Understanding adipocyte differentiation

Adipocyte-derived extracellular vesicles in health and diseases: Nano-packages with vast biological properties

As the largest human energy reservoir, adipocytes drive an intense dialog with other cells/organs throughout the body to regulate the size of adipose tissue and to communicate with other metabolic tissues and the brain to regulate energy supply. Adipokines have long been described as mediators of this crosstalk, participating in obesity‐associated complications. Recently, adipocyte‐derived extracellular vesicles (Ad‐EVs) have emerged as new key actors in this communication due to their powerful capacity to convey complex messages between cells. Ad‐EVs convey specific subpopulations of RNA, proteins, and lipids from their parental cells, and can transfer these cargoes into various recipient cells, modulating their metabolism and cell cycle. In healthy individuals, Ad‐EVs actively participate in adipose tissue remodeling to compensate energy supply variations by exchanging information between adipocytes or stroma‐vascular cells, including immune cells. Besides this, recent evidence points out that Ad‐EV secretion and composition from dysfunctional adipocytes are strongly impacted within adipose tissue where they modulate local intercellular communication, contributing to inflammation, fibrosis, abnormal angiogenesis, and at distance with other cells/tissues intrinsically linked to fat (muscle, hepatocytes and even cancer cells). Additionally, some data even suggests that Ad‐EVs might have a systemic action. In this review, we will describe the particular properties of Ad‐EVs and their involvement in health and diseases, with a particular focus on metabolic and cardiovascular diseases as well as cancer.

Transcriptome analysis of ciliary-dependent MCH signaling in differentiating 3T3-L1 pre-adipocytes

An understanding of adipocyte responsiveness to G-protein-coupled receptor-(GPCR) derived signals must take into consideration the role of membrane microenvironments; that individual sub-populations of proteins may vary significantly across different regions of the cell, and that cell differentiation alters those microenvironments. 3T3-L1 pre-adipocytes undergo a dramatic phenotypic transformation during differentiation into adipocytes, requiring the development of a transient primary cilium. We demonstrate that melanin-concentrating hormone (MCH) receptor 1, a GPCR that stimulates appetite, translocates to the transient primary cilium during early 3T3-L1 cell adipogenesis. Furthermore, we used RNA-Seq to investigate whether MCH signaling is influenced by its receptor localization and whether MCH can influence the transcriptome of early adipocyte development. We found that MCH signaling is sensitive to receptor localization to cilia, and this alters the adipogenic transcriptional program. Also, novel MCH signaling pathways in 3T3-L1 cells are identified, including those for circadian rhythm, the inflammatory response, and ciliary biogenesis. The presence of active MCH-signaling pathways in pre-adipocytes and the discovery that these pathways intersect with the early adipogenic program, among other newly-identified signaling pathways, suggests that the use of MCH receptor 1 antagonists for clinical interventions may have unintended consequences on adipose tissue development.

All-trans retinoic acid controls differentiation, proliferation, and lipolysis in isolated subcutaneous adipocytes from peripartal Holstein cows

