Sesamol promotes browning of white adipocytes to ameliorate obesity by inducing mitochondrial biogenesis and inhibition mitophagy via β3-AR/PKA signaling pathway

The prospective therapeutic benefits of sesamol: neuroprotection in neurological diseases

Oxidative stress is recognized as a critical contributor to the advancement of neurological diseases, thereby rendering the alleviation of oxidative stress a pivotal strategy in the therapeutic management of such conditions. Sesamol, the principal constituent of sesame oil, has been the subject of extensive research due to its significant antioxidant properties, especially its ability to effectively counteract oxidative stress within the central nervous system and confer neuroprotection. While sesamol demonstrates potential in the treatment and prevention of neurological diseases, its modulation of oxidative stress is complex and not yet fully understood. This review delves into the neuroprotective effects arising from sesamol's antioxidant properties, analyzing how its antioxidative capabilities impact neurological diseases. It provides a theoretical foundation and unveils potential novel therapeutic applications of sesamol in the treatment of neurological disorders through the modulation of oxidative stress.

Sesamol Ameliorates Lipid Deposition by Maintaining the Integrity of the Lipid Droplet-Mitochondria Connection in Diabetic Nephropathy

Diabetic nephropathy (DN) is a serious complication of diabetes mellitus and an important cause of end-stage renal disease (ESRD). However, there is still a lack of effective prevention and treatment strategies in clinical practice. As a metabolic disease, DN is accompanied by renal ectopic lipid deposition, and the deposited lipids further aggravate kidney injury. However, the molecular mechanism of renal ectopic lipid deposition is currently unknown. In this study, we observed changes in lipid droplet (LD)-mitochondria connections in the kidney for the first time. Destruction of LD-mitochondria connection was involved in renal lipid deposition in the kidneys of patients and mice with DN or in high-glucose-treated HK-2 cells. Furthermore, sesamol treatment significantly increased the integrity of the LD-mitochondria connection and ameliorated renal lipotoxicity. Finally, we demonstrated that sesamol maintains the integrity of the LD-mitochondria connection by activating the peroxisome proliferator-activated receptor α (PPARα)/perilipin 5 (PLIN5) signaling pathway. Our study is the first to show that the LD-mitochondria connection may be a target for ameliorating lipid deposition in diabetic kidneys.

Pachymic acid promotes brown/beige adipocyte differentiation and lipid metabolism in preadipocytes 3T3-L1 MBX

OBJECTIVES

To investigate the effect of pachymic acid on brown/beige adipocyte differentiation and lipid metabolism in preadipocytes 3T3-L1 MBX.

METHODS

The brown cocktail method was employed to induce 3T3-L1 MBX cells to differentiate into beige adipocytes. The impact of pachymic acid on the viability of 3T3-L1 MBX preadipocytes was evaluated using the CCK-8 assay. The formation of lipid droplets following treatment with pachymic acid was observed through oil red O staining, and the content of lipids in differentiated cells was determined. The expression levels of key browning genes, including uncoupling protein (Ucp) 1, the peroxisome proliferation-activating receptor gamma coactivator (Pgc)-1α, and the transcription factor containing PR domain 16 (Prdm16) were detected by quantitative reverse transcription polymerase chain reaction. The expression of sterol regulatory element binding protein (Srebp) 1c, acetyl-CoA carboxylase (Acc), fatty acid synthetase (Fas), and steroid-sensitive lipase (Hsl), fatty triglyceride hydrolase (Atgl), and carnitine palmitoyl transferase (Cpt) 1 of lipolysis-related genes were also examined.

RESULTS

The 3T3-L1 MBX was induced in vitro to form beige adipocytes with high expression of key browning genes, including Ucp1, Pgc-1α, Prdm16, and beige adipose-marker genes, including Cd137, Tbx1, and Tmem26. The concentration range of 0-80 μM pachymic acid was non-cytotoxic to 3T3-L1 MBX. Pachymic acid treatment significantly inhibited the differentiation of 3T3-L1 MBX, resulting in a notable decrease in lipid accumulation content (P<0.01). Additionally, there was a marked increase in the expression of key browning genes and their proteins, such as Ucp1, Pgc-1α, and Prdm16, while the expressions of fat synthesis-related genes Srebp1c, Acc and Fas were significantly decreased (all P<0.05). The expressions of lipolysis-related genes, including Hsl, Atgl, and Cpt1, were significantly increased (all P<0.05). Besides, treating with 20 μmol/L pachymic acid showed the most pronounced effect.

