New Advances in Adaptive Thermogenesis: UCP1 and Beyond

Cellular Feimin enhances exercise performance by suppressing muscle thermogenesis

Exercise can rapidly increase core body temperature, and research has indicated that elevated internal body temperature can independently contribute to fatigue during physical activity. However, the precise mechanisms responsible for regulating thermogenesis in muscles during exercise have remained unclear. Here, we demonstrate that cellular Feimin (cFeimin) enhances exercise performance by inhibiting muscle thermogenesis during physical activity. Mechanistically, we found that AMP-activated protein kinase (AMPK) phosphorylates cFeimin and facilitates its translocation into the cell nucleus during exercise. Within the nucleus, cFeimin binds to the forkhead transcription factor FOXC2, leading to the suppressed expression of sarcolipin (Sln), which is a key regulator of muscle thermogenesis. In addition, our results further reveal that short-term AMPK agonist treatments can enhance exercise performance through the activation of the AMPK-cFeimin signalling pathway. In summary, these results underscore the crucial role of cFeimin in enhancing exercise performance by modulating SLN-mediated thermogenesis.

Spop deficiency impairs adipogenesis and promotes thermogenic capacity in mice

As the adaptor protein that determines substrate specificity of the Cul3-SPOP-Rbx1 E3 ligase complex, SPOP is involved in numerous biological processes. However, its physiological connections with adipogenesis and thermogenesis remain poorly understood. In the current study, we report that the conditional knockout of Spop in mice results in substantial changes in protein expression, including the upregulation of a critical factor associated with thermogenesis, UCP1. Loss of SPOP also led to defects in body weight gain. In addition, conditional knockout mice exhibited resistance to high-fat-diet-induced obesity. Proteomics analysis found that proteins upregulated in the knockout mice are primarily enriched for functions in glycolysis/gluconeogenesis, oxidative phosphorylation, and thermogenesis. Furthermore, Spop knockout mice were more resilient during cold tolerance assay compared with the wild-type controls. Finally, the knockout of SPOP efficiently impaired adipogenesis in primary preadipocytes and the expression of associated genes. Collectively, these findings demonstrate the critical roles of SPOP in regulating adipogenesis and thermogenic capacity in mice.

Flll32, a curcumin analog, improves adipose tissue thermogenesis

Adipose tissue is a key regulator of systemic energy homeostasis and improving adipose tissue function provides a brand-new theoretical reference for the prevention and treatment of obesity. FLLL32, a curcumin analog, can hinder various carcinogenic processes, however, its role in adipose tissue has not been fully elucidated. In this study, we observed that FLLL32 treatment significantly improved cold intolerance and reduced white adipose tissue (WAT) adipocyte size in mice, but had no effect on body weight and adipose tissues weight. Furthermore, FLLL32 treatment upregulated the expression level of uncoupling protein 1 and downregulated the expression level of peroxisome proliferator-activated receptor gamma in adipose tissue. Additionally, FLLL32 promoted the mRNA level of transferrin receptor protein 1, a key iron transporter on the cell membrane, and the lipid peroxidation in inguinal WAT. Finally, FLLL32 significantly inhibited the differentiation and maturation of preadipocytes. In summary, our results demonstrated that FLLL32 plays a crucial role in regulating adipose tissue function.

High-temperature exposure during the early embryonic stage lowers core body temperature after growth via a hypothalamic Igfbp2-dependent mechanism

The mechanisms underlying individual differences in core body temperature (Tc) are unexplained by genetic factors and poorly understood. Here, we investigated whether the environmental temperature during early development affects postnatal Tc. Mouse embryos were cultured from pronuclear to blastocyst stage in either standard (37 °C) or high (38 °C) temperature, and the Tc of each grown-up adult was measured. The adult 38 °C-incubated mice showed lower Tc than the 37 °C group without changes in activity levels. In the hypothalamus of the 38 °C group, insulin-like growth factor 1 (Igf1) and IGF binding protein 2 (Igfbp2) gene expression increased. The decrease in Tc in the wild-type 38 °C group was alleviated by brain neuron-specific Igfbp2 knockout. This suggests that IGFBP2 binds to IGF-1 and, inhibits its binding to the receptor, thereby interfering with the thermogenic signaling of IGF-1. These results suggest that one of the factors determining individual postnatal Tc is the ambient temperature of embryos at an early developmental stage, which could affect epigenetic changes, such as DNA methylation, leading to alterations in the Igf1 and Igfbp2 gene expressions in adulthood.

A possibility of uncoupling protein 1 induction with the enhancement of myogenesis related to ruminal fermentation

The expression of uncoupling protein 1 (UCP1), which regulates energy expenditure, is limited to brown/beige adipocytes in most mammals; however, it is also detected in the skeletal muscles of cattle. We previously observed a positive relationship between Ucp1 and fast-twitch myosin heavy chain (Myh) expression in bovine skeletal muscles. In the present study, we explored the regulatory expression of Ucp1 in bovine myogenic cells using cell culture. Vitamin C and high-dose capsaicin, which induce the formation of fast-twitch myotubes in murine myogenic cells, did not stimulate myogenesis in bovine myosatellite cells. Treatment with 4-phenylbutyric acid (PBA), a histone deacetylase inhibitor that enhances histone acetylation, upregulates the expression of all myogenic regulatory factors (MRFs), except Myog, in bovine myogenic cells. Consistent with this, PBA increased the expression levels of acetylated lysine 27 of histone 3 (H3K27), the fast-twitch component MYH1/2, and Ucp1 in bovine myogenic cells. SB203580, an inhibitor of p38 MAP kinase, blocked PBA-induced myogenesis and Ucp1 upregulation. PBA is a butyric acid-related molecule, and cattle produce large amounts of volatile fatty acids (VFAs), including acetic acid, propionic acid, and butyric acid, through ruminal fermentation. Propionic acid treatment stimulated H3K27 acetylation, myogenesis, and Ucp1 induction. Thus, the upregulation of muscular Ucp1 may be related to myogenic stimulation through the modulation of histone acetylation status in cattle; we propose that the cattle-specific expression of muscular UCP1 results from VFA production through ruminal fermentation.

Species differences in glycerol-3-phosphate metabolism reveals trade-offs between metabolic adaptations and cell proliferation

The temperate climate-adapted brown hare (Lepus europaeus) and the cold-adapted mountain hare (Lepus timidus) are closely related and interfertile species. However, their skin fibroblasts display distinct gene expression profiles related to fundamental cellular processes. This indicates important metabolic divergence between the two species. Through targeted metabolomics and metabolite tracing, we identified species-specific variations in glycerol 3-phosphate (G3P) metabolism. G3P is a key metabolite of the G3P shuttle, which transfers reducing equivalents from cytosolic NADH to the mitochondrial electron transport chain (ETC), consequently regulating glycolysis, lipid metabolism, and mitochondrial bioenergetics. Alterations in G3P metabolism have been implicated in multiple human pathologies including cancer and diabetes. We observed that mountain hare mitochondria exhibit elevated G3P shuttle activity, alongside increased membrane potential and decreased mitochondrial temperature. Silencing mitochondrial G3P dehydrogenase (GPD2), which couples the conversion of G3P to the ETC, uncovered its species-specific role in controlling mitochondrial membrane potential and highlighted its involvement in skin fibroblast thermogenesis. Unexpectedly, GPD2 silencing enhanced wound healing and cell proliferation rates in a species-specific manner. Our study underscores the pivotal role of the G3P shuttle in mediating physiological, bioenergetic, and metabolic divergence between these hare species.

FK506 binding protein 51: Its role in the adipose organ and beyond

There is a great body of evidence that the adipose organ plays a central role in the control not only of energy balance, but importantly, in the maintenance of metabolic homeostasis. Interest in the study of different aspects of its physiology grew in the last decades due to the pandemic of obesity and the consequences of metabolic syndrome. It was not until recently that the first evidence for the role of the high molecular weight immunophilin FK506 binding protein (FKBP) 51 in the process of adipocyte differentiation have been described. Since then, many new facets have been discovered of this stress-responsive FKBP51 as a central node for precise coordination of many cell functions, as shown for nuclear steroid receptors, autophagy, signaling pathways as Akt, p38 MAPK, and GSK3, as well as for insulin signaling and the control of glucose homeostasis. Thus, the aim of this review is to integrate and discuss the recent advances in the understanding of the many roles of FKBP51 in the adipose organ.