Preadipocyte proliferation and differentiation are critical for normal adipose tissue development, including achieving a mature phenotype, characterized by its ability to accumulate triacylglycerol and release fatty acids. In nonruminants, it is well known that all-trans retinoic acid (ATRA), the most-active form of vitamin A, helps regulate proliferation, differentiation, and apoptosis in several types of cells including adipocytes. The purpose of this study was to evaluate the effect of ATRA on proliferation, apoptosis, differentiation, and lipolysis of primary bovine adipocytes isolated from subcutaneous adipose tissue of 5 healthy Holstein cows at 17 (±4 standard deviations) d postpartum. Cells were stimulated with increasing concentrations of ATRA (0.2, 2, and 20 nM) at the preconfluent (2 d) and postconfluent (8 d) preadipocyte stage or at the mature adipocyte stage (2 d). All concentrations of ATRA inhibited preconfluent preadipocyte proliferation with decreased proportion of S-phase cells and reduced protein abundance of cyclins (CCND1, CCND2, CCND3, CCNE1) and cyclin-dependent kinases (CDK2, CDK4, CDK6). Compared with vehicle, ATRA treatment induced apoptosis in preconfluent preadipocytes. Additionally, ATRA (0.2, 2, and 20 nM) supplementation also inhibited differentiation of postconfluent preadipocytes through downregulation of protein abundance of PPARγ and C/EBPα. After induction of differentiation, basal lipolysis in mature adipocytes increased upon treatment with all concentrations of ATRA. However, data on phosphorylated hormone-sensitive lipase or PLIN1 indicated that ATRA had no effect on epinephrine-stimulated lipolysis in mature adipocytes. Overall, these results demonstrate that ATRA might inhibit lipid accumulation by suppressing preadipocyte proliferation and differentiation, subsequently leading to apoptosis in postconfluent preadipocytes and promoting basal lipolysis in mature adipocytes. Overall, these in vitro responses provide some insights into the potential for nutritional management to modulate adipose tissue lipolysis, particularly in overconditioned cows during the dry period, which are more susceptible to suffer metabolic disorders due to excessive fat mobilization postpartum.

Antiobesity and antidiabetic effects of the dairy bacterium Propionibacterium freudenreichii MJ2 in high-fat diet-induced obese mice by modulating lipid metabolism

Obesity can cause chronic metabolic disorders such as type 2 diabetes, hyperlipidemia, and nonalcoholic fatty liver diseases. The aim of this study was to investigate the antiobesity and antidiabetic effects of the dairy bacterium P. freudenreichii MJ2 isolated from raw milk using 3T3-L1 cells and high-fat diet (HFD)-induced obese mice. Lipid accumulation and the expression levels of genes related to lipid metabolism, such as preadipocytic gene (Pref-1), adipogenic genes (PPARγ and C/EBPα), and lipogenic genes (FAS, SCD-1, and ACC), significantly decreased in heat-killed P. freudenreichii MJ2 (hkMJ2)-treated adipocytes. Live P. freudenreichii MJ2 (MJ2), hkMJ2, and Lactobacillus plantarum (LP) decreased body weight gain in HFD-induced obese mice compared with the model group. The liver and epididymal white adipose tissue weights in the MJ2-, hkMJ2- and LP-treated groups were significantly lower than those in the model group. The expression levels of genes and proteins related to adipogenesis and lipogenesis significantly decreased and lipolysis (HSL and ATGL) increased in the MJ2-, hkMJ2-, and LP-treated groups. The expression levels of genes related to fatty acid β-oxidation (CPT-1α and ACOX1) increased in the MJ2-, hkMJ2-, and LP-treated groups. In addition, blood glucose and fasting insulin levels in the MJ2- and hkMJ2-treated groups decreased compared with those in the model group. P. freudenreichii MJ2 ameliorate insulin resistance by obesity. In conclusion, both MJ2 and hkMJ2 alleviate obesity and metabolic syndrome.

Adipocyte-induced transdifferentiation of osteoblasts and its potential role in age-related bone loss

Our preliminary findings have lead us to propose bone marrow adipocyte secretions as new contributors to bone loss. Indeed, using a coculture model based on human bone marrow stromal cells, we previously showed that soluble factors secreted by adipocytes induced the conversion of osteoblasts towards an adipocyte-like phenotype. In this study, microarray gene expression profiling showed profound transcriptomic changes in osteoblasts following coculture and confirmed the enrichment of the adipocyte gene signature. Double immunofluorescence microscopic analyses demonstrated the coexpression of adipogenic and osteoblastic specific markers in individual cells, providing evidence for a transdifferentiation event. At the molecular level, this conversion was associated with upregulated expression levels of reprogramming genes and a decrease in the DNA methylation level. In line with these in vitro results, preliminary immunohistochemical analysis of bone sections revealed adipogenic marker expression in osteoblasts from elderly subjects. Altogether, these data suggest that osteoblast transdifferentiation could contribute to decreased bone mass upon ageing.

