Angiotensin II participates in mitochondrial thermogenic functions via the activation of glycolysis in chemically induced human brown adipocytes.

Brown adipocytes are potential therapeutic targets for the prevention of obesity-associated metabolic diseases because they consume circulating glucose and fatty acids for heat production. Angiotensin II (Ang II) peptide is involved in the pathogenesis of obesity- and cold-induced hypertension; however, the mechanism underlying the direct effects of Ang II on human brown adipocytes remains unclear. Our transcriptome analysis of chemical compound-induced brown adipocytes (ciBAs) showed that the Ang II type 1 receptor (AGTR1), but not AGTR2 and MAS1 receptors, was expressed. The Ang II/AGTR1 axis downregulated the expression of mitochondrial uncoupling protein 1 (UCP1). The simultaneous treatment with ß-adrenergic receptor agonists and Ang II attenuated UCP1 expression, triglyceride lipolysis, and cAMP levels, although cAMP response element-binding protein (CREB) phosphorylation was enhanced by Ang II mainly through the protein kinase C pathway. Despite reduced lipolysis, both coupled and uncoupled mitochondrial respiration was enhanced in Ang II-treated ciBAs. Instead, glycolysis and glucose uptake were robustly activated upon treatment with Ang II without a comprehensive transcriptional change in glucose metabolic genes. Elevated mitochondrial energy status induced by Ang II was likely associated with UCP1 repression. Our findings suggest that the Ang II/AGTR1 axis participates in mitochondrial thermogenic functions via glycolysis.

Unveiling the Potential of Natural Compounds: A Comprehensive Review on Adipose Thermogenesis Modulation.

The process of adipocyte browning has recently emerged as a novel therapeutic target for combating obesity and obesity-related diseases. Non-shivering thermogenesis is the process of biological heat production in mammals and is primarily mediated via brown adipose tissue (BAT). The recruitment and activation of BAT can be induced through chemical drugs and nutrients, with subsequent beneficial health effects through the utilization of carbohydrates and fats to generate heat to maintain body temperature. However, since potent drugs may show adverse side effects, nutritional or natural substances could be safe and effective as potential adipocyte browning agents. This review aims to provide an extensive overview of the natural food compounds that have been shown to activate brown adipocytes in humans, animals, and in cultured cells. In addition, some key genetic and molecular targets and the mechanisms of action of these natural compounds reported to have therapeutic potential to combat obesity are discussed.

Apoptotic brown adipocytes enhance energy expenditure via extracellular inosine.

Brown adipose tissue (BAT) dissipates energy1,2 and promotes cardiometabolic health3. Loss of BAT during obesity and ageing is a principal hurdle for BAT-centred obesity therapies, but not much is known about BAT apoptosis. Here, untargeted metabolomics demonstrated that apoptotic brown adipocytes release a specific pattern of metabolites with purine metabolites being highly enriched. This apoptotic secretome enhances expression of the thermogenic programme in healthy adipocytes. This effect is mediated by the purine inosine that stimulates energy expenditure in brown adipocytes by the cyclic adenosine monophosphate-protein kinase A signalling pathway. Treatment of mice with inosine increased BAT-dependent energy expenditure and induced 'browning' of white adipose tissue. Mechanistically, the equilibrative nucleoside transporter 1 (ENT1, SLC29A1) regulates inosine levels in BAT: ENT1-deficiency increases extracellular inosine levels and consequently enhances thermogenic adipocyte differentiation. In mice, pharmacological inhibition of ENT1 as well as global and adipose-specific ablation enhanced BAT activity and counteracted diet-induced obesity, respectively. In human brown adipocytes, knockdown or blockade of ENT1 increased extracellular inosine, which enhanced thermogenic capacity. Conversely, high ENT1 levels correlated with lower expression of the thermogenic marker UCP1 in human adipose tissues. Finally, the Ile216Thr loss of function mutation in human ENT1 was associated with significantly lower body mass index and 59% lower odds of obesity for individuals carrying the Thr variant. Our data identify inosine as a metabolite released during apoptosis with a 'replace me' signalling function that regulates thermogenic fat and counteracts obesity.

Inhibition of STAT3 enhances UCP1 expression and mitochondrial function in brown adipocytes.