CONCLUSIONS

Pachymic acid can inhibit fat synthesis and promote lipid decomposition by regulating the brown formation and lipid differentiation of 3T3-L1 MBX preadipocytes.

Sesamol Alleviated Lipotoxicity-Induced Dysfunction in MIN6 Cells via Facilitating Cellular Senescence Caused by Endoplasmic Reticulum Stress

Obesity is found to be a significant risk factor for type 2 diabetes mellitus (T2DM), attributed to lipotoxicity-induced β-cell dysfunction. However, the specific mechanism involved in the process remains incompletely unclarified. The current study demonstrated lipotoxicity resulted in the activation of ER stress, which increased the protein level of TXNIP, thereby inducing senescence-assiciated dysfunction in MIN6 cells under high fat environment. And we also found sesamol, a natural functional component extracted from sesame, was able to alleviate senescence-associated β-cell dysfunction induced by lipotoxicity by inhibiting ER stress and TXNIP. Our findings provided novel insights into senescence-related T2DM and propose innovative therapeutic approaches for utilizing sesamol in the treatment of T2DM in the obese elderly population.

Keys to the switch of fat burning: stimuli that trigger the uncoupling protein 1 (UCP1) activation in adipose tissue

As one of the main pathogenic factors of cardiovascular and cerebrovascular diseases, the incidence of metabolic diseases such as adiposity and metabolic dysfunction-associated steatotic liver disease (MASLD) is increasing annually. It is urgent and crucial to find more therapeutic targets to treat these diseases. Mainly expressed in brown adipocytes, mitochondrial uncoupling protein 1 (UCP1) is key to the thermogenesis of classical brown adipose tissue (BAT). Furthermore, white adipose tissue (WAT) is likely to express more UCP1 and subsequently acquire the ability to undergo thermogenesis under certain stimuli. Therefore, targeting and activating UCP1 to promote increased BAT thermogenesis and browning of WAT are helpful in treating metabolic diseases, such as adiposity and MASLD. In this case, the stimuli that activate UCP1 are emerging. Therefore, we summarize the thermogenic stimuli that have activated UCP1 in recent decades, among which cold exposure is one of the stimuli first discovered to activate BAT thermogenesis. As a convenient and efficient therapy with few side effects and good metabolic benefits, physical exercise can also activate the expression of UCP1 in adipose tissue. Notably, for the first time, we have summarized and demonstrated the stimuli of traditional Chinese medicines that can activate UCP1, such as acupuncture, Chinese herbal formulas, and Chinese medicinal herbs. Moreover, pharmacological agents, functional foods, food ingredients, and the gut microbiota are also commonly associated with regulating and activating UCP1. The identification and analysis of UCP1 stimuli can greatly facilitate our understanding of adipose tissue thermogenesis, including the browning of WAT. Thus, it is more conducive to further research and therapy for glucose and lipid metabolism disorders.

Sesamolin suppresses adipocyte differentiation through Keap1-dependent Nrf2 activation in adipocytes

Sesamolin, a lignan isolated from sesame oils, has been found to possess neuroprotective, anticancer, and free radical scavenging properties. We hypothesized that sesamolin could stimulate the activity of nuclear factor erythroid-derived 2-like 2 (Nrf2) and inhibit adipocyte differentiation of preadipocytes. The objective of this study was to investigate effects of sesamolin on adipocyte differentiation and its underlying molecular mechanisms. In this study, we determined the effects of treatment with 25 to 100 µM sesamolin on adipogenesis in cell culture systems. Sesamolin inhibited lipid accumulation and suppressed the expression of adipocyte markers during adipocyte differentiation of C3H10T1/2, 3T3-L1, and primary preadipocytes. Mechanism studies revealed that sesamolin increased Nrf2 protein expression without inducing its mRNA, leading to an increase in the expression of Nrf2 target genes such as heme oxygenase 1 and NAD(P)H:quinone oxidoreductase 1 (Nqo1) in C3H10T1/2 adipocytes and mouse embryonic fibroblasts. These effects were significantly attenuated in Nrf2 knockout (KO) mouse embryonic fibroblasts, indicating that effects of sesamolin were dependent on Nrf2. In H1299 human lung cancer cells with KO of Kelch like-ECH-associated protein 1 (Keap1), a negative regulator of Nrf2, sesamolin failed to further increase Nrf2 protein expression. However, upon reexpressing Keap1 in Keap1 KO cells, the ability of sesamolin to elevate Nrf2 protein expression was restored, highlighting the crucial role of Keap1 in sesamolin-induced Nrf2 activation. Taken together, these findings show that sesamolin can inhibit adipocyte differentiation through Keap1-mediated Nrf2 activation.