Direct and Indirect Effect of Honey as a Functional Food Against Metabolic Syndrome and Its Skeletal Complications

Metabolic syndrome (MetS) refers to the simultaneous presence of hypertension, hyperglycemia, dyslipidemia and/or visceral obesity, which predisposes a person to cardiovascular diseases and diabetes. Evidence suggesting the presence of direct and indirect associations between MetS and osteoporosis is growing. Many studies have reported the beneficial effects of polyphenols in alleviating MetS in in vivo and in vitro models through their antioxidant and anti-inflammation actions. This review aims to summarize the effects of honey (based on unifloral and multi-floral nectar sources) on bone metabolism and each component of MetS. A literature search was performed using the PubMed and Scopus databases using specific search strings. Original studies related to components of MetS and bone, and the effects of honey on components of MetS and bone were included. Honey polyphenols could act synergistically in alleviating MetS by preventing oxidative damage and inflammation. Honey intake is shown to reduce blood glucose levels and prevent excessive weight gain. It also improves lipid metabolism by reducing total cholesterol, triglycerides and low-density lipoprotein, as well as increasing high-density lipoprotein. Honey can prevent bone loss by reducing the adverse effects of MetS on bone homeostasis, apart from its direct action on the skeletal system. In conclusion, honey supplementation could be integrated into the management of MetS and MetS-induced bone loss as a preventive and adjunct therapeutic agent.

In vitro and ex vivo models of adipocytes

Adipocytes are specialized cells with pleiotropic roles in physiology and pathology. Several types of fat cells with distinct metabolic properties coexist in various anatomically defined fat depots in mammals. White, beige, and brown adipocytes differ in their handling of lipids and thermogenic capacity, promoting differences in size and morphology. Moreover, adipocytes release lipids and proteins with paracrine and endocrine functions. The intrinsic properties of adipocytes pose specific challenges in culture. Mature adipocytes float in suspension culture due to high triacylglycerol content and are fragile. Moreover, a fully differentiated state, notably acquirement of the unilocular lipid droplet of white adipocyte, has so far not been reached in two-dimensional culture. Cultures of mouse and human-differentiated preadipocyte cell lines and primary cells have been established to mimic white, beige, and brown adipocytes. Here, we survey various models of differentiated preadipocyte cells and primary mature adipocyte survival describing main characteristics, culture conditions, advantages, and limitations. An important development is the advent of three-dimensional culture, notably of adipose spheroids that recapitulate in vivo adipocyte function and morphology in fat depots. Challenges for the future include isolation and culture of adipose-derived stem cells from different anatomic location in animal models and humans differing in sex, age, fat mass, and pathophysiological conditions. Further understanding of fat cell physiology and dysfunction will be achieved through genetic manipulation, notably CRISPR-mediated gene editing. Capturing adipocyte heterogeneity at the single-cell level within a single fat depot will be key to understanding diversities in cardiometabolic parameters among lean and obese individuals.

Epigenetic Regulators of White Adipocyte Browning

Adipocytes play an essential role in maintaining energy homeostasis in mammals. The primary function of white adipose tissue (WAT) is to store energy; for brown adipose tissue (BAT), primary function is to release fats in the form of heat. Dysfunctional or excess WAT can induce metabolic disorders such as dyslipidemia, obesity, and diabetes. Preadipocytes or adipocytes from WAT possess sufficient plasticity as they can transdifferentiate into brown-like beige adipocytes. Studies in both humans and rodents showed that brown and beige adipocytes could improve metabolic health and protect from metabolic disorders. Brown fat requires activation via exposure to cold or β-adrenergic receptor (β-AR) agonists to protect from hypothermia. Considering the fact that the usage of β-AR agonists is still in question with their associated side effects, selective induction of WAT browning is therapeutically important instead of activating of BAT. Hence, a better understanding of the molecular mechanisms governing white adipocyte browning is vital. At the same time, it is also essential to understand the factors that define white adipocyte identity and inhibit white adipocyte browning. This literature review is a comprehensive and focused update on the epigenetic regulators crucial for differentiation and browning of white adipocytes.

