% in broccoli and anti-inflammatory potential by 22% in carrots. In terms of gene expression, UVB treatment upregulated UCP-1 expression by 555% in carrots, enhanced thermogenesis, and increased SIRT-1 and ATGL expression by over 200%, promoting lipid metabolism. This process provides a convenient and efficient method for consumers to boost the health benefits of their vegetables. The study concludes that UVB-induced abiotic stress is an effective strategy to improve vegetable nutritional quality, offering a novel approach to increasing bioactive compound intake and aiding in the prevention of diet-related diseases.

Regulation of cancer cell lipid metabolism and oxidative phosphorylation by microenvironmental acidosis

The expansion of cancer cell mass in solid tumors generates a harsh environment characterized by dynamically varying levels of acidosis, hypoxia, and nutrient deprivation. Because acidosis inhibits glycolytic metabolism and hypoxia inhibits oxidative phosphorylation, cancer cells that survive and grow in these environments must rewire their metabolism and develop a high degree of metabolic plasticity to meet their energetic and biosynthetic demands. Cancer cells frequently upregulate pathways enabling the uptake and utilization of lipids and other nutrients derived from dead or recruited stromal cells, and in particular lipid uptake is strongly enhanced in acidic microenvironments. The resulting lipid accumulation and increased reliance on β-oxidation and mitochondrial metabolism increase susceptibility to oxidative stress, lipotoxicity, and ferroptosis, in turn driving changes that may mitigate such risks. The spatially and temporally heterogeneous tumor microenvironment thus selects for invasive, metabolically flexible, and resilient cancer cells capable of exploiting their local conditions and of seeking out more favorable surroundings. This phenotype relies on the interplay between metabolism, acidosis, and oncogenic mutations, driving metabolic signaling pathways such as peroxisome proliferator-activated receptors (PPARs). Understanding the particular vulnerabilities of such cells may uncover novel therapeutic liabilities of the most aggressive cancer cells.

Iron supplementation and iron accumulation promote adipocyte thermogenesis through PGC1α-ATGL-mediated lipolysis

Iron homeostasis is essential for maintaining metabolic health and iron disorder has been linked to chronic metabolic diseases. Increasing thermogenic capacity in adipose tissue has been considered as a potential approach to regulate energy homeostasis. Both mitochondrial biogenesis and mitochondrial function are iron-dependent and essential for adipocyte thermogenic capacity, but the underlying relationships between iron accumulation and adipose thermogenesis is unclear. Firstly, we confirmed that iron homeostasis and the iron regulatory markers (e.g., Tfr1 and Hfe) are involved in cold-induced thermogenesis in subcutaneous adipose tissues using RNA-seq and bioinformatic analysis. Secondly, an Hfe (Hfe-/-)-deficient mouse model, in which tissues become overloaded with iron, was employed. We found iron accumulation caused by Hfe deficiency enhanced mitochondrial respiratory chain expression in subcutaneous white adipose in vivo and resulted in enhanced tissue thermogenesis with upregulation of PGC-1α and adipose triglyceride lipase, mitochondrial biogenesis and lipolysis. To investigate the thermogenic capacity in vitro, stromal vascular fraction from adipose tissues was isolated, followed with adipogenic differentiation. Primary adipocyte from Hfe-/- mice exhibited higher cellular oxygen consumption, associated with enhanced expression of mitochondrial oxidative respiratory chain protein, while primary adipocytes or stromal vascular fractions from WT mice supplemented with iron citrate) exhibited similar effect in thermogenic capacity. Taken together, these findings indicate iron supplementation and iron accumulation (Hfe deficiency) can regulate adipocyte thermogenic capacity, suggesting a potential role for iron homeostasis in adipose tissues.

S-acylation of ATGL is required for lipid droplet homoeostasis in hepatocytes

Lipid droplets (LDs) are organelles specialized in the storage of neutral lipids, cholesterol esters and triglycerides, thereby protecting cells from the toxicity of excess lipids while allowing for the mobilization of lipids in times of nutrient deprivation. Defects in LD function are associated with many diseases. S-acylation mediated by zDHHC acyltransferases modifies thousands of proteins, yet the physiological impact of this post-translational modification on individual proteins is poorly understood. Here, we show that zDHHC11 regulates LD catabolism by modifying adipose triacylglyceride lipase (ATGL), the rate-limiting enzyme of lipolysis, both in hepatocyte cultures and in mice. zDHHC11 S-acylates ATGL at cysteine 15. Preventing the S-acylation of ATGL renders it catalytically inactive despite proper localization. Overexpression of zDHHC11 reduces LD size, whereas its elimination enlarges LDs. Mutating ATGL cysteine 15 phenocopies zDHHC11 loss, causing LD accumulation, defective lipolysis and lipophagy. Our results reveal S-acylation as a mode of regulation of ATGL function and LD homoeostasis. Modulating this pathway may offer therapeutic potential for treating diseases linked to defective lipolysis, such as fatty liver disease.

Toxicity mechanism of acrolein on energy metabolism disorder and apoptosis in human ovarian granulosa cells

Acrolein (ACR), an unsaturated, highly reactive aldehyde, is a widespread environmental toxin. ACR exerts permanent and irreversible side effects on ovarian functions. Granulosa cells play a crucial role in supporting ovarian function. Thus, in this study, we investigated the toxicity effects of granulosa cells induced by ACR. Following treatment with varying ACR concentrations (0, 12.5, 25, 50, and 100 μM), we observed that ACR exposure induced reactive oxygen species accumulation, mitochondrial energy metabolism disorder, and apoptosis in KGN cells (a human ovarian granulosa cell line) in a dose-dependent manner. In addition, mitochondrial biogenesis in KGN cells displayed biphasic changes after ACR exposure, with activation at a low ACR dose (12.5 μM), but inhibition at higher ACR doses (≥50 μM). SIRT1/PGC-1α-mediated mitochondrial biogenesis is crucial for maintaining intracellular mitochondrial homeostasis and cellular function. The inhibition/activation of the SIRT1/PGC-1α pathway in KGN cells validated its role in ACR-induced damage. The results indicated that the inhibition of the SIRT1/PGC-1α pathway aggravated ACR-induced cell damage, whereas its activation partially counteracted ACR-induced cell damage. This study attempted to uncover a novel mechanism of ACR-induced ovarian toxicity so as to provide an effective treatment option for safeguarding female reproductive health from the adverse effects of ACR.