Integrated analysis of omics reveals the role of scapular fat in thermogenesis adaptation in sunite sheep

Inhabiting some of the world's most inhospitable climatic regions, the Sunite Mongolian sheep generates average temperatures as low as 4.3 °C and a minimum temperature of -38.8 °C; in these environments, they make essential cold adaptations. In this regard, scapular fat tissues from Mongolian sheep were collected both in winter and summer for transcriptomic and proteomic analyses to identify genes related to adaptive thermogenesis. In the transcriptome analysis, 588 differentially expressed genes were identified to participate in smooth muscle activity and fat metabolism, as well as in nutrient regulation. There were 343 upregulated and 245 downregulated genes. GO and KEGG pathway analyses on these genes revealed their participation in regulating smooth muscle activity, metabolism of fats, and nutrients. Proteomic analysis showed the differential expression of 925 proteins: among them, there are 432 up- and 493 down-expressed proteins. These proteins are mainly involved in oxidative phosphorylation, respiratory chain complex assembly, and ATP production by electron transport. Furthermore, using both sets at a more detailed level of analysis revealed over-representation in gene ontology categories related to hormone signaling, metabolism of lipids, the pentose phosphate pathway, the TCA cycle, and especially the process of oxidative phosphorylation. The identified essential genes and proteins were further validated by quantitative real-time polymerase chain reaction and Western blotting, respectively; key metabolic network constriction was constructed. The present study emphasized the critical role of lipid turnover in scapular fat for thermogenic adaptation in Sunite sheep.

Computational insights into human UCP1 activators through molecular docking, MM-GBSA, and molecular dynamics simulation studies

The prevalence of obesity is rapidly increasing worldwide. Brown adipose tissue activates uncoupling protein 1 (UCP1) to generate heat through bypassing ATP synthesis, offering a potential target for obesity treatment. Targeting UCP1 activation to induce thermogenesis through small molecules presents a promising approach for obesity management. In this study, molecular docking of UCP1 activators, using 2,4-dinitrophenol (DNP) as a reference ligand (PDB ID: 8J1N, docking score: -5.343 kcal/mol), identified seven top-scoring compounds: naringin (-7.284 kcal/mol), quercetin (-6.661 kcal/mol), salsalate (-6.017 kcal/mol), rhein (-5.798 kcal/mol), mirabegron (-5.535 kcal/mol), curcumin (-5.479 kcal/mol), and formoterol (-5.451 kcal/mol). Prime MM-GBSA calculation of the top-scored molecule (i.e., naringin) in the docking study showed ΔGBind of -70.48 kcal/mol. Key interactions of these top 7 activators with UCP1 binding pocket residues Trp280, Arg276, Glu190, Arg83, and Arg91 were observed. Molecular dynamics simulations performed for 100 ns confirmed complex stability, with RMSD values below 6 Å. Additionally, most activators showed favorable intestinal absorption (>90 %) and lipophilicity (LogP 2-4), with pKa values supporting their pharmacological potential as UCP1-targeting therapeutics for obesity. These findings provide a foundation for designing potent UCP1 activators by integrating docking scores, interaction profiles, statistical profiles from MD simulations, and physicochemical assessments to develop effective anti-obesity therapies.

Diet-induced obesity and aging-induced upregulation of Trib3 interfere with energy homeostasis by downregulating the thermogenic capacity of BAT

Characterized by UCP1 expression and abundant mitochondria, brown adipose tissue (BAT) plays a crucial role in energy balance by converting chemical energy into heat through the cost of ATP production. In this study, it was demonstrated that Trib3 is a critical determinant of BAT-mediated energy expenditure and whole-body energy homeostasis. Under 60% high-fat diet conditions, Trib3 expression in BAT was elevated. Mice deficient in Trib3 are resistant to diet-induced obesity and exhibit improved glucose homeostasis due to enhanced BAT activity. Furthermore, brown adipocyte progenitor cells (APCs) lacking Trib3 exhibited increased proliferation and promoted brown adipocyte differentiation and mitochondrial biogenesis, contributing to the increase in the maximal thermogenic capacity of BAT in Trib3-deficient mice. Mechanistically, it was discovered that Trib3 expression is upregulated by free fatty acids at the transcriptional level and synergistically upregulated by DAG-PKC at the posttranslational level. This occurs through the modulation of COP1-mediated Trib3 protein turnover. Interestingly, the level of Trib3 expression in BAT increased with age. Trib3 knockout mice were protected from aging-related weight gain and impaired glucose homeostasis. These results suggest that Trib3 acts as an obesity- and aging-associated factor that negatively regulates BAT activity and that the loss of Trib3 may provide a beneficial approach to prevent obesity and aging-associated metabolic syndrome by increasing the thermogenic capacity of BAT.

Bisphenol A and its metabolites promote white adipogenesis and impair brown adipogenesis in vitro

Bisphenol A (BPA), an obesogen, can disrupt adipogenesis in vitro, but these studies did not distinguish adipocytes as white or brown. BPA can be metabolized into BPA-glucuronide (BPA-G) and BPA-sulfate (BPA-S). These metabolites are not completely inactive in the body, but the related studies remain limited. In this study, preadipocytes isolated from mouse white and brown adipose tissues were treated with 0.1, 1, and 10 μM of BPA and its metabolites for 6 days, which are equivalent to the exposure level of general and occupational populations, to investigate and compare the effects of BPA and its metabolites on white and brown adipogenesis. The results showed that BPA and BPA-G increased lipid accumulation during white adipogenesis, whereas only BPA induced this same effect during brown adipogenesis. Moreover, BPA and its metabolites upregulated the expression of pan-adipogenic markers, such as peroxisome proliferator-activated receptor gamma (PPARγ), during white adipogenesis, whereas they downregulated that of PPARγ during brown adipogenesis. Additionally, BPA also inhibited the mRNA and protein expression of brown fat-specific markers (e.g., PPARγ coactivator 1-1alpha (PGC1-α) and uncoupling protein 1 (UCP1)), and mitochondrial activity during brown adipogenesis, and BPA-G also reduced the mRNA expression levels of Pgc1-α and Ucp1. These findings indicated that BPA induced different effects on white and brown adipogenesis, enhancing the former and hindering the latter. Despite less potent than BPA, BPA-G and BPA-S might also affect white and brown adipogenesis. This research provides in-depth insights into the obesogenic effects of BPA and the biological activities of its metabolites.

Palm and interesterified palm oil-enhanced brown fat whitening contributes to metabolic dysfunction in C57BL/6J mice

Palm oil is widely used in the food industry owing to its high stability and versatility. The interesterified version has been used as an alternative to oils rich in trans fatty acids. However, the health effects of these vegetable oils are not yet fully understood. We hypothesized that the consumption of palm oil (noninteresterified and interesterified), even without excessive amounts of energy and lipids in the diet, could lead to morphofunctional changes in brown adipose tissue (BAT). To this end, male C57BL/6J mice were divided into 3 dietary groups (n = 10 each): soybean oil (SO), palm oil (PO), and interesterified palm oil (IPO) for 10 weeks. The PO and IPO groups had significant increases in the visceral fat mass and interscapular BAT (iBAT) lipid content. In iBAT, the PO and IPO groups showed lower mRNA expression of Ucp1, Adrb3, and Pgc1a, while the PO also showed lower mRNA levels of Ppara and Ampk, and the IPO showed lower Prdm16 expression. Moreover, PO had higher Il6 expression and lower catalase activity, while the IPO showed an upregulated Tnfa expression and lower catalase activity, but higher antioxidant activity of the glutathione peroxidase (GPx) enzyme. The consumption of PO and IPO had negative effects on weight and body fat, including the impairment of iBAT function. Our findings give rise to apprehensions regarding the safety and consequences of consuming PO and IPO for energy metabolism.

Ucp1 Ablation Improves Skeletal Muscle Glycolytic Function in Aging Mice

Muscular atrophy is among the systematic decline in organ functions in aging, while defective thermogenic fat functionality precedes these anomalies. The potential crosstalk between adipose tissue and muscle during aging is poorly understood. In this study, it is showed that UCP1 knockout (KO) mice characterized deteriorated brown adipose tissue (BAT) function in aging, yet their glucose homeostasis is sustained and energy expenditure is increased, possibly compensated by improved inguinal adipose tissue (iWAT) and muscle functionality compared to age-matched WT mice. To understand the potential crosstalk, RNA-seq and metabolomic analysis were performed on adipose tissue and muscle in aging mice and revealed that creatine levels are increased both in iWAT and muscle of UCP1 KO mice. Interestingly, molecular analysis and metabolite tracing revealed that creatine biosynthesis is increased in iWAT while creatine uptake is increased in muscle in UCP1 KO mice, suggesting creatine transportation from iWAT to muscle. Importantly, creatine analog β-GPA abolished the differences in muscle functions between aging WT and UCP1 KO mice, while UCP1 inhibitor α-CD improved muscle glycolytic function and glucose metabolism in aging mice. Overall, these results suggested that iWAT and skeletal muscle compensate for declined BAT function during aging via creatine metabolism to sustain metabolic homeostasis.