Anti-Obesity and Anti-Adipogenic Effects of Chitosan Oligosaccharide (GO2KA1) in SD Rats and in 3T3-L1 Preadipocytes Models

Excess body weight is a major risk factor for type 2 diabetes (T2D) and associated metabolic complications, and weight loss has been shown to improve glycemic control and decrease morbidity and mortality in T2D patients. Weight-loss strategies using dietary interventions produce a significant decrease in diabetes-related metabolic disturbance. We have previously reported that the supplementation of low molecular chitosan oligosaccharide (GO2KA1) significantly inhibited blood glucose levels in both animals and humans. However, the effect of GO2KA1 on obesity still remains unclear. The aim of the study was to evaluate the anti-obesity effect of GO2KA1 on lipid accumulation and adipogenic gene expression using 3T3-L1 adipocytes in vitro and plasma lipid profiles using a Sprague-Dawley (SD) rat model. Murine 3T3-L1 preadipocytes were stimulated to differentiate under the adipogenic stimulation in the presence and absence of varying concentrations of GO2KA1. Adipocyte differentiation was confirmed by Oil Red O staining of lipids and the expression of adipogenic gene expression. Compared to control group, the cells treated with GO2KA1 significantly decreased in intracellular lipid accumulation with concomitant decreases in the expression of key transcription factors, peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein alpha (CEBP/α). Consistently, the mRNA expression of downstream adipogenic target genes such as fatty acid binding protein 4 (FABP4), fatty acid synthase (FAS), were significantly lower in the GO2KA1-treated group than in the control group. In vivo, male SD rats were fed a high fat diet (HFD) for 6 weeks to induced obesity, followed by oral administration of GO2KA1 at 0.1 g/kg/body weight or vehicle control in HFD. We assessed body weight, food intake, plasma lipids, levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) for liver function, and serum level of adiponectin, a marker for obesity-mediated metabolic syndrome. Compared to control group GO2KA1 significantly suppressed body weight gain (185.8 ± 8.8 g vs. 211.6 ± 20.1 g, p < 0.05) with no significant difference in food intake. The serum total cholesterol, triglyceride, and low-density lipoprotein (LDL) levels were significantly lower in the GO2KA1-treated group than in the control group, whereas the high-density lipoprotein (HDL) level was higher in the GO2KA1 group. The GO2KA1-treated group also showed a significant reduction in ALT and AST levels compared to the control. Moreover, serum adiponectin levels were significantly 1.5-folder higher than the control group. These in vivo and in vitro findings suggest that dietary supplementation of GO2KA1 may prevent diet-induced weight gain and the anti-obesity effect is mediated in part by inhibiting adipogenesis and increasing adiponectin level.

Adipogenesis as a Potential Anti-Obesity Target: A Review of Pharmacological Treatment and Natural Products

Obesity is recognized as a severe threat to overall human health and is associated with type 2 diabetes mellitus, dyslipidemia, hypertension, and cardiovascular diseases. Abnormal expansion of white adipose tissue involves increasing the existing adipocytes' cell size or increasing the number through the differentiation of new adipocytes. Adipogenesis is a process of proliferation and differentiation of adipocyte precursor cells in mature adipocytes. As a key process in determining the number of adipocytes, it is a possible therapeutic approach for obesity. Therefore, it is necessary to identify the molecular mechanisms involved in adipogenesis that could serve as suitable therapeutic targets. Reducing bodyweight is regarded as a major health benefit. Limited efficacy and possible side effects and drug interactions of available anti-obesity treatment highlight a constant need for finding novel efficient and safe anti-obesity ingredients. Numerous studies have recently investigated the inhibitory effects of natural products on adipocyte differentiation and lipid accumulation. Possible anti-obesity effects of natural products include the induction of apoptosis, cell-cycle arrest or delayed progression, and interference with transcription factor cascade or intracellular signaling pathways during the early phase of adipogenesis.