The interplay between mitochondrial dysfunction and NLRP3 inflammasome in multiple sclerosis: Therapeutic implications and animal model studies

Multiple sclerosis (MS) is a complex autoimmune disorder that impacts the central nervous system (CNS), resulting in inflammation, demyelination, and neurodegeneration. The NOD-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome, a multiprotein complex of the innate immune system, serves an essential role in the pathogenesis of MS by regulating the production of pro-inflammatory cytokines (IL-1β & IL-18) and the induction of pyroptotic cell death. Mitochondrial dysfunction is one of the main potential factors that can trigger NLRP3 inflammasome activation and lead to inflammation and axonal damage in MS. This highlights the importance of understanding how mitochondrial dynamics modulate NLRP3 inflammasome activity and contribute to the inflammatory and neurodegenerative features of MS. The lack of a comprehensive understanding of the pathogenesis of MS and the urge for the introduction of new therapeutic strategies led us to review the therapeutic potential of targeting the interplay between mitochondrial dysfunction and the NLRP3 inflammasome in MS. This paper also evaluates the natural and synthetic compounds that can improve mitochondrial function and/or inhibit the NLRP3 inflammasome, thereby providing neuroprotection. Moreover, it summarizes the evidence from animal models of MS that demonstrate the beneficial effects of these compounds on reducing inflammation, demyelination, and neurodegeneration. Finally, this review advocates for a deeper investigation into the molecular crosstalk between mitochondrial dynamics and the NLRP3 inflammasome as a means to refine therapeutic targets for MS.

miR-21, miR-221, miR-29 and miR-34 are distinguishable molecular features of a metabolically unhealthy phenotype in young adults

Discrepancies between the measurement of body mass index (BMI) and metabolic health status have been described for the onset of metabolic diseases. Studying novel biomarkers, some of which are associated with metabolic syndrome, can help us to understand the differences between metabolic health (MetH) and BMI. A group of 1469 young adults with pre-specified anthropometric and blood biochemical parameters were selected. Of these, 80 subjects were included in the downstream analysis that considered their BMI and MetH parameters for selection as follows: norm weight metabolically healthy (MHNW) or metabolically unhealthy (MUNW); overweight/obese metabolically healthy (MHOW) or metabolically unhealthy (MUOW). Our results showed for the first time the differences when the MetH status and the BMI are considered as global MetH statures. First, all the evaluated miRNAs presented a higher expression in the metabolically unhealthy group than the metabolically healthy group. The higher levels of leptin, IL-1b, IL-8, IL-17A, miR-221, miR-21, and miR-29 are directly associated with metabolic unhealthy and OW/OB phenotypes (MUOW group). In contrast, high levels of miR34 were detected only in the MUNW group. We found differences in the SIRT1-PGC1α pathway with increased levels of SIRT1+ cells and diminished mRNA levels of PGCa in the metabolically unhealthy compared to metabolically healthy subjects. Our results demonstrate that even when metabolic diseases are not apparent in young adult populations, MetH and BMI have a distinguishable phenotype print that signals the potential to develop major metabolic diseases.

Fenofibrate alleviates NAFLD by enhancing the PPARα/PGC-1α signaling pathway coupling mitochondrial function

BACKGROUND

To comprehend the influences of fenofibrate on hepatic lipid accumulation and mitochondrial function-related signaling pathways in mice with non-alcoholic fatty liver disease (NAFLD) secondary to high-fat diets together with free fatty acids-influenced HepG2 cells model.

MATERIALS AND METHODS

A random allocation of male 6-week C57BL/6J mice into three groups was done, including controls, model (14 weeks of a high-fat diet), and fenofibrate [similar to the model one with administered 0.04 g/(kg.d) fenofibrate by gavage at 11 weeks for 4 weeks] groups, which contained 10 mice each. This study verified NAFLD pathogenesis via mitochondrial functions in hepatic pathological abnormalities, liver index and weight, body weight, serum biochemical indexes, oxidative stress indicators, mitochondrial function indexes, and related signaling pathways. The effect of fenofibrate intervention was investigated in NAFLD model mice. In vitro, four groups based on HepG2 cells were generated, including controls, the FFA model (1.5 mmol/L FFA incubation for 24 h), LV-PGC-1α intervention (similar to the FFA model one after PPARGC1A lentivirus transfection), and LV control intervention (similar to the FFA model one after negative control lentivirus transfection) groups. The study investigated the mechanism of PGC-1α related to lipid decomposition and mitochondrial biosynthesis by Oil red O staining, colorimetry and western blot.

RESULTS

In vivo experiments, a high-fat diet achieved remarkable changes regarding liver weight, liver index, serum biochemical indicators, oxidative stress indicators, liver pathological changes, mitochondrial function indicators, and body weight of the NAFLD model mice while fenofibrate improved the objective indicators. In the HepG2 cells model, the lipid accumulation increased significantly within the FFA model group, together with aggravated hepatocytic damage and boosted oxidative stress levels. Moreover, FFA induced excessive mitosis into fragmented in mitochondrial morphology, ATP content in cells decreased, mtDNA replication fold decreased, the expression of lipid decomposition protein PPARα reduced, mitochondrial biosynthesis related protein PGC-1α, NRF-1 and TFAM decreased. PGC-1α overexpression inhibited lipid deposition by improving mitochondrial biosynthesis and lipid decomposition.

CONCLUSION

Fenofibrate up-regulated PPARα/PGC-1α signaling pathway, promoted mitochondrial β-oxidation, reduced oxidative stress damage and lipid accumulation of liver. PGC-1α overexpression enhanced mitochondrial biosynthesis and ATP production, and reduced HepG2 intracellular accumulation of lipids and oxidative stress.

A single 1,500 m freestyle at maximal speed decreases cognitive function in athletes

Introduction

Physical exercise can improve cognitive function, and the degree of impact on cognitive function is related to exercise modality, intensity, and duration. However, few studies have been conducted on the effects of competitive sports on cognitive function. The 1,500 m freestyle is the longest pool-based swimming event in the Olympic Games. This study explores the effects of 1,500 m freestyle at maximal speed on athletes' cognitive function and analyzes the potential mechanism of cognitive function reduction in freestyle at maximal speed from the perspective of hemoglobin oxygenation difference (Hbdiff).

Methods

A total of 13 male university swimmers were required to take part in a 1,500 m freestyle competition, swimming at maximal speed. The relevant indicators, including cognitive function and freestyle at maximal speed, before and after the competition were tested and analyzed. Cognitive function was assessed using the Schulte grid test (SGT), the trail-making test (TMT), and the digit span test (DST). The neurobiological characteristics of cognitive function, such as the prefrontal cortex (PFC), response time (RT), and accuracy rate (ACC), were tested using functional near-infrared spectroscopy (fNIRS).

Results

A significant decrease in scores for SGT, TMT, and digit span test-backward (DST-B) (p < 0.01). Oxygenated hemoglobin (Oxy-Hb) concentrations in the right frontopolar area (R-FPA) of brain channels 8 (p < 0.01) and 9 (CH8, 9) (p < 0.05), the right dorsolateral prefrontal cortex (R-DLPFC) CH10 (p < 0.05), and the middle dorsolateral prefrontal cortex (M-DLPFC) CH18 (p < 0.01) were significantly altered, and the right area of the brain was activated. The total Oxy-Hb concentrations in the regions of interest (ROIs) of R-FPA, R-DLFPC, and M-DLFPC were changed significantly (p < 0.01).