Myricetin and myricitrin indirectly and directly increases uncoupling protein-1 mRNA expression in C3H10T1/2 beige adipocytes

In thermogenic brown and beige adipocytes, the proton gradient formed by energy derived from nutrients such as lipids and carbohydrates is consumed by uncoupling protein-1 (UCP-1), resulting in thermogenesis without ATP production in the mitochondria. Accordingly, increased UCP-1 expression represents a crucial aspect of dietary management for individuals with overweight and obesity. Myricetin and its glycoside, myricitrin, are food-derived flavonoids that possess various beneficial effects. This is the first study to examine the effects of myricetin and myricitrin on the inflammation-inhibited expression of Ucp-1 using a modified cell-based assay with conditioned medium (CM). The CM derived from lipopolysaccharide (LPS)-activated RAW264.7 macrophages was observed to inhibit the Ucp-1 expression induced by adrenergic stimulation in 10T1/2 adipocytes. Conversely, the CM derived from activated macrophages treated with myricetin or myricitrin reversed this inhibition of Ucp-1 expression. Subsequently, the direct effects of both the compounds on basal and adrenaline-induced expression of Ucp-1 were investigated. In contrast to a previous report, myricetin and myricitrin did not increase the basal Ucp-1 mRNA expression in 10T1/2 adipocytes when treated during the differentiation-promoting period. However, we have found for the first time that both compounds enhanced the adrenergic sensitivity of 10T1/2 adipocytes when treated during the differentiation-inducing period. These results indicate that myricetin and myricitrin have indirect effects on inflammation-induced suppression and direct effects on adrenergic sensitivity, suggesting a novel mechanism that both compounds increase Ucp-1 expression in vivo by both indirect and direct effects, rather than by affecting basal expression.

The bioavailability, absorption, metabolism, and regulation of glucolipid metabolism disorders by quercetin and its important glycosides: A review

Quercetin and its glycosides (QG), vitally natural flavonoid, have been popular for health benefits. However, the absorption and metabolism affect their bioavailability, and the metabolic transformation alters their biological activities. This review systematically summarizes the bioavailability and pathways for the absorption and metabolism of quercetin/QG in vivo and in vitro, the biological activities and mechanism of quercetin/QG and their metabolites in treating glucolipid metabolism are discussed. After oral administration, quercetin/QG are mainly absorbed by the intestine, undergo phase II metabolism in the small intestine and liver to form conjugates and are metabolized into small phenolic acids by intestinal microbiota. Quercetin/QG and their metabolites exert beneficial effects on regulating glucolipid metabolism disorders, including improving insulin resistance, inhibiting lipogenesis, enhancing thermogenesis, modulating intestinal microbiota, relieving oxidative stress, and attenuating inflammation. This review enhances understanding of the mechanism of quercetin/QG regulate glucolipid metabolism and provides scientific support for the development of functional foods.

Gene Therapy Approach for Treatment of Obese Agouti Mice

Obesity is a significant metabolic disorder associated with excessive fat accumulation and insulin resistance. In this study, we explored a gene therapy approach to treat obesity in agouti mice using adeno-associated viruses (AAVs) carrying PRDM16, FoxP4, or Follistatin (FST) genes, which are known to promote the browning of white adipose tissue. Mice treated with AAVs encoding PRDM16, FoxP4, or FST genes showed a reduction in body weight (10-14%) within the first three weeks after administration, compared to the control groups. A lipidomic analysis of the adipose tissue revealed a dramatic reduction in triacylglycerol (TAG) species with low carbon numbers (40-54 acyl carbons) in treated mice.

Rosiglitazone-induced white adipocyte browning is regulated by actin and Myh9

AIMS

This study investigates the role of actin polymerization and Myh9 in mediating lipid droplet (LD) fission during rosiglitazone-induced browning of white adipocytes. The aim is to understand how LD splitting might contribute to the beige conversion of white adipose tissue, providing insights into adipocyte plasticity and metabolic regulation.

MATERIALS AND METHODS

C3H10 T1/2-differentiated adipocytes were used as a classical model to study white adipocyte browning. Rosiglitazone was applied to induce browning, and the interactions between LDs and actin, as well as the distribution of Myh9, were assessed using immunofluorescence and Western blotting. In vivo, we employed a microfilament inhibitor to block actin polymerization in cold-stimulated mice and evaluated changes in LD morphology and browning. Furthermore, dynamic live-cell imaging using confocal microscopy was conducted to observe the real-time behavior of LDs during the browning process and to determine whether they undergo fission.

MAIN FINDINGS

Our results demonstrate that rosiglitazone significantly induces LD size reduction, a process correlated with the increased contact of LDs with microfilaments. Inhibition of actin polymerization prevented both the reduction in LD size and the browning of white adipocytes, indicating that actin plays a critical role. Myh9 was enriched at the LD fission sites, forming a structure resembling a contractile ring. Overexpression of Myh9 promoted the shrinkage of LD, suggesting that it may be involved in LD fission.

SIGNIFICANCE

This study identifies actin and Myh9 as key regulators of LD fission in rosiglitazone-induced browning of white adipocytes, offering new insights into the cellular mechanisms of adipocyte plasticity. The findings propose a novel pathway by which LD dynamics contribute to the beige conversion of white fat, with potential implications for metabolic disease therapies targeting adipocyte function and energy expenditure.

Myeloid-derived suppressor cells in the tumor microenvironment reduce uncoupling protein 1 expression to boost immunosuppressive activity

Uncoupling protein 1 (UCP1) is located at the inner membrane of mitochondria and mediates nonshivering thermogenesis. Its abnormal expression is associated with metabolic diseases, cancer, and acute kidney injury. Myeloid-derived suppressor cells (MDSCs) with immunosuppressive activity accumulate in the tumor microenvironment (TME). Here, decreased UCP1 expression in MDSCs was observed in the peripheral blood of patients with colorectal cancer and transplanted mouse tumors. Aggravated tumor progression was observed in UCP1-knockout mice and conditional knockout mice (UCP1fl/fl-S100A8cre). The number of G-MDSCs and M-MDSCs increased in the transplanted tumor tissues from UCP1-deficient mice compared with those from wild-type mice. The tumor-promoting effect disappeared when the tumor-bearing mice were depleted of MDSCs by the α-DR5 administration. Adoptive transfer of tumor-derived MDSCs sharply promoted the tumor growth in vivo. Furthermore, these tumor-derived MDSCs enhanced the proliferation, reduced death, inhibited IFN-γ production of CD4+ and CD8+T cells, and induced Treg cells ex vivo. In conclusion, MDSCs in the TME alter the metabolic pattern by decreasing UCP1 expression to enhance immunosuppressive activity for tumor escape.

IF1 is a cold-regulated switch of ATP synthase hydrolytic activity to support thermogenesis in brown fat

While mechanisms controlling uncoupling protein-1 (UCP1) in thermogenic adipocytes play a pivotal role in non-shivering thermogenesis, it remains unclear whether F1Fo-ATP synthase function is also regulated in brown adipose tissue (BAT). Here, we show that inhibitory factor 1 (IF1, encoded by Atp5if1), an inhibitor of ATP synthase hydrolytic activity, is a critical negative regulator of brown adipocyte energy metabolism. In vivo, IF1 levels are diminished in BAT of cold-adapted mice compared to controls. Additionally, the capacity of ATP synthase to generate mitochondrial membrane potential (MMP) through ATP hydrolysis (the so-called "reverse mode" of ATP synthase) is increased in brown fat. In cultured brown adipocytes, IF1 overexpression results in an inability of mitochondria to sustain the MMP upon adrenergic stimulation, leading to a quiescent-like phenotype in brown adipocytes. In mice, adeno-associated virus-mediated IF1 overexpression in BAT suppresses adrenergic-stimulated thermogenesis and decreases mitochondrial respiration in BAT. Taken together, our work identifies downregulation of IF1 upon cold as a critical event for the facilitation of the reverse mode of ATP synthase as well as to enable energetic adaptation of BAT to effectively support non-shivering thermogenesis.

Subcutaneously transplanted xenogeneic protein recruits treg cells and M2 macrophages to induce browning of inguinal white adipose tissue

OBJECTIVE

To study whether subcutaneously embedding xenogeneic protein threads or synthetic polymer absorbable threads can improve obesity phenotypes and metabolic conditions, and to further explore its underlying mechanism.

METHODS

Thirty-six 8-week-old ob/ob mice were randomly allocated to three groups, respectively, receiving catgut embedding, PGA thread embedding or sham treatment bilaterally to the groin. Individual parameters including weight, food intake, and core temperature are recorded and metabolism assessment, energy expenditure analysis, and PET/CT scanning are also performed at fixed timepoints. After surgical incision, the inguinal white adipose tissue was histologically examined and its expression profile was tested and compared among groups 4 weeks and 12 weeks after operation.