Sesamol as a potent anticancer compound: from chemistry to cellular interactions

Sesamol (SM), a well-known component isolated from sesame seeds (Sesamum indicum), used in traditional medicines in treating numerous ailments. However, numerous molecular investigations revealed the various mechanisms behind its activity, emphasizing its antiproliferative, anti-inflammatory, and apoptosis-inducing properties, preventing cancer cell spread to distant organs. In several cells derived from various malignant tissues, SM-regulated signal transduction pathways and cellular targets have been identified. This review paper comprehensively describes the anticancer properties of SM and SM-viable anticancer drugs. Additionally, the interactions of this natural substance with standard anticancer drugs are examined, and the benefits of using nanotechnology in SM applications are explored. This makes SM a prime example of how ethnopharmacological knowledge can be applied to the development of contemporary drugs.

Dysfunctional Mitochondria Clearance in Situ: Mitophagy in Obesity and Diabetes-Associated Cardiometabolic Diseases

Several mitochondrial dysfunctions in obesity and diabetes include impaired mitochondrial membrane potential, excessive mitochondrial reactive oxygen species generation, reduced mitochondrial DNA, increased mitochondrial Ca2+ flux, and mitochondrial dynamics disorders. Mitophagy, specialized autophagy, is responsible for clearing dysfunctional mitochondria in physiological and pathological conditions. As a paradox, inhibition and activation of mitophagy have been observed in obesity and diabetes-related heart disorders, with both exerting bidirectional effects. Suppressed mitophagy is beneficial to mitochondrial homeostasis, also known as benign mitophagy. On the contrary, in most cases, excessive mitophagy is harmful to dysfunctional mitochondria elimination and thus is defined as detrimental mitophagy. In obesity and diabetes, two classical pathways appear to regulate mitophagy, including PTEN-induced putative kinase 1 (PINK1)/Parkin-dependent mitophagy and receptors/adapters-dependent mitophagy. After the pharmacologic interventions of mitophagy, mitochondrial morphology and function have been restored, and cell viability has been further improved. Herein, we summarize the mitochondrial dysfunction and mitophagy alterations in obesity and diabetes, as well as the underlying upstream mechanisms, in order to provide novel therapeutic strategies for the obesity and diabetes-related heart disorders.

Lipid Droplet-Mitochondria Contacts in Health and Disease

The orchestration of cellular metabolism and redox balance is a complex, multifaceted process crucial for maintaining cellular homeostasis. Lipid droplets (LDs), once considered inert storage depots for neutral lipids, are now recognized as dynamic organelles critical in lipid metabolism and energy regulation. Mitochondria, the powerhouses of the cell, play a central role in energy production, metabolic pathways, and redox signaling. The physical and functional contacts between LDs and mitochondria facilitate a direct transfer of lipids, primarily fatty acids, which are crucial for mitochondrial β-oxidation, thus influencing energy homeostasis and cellular health. This review highlights recent advances in understanding the mechanisms governing LD-mitochondria interactions and their regulation, drawing attention to proteins and pathways that mediate these contacts. We discuss the physiological relevance of these interactions, emphasizing their role in maintaining energy and redox balance within cells, and how these processes are critical in response to metabolic demands and stress conditions. Furthermore, we explore the pathological implications of dysregulated LD-mitochondria interactions, particularly in the context of metabolic diseases such as obesity, diabetes, and non-alcoholic fatty liver disease, and their potential links to cardiovascular and neurodegenerative diseases. Conclusively, this review provides a comprehensive overview of the current understanding of LD-mitochondria interactions, underscoring their significance in cellular metabolism and suggesting future research directions that could unveil novel therapeutic targets for metabolic and degenerative diseases.