Discussion

The exhaustive performance of a 1,500 m freestyle event resulted in both physical fatigue and a decline in cognitive function. This decline may be attributed to the activation of specific regions of interest, namely the FPA, DLPFC, and M-DLPFC, within the prefrontal cortex (PFC), as well as alterations in functional connectivity.

Targeting mitochondrial quality control for diabetic cardiomyopathy: Therapeutic potential of hypoglycemic drugs

Diabetic cardiomyopathy is a chronic cardiovascular complication caused by diabetes that is characterized by changes in myocardial structure and function, ultimately leading to heart failure and even death. Mitochondria serve as the provider of energy to cardiomyocytes, and mitochondrial dysfunction plays a central role in the development of diabetic cardiomyopathy. In response to a series of pathological changes caused by mitochondrial dysfunction, the mitochondrial quality control system is activated. The mitochondrial quality control system (including mitochondrial biogenesis, fusion and fission, and mitophagy) is core to maintaining the normal structure of mitochondria and performing their normal physiological functions. However, mitochondrial quality control is abnormal in diabetic cardiomyopathy, resulting in insufficient mitochondrial fusion and excessive fission within the cardiomyocyte, and fragmented mitochondria are not phagocytosed in a timely manner, accumulating within the cardiomyocyte resulting in cardiomyocyte injury. Currently, there is no specific therapy or prevention for diabetic cardiomyopathy, and glycemic control remains the mainstay. In this review, we first elucidate the pathogenesis of diabetic cardiomyopathy and explore the link between pathological mitochondrial quality control and the development of diabetic cardiomyopathy. Then, we summarize how clinically used hypoglycemic agents (including sodium-glucose cotransport protein 2 inhibitions, glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors, thiazolidinediones, metformin, and α-glucosidase inhibitors) exert cardioprotective effects to treat and prevent diabetic cardiomyopathy by targeting the mitochondrial quality control system. In addition, the mechanisms of complementary alternative therapies, such as active ingredients of traditional Chinese medicine, exercise, and lifestyle, targeting mitochondrial quality control for the treatment of diabetic cardiomyopathy are also added, which lays the foundation for the excavation of new diabetic cardioprotective drugs.

The promising roles of medicinal plants and bioactive compounds on hepatic lipid metabolism in the treatment of non-alcoholic fatty liver disease in animal models: molecular targets

Imbalance in hepatic lipid metabolism can lead to an abnormal triglycerides deposition in the hepatocytes which can cause non-alcoholic fatty liver disease (NAFLD). Four main mechanisms responsible for regulating hepatic lipid metabolism are fatty acid uptake, de novo lipogenesis, lipolysis and fatty acid oxidation. Controlling the expression of transcription factors at molecular level plays a crucial role in NAFLD management. This paper reviews various medicinal plants and their bioactive compounds emphasising mechanisms involved in hepatic lipid metabolism, other important NAFLD pathological features, and their promising roles in managing NAFLD through regulating key transcription factors. Although there are many medicinal plants popularly investigated for NAFLD treatment, there is still little information and scientific evidence available and there has been no research on clinical trials scrutinised on this matter. This review also aims to provide molecular information of medicinal plants in NALFD treatment that might have potentials for future scientifically controlled studies.

The roles of DGAT1 and DGAT2 in human myotubes are dependent on donor patho-physiological background

The roles of DGAT1 and DGAT2 in lipid metabolism and insulin responsiveness of human skeletal muscle were studied using cryosections and myotubes prepared from muscle biopsies from control, athlete, and impaired glucose regulation (IGR) cohorts of men. The previously observed increases in intramuscular triacylglycerol (IMTG) in athletes and IGR were shown to be related to an increase in lipid droplet (LD) area in type I fibers in athletes but, conversely, in type II fibers in IGR subjects. Specific inhibition of both diacylglycerol acyltransferase (DGAT) 1 and 2 decreased fatty acid (FA) uptake by myotubes, whereas only DGAT2 inhibition also decreased fatty acid oxidation. Fatty acid uptake in myotubes was negatively correlated with the lactate thresholds of the respective donors. DGAT2 inhibition lowered acetate uptake and oxidation in myotubes from all cohorts whereas DGAT1 inhibition had no effect. A positive correlation between acetate oxidation in myotubes and resting metabolic rate (RMR) from fatty acid oxidation in vivo was observed. Myotubes from athletes and IGR had higher rates of de novo lipogenesis from acetate that were normalized by DGAT2 inhibition. Moreover, DGAT2 inhibition in myotubes also resulted in increased insulin-induced Akt phosphorylation. The differential effects of DGAT1 and DGAT2 inhibition suggest that the specialized role of DGAT2 in esterifying nascent diacylglycerols and de novo synthesized FA is associated with synthesis of a pool of triacylglycerol, which upon hydrolysis results in effectors that promote mitochondrial fatty acid oxidation but decrease insulin signaling in skeletal muscle cells.

Tapping lipid droplets: A rich fat diet of intracellular bacterial pathogens

Lipid droplets (LDs) are dynamic and versatile organelles present in most eukaryotic cells. LDs consist of a hydrophobic core of neutral lipids, a phospholipid monolayer coat, and a variety of associated proteins. LDs are formed at the endoplasmic reticulum and have diverse roles in lipid storage, energy metabolism, membrane trafficking, and cellular signaling. In addition to their physiological cellular functions, LDs have been implicated in the pathogenesis of several diseases, including metabolic disorders, cancer, and infections. A number of intracellular bacterial pathogens modulate and/or interact with LDs during host cell infection. Members of the genera Mycobacterium, Legionella, Coxiella, Chlamydia, and Salmonella exploit LDs as a source of intracellular nutrients and membrane components to establish their distinct intracellular replicative niches. In this review, we focus on the biogenesis, interactions, and functions of LDs, as well as on their role in lipid metabolism of intracellular bacterial pathogens.

Late Effects of Chronic Low Dose Rate Total Body Irradiation on the Heart Proteome of ApoE-/- Mice Resemble Premature Cardiac Ageing

Recent epidemiologic studies support an association between chronic low-dose radiation exposure and the development of cardiovascular disease (CVD). The molecular mechanisms underlying the adverse effect of chronic low dose exposure are not fully understood. To address this issue, we have investigated changes in the heart proteome of ApoE deficient (ApoE^-/-) C57Bl/6 female mice chronically irradiated for 300 days at a very low dose rate (1 mGy/day) or at a low dose rate (20 mGy/day), resulting in cumulative whole-body doses of 0.3 Gy or 6.0 Gy, respectively. The heart proteomes were compared to those of age-matched sham-irradiated ApoE^-/- mice using label-free quantitative proteomics. Radiation-induced proteome changes were further validated using immunoblotting, enzyme activity assays, immunohistochemistry or targeted transcriptomics. The analyses showed persistent alterations in the cardiac proteome at both dose rates; however, the effect was more pronounced following higher dose rates. The altered proteins were involved in cardiac energy metabolism, ECM remodelling, oxidative stress, and ageing signalling pathways. The changes in PPARα, SIRT, AMPK, and mTOR signalling pathways were found at both dose rates and in a dose-dependent manner, whereas more changes in glycolysis and ECM remodelling were detected at the lower dose rate. These data provide strong evidence for the possible risk of cardiac injury following chronic low dose irradiation and show that several affected pathways following chronic irradiation overlap with those of ageing-associated heart pathology.