RESULTS

Catgut embedding reduced weight gain and improved metabolic status in ob/ob mice. Browning of bilateral inguinal WAT (white adipose tissue) was induced after catgut embedding, with massive infiltration of Treg cells and M2 macrophages in the tissue slices of fat pads. IL-10 and TGF-β released by Treg cells targeted macrophages and the induced M2 macrophages increased the expression of thermogenic and anti-inflammatory genes in fat. The secretion of catecholamines by polarized M2 macrophages led to the activation of β3-AR-related pathways in adipocytes and the browning of adipose tissue.

CONCLUSIONS

Abdominal subcutaneous catgut embedding has the potential to combat obesity through the induction of WAT browning mediated by infiltrated Treg cells and macrophages.

Brown adipose tissue thermogenesis rhythms are driven by the SCN independent of adipocyte clocks

Circadian misalignment has been associated with obesity both in rodents and humans. Brown adipose tissue (BAT) thermogenesis contributes to energy expenditure and can be activated in adults to reduce body weight. Although previous studies suggest control of BAT thermogenesis by the circadian clock, the site and mechanisms of regulation remain unclear. We used mice with genetic disruption of the circadian clock in the suprachiasmatic nucleus (SCN) and peripheral tissues to delineate their role in BAT thermogenesis. Global post-natal deletion of Bmal1 in adult mice ( Bmal1 -/- ) abolishes the rhythms of interscapular BAT temperature, a measure of thermogenesis, while normal locomotor activity rhythms are maintained under a regular 12h light-12h dark schedule. Activation of thermogenesis either by exposure to cold or adrenergic stimulation of BAT displays a diurnal rhythm with higher activation during the active period. Both the rhythm and the magnitude of the thermogenic response is preserved in Bmal1 -/- mice. In contrast to mice with global deletion of Bmal1 , mice with brown adipocyte (Ucp1- Bmal1 -/- ) or brown and white adipocyte (Ad- Bmal1 -/- ) deletion of Bmal1 show intact rhythms of BAT thermogenic activity. The capacity of Ucp1- Bmal1 -/- mice to activate thermogenesis in response to exposure to cold is identical to WT mice, independent of time of stimulation. Circadian rhythmicity of interscapular BAT temperature is lost in mice with SCN deletion of Bmal1 (SCN- Bmal1 -/- ), indicating control of BAT thermogenesis rhythms by the SCN. Control mice exhibit rhythmic BAT glucose and fatty acid uptake - a rhythm that is not recapitulated in Bmal1 -/- and SCN- Bmal1 -/- mice but is present in Ucp1- Bmal1 -/- and Ad- Bmal1 -/- mice. BAT cAMP and phosphorylated hormone-sensitive lipase (pHSL) is reduced during the active period in Bmal1 -/- and SCN- Bmal1 -/- mice consistent with reduced sympathetic tone. Furthermore, sympathetic denervation of BAT ablates BAT temperature rhythms in WT mice. Taken together, our findings suggest that the SCN drives rhythms of BAT thermogenesis through adipocyte clock-independent, sympathetic signaling to the BAT.

Withanolides-enriched leaf extract of Withania somnifera exert anti-obesity effects by inducing brown adipocyte-like phenotype via tuning MAP-kinase signaling axis

Present study investigated anti-obesity potential of Withania somnifera (L.) Dunal leaf extract (WSLE). Phytochemical characterization of WSLE was performed by UPLC/MS-QToF and HPLC-based analysis. WSLE was assessed for its effect on lipid metabolism and mitochondrial biogenesis in vitro using differentiated 3T3-L1 adipocytes. WSLE was found to contain 59 phytometabolites with a total of 10.601 μg withanolides per mg of extract. WSLE (30 μg/ml) treatment decreased basal levels of intracellular lipids and triglycerides to 13.85 % and 41.58 %, respectively. WSLE downregulated the expression of PPARγ, C/EBPα, C/EBPβ, and their target genes responsible for lipogenesis dose-dependently. An upregulation in expression of lipolytic (ATGL and HSL), thermogenic (PGC1α, UCP1, and PRDM16), and glucose transporter (GLUT4) genes was also observed. Furthermore, WSLE treatment increased glucose uptake by 1.5-fold. These beneficial effects of WSLE were abolished in presence of AMPK, p38MAPK, and ERK inhibitors. These observations were then validated in vivo using Caenorhabditis elegans as a model organism. Intriguingly, WSLE diminished fat accumulation in wild-type N2 worms as evident from reduced Oil-red-O staining and reduction in GFP expression of fat-5, 6, and 7 in transgenic strains. Overall, these results highlight anti-obesity potential of WSLE exerting its effects via alterations in AMPK/p38MAPK/ERK axis.

Expression of PGC-1α, PPAR-α and UCP1 genes, metabolic and anthropometric factors in response to sodium butyrate supplementation in patients with obesity: a triple-blind, randomized placebo-controlled clinical trial

OBJECTIVES

There is increasing evidence that gut metabolites have a role in the etiology of obesity. This study aimed to investigate the effects of sodium butyrate (NaB) supplementation on the expression of peroxisome proliferator-activated receptor (PPAR) gamma coactivator-1α (PGC-1α), PPAR-α, and uncoupling protein-1 (UCP-1) genes, as well as on the metabolic parameters and anthropometric indices in persons with obesity.

METHODS

In this triple-blind placebo-controlled randomized clinical trial, 50 individuals with obesity were randomly assigned to NaB (600 mg/day) + hypo-caloric diet or placebo group + hypo-caloric diet for 8 weeks. The study measured the participants' anthropometric characteristics, food consumption, and feelings of hunger in addition to the serum levels of metabolic indices and the mRNA expression of the PGC-1α, PPAR-α, and UCP-1 genes in peripheral blood mononuclear cells (PBMCs).

RESULTS

PGC-1α and UCP-1 genes expression significantly increased in NaB group compared to the placebo at the endpoint. A significant decrease in weight, BMI, and waist circumference (WC) was observed in NaB group. Among the metabolic factors, NaB significantly decreased fasting blood sugar (FBS) (P = 0.04), low-density lipoprotein cholesterol (LDL-C) (P = 0.038) and increased high-density lipoprotein cholesterol (HDL-C) (P = 0.016). NaB could not significantly change serum GLP-1 level.

CONCLUSIONS

This study unveiled NaB supplementation alone cannot have significant beneficial effects on anthropometric, and biochemical factors. NaB could affect anthropometric and metabolic risk variables associated with obesity only when prescribed, along with calorie restriction.

CLINICAL TRIAL REGISTRATION

This study was registered in the Iranian Registry of Clinical Trials ( https://en.irct.ir/trial/53968 ) on 31 January 2021 (registry number IRCT20190303042905N2).

Hederagenin from Hedera helix Promotes Fat Browning in 3T3-L1 Adipocytes

The prevalence of obesity is increasing globally, with approximately 700 million obese people worldwide. Currently, regulating energy homeostasis by increasing energy expenditure is attracting attention as a strategy for treating obesity. White adipose tissue is known to play a role in accumulating energy by storing excess energy, while brown adipose tissue expends energy and maintains body temperature. Thus, the browning of white adipose tissue has been shown to be effective in controlling obesity. Hedera helix (H. helix) has been widely used as a traditional medicine for various diseases. In several previous studies, hederagenin (HDG) from H. helix has demonstrated many biological activities. In this study, we investigated the antiobesity effect of HDG on fat browning in 3T3-L1 adipocytes. Consequent to HDG treatment, a reduction in lipid accumulation was measured through oil red O staining. In addition, this study investigated that HDG increases energy expenditure by upregulating the expression of several targets related to thermogenesis, including uncoupling protein 1 (UCP1). This process involves inhibiting lipogenesis via the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway and promoting lipolysis through the protein kinase A (PKA) pathway. HDG is expected to be effective in promoting fat browning, indicating its potential as a natural antiobesity candidate.

A review: Polysaccharides targeting mitochondria to improve obesity

Polysaccharides are one of the most important and widely used bioactive components of natural products, which can be used to treat metabolic diseases. Natural polysaccharides (NPs) have been the subject of much study and research in the field of treating obesity in recent years. Studies in the past have demonstrated that mitochondria are important for the initiation, progression, and management of obesity. Additionally, NPs have the ability to improve mitochondrial dysfunction via a variety of mechanisms. This review summarized the relationship between the structure of NPs and their anti-obesity activity, focusing on the anti-obesity effects of these compounds at the mitochondrial level. We discussed the association between the structure and anti-obesity action of NPs, including molecular weight, monosaccharide composition, glycosidic linkage, conformation and extraction methods. Furthermore, NPs can demonstrate a range of functions in adipose tissue, including but not limited to improving the mitochondrial oxidative respiratory chain, inhibiting oxidative stress, and maintaining mitochondrial mass homeostasis. The purpose of this work is to acquire a thorough understanding of the function that mitochondria play in the anti-obesity effects of NPs and to offer fresh insights for the investigation of how NPs prevent obesity and the creation of natural anti-obesity medications.