Extensive studies have shown that the increasing brown adipose tissue (BAT) mass/activity possesses a strong ability to prevent obesity and its related complications. The Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signal pathway is known to play a role in adipocyte differentiation and development. However, its impact on thermogenic properties of mature brown adipocytes has not yet been clarified. Nifuroxazide (NFX), a potent inhibitor of STAT3, has received widespread attention due to its alternative anti-tumor and anti-inflammatory effects. Herein, we report that NFX induces lipolysis with subsequent downregulation of ACCα and FAS, while ATGL and pHSL levels are elevated in mature brown adipocytes. Furthermore, NFX treatment promotes the mitochondrial respiration of mature brown adipocytes, as evidenced by increased expression of thermogenic transcriptional factors and mitochondrial content. In addition, it also alleviates the IL-6 and TNFα inhibition on brown thermogenic programming via suppressing the STAT3/NF-κB/IL-6 signaling pathway. In general, these findings suggest that the blockade of the JAK/STAT3 pathway by NFX has a pro-thermogenic effect on mature brown adipocytes which opens new perspectives for NFX repurposing and potential therapeutic route to counteract obesity and related metabolic disorders.

ACSS3 in brown fat drives propionate catabolism and its deficiency leads to autophagy and systemic metabolic dysfunction.

Propionate is a gut microbial metabolite that has been reported to have controversial effects on metabolic health. Here we show that propionate is activated by acyl-CoA synthetase short-chain family member 3 (ACSS3), located on the mitochondrial inner membrane in brown adipocytes. Knockout of Acss3 gene (Acss3-/- ) in mice reduces brown adipose tissue (BAT) mass but increases white adipose tissue (WAT) mass, leading to glucose intolerance and insulin resistance that are exacerbated by high-fat diet (HFD). Intriguingly, Acss3-/- or HFD feeding significantly elevates propionate levels in BAT and serum, and propionate supplementation induces autophagy in cultured brown and white adipocytes. The elevated levels of propionate in Acss3-/- mice similarly drive adipocyte autophagy, and pharmacological inhibition of autophagy using hydroxychloroquine ameliorates obesity, hepatic steatosis and insulin resistance of the Acss3-/- mice. These results establish ACSS3 as the key enzyme for propionate metabolism and demonstrate that accumulation of propionate promotes obesity and Type 2 diabetes through triggering adipocyte autophagy.

Prednisone stimulates white adipocyte browning via ß3-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 ß3-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.

Lipoxin A4 promotes adipogenic differentiation and browning of mouse embryonic fibroblasts.

Recently, it has been irrefutably discovered that brown adipocytes dissipate energy as heat and protect against obesity. Researchers make great efforts to explore approaches for its activation. Lipoxin A4 (LXA4) has been proven to reverse adipose tissue inflammation and improve insulin resistance, but its function on brown adipocyte differentiation has been poorly understood, which therefore to be investigated in the present study. Mouse embryonic fibroblasts (MEFs) were induced and differentiated to model brown adipocytes, and treated with LXA4 at 0, 1, 5, and 10 nM for 0-14 d. Afterwards, Oil Red O staining detected lipid droplets. In differentiated MEFs with or without LXA4 (10 nM) treatment, western blot and quantitative real-time polymerase chain reaction (qRT-PCR) assessed adipocyte browning marker uncoupling protein 1 (UCP-1), and brown adipogenesis markers peroxisome proliferator-activated receptor gamma (PPARγ), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), cyclooxygenase-2 (COX-2), and positive regulation domain containing 16 (PRDM16) as well as lipogenic genes of stearoyl-CoA desaturase 1 (SCD1), fatty acid synthase (FASN), glucose transporter type 4 (GLUT4), and carbohydrate response element binding protein (ChREBP). The induced differentiation of MEFs toward brown adipocytes was successful. LXA4 promoted intracellular accumulation of lipid droplets of induced cells and increased UCP-1 expression in a dose- or time-dependent manner. Under the administration of LXA4, brown adipogenesis markers and lipogenic genes were further upregulated. LXA4 made a contribution to induce differentiation of MEFs to brown adipocytes, which could be regarded a new drug target for obesity management.

The Mechanism of Leptin on Inhibiting Fibrosis and Promoting Browning of White Fat by Reducing ITGA5 in Mice.