EGCG Suppresses Adipogenesis and Promotes Browning of 3T3-L1 Cells by Inhibiting Notch1 Expression

BACKGROUND

With the changes in lifestyle and diet structure, the incidence of obesity has increased year by year, and obesity is one of the inducements of many chronic metabolic diseases. Epigallocatechin gallate (EGCG), which is the most abundant component of tea polyphenols, has been used for many years to improve obesity and its complications. Though it has been reported that EGCG can improve obesity through many molecular mechanisms, EGCG may have many mechanisms yet to be explored. In this study, we explored other possible mechanisms through molecular docking and in vitro experiments.

METHODS

AutoDock Vina was selected for conducting the molecular docking analysis to elucidate the interaction between EGCG and Notch1, while molecular dynamics simulations were employed to validate this interaction. Then, the new regulation mechanism of EGCG on obesity was verified with in vitro experiments, including a Western blot experiment, immunofluorescence experiment, oil red O staining, and other experiments in 3T3-L1 adipocytes.

RESULTS

The molecular docking results showed that EGCG could bind to Notch1 protein through hydrogen bonding. In vitro cell experiments demonstrated that EGCG can significantly reduce the sizes of lipid droplets of 3T3-L1 adipocytes and promote UCP-1 expression by inhibiting the expression of Notch1 in 3T3-L1 adipocytes, thus promoting mitochondrial biogenesis.

CONCLUSIONS

In this study, molecular docking and in vitro cell experiments were used to explore the possible mechanism of EGCG to improve obesity by inhibiting Notch1.

Mitophagy suppression by miquelianin-rich lotus leaf extract induces 'beiging' of white fat via AMPK/DRP1-PINK1/PARKIN signaling axis

BACKGROUND

Lotus (Nelumbo nucifera) leaf has been described to have anti-obesity activity, but the role of white fat 'browning' or 'beiging' in its beneficial metabolic actions remains unclear. Here, 3T3-L1 cells and high-fat-diet (HFD)-fed mice were used to evaluate the effects of miquelianin-rich lotus leaf extract (LLE) on white-to-beige fat conversion and its regulatory mechanisms.

RESULTS

Treatment with LLE increased mitochondrial abundance, mitochondrial membrane potential and NAD+ /NADH ratio in 3T3-L1 cells, suggesting its potential in promoting mitochondrial activity. qPCR and/or western blotting analysis confirmed that LLE induced the expression of beige fat-enriched gene signatures (e.g. Sirt1, Cidea, Dio2, Prdm16, Ucp1, Cd40, Cd137, Cited1) and mitochondrial biogenesis-related markers (e.g. Nrf1, Cox2, Cox7a, Tfam) in 3T3-L1 cells and inguinal white adipose tissue of HFD-fed mice. Furthermore, we found that LLE treatment inhibited mitochondrial fission protein DRP1 and blocked mitophagy markers such as PINK1, PARKIN, BECLIN1 and LC-3B. Chemical inhibition experiments revealed that AMPK/DRP1 signaling was required for LLE-induced beige fat formation via suppressing PINK1/PARKIN/mitophagy.

CONCLUSION

Our data reveal a novel mechanism underlying the anti-obesity effect of LLE, namely the induction of white fat beiging via AMPK/DRP1/mitophagy signaling. © 2023 Society of Chemical Industry.

The role of mitophagy in metabolic diseases and its exercise intervention

Mitochondria are energy factories that sustain life activities in the body, and their dysfunction can cause various metabolic diseases that threaten human health. Mitophagy, an essential intracellular mitochondrial quality control mechanism, can maintain cellular and metabolic homeostasis by removing damaged mitochondria and participating in developing metabolic diseases. Research has confirmed that exercise can regulate mitophagy levels, thereby exerting protective metabolic effects in metabolic diseases. This article reviews the role of mitophagy in metabolic diseases, the effects of exercise on mitophagy, and the potential mechanisms of exercise-regulated mitophagy intervention in metabolic diseases, providing new insights for future basic and clinical research on exercise interventions to prevent and treat metabolic diseases.