Ndufa8 promotes white fat Browning by improving mitochondrial respiratory chain complex I function to ameliorate obesity by in vitro and in vivo

Obesity and its complications have become a global health problem that needs to be addressed urgently. White adipose tissue (WAT) browning contributes to consuming excess energy in WAT, which is important for improving obesity and maintaining a healthy energy homeostasis. Mitochondria, as the energy metabolism center of cells, are extensively involved in many metabolic processes, including the browning of WAT. NADH: Ubiquinone oxidoreductase subunit A8 (NDUFA8) is a constituent subunit of respiratory chain complex I (CI), which has been found to participate in a wide range of physiological processes by affecting the activity of respiratory CI. However, the regulatory effect of Ndufa8 on the browning of WAT has not been reported. Here, we used β3-adrenergic agonis CL316, 243 to construct WAT browning models in vivo and in vitro to investigate the role and mechanism of Ndufa8 in the regulation of WAT browning. Briefly, Ndufa8 significantly increased CI activity and suppressed mitochondrial ROS levels in vitro, thereby improving mitochondrial function. Ndufa8 also increased the transcriptional levels and protein levels of UCP1 in vitro and in vivo, which promoted WAT browning. Our findings provide a new molecular approach for the research of browning of WAT in animals, as well as a new target for animal metabolism improvement and obesity treatments.

Silencing of dopamine receptor D5 inhibits the browning of 3T3-L1 adipocytes and ATP-consuming futile cycles in C2C12 muscle cells

BACKGROUND

As a part of the catecholamines, dopamine receptors (DRs) have not been extensively studied like β3-AR in the thermogenesis process. The present study investigates the effect of DRD5 in browning events and ATP-consuming futile cycles.

METHODS

siRNA technology, qPCR, immunoblot analysis, immunofluorescence, and staining methods were used to investigate the effect of DRD5 on 3T3-L1 and C2C12 cells.

RESULTS

siDdr5 increased lipogenesis-associated effectors, and adipogenesis markers while reducing the expression of beige fat effectors. ATP-consuming futile cycle markers were also reduced following the siDrd5. On the contrary, pharmacological activation of DRD5 stimulated these effectors. Our mechanistic studies elucidated that DRD5 mediates fat browning via the cAMP-PKA-p38 MAPK signalling pathway in 3T3-L1 cells as well as the cAMP-SERCA-RyR pathway for the ATP-consuming futile cycles in both cells.

CONCLUSIONS

siDrd5 positively regulates browning and ATP-consuming futile cycles, and understanding its functions will provide insights into novel strategies to treat obesity.

Legumain-deficient macrophages regulate inflammation and lipid metabolism in adipose tissues to protect against diet-induced obesity

Adipose tissue macrophages (ATMs) are key players in the development of obesity and associated metabolic inflammation, which contributes to systemic metabolic dysfunction, and understanding the interaction between macrophages and adipocytes is crucial for developing novel macrophage-based strategies against obesity. Here, we found that Legumain (Lgmn), a well-known lysosomal cysteine protease, is expressed mainly in the ATMs of obese mice. To further define the potential role of Lgmn-expressing macrophages in the generation of an aberrant metabolic state, LgmnF/F; LysMCre mice, which do not express Lgmn in macrophages, were maintained on a high-fat diet (HFD), and metabolic parameters were assessed. Macrophage-specific Lgmn deficiency protects mice against HFD-induced obesity, diminishes the quantity of proinflammatory macrophages in obese adipose tissues, and alleviates hepatic steatosis and insulin resistance. By analysing the transcriptome and proteome of murine visceral white adipose tissue (vWAT) after HFD feeding, we determined that macrophage Lgmn deficiency causes changes in lipid metabolism and the inflammatory response. Furthermore, the reciprocity of macrophage-derived Lgmn with integrin α5β1 in adipocytes was tested via colocalization analyses. It is further demonstrated in macrophage and adipocyte coculture system that macrophage derived Lgmn bound to integrin α5β1 in adipocytes, therefore attenuating PKA activation, downregulating lipolysis-related proteins and eventually exacerbating obesity development. Overall, our study identified Lgmn as a previously unrecognized regulator involved in the interaction between ATMs and adipocytes contributing to diet-induced obesity and suggested that Lgmn is a potential target for treating metabolic disorders.

Understanding coenzyme Q

Coenzyme Q (CoQ), also known as ubiquinone, comprises a benzoquinone head group and a long isoprenoid side chain. It is thus extremely hydrophobic and resides in membranes. It is best known for its complex function as an electron transporter in the mitochondrial electron transport chain (ETC) but is also required for several other crucial cellular processes. In fact, CoQ appears to be central to the entire redox balance of the cell. Remarkably, its structure and therefore its properties have not changed from bacteria to vertebrates. In metazoans, it is synthesized in all cells and is found in most, and maybe all, biological membranes. CoQ is also known as a nutritional supplement, mostly because of its involvement with antioxidant defenses. However, whether there is any health benefit from oral consumption of CoQ is not well established. Here we review the function of CoQ as a redox-active molecule in the ETC and other enzymatic systems, its role as a prooxidant in reactive oxygen species generation, and its separate involvement in antioxidant mechanisms. We also review CoQ biosynthesis, which is particularly complex because of its extreme hydrophobicity, as well as the biological consequences of primary and secondary CoQ deficiency, including in human patients. Primary CoQ deficiency is a rare inborn condition due to mutation in CoQ biosynthetic genes. Secondary CoQ deficiency is much more common, as it accompanies a variety of pathological conditions, including mitochondrial disorders as well as aging. In this context, we discuss the importance, but also the great difficulty, of alleviating CoQ deficiency by CoQ supplementation.

Characterization of Ucp1-iCre knockin mice reveals the recombination activity in male germ cells

Ucp1 promoter-driven Cre transgenic mice are useful in the manipulation of gene expression specifically in thermogenic adipose tissues. However, the wildly used Ucp1-Cre line was generated by random insertion into the genome and showed ectopic activity in some tissues beyond adipose tissues. Here, we characterized a knockin mouse line Ucp1-iCre generated by targeting IRES-Cre cassette immediately downstream the stop codon of the Ucp1 gene. The Cre insertion had little to no effect on uncoupling protein 1 (UCP1) levels in brown adipose tissue. Ucp1-iCre mice of both genders exhibited normal thermogenesis and cold tolerance. When crossed with Rosa-tdTomato reporter mice, Ucp1-iCre mice showed robust Cre activity in thermogenic adipose tissues. In addition, limited Cre activity was sparsely present in the ventromedial hypothalamus (VMH), choroid plexus, kidney, adrenal glands, ovary, and testis in Ucp1-iCre mice, albeit to a much lesser extent and with reduced intensity compared with the conventional Ucp1-Cre line. Single-cell transcriptome analysis revealed Ucp1 mRNA expression in male spermatocytes. Moreover, male Ucp1-iCre mice displayed a high frequency of Cre-mediated recombination in the germline, whereas no such effect was observed in female Ucp1-iCre mice. These findings suggest that Ucp1-iCre mice offer promising utility in the context of conditional gene manipulation in thermogenic adipose tissues, while also highlighting the need for caution in mouse mating and genotyping procedures.NEW & NOTEWORTHY Ucp1 promoter-driven Cre transgenic mice are useful in the manipulation of gene expression specifically in thermogenic adipose tissues. The widely used Ucp1-Cre mouse line (Ucp1-CreEvdr), which was generated using the bacterial artificial chromosome (BAC) strategy, exhibits major brown and white fat transcriptomic dysregulation and ectopic activity beyond adipose tissues. Here, we comprehensively validate Ucp1-iCre knockin mice, which serve as another optional model besides Ucp1-CreEvdr mice for specific genetic manipulation in thermogenic tissue.

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.

Single-nucleus transcriptomics identifies separate classes of UCP1 and futile cycle adipocytes

Adipose tissue can recruit catabolic adipocytes that utilize chemical energy to dissipate heat. This process occurs either by uncoupled respiration through uncoupling protein 1 (UCP1) or by utilizing ATP-dependent futile cycles (FCs). However, it remains unclear how these pathways coexist since both processes rely on the mitochondrial membrane potential. Utilizing single-nucleus RNA sequencing to deconvolute the heterogeneity of subcutaneous adipose tissue in mice and humans, we identify at least 2 distinct subpopulations of beige adipocytes: FC-adipocytes and UCP1-beige adipocytes. Importantly, we demonstrate that the FC-adipocyte subpopulation is highly metabolically active and utilizes FCs to dissipate energy, thus contributing to thermogenesis independent of Ucp1. Furthermore, FC-adipocytes are important drivers of systemic energy homeostasis and linked to glucose metabolism and obesity resistance in humans. Taken together, our findings identify a noncanonical thermogenic adipocyte subpopulation, which could be an important regulator of energy homeostasis in mammals.