Leptin is a small molecule protein secreted by adipocytes, which can promote white fat browning through activating the hypothalamic nervous system and inhibiting downstream signaling pathways. Moreover, white fat browning has been proven to alleviate fat tissue fibrosis. This study explores the mechanism of leptin in regulating adipose tissue fibrosis and white fat browning. After treating mice with leptin, we screened out the recombinant integrin alpha 5 (ITGA5) through proteomics sequencing, which may play a role in adipose tissue fibrosis. Through real-time quantitative PCR (qPCR), western blotting (WB), hematoxylin-eosin (HE) staining, Masson's trichrome, immunofluorescence, immunohistochemistry, etc., the results showed that after leptin treated adipocytes, the expression of fibrosis-related genes and ITGA5 was significantly down-regulated in adipocytes. We constructed fibrosis model through transforming growth factor-ß (TGF-ß) and a high-fat diet (HFD), and treated with ITGA5 overexpression vector and interference fragments. The results indicated the expression of fibrosis-related genes were significantly down-regulated after interfering with ITGA5. After treating adipocytes with wortmannin, fibrosis-related gene expression was inhibited after overexpression of ITGA5. Moreover, after injecting mice with leptin, we also found that leptin significantly up-regulated the expression of adipose tissue browning-related genes. Overall, our research shows that leptin can inhibit the activation of phosphatidylinositol 3 kinase (PI3K)-protein kinase B (AKT) signaling pathway by reducing the expression of ITGA5, which could alleviate adipose tissue fibrosis, and further promote white fat browning. Our research provides a theoretical basis for further research on the effect of leptin in fibrosis-related adipose tissue metabolism.

ASKA technology-based pull-down method reveals a suppressive effect of ASK1 on the inflammatory NOD-RIPK2 pathway in brown adipocytes.

Recent studies have shown that adipose tissue is an immunological organ. While inflammation in energy-storing white adipose tissues has been the focus of intense research, the regulatory mechanisms of inflammation in heat-producing brown adipose tissues remain largely unknown. We previously identified apoptosis signal-regulating kinase 1 (ASK1) as a critical regulator of brown adipocyte maturation; the PKA-ASK1-p38 axis facilitates uncoupling protein 1 (UCP1) induction cell-autonomously. Here, we show that ASK1 suppresses an innate immune pathway and contributes to maintenance of brown adipocytes. We report a novel chemical pull-down method for endogenous kinases using analog sensitive kinase allele (ASKA) technology and identify an ASK1 interactor in brown adipocytes, receptor-interacting serine/threonine-protein kinase 2 (RIPK2). ASK1 disrupts the RIPK2 signaling complex and inhibits the NOD-RIPK2 pathway to downregulate the production of inflammatory cytokines. As a potential biological significance, an in vitro model for intercellular regulation suggests that ASK1 facilitates the expression of UCP1 through the suppression of inflammatory cytokine production. In parallel to our previous report on the PKA-ASK1-p38 axis, our work raises the possibility of an auxiliary role of ASK1 in brown adipocyte maintenance through neutralizing the thermogenesis-suppressive effect of the NOD-RIPK2 pathway.

A Population of M2 Macrophages Associated With Bone Formation.

We previously identified transient brown adipocyte-like cells associated with heterotopic ossification (HO). These ancillary cells support new vessel synthesis essential to bone formation. Recent studies have shown that the M2 macrophage contributes to tissue regeneration in a similar way. To further define the phenotype of these brown adipocyte-like cells they were isolated and characterized by single-cell RNAseq (scRNAseq). Analysis of the transcriptome and the presence of surface markers specific for macrophages suggest that these cells are M2 macrophages. To validate these findings, clodronate liposomes were delivered to the tissues during HO, and the results showed both a significant reduction in these macrophages as well as bone formation. These cells were isolated and shown in culture to polarize towards either M1 or M2 similar to other macrophages. To confirm that these are M2 macrophages, mice received lipopolysacheride (LPS), which induces proinflammation and M1 macrophages. The results showed a significant decrease in this specific population and bone formation, suggesting an essential role for M2 macrophages in the production of bone. To determine if these macrophages are specific to HO, we isolated these cells using fluorescence-activated cell sorting (FACS) from a bone defect model and subjected them to scRNAseq. Surprisingly, the macrophage populations overlapped between the two groups (HO-derived versus callus) suggesting that they may be essential ancillary cells for bone formation in general and not selective to HO. Of further note, their unique metabolism and lipogenic properties suggest the potential for unique cross talk between these cells and the newly forming bone.