Sesamol Alleviates High-Fat Diet-Induced Hepatic Insulin Resistance in C57BL/6 J Mice Through AMPK Activation Mediated by Adipose Adiponectin

Sesamol is the major bioactive constituent isolated from sesame seeds and has a variety of bioactivities. However, its role and mechanism in liver insulin resistance remain unknown. The current study was designed to investigate the underlying adipose-liver crosstalk mechanism of sesamol ameliorating hepatic insulin sensitivity. The therapeutic effect of sesamol was evaluated in high-fat diet (HFD)-fed C57BL/6 J mice (100 mg/kg for 8 weeks, XYGW-2021-75) and the mechanism was further explored in HepG2 cells with/without adiponectin and adenosine 5 '-monophosphate-activated protein kinase (AMPK) inhibitor administration. Our in vivo data showed that sesamol reduced hepatic insulin resistance in HFD-induced mice with obesity by modulating protein expression levels of glycogen synthase (GS), phosphoenolpyruvate carboxykinase (PEPCK) and protein kinase B (AKT). Moreover, sesamol not only increased the serum and adipose tissue adiponectin concentrations but also activated the phosphorylation of AMPK in the liver. Furthermore, in vitro studies using recombinant human adiponectin and an AMPK inhibitor revealed that adiponectin and sesamol have a synergic impact on increasing glycogenesis and reducing gluconeogenesis, of which the effects could be attenuated by the AMPK inhibitor. Taken together, our results suggested that sesamol stimulated adiponectin secretion from adipocytes, whereby exhibited a co-effect on activating the downstream signal of hepatic AMPK, resulting in the alleviation of hepatic insulin resistance. The novel findings of sesamol on hepatic effects provides prospective therapeutic approaches to treat insulin resistance.

Miquelianin in Folium Nelumbinis extract promotes white-to-beige fat conversion via blocking AMPK/DRP1/mitophagy and modulating gut microbiota in HFD-fed mice

The main purpose of the present study was to investigate the effect of miquelianin (quercetin 3-O-glucuronide, Q3G), one of the main flavonoids in the Folium Nelumbinis extract (FNE), on beige adipocyte formation and its underlying mechanisms. In 3T3-L1 adipocytes Q3G (12.8%)-rich FNE treatment upregulated beige-related markers such as SIRT1, COX2, PGC-1α, TFAM, and UCP1. Furthermore, Q3G enhanced mitochondrial biosynthesis and inhibited mitophagy by downregulating the expression of PINK1, PARKIN, BECLIN1 and LC-3B in 3T3-L1 cells. Moreover, in high-fat-diet (HFD)-fed mice, Q3G markedly inhibited body weight gain, reduced blood glucose/lipid levels, reduced white adipose tissues (WAT) and mitigated hepatic steatosis. Meanwhile, the induced beiging accompanied by suppressed mitophagy was also demonstrated in inguinal WAT (iWAT). Chemical intervention of AMPK activity with Compound C (Com C) and Acadesine (AICAR) revealed that AMPK/DRP1 signaling was involved in Q3G-mediated mitophagy and the beiging process. Importantly, 16S rRNA sequencing analysis showed that Q3G beneficially reshaped gut microbiota structure, specifically inhibiting unclassified_Lachnospiraceae, Faecalibaculum, Roseburia and Colidextribacter while increasing Bacteroides, Akkermansia and Mucispirillum, which may potentially facilitate WAT beiging. Collectively, our findings provide a novel biological function for Folium Nelumbinis and Q3G in the fight against obesity through activating the energy-dissipating capacity of beige fat.

High-intensity interval training improves fatty infiltration in the rotator cuff through the β3 adrenergic receptor in mice

Aims

Rotator cuff muscle atrophy and fatty infiltration affect the clinical outcomes of rotator cuff tear patients. However, there is no effective treatment for fatty infiltration at this time. High-intensity interval training (HIIT) helps to activate beige adipose tissue. The goal of this study was to test the role of HIIT in improving muscle quality in a rotator cuff tear model via the β3 adrenergic receptor (β3AR).