Lactating striped hamsters (Cricetulus barabensis) do not decrease the thermogenic capacity to cope with extreme cold temperature

For small non-hibernating mammals, a high thermogenic capacity is important to increase activity levels in the cold. It has been previously reported that lactating females decrease their thermogenic activity of brown adipose tissue (BAT), whereas their capacity to cope with extreme cold remains uncertain. In this study we examined food intake, body temperature and locomotor behavior, resting metabolic rate, non-shivering thermogenesis, and cytochrome c oxidase activity, and the rate of state 4 respiration of liver, skeletal muscle, and BAT in striped hamsters (Cricetulus barabensis) at peak lactation and non- breeding hamsters (controls). The lactating hamsters and non- breeding controls were acutely exposed to -15°C, and several markers indicative of thermogenic capacity were examined. In comparison to non-breeding females, lactating hamsters significantly increased food intake and body temperature, but decreased locomotor behavior, and the BAT mass, indicative of decreased BAT thermogenesis at peak lactation. Unexpectedly, lactating hamsters showed similar body temperature, resting metabolic rate, non-shivering thermogenesis with non-breeding females after acute exposure to -15°C. Furthermore, cytochrome c oxidase activity of liver, skeletal muscle and BAT, and serum thyroid hormone concentration, and BAT uncoupling protein 1 expression, in lactating hamsters were similar with that in non-breeding hamsters after acute extreme cold exposure. This suggests that lactating females have the same thermogenic capacity to survive cold temperatures compared to non-breeding animals. This is particularly important for females in the field to cope with cold environments during the period of reproduction. Our findings indicate that the females during lactation, one of the highest energy requirement periods, do not impair their thermogenic capacity in response to acute cold exposure.

Kinin B1 receptor deficiency promotes enhanced adipose tissue thermogenic response to β3-adrenergic stimulation

OBJECTIVE AND DESIGN

Kinin B1 receptor (B1R) has a key role in adipocytes to protect against obesity and glycemic metabolism, thus becoming a potential target for regulation of energy metabolism and adipose tissue thermogenesis.

MATERIAL OR SUBJECTS

Kinin B1 knockout mice (B1KO) were subjected to acute induction with CL 316,243 and chronic cold exposure.

METHODS

Metabolic and histological analyses, gene and protein expression and RNA-seq were performed on interscapular brown adipose tissue (iBAT) and inguinal white adipose tissue (iWAT) of mice.

RESULTS

B1KO mice, under acute effect of CL 316,243, exhibited increased energy expenditure and upregulated thermogenic genes in iWAT. They were also protected from chronic cold, showing enhanced non-shivering thermogenesis with increased iBAT mass (~ 90%) and recruitment of beige adipocytes in iWAT (~ 50%). Positive modulation of thermogenic and electron transport chain genes, reaching a 14.5-fold increase for Ucp1 in iWAT. RNA-seq revealed activation of the insulin signaling pathways for iBAT and oxidative phosphorylation, tricarboxylic acid cycle, and browning pathways for iWAT.

CONCLUSION

B1R deficiency induced metabolic and gene expression alterations in adipose tissue, activating thermogenic pathways and increasing energy metabolism. B1R antagonists emerge as promising therapeutic targets for regulating obesity and associated metabolic disorders, such as inflammation and diabetes.

Therapeutic of a white adipose tissue-specific bivalent aptamer in obesity

The white adipose tissue-specific aptamer Adipo8 can specificity bindwith mature adipocytes or tissues and inhibit adipogenesis.In this research, we exploredthe effect of Adipo8 intervention on the transcriptome in the process of adipogenesis using mRNA-level sequencing,analyzed the mechanism ofAdipo8 ininhibiting adipogenesis. The results showed that Adipo8 can inhibit lipid formation and downregulate PPARγ and C/EBPα in differentiated 3 T3-L1 cells. Transcriptome mRNA sequencing of 3 T3-L1 cells after Adipo8 interventionrevealed that Adipo8 might inhibit the biological function of adipogenesis by downregulating Acsl1 and Plin1 to inhibit fatty acid metabolism and PPAR signaling pathways.After that, using Spacer18 to connect the optimized and truncated Adipo8, we constructed a bivalent aptamer Adipo8cBand compared the affinity, biological effects, and biological stability between the aptamers in differentiated and mature 3 T3-L1 cells. At the cellular level,the affinity, biological effects, and serum stability of Adipo8cB were verified to be superior to those of Adipo8in 3 T3-L1 cells.We then investigated the biological properties of Adipo8cB as a lipid-inhibiting drug invivo, using C57BL/6J mice with diet-induced obesity. The body weight, blood sugar, lipid levels, liver function, glucose tolerance, and other related indicators in each group of mice were observed and compared after intervention with the bivalent aptamers Adipo8cB and Adipo8. Both Adipo8cB and Adipo8 effectively prevented weight gain caused by fat accumulation in micewith diet induced obesity, while also reducing blood lipid levels, improving glucose tolerance, and protecting against liver steatosis, moreover, Adipo8cB has a better effect than Adipo8.

Development and Evaluation of Reconstructed Nanovesicles from Turmeric for Multifaceted Obesity Intervention

The escalating prevalence of obesity poses significant health challenges due to its direct association with various diseases. Most existing medications, such as appetite suppressants and fat absorption inhibitors, suffer from limited effectiveness and undesirable side effects. Here, inspired by the versatile metabolic effects of turmeric, we developed a naturally derived nanoformulation of "Reconstructed Turmeric-derived Nanovesicles (Rec-tNVs)" for obesity treatment. Employing quantitative nanoflow cytometry, a four-orders-of-magnitude increase in curcumin content (∼108 molecules per particle) was identified in individual Rec-tNVs compared to their ultracentrifugation-isolated counterparts. Rec-tNVs, featuring highly aggregated curcumin arrangements and other coencapsulated bioactive compounds, demonstrated a dose-dependent lipid-lowering effect in mature 3T3-L1 cells by promoting lipolysis, suppressing lipogenesis, inducing adipocyte browning, and triggering apoptosis after internalization via multiple pathways. In vivo experiments revealed that Rec-tNVs alleviated obesity more effectively than free curcumin and achieved weight reductions of 18.68 and 14.56% through intragastric and subcutaneous delivery, respectively, in high-fat-diet mouse models over a four-week treatment period. These effects were attributed to targeted actions on adipose tissues and systemic impacts on metabolism and gut microbiota composition. Overall, this study underscores the multifaceted antiobesity efficacy of Rec-tNVs, and offers a promising paradigm for developing plant-derived nanovesicle-based therapeutics.

TRPV1 Activation Antagonizes High-Fat Diet-Induced Obesity at Thermoneutrality and Enhances UCP-1 Transcription via PRDM-16

Body weight is a balance between energy intake and energy expenditure. Energy expenditure is mainly governed by physical activity and adaptive thermogenesis. Adaptive dietary thermogenesis in brown and beige adipose tissue occurs through mitochondrial uncoupling protein (UCP-1). Laboratory mice, when housed at an ambient temperature of 22-24 °C, maintain their body temperature by dietary thermogenesis, eating more food compared to thermoneutrality. Humans remain in the thermoneutral zone (TNZ) without expending extra energy to maintain normal body temperature. TRPV1 activation by capsaicin (CAP) inhibited weight gain in mice housed at ambient temperature by activating UCP-1-dependent adaptive thermogenesis. Hence, we evaluated the effect of CAP feeding on WT and UCP-1-/- mice maintained under thermoneutral conditions. Our research presents novel findings that TRPV1 activation by CAP at thermoneutrality counters obesity in WT mice and promotes PRDM-16-dependent UCP-1 transcription. CAP fails to inhibit weight gain in UCP-1-/- mice housed at thermoneutrality and in adipose tissue-specific PRDM-16-/- mice. In vitro, capsaicin treatment increases UCP-1 transcription in PRDM-16 overexpressing cells. Our data indicate for the first time that TRPV1 activation counters obesity at thermoneutrality permissive for UCP-1 and the enhancement of PRDM-16 is not beneficial in the absence of UCP-1.

Rhein targets macrophage SIRT2 to promote adipose tissue thermogenesis in obesity in mice

Rhein, a component derived from rhubarb, has been proven to possess anti-inflammatory properties. Here, we show that rhein mitigates obesity by promoting adipose tissue thermogenesis in diet-induced obese mice. We construct a macrophage-adipocyte co-culture system and demonstrate that rhein promotes adipocyte thermogenesis through inhibiting NLRP3 inflammasome activation in macrophages. Moreover, clues from acetylome analysis identify SIRT2 as a potential drug target of rhein. We further verify that rhein directly interacts with SIRT2 and inhibits NLRP3 inflammasome activation in a SIRT2-dependent way. Myeloid knockdown of SIRT2 abrogates adipose tissue thermogenesis and metabolic benefits in obese mice induced by rhein. Together, our findings elucidate that rhein inhibits NLRP3 inflammasome activation in macrophages by regulating SIRT2, and thus promotes white adipose tissue thermogenesis during obesity. These findings uncover the molecular mechanism underlying the anti-inflammatory and anti-obesity effects of rhein, and suggest that rhein may become a potential drug for treating obesity.