The Effect of TLR Agonists and Myokines on Secretory Activity of Adipogenically Differentiated MSC Cultures.

We studied the effect of bacterial pathogen-associated molecular patterns and myokines on the secretion of adipokines by mesenchymal stem cells (MSC) and products of their adipogenic differentiation. The secretion of adiponectin, adipsin, leptin, and insulin by adipogenically differentiated cell cultures was quantitatively determined using multiplex ELISA. MSC obtained from the stromal vascular fraction of human subcutaneous adipose tissue were shown to secrete a known adipokine adipsin. The ability of white adipocytes to secrete significant amounts of insulin (in vitro) has been shown for the first time. Control cultures of white adipocytes secreted much higher levels of adiponectin, leptin, and insulin when compared to other adipocytes cultures. On the other hand, beige and brown adipocyte cultures secreted more adipsin than white adipocyte cultures. The influence of myokine ß-aminoisobutyric acid on the secretion of adipsin in MSC, white, beige, and brown adipocytes was also studied.

Astragalus polysaccharide regulates brown adipogenic differentiation through miR-1258-5p-modulated cut-like homeobox 1 expression.

Astragalus polysaccharide (APS) is the major natural active component of Astragalus membranaceus, which has been recognized as one of the most popular herbal medicines worldwide. Enhancing the formation and function of brown adipose tissue increases energy expenditure and hence may potentially be used against obesity and type 2 diabetes. The aim of the present study was to explore the effect and mechanism of APS on brown adipocyte formation. Mouse C3H10T 1/2 cells were subject to APS, and both proliferation and brown adipogenic differentiation were determined. The results showed that APS exhibits a decreased proliferation ability, which is accompanied by downregulated proliferating cell nuclear antigen, cyclin D1, and cyclin-dependent kinase 4. APS promotes the differentiation of C3H10T 1/2 cells into brown adipocytes and induces the expressions of key brown adipogenic transcriptional factors, including CCAAT/enhancer-binding protein ß, uncoupling protein 1, and PR domain-containing 16. Importantly, APS enables insulin sensitization in brown adipocytes, which may proceed through activation of the canonical phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) signaling pathway and AMP-activated protein kinase (AMPK). Furthermore, the level of cut-like homeobox 1 (CUX1) is positively related to brown adipogenic differentiation, while APS regulates Cux1 expression through interaction with miR-1258-5p. Notably, the promotional effect of APS on brown adipogenic differentiation was abolished by Cux1 knockout. Collectively, our results suggest that APS enhances the differentiation of C3H10T 1/2 cells into brown adipocytes through regulating Cux1 via miR-1258-5p.

DHA but not EPA induces the trans-differentiation of C2C12 cells into white-like adipocytes phenotype.

Muscle derived stem cells (MDSCs) and myoblast play an important role in myotube regeneration when muscle tissue is injured. However, these cells can be induced to differentiate into adipocytes once exposed to PPARγ activator like EPA and DHA that are highly suggested during pregnancy. The objective of this study aims at determining the identity of trans-differentiated cells by exploring the effect of EPA and DHA on C2C12 undergoing differentiation into brown and white adipocytes. DHA but not EPA committed C2C12 cells reprograming into white like adipocyte phenotype. Also, DHA promoted the expression of lipolysis regulating genes but had no effect on genes regulating ß-oxidation referring to its implication in lipid re-esterification. Furthermore, DHA impaired C2C12 cells differentiation into brown adipocytes through reducing the thermogenic capacity and mitochondrial biogenesis of derived cells independent of UCP1. Accordingly, DHA treated groups showed an increased accumulation of lipid droplets and suppressed mitochondrial maximal respiration and spare respiratory capacity. EPA, on the other hand, reduced myogenesis regulating genes, but no significant differences were observed in the expression of adipogenesis key genes. Likewise, EPA suppressed the expression of WAT signature genes indicating that EPA and DHA have an independent role on white adipogensis. Unlike DHA treatment, EPA supplementation had no effect on the differential of C2C12 cells into brown adipocytes. In conclusion, DHA is a potent adipogenic and lipogenic factor that can change the metabolic profile of muscle cells by increasing myocellular fat.

3-hydroxymorphinan enhances mitochondrial biogenesis and adipocyte browning through AMPK-dependent pathway.