Methods

Three-month-old C57BL/6 J mice underwent a unilateral rotator cuff injury procedure. Mice were forced to run on a treadmill with the HIIT programme during the first to sixth weeks or seventh to 12th weeks after tendon tear surgery. To study the role of β3AR, SR59230A, a selective β3AR antagonist, was administered to mice ten minutes before each exercise through intraperitoneal injection. Supraspinatus muscle, interscapular brown fat, and inguinal subcutaneous white fat were harvested at the end of the 12th week after tendon tear and analyzed biomechanically, histologically, and biochemically.

Results

Histological analysis of supraspinatus muscle showed that HIIT improved muscle atrophy, fatty infiltration, and contractile force compared to the no exercise group. In the HIIT groups, supraspinatus muscle, interscapular brown fat, and inguinal subcutaneous white fat showed increased expression of tyrosine hydroxylase and uncoupling protein 1, and upregulated the β3AR thermogenesis pathway. However, the effect of HIIT was not present in mice injected with SR59230A, suggesting that HIIT affected muscles via β3AR.

Conclusion

HIIT improved supraspinatus muscle quality and function after rotator cuff tears by activating systemic sympathetic nerve fibre near adipocytes and β3AR.

Molecular and cellular regulation of thermogenic fat

Thermogenic fat, consisting of brown and beige adipocytes, dissipates energy in the form of heat, in contrast to the characteristics of white adipocytes that store energy. Increasing energy expenditure by activating brown adipocytes or inducing beige adipocytes is a potential therapeutic strategy for treating obesity and type 2 diabetes. Thus, a better understanding of the underlying mechanisms of thermogenesis provides novel therapeutic interventions for metabolic diseases. In this review, we summarize the recent advances in the molecular regulation of thermogenesis, focusing on transcription factors, epigenetic regulators, metabolites, and non-coding RNAs. We further discuss the intercellular and inter-organ crosstalk that regulate thermogenesis, considering the heterogeneity and complex tissue microenvironment of thermogenic fat.

Mitochondria-associated regulation in adipose tissues and potential reagents for obesity intervention

Introduction

A systematic review analysis was used to assess the profile of mitochondrial involvement in adipose tissue regulation and potential reagents to intervene in obesity through the mitochondrial pathway.

Methods

Three databases, PubMed, Web of Science, and Embase, were searched online for literature associated with mitochondria, obesity, white adipose tissue, and brown adipose tissue published from the time of their creation until June 22, 2022, and each paper was screened.

Results

568 papers were identified, of which 134 papers met the initial selection criteria, 76 were selected after full-text review, and 6 were identified after additional searches. A full-text review of the included 82 papers was performed.

Conclusion

Mitochondria play a key role in adipose tissue metabolism and energy homeostasis, including as potential therapeutic agents for obesity.

Hypolipidemic and Anti-Atherogenic Effects of Sesamol and Possible Mechanisms of Action: A Comprehensive Review

Sesamol is a phenolic lignan isolated from Sesamum indicum seeds and sesame oil. Numerous studies have reported that sesamol exhibits lipid-lowering and anti-atherogenic properties. The lipid-lowering effects of sesamol are evidenced by its effects on serum lipid levels, which have been attributed to its potential for significantly influencing molecular processes involved in fatty acid synthesis and oxidation as well as cholesterol metabolism. In this review, we present a comprehensive summary of the reported hypolipidemic effects of sesamol, observed in several in vivo and in vitro studies. The effects of sesamol on serum lipid profiles are thoroughly addressed and evaluated. Studies highlighting the ability of sesamol to inhibit fatty acid synthesis, stimulate fatty acid oxidation, enhance cholesterol metabolism, and modulate macrophage cholesterol efflux are outlined. Additionally, the possible molecular pathways underlying the cholesterol-lowering effects of sesamol are presented. Findings reveal that the anti-hyperlipidemic effects of sesamol are achieved, at least in part, by targeting liver X receptor α (LXRα), sterol regulatory element binding protein-1 (SREBP-1), and fatty acid synthase (FAS) expression, as well as peroxisome proliferator-activated receptor α (PPARα) and AMP activated protein kinase (AMPK) signaling pathways. A detailed understanding of the molecular mechanisms underlying the anti-hyperlipidemic potential of sesamol is necessary to assess the possibility of utilizing sesamol as an alternative natural therapeutic agent with potent hypolipidemic and anti-atherogenic properties. Research into the optimal sesamol dosage that may bring about such favorable hypolipidemic effects should be further investigated, most importantly in humans, to ensure maximal therapeutic benefit.