Ling-gui-zhu-gan promotes adipocytes browning via targeting the miR-27b/PRDM16 pathway in 3T3-L1 cells

Introduction: Obesity, a global epidemic, is caused by an imbalance between energy intake and expenditure. The induction of white adipose browning to increase heat production has emerged as a potential effective strategy to address obesity. Ling-gui-zhu-gan (LGZG), a traditional Chinese medicine formula, has been proved to achieve promising results to combat obesity and related metabolic diseases, yet the mechanisms remain largely unexplored. This study aimed to elucidate the anti-obesity properties and the mechanisms of LGZG by investigating its browning effect on 3T3-L1 adipocytes. Methods: LGZG-containing serum obtained by oral administration of LGZG to animals was added to 3T3-L1 adipocytes to simulate in vivo conditions. Results: The results showed that 49 compounds were identified in LGZG-containing serum by UHPLC-Q-Orbitrap HRMS, including compounds such as atractylenolides and polyporenic acid C, etc. LGZG-containing serum alleviated the lipid accumulation and decreased both intracellular and extracellular triglyceride contents in a dose-dependent manner. This reduction is accompanied by enhanced mitochondrial respiratory and heat production function. Mechanistically, LGZG-containing serum led to a decrease in miR-27b expression and an increase in the mRNA and protein levels of browning-related markers, including UCP1, PRDM16, PGC-1α, PPARγ, CTBP1, and CTBP2. Further investigation using miR-27b mimic transfection confirmed that miR-27b/PRDM16 pathway might be a potential mechanism by which LGZG-containing serum promotes browning of 3T3-L1 adipocytes. Discussion: These results underscore the therapeutic potential of LGZG in addressing obesity and its associated metabolic disorders through the promotion of adipose browning.

Cysteine depletion triggers adipose tissue thermogenesis and weight-loss

Dietary interventions such as caloric restriction (CR)1 and methionine restriction2 that prolong lifespan induce the 'browning' of white adipose tissue (WAT), an adaptive metabolic response that increases heat production to maintain health3,4. However, how diet influences adipose browning and metabolic health is unclear. Here, we identified that weight-loss induced by CR in humans5 reduces cysteine concentration in WAT suggesting depletion of this amino-acid may be involved in metabolic benefits of CR. To investigate the role of cysteine on organismal metabolism, we created a cysteine-deficiency mouse model in which dietary cysteine was eliminated and cystathionine γ-lyase (CTH)6, the enzyme that synthesizes cysteine was conditionally deleted. Using this animal model, we found that systemic cysteine-depletion causes drastic weight-loss with increased fat utilization and browning of adipose tissue. The restoration of dietary cysteine in cysteine-deficient mice rescued weight loss together with reversal of adipose browning and increased food-intake in an on-demand fashion. Mechanistically, cysteine deficiency induced browning and weight loss is dependent on sympathetic nervous system derived noradrenaline signaling via β3-adrenergic-receptors and does not require UCP1. Therapeutically, in high-fat diet fed obese mice, one week of cysteine-deficiency caused 30% weight-loss and reversed inflammation. These findings thus establish that cysteine is essential for organismal metabolism as removal of cysteine in the host triggers adipose browning and rapid weight loss.

Cationic polymer effect on brown adipogenic induction of dedifferentiated fat cells

Obesity and its associated comorbidities place a substantial burden on public health. Given the considerable potential of brown adipose tissue in addressing metabolic disorders that contribute to dysregulation of the body's energy balance, this area is an intriguing avenue for research. This study aimed to assess the impact of various polymers, including collagen type I, fibronectin, laminin, gelatin, gellan gum, and poly-l-lysine (PLL), on the in vitro brown adipogenic differentiation of dedifferentiated fat cells within a fibrin gel matrix. The findings, obtained through RT-qPCR, immunofluorescent imaging, ELISA assay, and mitochondria assessment, revealed that PLL exhibited a significant browning-inducing effect. Compared to fibrin-only brown-like drops after two weeks of incubation in brown adipogenic medium, PLL showed 6 (±3) times higher UCP1 gene expression, 5 (±2) times higher UCP1 concentration by ELISA assay, and 2 (±1) times higher mitochondrial content. This effect can be attributed to PLL's electrostatic properties, which potentially facilitate the cellular uptake of crucial brown adipogenic inducers such as the thyroid hormone, triiodothyronine (T3), and insulin from the induction medium.

Interleukin-10 deficiency induces thoracic perivascular adipose tissue whitening and vascular remodeling

Perivascular adipose tissue (PVAT) is an adipose layer, surrounding blood vessels, with a local modulatory role. Interleukin-10 (IL-10) has been shown to modulate vascular tissue. This study aimed to characterize the endogenous role of IL-10 in vascular remodeling, and PVAT phenotyping. Thoracic aortic segments from control (C57BL/6J) and IL-10 knockout (IL-10-/-) male mice were used. Analyzes of aorta/PVAT morphometry, and elastin, collagen and reticulin deposition were performed. Tissue uncoupling protein 1 (UCP1) was accessed by Western blotting. Endogenous absence of IL-10 reduced total PVAT area (p = 0.0310), and wall/lumen ratio (p = 0.0024), whereas increased vascular area and thickness (p < 0.0001). Total collagen deposition was augmented in IL-10-/-, but under polarized light, the reduction of collagen-I (p = 0.0075) and the increase of collagen-III (p = 0.0055) was found, simultaneously with reduced elastic fibers deposition (p = 0.0282) and increased deposition of reticular fibers (p < 0.0001). Adipocyte area was augmented in the IL-10 absence (p = 0.0225), and UCP1 expression was reduced (p = 0.0420). Moreover, relative frequency of white adipose cells and connective tissue was augmented in IL-10-/- (p < 0.0001), added to a reduction in brown adipose cells (p < 0.0001). Altogether, these data characterize aorta PVAT from IL-10-/- as a white-like adipocyte phenotype. Endogenous IL-10 prevents vascular remodeling and favors a brown-like adipocyte phenotype, suggesting a modulatory role for IL-10 in PVAT plasticity.

Tetrahydroberberrubine exhibits preventive effect on obesity by activating PGC1α-mediated thermogenesis in white and brown adipose tissue

The escalating prevalence of obesity presents formidable challenges, necessitating the development of effective therapeutic strategies. In this study, we aimed to elucidate the preventive effects on obesity of tetrahydroberberrubine (THBru), a derivative of berberine (BBR) and to unravel its underlying mechanism. Using an obese mouse model induced by a high-fat diet (HFD), THBru was found to markedly ameliorate obesity, as evidenced by reduced body weight, decreased Lee's index, diminished fat mass in epididymal white adipose tissue (WAT) and brown adipose tissue (BAT), alongside improved dyslipidemia. Notably, at the same dose, THBru exhibited superior efficacy compared to BBR. RNA-sequencing and gene set enrichment analysis indicated THBru activated thermogenesis, which was further confirmed in WAT, BAT, and 3T3-L1 cells. Bioinformatics analysis of RNA-sequencing data revealed the candidate gene Pgc1α, a key regulator involved in thermogenesis. Moreover, THBru was demonstrated to elevate the expression of PGC1α by stabilizing its mRNA in WAT, BAT and 3T3-L1 cells. Furthermore, PGC1α knockdown blocked the pro-thermogenic and anti-obesity action of THBru both in vivo and in vitro. This study unravels the preventive effects of THBru on obesity through the activation of PGC1α-mediated thermogenesis, thereby delineating its potential therapeutic implications for obesity and associated disorders.

Changes in brown adipose tissue induced by resveratrol and its analogue pterostilbene in rats fed with a high-fat high-fructose diet

Natural bioactive compounds have attracted a great deal of attention since some of them can act as thermogenesis activators. In recent years, special interest has been placed on resveratrol and its analogue pterostilbene, a dimethylether derivative that shows higher bioavailability. The aim of the present study is to compare the effects of resveratrol and its derivative pterostilbene on the thermogenic capacity of interscapular brown adipose tissue (iBAT) in rats under a high-fat high-fructose diet. Rats were divided into four experimental groups: control, high-fat high-fructose diet (HFHF) and HFHF diet supplemented with 30 mg/kg body weight/day of pterostilbene (PT30) or resveratrol (RSV30), for eight weeks. Weights of adipose tissues, iBAT triglycerides, carnitine palmitoyltransferase 1A (CPT1A) and citrate synthase (CS) activities, protein levels of uncoupling protein 1 (UCP1), sirtuins (SIRT1 and 3), AMP-activated protein kinase (AMPK), glucose transporter (GLUT4), fatty acid synthase (FAS), nuclear respiratory factor (NRF1), hormone-sensitive lipase (HSL), adipose triglyceride lipase (ATGL), CD36 and FATP1 fatty acid transporters, peroxisome proliferator-activated receptor gamma coactivator 1 (PGC1) activation and the batokines EPDR1 and NRG4 were assessed in iBAT. The results show that some key proteins related to thermogenesis were modified by either pterostilbene or resveratrol, although the lack of effects on other crucial proteins of the thermogenic machinery suggest that these compounds were not able to stimulate this process in iBAT. Overall, these data suggest that the effects of stilbenes on brown adipose tissue thermogenic capacity depend on the metabolic status, and more precisely on the presence or absence of obesity, although further studies are needed to confirm this hypothesis.