3-hydroxymorphinan (3-HM), a metabolite of dextromethorphan, has previously been reported to have anti-inflammatory, anti-oxidative stress, and neuroprotective effects. However, its effect on energy metabolism in adipocytes remains unclear. Herein, we investigated 3-hydroxymorphinan (3-HM) effects on mitochondrial biogenesis, oxidative stress, and lipid accumulation in 3T3-L1 adipocytes. Further, we explored 3-HM-associated molecular mechanisms. Mouse adipocyte 3T3-L1 cells were treated with 3-HM, and various protein expression levels were determined by western blotting analysis. Mitochondria accumulation and lipid accumulation were measured by staining methods. Cell toxicity was assessed by cell viability assay. We found that treatment of 3T3-L1 adipocytes with 3-HM increased expression of brown adipocyte markers, such as uncoupling protein-1 (UCP-1) and peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC-1α). 3-HM promotes mitochondrial biogenesis and its-mediated gene expression. Additionally, 3-HM treatment suppressed mitochondrial ROS generation and superoxide along with improved mitochondrial complex I activity. We found that treatment of 3-HM enhanced AMPK phosphorylation. siRNA-mediated suppression of AMPK reversed all these changes in 3T3-L1 adipocytes. In sum, 3-HM promotes mitochondrial biogenesis and browning and attenuates oxidative stress and lipid accumulation in 3T3-L1 adipocytes via AMPK signaling. Thus, 3-HM-mediated AMPK activation can be considered a therapeutic approach for treating obesity and related diseases.

Strategies for Browning Agent Delivery.

Obesity expands as a global climbing epidemic that is often correlated to cardiovascular diseases and endocrine disorders. Converting white adipocytes to brown adipocytes for enhanced energy expenditure has recently emerged as a promising anti-obesity treatment. However, the conventional approaches to apply browning agents systematically suffer from off-target effects, multiple dosage requirements, and poor patient compliance. To date, various delivery strategies have been reported to deliver browning agents for obesity treatment in a safer and more controllable manner. This review will discuss the latest designs in browning agent delivery systems with a focus on nanomedicines and transdermal patches.

Pyruvate carboxylase supports basal ATP-linked respiration in human pluripotent stem cell-derived brown adipocytes.

Brown adipocytes (BA) are a specialized fat cell which possesses a high capacity for fuel oxidation combined with heat production. The maintenance of high metabolic activity in BA requires elevated oxidation of fuel through the tricarboxylic acid cycle. Pyruvate carboxylase (PC) was previously proposed to be essential for coordination between fuel oxidation and thermogenesis. By differentiating human pluripotent stem cells to mature BA in vitro, we showed that ablation of PC gene by CRISPR Cas9 genome engineering did not impair the ability of stem cells to generate mature BA. However, brown adipocytes deficient for PC expression displayed a 35% reduction in ATP-linked respiration, but not thermogenesis under both basal and isoproterenol-stimulated conditions. This relatively mild impairment of ATP-link respiration in PC knockout BA was protected by increased spare mitochondrial respiratory capacity. Taken together, this study highlights the role of PC in supporting fuel oxidation rather than thermogenesis in human BA.

The Use of Reactive Oxygen Species Production by Succinate-Driven Reverse Electron Flow as an Index of Complex 1 Activity in Isolated Brown Adipose Tissue Mitochondria.

We compared the activity of complex 1, complex 2, and the expression of the complex 1 subunit, NDUFA9, in isolated brown adipose tissue mitochondria from wild type and mitochondrial uncoupling protein 1 (UCP1) knockout mice. Direct spectrophotometric measurement revealed that complex 2 activity was similar, but complex 1 activity was greater (~2.7 fold) in isolated mitochondria from wild-type mice compared to UCP1 knockout mice, an observation endorsed by greater complex 1 subunit expression (NDUFA9) in mitochondria of wild-type mice. We also measured reactive oxygen species (ROS) production by isolated brown adipose mitochondria respiring on succinate, without rotenone, thus facilitating reverse electron flow through complex 1. We observed that reverse electron flow in isolated mitochondria from wild-type mice, with UCP1 inhibited, produced significantly greater (~1.6 fold) ROS when compared with isolated brown adipose mitochondria from UCP1 knockout mice. In summary, we demonstrate that ROS production by succinate-driven reverse electron flow can occur in brown adipose tissue mitochondria and is a good index of complex 1 activity.