Sphingosylphosphorylcholine ameliorates doxorubicin-induced cardiotoxicity in zebrafish and H9c2 cells by reducing excessive mitophagy and mitochondrial dysfunction

Doxorubicin (DOX, C₂₇H₂₉NO₁₁), is an anthracycline tumor chemotherapy drug, which has significant side effects on many organs including the heart. In recent years, mitochondrial dysfunction caused by DOX was identified as an important reason for cardiotoxic injury. Sphingosylphosphorylcholine (SPC) is essential for mitochondrial homeostasis in our previous report, however, its role in DOX-caused cardiomyopathy has remained elusive. Herein, DOX treated zebrafish embryos (90 μM) and adult fish (2.5 μM/g) were used to simulate DOX-induced cardiotoxic damage. Histopathological and ultrastructural observations showed that SPC (2.5 μM) significantly ameliorated DOX-induced pericardial edema, myocardial vacuolization and apoptosis. Furthermore, SPC (2.5 μM) can significantly inhibit DOX-induced apoptosis and promote cell proliferation in DOX treated H9c2 cells (1 μM), which is dependent on the restoration of mitochondrial homeostasis, including restored mitochondrial membrane potential, mitochondrial superoxide and ATP levels. We finally confirmed that SPC restored mitochondrial homeostasis through ameliorating DOX-induced excessive mitophagy. Mechanistically, SPC reduced calmodulin (CaM) levels and thus inhibiting Parkin activation and Parkin-dependent mitophagy. These results suggest that reducing the cardiotoxicity of chemotherapeutic drugs by targeting SPC may be a new solution to rescue chemotherapy injury.

Factors Associated with White Fat Browning: New Regulators of Lipid Metabolism

Mammalian adipose tissue can be divided into white and brown adipose tissue based on its colour, location, and cellular structure. Certain conditions, such as sympathetic nerve excitement, can induce the white adipose adipocytes into a new type of adipocytes, known as beige adipocytes. The process, leading to the conversion of white adipocytes into beige adipocytes, is called white fat browning. The dynamic balance between white and beige adipocytes is closely related to the body’s metabolic homeostasis. Studying the signal transduction pathways of the white fat browning might provide novel ideas for the treatment of obesity and alleviation of obesity-related glucose and lipid metabolism disorders. This article aimed to provide an overview of recent advances in understanding white fat browning and the role of BAT in lipid metabolism.

Prednisone stimulates white adipocyte browning via β3-AR/p38 MAPK/ERK signaling pathway

AIMS

Prednisone is a corticosteroid-derived drug which is widely used for its role in immunosuppression and treatment of lung disorders. The current study reports, for the first time, the critical role of prednisone in the induction of white fat browning, thereby promoting thermogenic effect in cultured white adipocytes.

MAIN METHODS

The fat-browning activity of prednisone was evaluated in 3T3-L1 cells by quantitative real-time PCR, immunoblot analysis, immunofluorescence, and molecular docking techniques.

KEY FINDINGS

Exposure to prednisone stimulated browning in 3T3-L1 white adipocytes by increasing the expressions of core fat browning marker proteins (UCP1, PGC-1α and PRDM16) as well as beige-specific genes (Cd137, Cidea, Cited1, and Tbx1) via ATF2 and CREB activation mediated by p38 MAPK and ERK signaling, respectively. Prednisone exposure also resulted in the robust activation of lipolytic and fatty acid oxidation marker proteins, thereby increasing mitochondrial biogenesis. In addition, prednisone treatment resulted in reduced expression levels of adipogenic transcription factors while elevating SIRT1, as well as attenuation of lipogenesis and lipid droplets formation. Furthermore, molecular docking and mechanistic studies demonstrated the recruitment of beige fat by prednisone via the β3-AR/p38 MAPK/ERK signaling pathway.

SIGNIFICANCE

Taken together, these results indicate the unique role of prednisone as a fat-browning stimulant, and demonstrate its therapeutic potential in the treatment of obesity by enhancing thermogenesis.