Different parts of the mussel Gigantidas haimaensis holobiont responded differently to deep-sea sampling stress

Acute environmental changes cause stress during conventional deep-sea biological sampling without in situ fixation and affect gene expressions of samples collected. However, the degree of influence and underlying mechanisms are hardly investigated. Here, we conducted comparative transcriptomic analyses between in situ and onboard fixed gills and between in situ and onboard fixed mantles of deep-sea mussel Gigantidas haimaensis to assess the effects of incidental sampling stress. Results showed that transcription, translation, and energy metabolism were upregulated in onboard fixed gills and mantles, thereby mobilizing rapid gene expression to tackle the stress. Autophagy and phagocytosis that related to symbiotic interactions between the host and endosymbiont were downregulated in the onboard fixed gills. These findings demonstrated that symbiotic gill and nonsymbiotic mantle responded differently to sampling stress, and symbiosis in the gill was perturbed. Further comparative metatranscriptomic analysis between in situ and onboard fixed gills revealed that stress response genes, peptidoglycan biosynthesis, and methane fixation were upregulated in the onboard fixed endosymbiotic Gammaproteobacteria inside the gills, implying that energy metabolism of the endosymbiont was increased to cope with sampling stress. Furthermore, comparative analysis between the mussel G. haimaensis and the limpet Bathyacmaea lactea transcriptomes resultedidentified six transcription factor orthologs upregulated in both onboard fixed mussel mantles and limpets, including sharply increased early growth response protein 1 and Kruppel-like factor 5. They potentially play key roles in initiating the response of sampled deep-sea macrobenthos to sampling stress. Our results clearly show that in situ fixed biological samples are vital for studying deep-sea environmental adaptation.

Engineering an energy-dissipating hybrid tissue in vivo for obesity treatment

Obesity is a global health challenge with limited therapeutic solutions. Here, we demonstrate the engineering of an energy-dissipating hybrid tissue (EDHT) in the body for weight control. EDHT is constructed by implanting a synthetic gel matrix comprising immunomodulatory signals and functional cells into the recipient mouse. The immunomodulatory signals induce the host stromal cells to create an immunosuppressive niche that protects the functional cells, which are overexpressing the uncoupling protein 1 (UCP1), from immune rejection. Consequently, these endogenous and exogenous cells co-develop a hybrid tissue that sustainedly produces UCP1 to accelerate the host's energy expenditure. Systematic experiments in high-fat diet (HFD) and transgenic (ob/ob) mice show that EDHT efficiently reduces body weight and relieves obesity-associated pathological conditions. Importantly, an 18-month observation for safety assessment excludes cell leakage from EDHT and reports no adverse physiological responses. Overall, EDHT demonstrates convincing efficacy and safety in controlling body weight.

Decrease in UCP1 by sustained high lipid promotes NK cell necroptosis to exacerbate nonalcoholic liver fibrosis

Uncoupling protein 1 (UCP1) catalyzes the leak of protons across the mitochondrial inner membrane for thermogenesis. Compromised NK cell activity is involved in the occurrence of nonalcoholic liver fibrosis. Here, decreased UCP1 in NK cells was identified in patients with advanced nonalcoholic fatty liver disease. Although no obvious changes were observed in the NK cells of physiologic UCP1-/- mice (8-10 weeks old), impaired NK cell bioactivity was shown in methionine-choline-diet (MCD)-fed UCP1-/- mice and involved in the acerbation of nonalcoholic steatohepatitis (NASH) progress to liver fibrosis. Moreover, UCP1-deficient NK cells were responsible for the aggravation of liver fibrosis, as confirmed in MCD-fed UCP1flox/flox-NCR1cre mice. Acerbation of liver fibrosis was also seen in wild-type mice when their endogenous NK cells were replaced with UCP1-/- NK cells. Transcriptions of mitophagy-associated molecules in UCP1-/- NK cells were enhanced according to RNA-seq. Electron microscopic results showed mitochondrial injuries and autophagic vesicles in MCD-fed NKWT cells, PA-treated NKWT cells, or physiologic NKKO cells. However, the co-existence of UCP1 deficiency and high lipid can synergistically induce NK cell necroptosis via DRP1S616 accompanied with reduced mitophagy. Finally, The UCP1 in NK cells was downregulated when treated by sustained high PA (600 μM) via the PPARγ/ATF2 axis. Thus, persistent high-lipid treatment not only decreases UCP1 expression but also combines with reduced UCP1 to promote NK cell necroptosis, and it is involved in NASH progression to fibrosis.

Ginsenoside Rb1 regulates CPT1A deacetylation to inhibit intramuscular fat infiltration after rotator cuff tear

Fat infiltration (FI) in the rotator cuff muscle is associated with poor clinical outcomes and failed repair of rotator cuff tears (RCTs) in patients. In this study, we aimed to investigate the function of ginsenoside Rb1 in inhibiting FI in muscles after RCT and its underlying molecular mechanism. After TT modeling, mice treated with Rb1 for 6 weeks showed lower FI in the SS muscle compared with mice in the control groups and those treated with other ginsenoside components. Mechanically, Rb1 binds to the NAD+ domain of SIRT1, activating its expression and enzyme activity. This activation stimulates the deacetylation of CPT1A at site K195, thereby promoting fatty acid β-oxidation in adipocyte cells and improving lipolysis. These findings suggest that Rb1 is a potential therapeutic component for improving the outcomes of patients with RCTs.

Adipose Tissue Dysfunction Related to Climate Change and Air Pollution: Understanding the Metabolic Consequences

Obesity, a global pandemic, poses a major threat to healthcare systems worldwide. Adipose tissue, the energy-storing organ during excessive energy intake, functions as a thermoregulator, interacting with other tissues to regulate systemic metabolism. Specifically, brown adipose tissue (BAT) is positively associated with an increased resistance to obesity, due to its thermogenic function in the presence of uncoupled protein 1 (UCP1). Recently, studies on climate change and the influence of environmental pollutants on energy homeostasis and obesity have drawn increasing attention. The reciprocal relationship between increasing adiposity and increasing temperatures results in reduced adaptive thermogenesis, decreased physical activity, and increased carbon footprint production. In addition, the impact of climate change makes obese individuals more prone to developing type 2 diabetes mellitus (T2DM). An impaired response to heat stress, compromised vasodilation, and sweating increase the risk of diabetes-related comorbidities. This comprehensive review provides information about the effects of climate change on obesity and adipose tissue, the risk of T2DM development, and insights into the environmental pollutants causing adipose tissue dysfunction and obesity. The effects of altered dietary patterns on adiposity and adaptation strategies to mitigate the detrimental effects of climate change are also discussed.

Dietary Pectin from Premna microphylla Turcz Leaves Prevents Obesity by Regulating Gut Microbiota and Lipid Metabolism in Mice Fed High-Fat Diet

The present study was designed to investigate the protective effects of pectin extracted from Premna microphylla Turcz leaves (PTP) against high-fat-diet (HFD)-induced lipid metabolism disorders and gut microbiota dysbiosis in obese mice. PTP was made using the acid extraction method, and it was found to be an acidic pectin that had relative mole percentages of 32.1%, 29.2%, and 26.2% for galacturonic acid, arabinose, and galactose, respectively. The administration of PTP in C57BL/6J mice inhibited the HFD-induced abnormal weight gain, visceral obesity, and dyslipidemia, and also improved insulin sensitivity, as revealed by the improved insulin tolerance and the decreased glucose levels during an insulin sensitivity test. These effects were linked to increased energy expenditure, as demonstrated by the upregulation of thermogenesis-related protein UCP1 expression in the brown adipose tissue (BAT) of PTP-treated mice. 16S rRNA gene sequencing revealed that PTP dramatically improved the HFD-induced gut dysbiosis by lowering the ratio of Firmicutes to Bacteroidetes and the quantity of potentially harmful bacteria. These findings may provide a theoretical basis for us to understand the functions and usages of PTP in alleviating obesity.