Effects of dietary niacinamide and CP concentrations on the nitrogen excretion, growth performance, and meat quality of pigs

Reducing the dietary CP concentration in the formulation of low-protein diets without adverse effects on animal growth performance and meat quality remains challenging. In this study, we investigated the effects of nicotinamide (NAM) on the nitrogen excretion, growth performance, and meat quality of growing-finishing pigs fed low-protein diets. To measure the nitrogen balance, we conducted two trials: in nitrogen balance trial 1, four crossbred (Duroc × Landrace × Large White) barrows (40 ± 0.5 kg BW) were used in a 4 × 4 Latin square design with four diets and periods. The diets consisted of a basal diet + 30 mg/kg NAM (a control dose), basal diet + 90 mg/kg NAM, basal diet + 210 mg/kg NAM, and basal diet + 360 mg/kg NAM. In nitrogen balance trial 2, another four barrows (40 ± 0.5 kg BW) were used in a 4 × 4 Latin square design. The diets consisted of a basal diet + including 30 mg/kg NAM (control), basal diet + 360 mg/kg NAM, low-protein diet + 30 mg/kg NAM, and low-protein diet + 360 mg/kg NAM. To measure growth performance, two trials were conducted. In growth performance trial 1, 40 barrows (37.0 ± 1.0 kg) were randomly allocated to one of four dietary treatments (n = 10 per group), whereas in growth performance trial 2, 300 barrows (41.4 ± 2.0 kg) were randomly allocated to one of four dietary treatments, with each dietary treatment conducted in five repetitions with 15 pigs each. The four diets in the two growth performance trials were similar to those in nitrogen balance trial 2. Supplementing the diet with 210 or 360 mg/kg NAM reduced urinary nitrogen excretion and total nitrogen excretion and increased nitrogen retention comparted with the control diet (P < 0.05). Compared with the control diet, the low-protein diet with 360 mg/kg NAM reduced faecal, urinary, and total nitrogen excretion (P < 0.05) without affecting nitrogen retention and average daily gain (P > 0.05). Pigs fed the low-protein diet with 360 mg/kg NAM showed a decreased intramuscular fat content in the longissimus thoracis muscle when compared with pigs fed the control diet (P > 0.05). Our results suggest NAM as a suitable dietary additive to reduce dietary CP concentration, maximise nitrogen retention and growth performance, and decrease fat deposition in pigs.

Organelle interactions compartmentalize hepatic fatty acid trafficking and metabolism

Organelle interactions play a significant role in compartmentalizing metabolism and signaling. Lipid droplets (LDs) interact with numerous organelles, including mitochondria, which is largely assumed to facilitate lipid transfer and catabolism. However, quantitative proteomics of hepatic peridroplet mitochondria (PDM) and cytosolic mitochondria (CM) reveals that CM are enriched in proteins comprising various oxidative metabolism pathways, whereas PDM are enriched in proteins involved in lipid anabolism. Isotope tracing and super-resolution imaging confirms that fatty acids (FAs) are selectively trafficked to and oxidized in CM during fasting. In contrast, PDM facilitate FA esterification and LD expansion in nutrient-replete medium. Additionally, mitochondrion-associated membranes (MAM) around PDM and CM differ in their proteomes and ability to support distinct lipid metabolic pathways. We conclude that CM and CM-MAM support lipid catabolic pathways, whereas PDM and PDM-MAM allow hepatocytes to efficiently store excess lipids in LDs to prevent lipotoxicity.

Targeting PPARs for therapy of atherosclerosis: A review

Atherosclerosis, a chief pathogenic factor of cardiovascular disease, is associated with many factors including inflammation, dyslipidemia, and oxidative stress. Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors and are widely expressed with tissue- and cell-specificity. They control multiple genes that are involved in lipid metabolism, inflammatory response, and redox homeostasis. Given the diverse biological functions of PPARs, they have been extensively studied since their discovery in 1990s. Although controversies exist, accumulating evidence have demonstrated that PPAR activation attenuates atherosclerosis. Recent advances are valuable for understanding the mechanisms of action of PPAR activation. This article reviews the recent findings, mainly from the year of 2018 to present, including endogenous molecules in regulation of PPARs, roles of PPARs in atherosclerosis by focusing on lipid metabolism, inflammation, and oxidative stress, and synthesized PPAR modulators. This article provides information valuable for researchers in the field of basic cardiovascular research, for pharmacologists that are interested in developing novel PPAR agonists and antagonists with lower side effects as well as for clinicians.

Chronic acidosis rewires cancer cell metabolism through PPARα signaling

The mechanisms linking tumor microenvironment acidosis to disease progression are not understood. Here, we used mammary, pancreatic, and colon cancer cells to show that adaptation to growth at an extracellular pH (pHe ) mimicking acidic tumor niches is associated with upregulated net acid extrusion capacity and elevated intracellular pH at physiological pHe , but not at acidic pHe . Using metabolic profiling, shotgun lipidomics, imaging and biochemical analyses, we show that the acid adaptation-induced phenotype is characterized by a shift toward oxidative metabolism, increased lipid droplet-, triacylglycerol-, peroxisome content and mitochondrial hyperfusion. Peroxisome proliferator-activated receptor-α (PPARA, PPARα) expression and activity are upregulated, at least in part by increased fatty acid uptake. PPARα upregulates genes driving increased mitochondrial and peroxisomal mass and β-oxidation capacity, including mitochondrial lipid import proteins CPT1A, CPT2 and SLC25A20, electron transport chain components, peroxisomal proteins PEX11A and ACOX1, and thioredoxin-interacting protein (TXNIP), a negative regulator of glycolysis. This endows acid-adapted cancer cells with increased capacity for utilizing fatty acids for metabolic needs, while limiting glycolysis. As a consequence, the acid-adapted cells exhibit increased sensitivity to PPARα inhibition. We conclude that PPARα is a key upstream regulator of metabolic changes favoring cancer cell survival in acidic tumor niches.

PGC-1α in osteoarthritic chondrocytes: From mechanism to target of action

Osteoarthritis (OA) is one of the most common degenerative joint diseases, often involving the entire joint. The degeneration of articular cartilage is an important feature of OA, and there is growing evidence that the mitochondrial biogenesis master regulator peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) exert a chondroprotective effect. PGC-1α delays the development and progression of OA by affecting mitochondrial biogenesis, oxidative stress, mitophagy and mitochondrial DNA (mtDNA) replication in chondrocytes. In addition, PGC-1α can regulate the metabolic abnormalities of OA chondrocytes and inhibit chondrocyte apoptosis. In this paper, we review the regulatory mechanisms of PGC-1α and its effects on OA chondrocytes, and introduce potential drugs and novel nanohybrid for the treatment of OA which act by affecting the activity of PGC-1α. This information will help to further elucidate the pathogenesis of OA and provide new ideas for the development of therapeutic strategies for OA.