Secreted Frizzled Related Proteins in Cardiovascular and Metabolic Diseases

Abnormal gene expression and secreted protein levels are accompanied by extensive pathological changes. Secreted frizzled related protein (SFRP) family members are antagonistic inhibitors of the Wnt signaling pathway, and they were recently found to be involved in the pathogenesis of a variety of metabolic diseases, which has led to extensive interest in SFRPs. Previous reports highlighted the importance of SFRPs in lipid metabolism, obesity, type 2 diabetes mellitus and cardiovascular diseases. In this review, we provide a detailed introduction of SFRPs, including their structural characteristics, receptors, inhibitors, signaling pathways and metabolic disease impacts. In addition to summarizing the pathologies and potential molecular mechanisms associated with SFRPs, this review further suggests the potential future use of SFRPs as disease biomarkers therapeutic targets.

Beige Adipose Tissue Identification and Marker Specificity-Overview

Adipose tissue (AT) is classified based on its location, physiological and functional characteristics. Although there is a clear demarcation of anatomical and molecular features specific to white (WAT) and brown adipose tissue (BAT), the factors that uniquely differentiate beige AT (BeAT) remain to be fully elaborated. The ubiquitous presence of different types of AT and the inability to differentiate brown and beige adipocytes because of similar appearance present a challenge when classifying them one way or another. Here we will provide an overview of the latest advances in BeAT, BAT, and WAT identification based on transcript markers described in the literature. The review paper will highlight some of the difficulties these markers pose and will offer new perspectives on possible transcript-specific identification of BeAT. We hope that this will advance the understanding of the biology of different ATs. In addition, concrete strategies to distinguish different types of AT may be relevant to track the efficacy and mechanisms around interventions aimed to improve metabolic health and thwart excessive weight gain.

Prostaglandin F2α Agonists Negatively Modulate the Size of 3D Organoids from Primary Human Orbital Fibroblasts

Purpose

To elucidate the molecular etiology of deepening of the upper eyelid sulcus (DUES) induced by prostaglandin (PG) analogs, a three-dimensional (3D) tissue culture system was employed using human orbital fibroblasts (HOFs).

Methods

During adipogenesis, changes in HOF 3D organoid sizes, as well as their lipids stained by BODIPY and expression of the extracellular matrix (ECM) by immunolabeling and/or quantitative PCR, were studied in the presence or absence of either 100-nM bimatoprost acid or 100-nM prostaglandin F2α.

Results

The size of the 3D organoids increased remarkably during adipogenesis, but such increases were significantly inhibited by the presence of PG analogs. Staining intensities by BODIPY and mRNA expression of peroxisome proliferator-activated receptor gamma were significantly increased upon adipogenesis but were not influenced by the presence of PG analogs. Unique changes in ECM expression observed with or without adipogenic differentiation were significantly modified by the presence of PG analogs.

Conclusions

Our present study indicates that PG analogs have the potential to modulate the ECM network within HOF 3D organoids. Thus, a 3D tissue culture system may be a suitable strategy for understanding the disease etiology of DUES.