Zeaxanthin promotes browning by enhancing mitochondrial biogenesis through the PKA pathway in 3T3-L1 adipocytes.

Obesity is closely associated with maintaining mitochondrial homeostasis, and mitochondrial dysfunction can lead to systemic lipid metabolism disorders. Zeaxanthin (ZEA) is a kind of carotenoid with potent antioxidant activity and has been reported to promote mitochondrial biogenesis. Nevertheless, the molecular mechanism has not been explained. In this study, we first discovered that ZEA stimulated 3T3-L1 adipocyte browning by increasing the expression of specific markers (Cd137, Tbx1, Sirt1, Cidea, Ucp1, Tmem26, and Cited1), thereby reducing lipid accumulation. Besides, ZEA promoted mitochondrial biogenesis by increasing the expression of PRDM16, UCP1, NRF2, PGC-1α, and SIRT1. Moreover, the uncoupled oxygen consumption rate (OCR) of protons leaked in 3T3-L1 adipocytes was rapidly increased by ZEA treatment, which improved mitochondrial respiration and energy metabolism. Furthermore, we found that ZEA promotes browning by enhancing mitochondrial biogenesis partly through the protein kinase A (PKA) pathway. This study provided new insight into the promotion of browning and mitochondrial biogenesis by ZEA, suggesting that ZEA probably has potential therapeutic effects on obesity.

SAHA induces white fat browning and rectifies metabolic dysfunctions via activation of ZFPs.

Several histone deacetylase (HDAC) inhibitors have been shown to play beneficial roles in treating obesity and its related metabolic syndromes. However, the underlying mechanisms are still not understood well. In this study, we examined the potential roles of SAHA, a potent inhibitor of HDACs, on energy expenditure and explored the molecular mechanism involved. Our data showed that SAHA induces less lipid accumulation and smaller lipid droplets in cultured adipocytes. In vivo studies showing SAHA reduces body weight gain and increases core temperature in lean and obese mice. Furthermore, SAHA accelerates blood glucose disposal, improves insulin sensitivity and attenuates fatty liver in obese animals. Transcriptome sequencing found that a group of zinc finger proteins (Zfps) was up-regulated by SAHA. Functional studies showed that the knockdown of Zfp691 or Zfp719 largely abolishes SAHA-induced Ucp1 expression in adipocytes. ChIP assay showed that SAHA stimulates histone H3 acetylation at Zfp719 promoter. Luciferase reporter analysis revealed that Zfp719 activates Ucp1 promoter. As a consequence, forced expression of Zfp719 increases Ucp1 expression and promotes lipid catabolism in adipocytes. Taken together, our data indicate that by stimulating axis of ZFPs-UCP1, SAHA induces white fat browning and energy consumption, which makes it a potential drug for treating obesity and related metabolic dysfunctions.

D-Mannitol Induces a Brown Fat-like Phenotype via a ß3-Adrenergic Receptor-Dependent Mechanism.

The presence of brown adipocytes within white adipose tissue is associated with phenotypes that exhibit improved metabolism and proper body weight maintenance. Therefore, a variety of dietary agents that facilitate the browning of white adipocytes have been investigated. In this study, we screened a natural product library comprising 133 compounds with the potential to promote the browning of white adipocytes, and found that D-mannitol induces the browning of 3T3-L1 adipocytes by enhancing the expression of brown fat-specific genes and proteins, and upregulating lipid metabolism markers. D-mannitol also increased the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase 1 (ACC), suggesting a possible role in lipolysis and fat oxidation. Moreover, an increase in the expression of genes associated with D-mannitol-induced browning was strongly correlated with the activation of the ß3-adrenergic receptor as well as AMPK, protein kinase A (PKA), and PPARγ coactivator 1α (PGC1α). D-mannitol effectively reduced the body weight of mice fed a high-fat diet, and increased the expression of ß1-oxidation and energy expenditure markers, such as Cidea, carnitine palmityl transferase 1 (CPT1), uncoupling protein 1 (UCP1), PGC1α, and acyl-coenzyme A oxidase (ACOX1) in the inguinal white adipose tissue. Our findings suggest that D-mannitol plays a dual regulatory role by inducing the generation of a brown fat-like phenotype and enhancing lipid metabolism. These results indicate that D-mannitol can function as an anti-obesity supplement.