Steatosis in metabolic diseases: A focus on lipolysis and lipophagy

Fatty acids (FAs), as part of lipids, are involved in cell membrane composition, cellular energy storage, and cell signaling. FAs can also be toxic when their concentrations inside and/or outside the cell exceed physiological levels, which is called "lipotoxicity", and steatosis is a form of lipotoxity. To facilitate the storage of large quantities of FAs in cells, they undergo a process called lipolysis or lipophagy. This review focuses on the effects of lipolytic enzymes including cytoplasmic "neutral" lipolysis, lysosomal "acid" lipolysis, and lipophagy. Moreover, the impact of related lipolytic enzymes on lipid metabolism homeostasis and energy conservation, as well as their role in lipid-related metabolic diseases. In addition, we describe how they affect lipid metabolism homeostasis and energy conservation in lipid-related metabolic diseases with a focus on hepatic steatosis and cancer and the pathogenesis and therapeutic targets of AMPK/SIRTs/FOXOs, PI3K/Akt, PPARs/PGC-1α, MAPK/ERK1/2, TLR4/NF-κB, AMPK/mTOR/TFEB, Wnt/β-catenin through immune inflammation, oxidative stress and autophagy-related pathways. As well as the current application of lipolytic enzyme inhibitors (especially Monoacylglycerol lipase (MGL) inhibitors) to provide new strategies for future exploration of metabolic programming in metabolic diseases.

PRDX6 Promotes Fatty Acid Oxidation via PLA2-Dependent PPARα Activation in Rats Fed High-Fat Diet

Aims: Nonalcoholic fatty liver disease (NAFLD) is becoming the most common chronic liver disease globally, which is defined as an excess accumulation of fat caused by the imbalance of lipogenesis and lipid catabolism. Recently, increasing evidence suggests that peroxiredoxin 6 (PRDX6) is involved in the pathogenesis and progression of NAFLD. However, little is known regarding its role in liver lipid catabolism. Results: We found that PRDX6 level was significantly increased in liver tissues after high-fat diet (HFD) treatment. PRDX6 knockout (KO) exacerbated HFD-induced hepatic steatosis. PRDX6 KO did not affect messenger RNA (mRNA) and protein levels of peroxisome proliferator-activated receptor alpha (PPARα). However, PRDX6 KO decreased the mRNA and protein levels of carnitine palmitoyltransferase-1alpha (CPT-1α) and acyl-CoA oxidase 1 (ACOX1), the target genes of PPARα. PRDX6 KO also did not activate AMP-activated protein kinase (AMPK)α/proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α), the upstream signal of PPARα. However, PRDX6 KO reduces the levels of PPARα activators, the oxidized fatty acids (9- and 13-hydroxyoctadecadienoic acid) in HFD rats. More interestingly, PRDX6 promoted the production of oxidized fatty acids by hydrolyzing oxidized low-density lipoprotein (Ox-LDL), which depends on its phospholipase A2 (PLA2) activity. PRDX6 mutation on its PLA2 and its competitive phospholipase inhibitor inhibited the production of the oxidized fatty acids as well as the activation of PPARα. Furthermore, PRDX6 overexpression enhanced the transcriptional activation of PPARα. Innovation and Conclusion: This study elucidates for the first time the role of PLA2 enzyme activity of PRDX6 in fatty acid oxidation and reveals a novel mechanism of PRDX6 involved in liver steatosis.

Serum Sirtuin1 level decreases in Parkinson's disease and vascular parkinsonism: A prospective observational study

OBJECTIVE

The present study aimed to investigate levels and clinical significance of serum SIRT1 in Parkinson's disease (PD) and Vascular parkinsonism (VP).

METHODS

This prospective observational research enrolled a total of 165 VP and 159 PD patients who were admitted during March 2018 to December 2021. Blood samples and medical characteristics were also obtained from 160 healthy volunteers. The serum Sirtuin1 (SIRT1) and cytokines levels of all subjects were measured by enzyme-linked immunosorbent assay (ELISA) method. Demographic and clinical data were also collected. Statistical analysis was conducted using SPSS software with P < 0.05 as statistically different.

RESULTS

The mean age, the UPDRSIII score of VP patients was significantly higher compared with the PD patients (p<0.05), while the MMSE score of VP patients was significantly lower than the PD patients (p<0.001). The serum SIRT1 levels of the VP patients were remarkably lower than the PD patients or the healthy persons (p<0.05). Pearson's analysis showed that SIRT1 levels were negatively correlated with levels of IL-6, TNF- α and hcy. The UPDRSIII of SIRT1 low levels group was remarkably higher than the SIRT1 high levels group (p=0.048), while the MMSE score was lower than the SIRT1 high levels group (p<0.001). In addition, ROC curves showed that SIRT1 could be a potential diagnostic biomarker of VP. SIRT1 was a risk factor for VP.

CONCLUSION

Our present study indicated that SIRT1 associated with disease severity and could discriminate PD from VP.

Diet Control and Swimming Exercise Ameliorate HFD-Induced Cognitive Impairment Related to the SIRT1-NF-κB/PGC-1α Pathways in ApoE-/- Mice

High-fat diet- (HFD-) induced neuroinflammation may ultimately lead to an increased risk of cognitive impairment. Here, we evaluate the effects of diet control and swimming or both on the prevention of cognitive impairment by enhancing SIRT1 activity. Twenty-week-old ApoE-/- mice were fed a HFD for 8 weeks and then were treated with diet control and/or swimming for 8 weeks. Cognitive function was assessed using the novel object recognition test (NORT) and Y-maze test. The expression of sirtuin-1 (SIRT1), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), brain-derived neurotrophic factor (BDNF), nuclear factor kappa B p65 (NF-κB p65), interleukin-1β (IL-1β), and tumour necrosis factor-α (TNF-α) in the hippocampus was measured by western blotting. The levels of fractional anisotropy (FA), N-acetylaspartate (NAA)/creatine (Cr) ratio, choline (Cho)/Cr ratio, and myo-inositol (MI)/Cr ratio in the hippocampus were evaluated by diffusion tensor imaging (DTI) and magnetic resonance spectroscopy (MRS) using 7.0-T magnetic resonance imaging (MRI). Our results showed that cognitive dysfunction and hippocampal neuroinflammation appeared to be remarkably observed in apolipoprotein E (ApoE)-/- mice fed with HFD. Diet control plus swimming significantly reversed HFD-induced cognitive decline, reduced the time spent exploring the novel object, and ameliorated spontaneous alternation in the Y-maze test. Compared with the HFD group, ApoE-/- mice fed diet control and/or subjected to swimming had an increase in FA, NAA/Cr, and Cho/Cr; a drop in MI/Cr; elevated expression levels of SIRT1, PGC-1α, and BDNF; and inhibited production of proinflammatory cytokines, including NF-κB p65, IL-1β, and TNF-α. SIRT1, an NAD⁺-dependent class III histone enzyme, deacetylases and regulates the activity of PGC-1α and NF-κB. These data indicated that diet control and/or swimming ameliorate cognitive deficits through the inhibitory effect of neuroinflammation via SIRT1-mediated pathways, strongly suggesting that swimming and/or diet control could be potentially effective nonpharmacological treatments for cognitive impairment.

Differential Mobilization of the Phospholipid and Triacylglycerol Pools of Arachidonic Acid in Murine Macrophages

Innate immune cells such as monocytes and macrophages contain high levels of arachidonic acid (AA), part of which can be mobilized during cellular activation for the formation of a vast array of bioactive oxygenated metabolites. Monocytes and macrophages present in inflammatory foci typically incorporate large amounts of AA, not only in membrane phospholipids, but also in neutral lipids such as triacylglycerol. Thus, it was of interest to investigate the metabolic fate of these two AA pools in macrophages. Utilizing a variety of radiolabeling techniques to distinguish the phospholipid and triacylglycerol pools, we show in this paper that during an acute stimulation of the macrophages with yeast-derived zymosan, the membrane phospholipid AA pool acts as the major, if not the only, source of releasable AA. On the contrary, the AA pool in triacylglycerol appears to be used at a later stage, when the zymosan-stimulated response has declined, as a source to replenish the phospholipid pools that were consumed during the activation process. Thus, phospholipids and triacylglycerol play different in roles AA metabolism and dynamics during macrophage activation.

Loss of G0/G1 switch gene 2 (G0S2) promotes disease progression and drug resistance in chronic myeloid leukaemia (CML) by disrupting glycerophospholipid metabolism

Tyrosine kinase inhibitors (TKIs) targeting BCR::ABL1 have turned chronic myeloid leukaemia (CML) from a fatal disease into a manageable condition for most patients. Despite improved survival, targeting drug-resistant leukaemia stem cells (LSCs) remains a challenge for curative CML therapy. Aberrant lipid metabolism can have a large impact on membrane dynamics, cell survival and therapeutic responses in cancer. While ceramide and sphingolipid levels were previously correlated with TKI response in CML, the role of lipid metabolism in TKI resistance is not well understood. We have identified downregulation of a critical regulator of lipid metabolism, G0/G1 switch gene 2 (G0S2), in multiple scenarios of TKI resistance, including (1) BCR::ABL1 kinase-independent TKI resistance, (2) progression of CML from the chronic to the blast phase of the disease, and (3) in CML versus normal myeloid progenitors. Accordingly, CML patients with low G0S2 expression levels had a worse overall survival. G0S2 downregulation in CML was not a result of promoter hypermethylation or BCR::ABL1 kinase activity, but was rather due to transcriptional repression by MYC. Using CML cell lines, patient samples and G0s2 knockout (G0s2-/- ) mice, we demonstrate a tumour suppressor role for G0S2 in CML and TKI resistance. Our data suggest that reduced G0S2 protein expression in CML disrupts glycerophospholipid metabolism, correlating with a block of differentiation that renders CML cells resistant to therapy. Altogether, our data unravel a new role for G0S2 in regulating myeloid differentiation and TKI response in CML, and suggest that restoring G0S2 may have clinical utility.

Systemic lipolysis promotes physiological fitness in Drosophila melanogaster

Since interventions such as caloric restriction or fasting robustly promote lipid catabolism and improve aging-related phenotypical markers, we investigated the direct effect of increased lipid catabolism via overexpression of bmm (brummer, FBgn0036449), the major triglyceride hydrolase in Drosophila, on lifespan and physiological fitness. Comprehensive characterization was carried out using RNA-seq, lipidomics and metabolomics analysis. Global overexpression of bmm strongly promoted numerous markers of physiological fitness, including increased female fecundity, fertility maintenance, preserved locomotion activity, increased mitochondrial biogenesis and oxidative metabolism. Increased bmm robustly upregulated the heat shock protein 70 (Hsp70) family of proteins, which equipped the flies with higher resistance to heat, cold, and ER stress via improved proteostasis. Despite improved physiological fitness, bmm overexpression did not extend lifespan. Taken together, these data show that bmm overexpression has broad beneficial effects on physiological fitness, but these effects did not impact lifespan.

Peri-implant crevicular fluid SIRT1 levels decrease in patients with peri-implant inflammatory: A prospective observational study

BACKGROUND

A dental Implant is a prosthetic device made of alloplastic materials implanted into the bone to provide retention and support for a dental prosthesis. Sirtuin1 (SIRT1) molecule, a nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylase, regulates a variety of physiological and pathological processes, including oxidative stress, metabolism, cell proliferation, cell differentiation, inflammatory, and apoptosis. We explored whether the expression of SIRT1 correlates in patients receiving implants with peri-implant mucositis (PIM) and peri-implantitis (PI) in comparison to patients with healthy peri-implant area (PIH).

METHODS

A number of 198 patients with dentition defects were enrolled in the study after their implants were functional for at least 6 months. All 198 subjects were divided into 3 groups: 1) control patients with PIH healthy implants; 2) patients with PIM mucositis; and 3) patients with PI implantitis. To distinguish these three groups, peri-implant crevicular fluid (PICF) was collected by inserting a sterile paper strip into the gap around the implant and the levels of SIRT1 and cytokines were measured by the enzyme linked immunosorbent assay (ELISA). Demographic and clinical data included age, sex, Body Mass Index (BMI), probing depth (PD), plaque index (PLI), bleeding on probing (BOP), oral health impact profile (OHIP-14), history of periodontitis and the use time of implants.

RESULTS

The PD, PLI, OHIP-14 evaluation scores in patients with periodontitis of PIM mucositis and PI implantitis were all significantly higher than in patients with PIH healthy implants. Overall, the SIRT1 levels in PICF of the PIM and PI patients were significantly lower than of the PIH patients. In comparison with PIM patients, SIRT1 levels of the PI patients were remarkably lower than the PIH patients. Pearson's analysis showed that SIRT1 levels were negatively correlated with levels of interleukin (IL)-6, C-reactive protein (CRP) and IL-1β in patients with PIM and PI. We suggest that SIRT1 levels could serve as a potential diagnostic biomarker of PI or PIM. The PICF levels of SIRT1, CRP, IL-6, IL-1β and the history of periodontitis were the risk factors for patients with peri-implant inflammatory process.

CONCLUSION

The measurement of SIRT1 expression in PICF may serve as a biomarker for the ongoing inflammatory process in patients with dental implants. The low SIRT1 levels correlated with PI implantitis and PIM mucositis as well as the elevated levels of pro-inflammatory cytokines (CRP, IL-6 and IL-1β).

Lipolysis of bone marrow adipocytes is required to fuel bone and the marrow niche during energy deficits

To investigate roles for bone marrow adipocyte (BMAd) lipolysis in bone homeostasis, we created a BMAd-specific Cre mouse model in which we knocked out adipose triglyceride lipase (ATGL, Pnpla2 gene). BMAd-Pnpla2-/- mice have impaired BMAd lipolysis, and increased size and number of BMAds at baseline. Although energy from BMAd lipid stores is largely dispensable when mice are fed ad libitum, BMAd lipolysis is necessary to maintain myelopoiesis and bone mass under caloric restriction. BMAd-specific Pnpla2 deficiency compounds the effects of caloric restriction on loss of trabecular bone in male mice, likely due to impaired osteoblast expression of collagen genes and reduced osteoid synthesis. RNA sequencing analysis of bone marrow adipose tissue reveals that caloric restriction induces dramatic elevations in extracellular matrix organization and skeletal development genes, and energy from BMAd is required for these adaptations. BMAd-derived energy supply is also required for bone regeneration upon injury, and maintenance of bone mass with cold exposure.

NAFLD: Mechanisms, Treatments, and Biomarkers

Nonalcoholic fatty liver disease (NAFLD), recently renamed metabolic-associated fatty liver disease (MAFLD), is one of the most common causes of liver diseases worldwide. NAFLD is growing in parallel with the obesity epidemic. No pharmacological treatment is available to treat NAFLD, specifically. The reason might be that NAFLD is a multi-factorial disease with an incomplete understanding of the mechanisms involved, an absence of accurate and inexpensive imaging tools, and lack of adequate non-invasive biomarkers. NAFLD consists of the accumulation of excess lipids in the liver, causing lipotoxicity that might progress to metabolic-associated steatohepatitis (NASH), liver fibrosis, and hepatocellular carcinoma. The mechanisms for the pathogenesis of NAFLD, current interventions in the management of the disease, and the role of sirtuins as potential targets for treatment are discussed here. In addition, the current diagnostic tools, and the role of non-coding RNAs as emerging diagnostic biomarkers are summarized. The availability of non-invasive biomarkers, and accurate and inexpensive non-invasive diagnosis tools are crucial in the detection of the early signs in the progression of NAFLD. This will expedite clinical trials and the validation of the emerging therapeutic treatments.

Plin5, a New Target in Diabetic Cardiomyopathy

Abnormal lipid accumulation is commonly observed in diabetic cardiomyopathy (DC), which can create a lipotoxic microenvironment and damage cardiomyocytes. Lipid toxicity is an important pathogenic factor due to abnormal lipid accumulation in DC. As a lipid droplet (LD) decomposition barrier, Plin5 can protect LDs from lipase decomposition and regulate lipid metabolism, which is involved in the occurrence and development of cardiovascular diseases. In recent years, studies have shown that Plin5 expression is involved in the pathogenesis of DC lipid toxicity, such as oxidative stress, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, and insulin resistance (IR) and has become a key target of DC research. Therefore, understanding the relationship between Plin5 and DC progression as well as the mechanism of this process is crucial for developing new therapeutic approaches and exploring new therapeutic targets. This review is aimed at exploring the latest findings and roles of Plin5 in lipid metabolism and DC-related pathogenesis, to explore possible clinical intervention approaches.

High intramuscular triglyceride turnover rates and the link to insulin sensitivity: influence of obesity, type 2 diabetes and physical activity

Large intramuscular triglyceride (IMTG) stores in sedentary, obese individuals have been linked to insulin resistance, yet well-trained athletes exhibit high IMTG levels whilst maintaining insulin sensitivity. Contrary to previous assumptions, it is now known that IMTG content per se does not result in insulin resistance. Rather, insulin resistance is caused, at least in part, by the presence of high concentrations of harmful lipid metabolites, such as diacylglycerols and ceramides in muscle. Several mechanistic differences between obese sedentary individuals and their highly trained counterparts have been identified, which determine the differential capacity for IMTG synthesis and breakdown in these populations. In this review, we first describe the most up-to-date mechanisms by which a low IMTG turnover rate (both breakdown and synthesis) leads to the accumulation of lipid metabolites and results in skeletal muscle insulin resistance. We then explore current and potential exercise and nutritional strategies that target IMTG turnover in sedentary obese individuals, to improve insulin sensitivity. Overall, improving IMTG turnover should be an important component of successful interventions that aim to prevent the development of insulin resistance in the ever-expanding sedentary, overweight and obese populations. Novelty: A description of the most up-to-date mechanisms regulating turnover of the IMTG pool. An exploration of current and potential exercise/nutritional strategies to target and enhance IMTG turnover in obese individuals. Overall, highlights the importance of improving IMTG turnover to prevent the development of insulin resistance.

The hsa-miR-214-3p/ATGL axis regulates aberrant lipolysis to promote acute myeloid leukemia progression via PPARα in vitro

Aberrant lipid metabolism is a hallmark of malignant cancers. Recent studies have shown that abnormal activation of the lipolysis pathway might contribute to acute myeloid leukemia (AML) progression. However, the molecular mechanism through which lipid metabolism mediates AML progression is unknown. RNA-sequencing was used to screen out the target gene pnpla2/ATGL(adipose triglyceride lipase), which showed differential expression in AML. A comparison was made of ATGL mRNA levels in different AML cell lines by real-time PCR. ATGL expression was blocked using siRNAs, and then ATGL expression, proliferation, apoptosis, and cell cycle progression of si-ATGL AML cell lines and si-control AML cell lines were respectively tested. Online tools were used to analyze the potential target microRNAs of ATGL. The mechanism through which hsa-miR-214-3p regulates ATGL was detected by western blotting, proliferation assays, flow cytometry, and dual-luciferase reporter assays. Our results showed that ATGL was overexpressed in AML cell lines. Moreover, ATGL promoted the growth of AML cells. Additionally, hsa-miR-214-3p could suppress ATGL. Finally, we show that hsa-miR-214-3p regulates ATGL through the hsa-miR-214-3p/ATGL/PPARα pathway. This study showed that hsa-miR-214-3p-regulates aberrant lipolysis by promoting ATGL expression, which causes AML progression through the PPARα pathway.

Eukaryotic lipid droplets: metabolic hubs, and immune first responders

As major eukaryotic lipid storage organelles, lipid droplets (LDs) are metabolic hubs coordinating energy flux and building block distribution. Infectious pathogens often promote accumulation and physically interact with LDs. The most accepted view is that host LDs are hijacked by invaders to draw on nutrients for host colonisation. However, unique traits such as biogenesis plasticity, dynamic proteome, signalling capacity, and ability to interact with other organelles endow LDs with competencies to face complex biological challenges. Here, we focus on published data suggesting that LDs are not usurped organelles but innate immunity first responders. By comparison with analogous mechanisms activated on LDs in nutrient-poor environments, our review supports the hypothesis that host LDs actively participate in immunometabolism, immune signalling, and microbial killing.

SIRT1 selectively exerts the metabolic protective effects of hepatocyte nicotinamide phosphoribosyltransferase

Calorie restriction abates aging and cardiometabolic disease by activating metabolic signaling pathways, including nicotinamide adenine dinucleotide (NAD⁺) biosynthesis and salvage. Nicotinamide phosphoribosyltransferase (NAMPT) is rate-limiting in NAD⁺ salvage, yet hepatocyte NAMPT actions during fasting and metabolic duress remain unclear. We demonstrate that hepatocyte NAMPT is upregulated in fasting mice, and in isolated hepatocytes subjected to nutrient withdrawal. Mice lacking hepatocyte NAMPT exhibit defective FGF21 activation and thermal regulation during fasting, and are sensitized to diet-induced glucose intolerance. Hepatocyte NAMPT overexpression induced FGF21 and adipose browning, improved glucose homeostasis, and attenuated dyslipidemia in obese mice. Hepatocyte SIRT1 deletion reversed hepatocyte NAMPT effects on dark-cycle thermogenesis, and hepatic FGF21 expression, but SIRT1 was dispensable for NAMPT insulin-sensitizing, anti-dyslipidemic, and light-cycle thermogenic effects. Hepatocyte NAMPT thus conveys key aspects of the fasting response, which selectively dissociate through hepatocyte SIRT1. Modulating hepatocyte NAD⁺ is thus a potential mechanism through which to attenuate fasting-responsive disease.

Screening of flavor compounds using Ucp1-luciferase reporter beige adipocytes identified 5-methylquinoxaline as a novel UCP1-inducing compound

Uncoupling protein 1 (UCP1) in brown or beige adipocytes is a mitochondrial protein that is expected to enhance whole-body energy expenditure. For the high-throughput screening of UCP1 transcriptional activity regulator, we established a murine inguinal white adipose tissue-derived Ucp1-luciferase reporter preadipocyte line. Using this reporter preadipocyte line, 654 flavor compounds were screened, and a novel Ucp1 expression-inducing compound, 5-methylquinoxaline, was identified. Adipocytes treated with 5-methylquinoxaline showed increased Ucp1 mRNA expression levels and enhanced oxygen consumption. 5-Methylquinoxaline induced Ucp1 expression through peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α), and 5-methylquinoxaline-induced PGC1α activation seemed to be partially regulated by its phosphorylation or deacetylation. Thus, our Ucp1-luciferase reporter preadipocyte line is a useful tool for screening of Ucp1 inductive compounds.

Early Lipid Metabolic Effects of the Anti-Psychotic Drug Olanzapine on Weight Gain and the Associated Gene Expression

BACKGROUND

Atypical antipsychotics such as olanzapine often cause metabolic side effects such as obesity and diabetes, leading to an increased risk of nonalcoholic fatty liver disease. The aim of the present study was to investigate the effects of olanzapine treatment on hepatic lipid metabolism and its possible relationship with adipose tissue status.

METHODS

Using a female rat model, we investigated the effects of chronic olanzapine administration on the regulation of carbohydrate and lipid metabolism including lipid biosynthesis, oxidation, efflux, and lipolysis in liver and adipose tissue.

RESULTS

The body weight, liver mass and visceral adiposity after olanzapine treatment (2 mg/kg) for five weeks were not significantly different compared with vehicle controls. The serum level of triglycerides was higher in the vehicle controls than in olanzapine-treated rats. Unexpectedly, olanzapine treatment did not reduce glucose tolerance in our model. The expression of functional thermogenic protein uncoupling protein 1 (UCP1) was increased in brown adipose tissue (BAT) of the olanzapine group. Additionally, olanzapine treatment also reduced adipose inflammation in white adipose tissue (WAT). The transcription factor sterol regulatory element-binding protein (SREBP)-1c, a key early regulator of lipogenesis, was downregulated following olanzapine treatment. The expression of genes related to the triglycerides synthesis apparatus in the liver was upregulated in the olanzapine group. Olanzapine treatment induced genes involved in PPAR-α signaling and mitochondrial fatty acid oxidation in response to increased ATGL-mediated lipolysis in the liver.

CONCLUSION

Together, our findings suggest a complicated link between olanzapine therapy and metabolic disturbance and may garner interest in assessing the action of antipsychotic-induced metabolic disturbances.

NAD kinase sustains lipogenesis and mitochondrial metabolismthrough fatty acid synthesis

Lipid storage in fat tissue is important for energy homeostasis and cellular functions. Through RNAi screening in Drosophila fat body, we found that knockdown of a Drosophila NAD kinase (NADK), which phosphorylates NAD to synthesize NADP de novo, causes lipid storage defects. NADK sustains lipogenesis by maintaining the pool of NADPH. Promoting NADPH production rescues the lipid storage defect in the fat body of NADK RNAi animals. Furthermore, NADK and fatty acid synthase 1 (FASN1) regulate mitochondrial mass and function by altering the levels of acetyl-CoA and fatty acids. Reducing the level of acetyl-CoA or increasing the synthesis of cardiolipin (CL), a mitochondrion-specific phospholipid, partially rescues the mitochondrial defects of NADK RNAi. Therefore, NADK- and FASN1-mediated fatty acid synthesis coordinates lipid storage and mitochondrial function.

SGLT2 Inhibition for Cardiovascular Diseases, Chronic Kidney Disease, and NAFLD

Sodium glucose cotransporter 2 (SGLT-2) inhibitors are the latest class of antidiabetic medications. They prevent glucose reabsorption in the proximal convoluted tubule to decrease blood sugar. Several animal studies revealed that SGLT-2 is profoundly involved in the inflammatory response, fibrogenesis, and regulation of numerous intracellular signaling pathways. Likewise, SGLT-2 inhibitors markedly attenuated inflammation and fibrogenesis and improved the function of damaged organ in animal studies, observational studies, and clinical trials. SGLT-2 inhibitors can decrease blood pressure and ameliorate hypertriglyceridemia and obesity. Likewise, they improve the outcome of cardiovascular diseases such as heart failure, arrhythmias, and ischemic heart disease. SGLT-2 inhibitors are associated with lower cardiovascular and all-cause mortality as well. Meanwhile, they protect against nonalcoholic fatty liver disease (NAFLD), chronic kidney disease, acute kidney injury, and improve micro- and macroalbuminuria. SGLT-2 inhibitors can reprogram numerous signaling pathways to improve NAFLD, cardiovascular diseases, and renal diseases. For instance, they enhance lipolysis, ketogenesis, mitochondrial biogenesis, and autophagy while they attenuate the renin-angiotensin-aldosterone system, lipogenesis, endoplasmic reticulum stress, oxidative stress, apoptosis, and fibrogenesis. This review explains the beneficial effects of SGLT-2 inhibitors on NAFLD and cardiovascular and renal diseases and dissects the underlying molecular mechanisms in detail. This narrative review explains the beneficial effects of SGLT-2 inhibitors on NAFLD and cardiovascular and renal diseases using the results of latest observational studies, clinical trials, and meta-analyses. Thereafter, it dissects the underlying molecular mechanisms involved in the clinical effects of SGLT-2 inhibitors on these diseases.