miR-381 Targets KCTD15 to Regulate Bovine Preadipocyte Differentiation In Vitro

MicroRNAs (miRNAs) are small, single-stranded, noncoding RNAs ~21 to ~23 nucleotides in length and have become a popular research topic in recent years due to their regulation of gene expression and many physiological processes, including fat metabolism; however, the precise functional mechanisms underlying their regulation of fat metabolism are not fully understood. Here, we identified miR-381, which specifically targets the 3' untranslated region (3' UTR) of potassium channel tetramerization-domain-containing 15 (KCTD15) , and verified the mechanism regulating its expression and participation in adipogenesis. We used a dual luciferase-reporter assay and transfection-mediated miR-381 overexpression and inhibition in Yanbian yellow cattle preadipocytes to investigate the role of miR-381 in adipogenesis. The results showed that miR-381 directly targets the 3' UTR of KCTD15 and downregulates its expression. Additionally, miR-381 overexpression using an miRNA mimic promoted triglyceride accumulation and upregulated adipogenic peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT enhancer-binding protein α (C/EBPα) at both the protein and mRNA levels, whereas miR-381 inhibition produced the opposite effect. These results indicated that miR-381 regulates the differentiation of Yanbian yellow cattle preadipocytes by inhibiting KCTD15 expression, thereby highlighting the importance of miRNA-mediated regulation of adipogenesis. Furthermore, our findings suggested that miR-381 and its target gene(s) might represent new targets for investigating intramuscular fat deposits in cattle and treating human obesity.

D-Mannose Inhibits Adipogenic Differentiation of Adipose Tissue-Derived Stem Cells via the miR669b/MAPK Pathway

The adipogenic differentiation of adipose tissue-derived stem cells (ADSCs) plays an important role in the process of obesity and host metabolism. D-Mannose shows a potential regulating function for fat tissue expansion and glucose metabolism. To explore the mechanisms through which D-mannose affects the adipogenic differentiation of adipose-derived stem cells in vitro, we cultured the ADSCs with adipogenic medium inducement containing D-mannose or glucose as the control. The adipogenic differentiation specific markers Pparg and Fabp4 were determined by real-time PCR. The Oil Red O staining was applied to measure the lipid accumulation. To further explore the mechanisms, microarray analysis was performed to detect the differences between glucose-treated ADSCs (G-ADSCs) and D-mannose-treated ADSCs (M-ADSCs) in the gene expression level. The microarray data were further analyzed by a Venn diagram and Gene Set Enrichment Analysis (GSEA). MicroRNA inhibitor transfection was used to confirm the role of key microRNA. Results. D-Mannose intervention significantly inhibited the adipogenic differentiation of ADSCs, compared with the glucose intervention. Microarray showed that D-mannose increased the expression of miR669b, which was an inhibitor of adipogenesis. In addition, GSEA and western blot suggested that D-mannose suppressed the adipogenic differentiation via inhibiting the MAPK pathway and further inhibited the expression of proteins related to glucose metabolism and tumorigenesis. Conclusion. D-Mannose inhibits adipogenic differentiation of ADSCs via the miR669b/MAPK signaling pathway and may be further involved in the regulation of glucose metabolism and the inhibition of tumorigenesis.

Pubertal mammary gland development is a key determinant of adult mammographic density

Mammographic density refers to the radiological appearance of fibroglandular and adipose tissue on a mammogram of the breast. Women with relatively high mammographic density for their age and body mass index are at significantly higher risk for breast cancer. The association between mammographic density and breast cancer risk is well-established, however the molecular and cellular events that lead to the development of high mammographic density are yet to be elucidated. Puberty is a critical time for breast development, where endocrine and paracrine signalling drive development of the mammary gland epithelium, stroma, and adipose tissue. As the relative abundance of these cell types determines the radiological appearance of the adult breast, puberty should be considered as a key developmental stage in the establishment of mammographic density. Epidemiological studies have pointed to the significance of pubertal adipose tissue deposition, as well as timing of menarche and thelarche, on adult mammographic density and breast cancer risk. Activation of hypothalamic-pituitary axes during puberty combined with genetic and epigenetic molecular determinants, together with stromal fibroblasts, extracellular matrix, and immune signalling factors in the mammary gland, act in concert to drive breast development and the relative abundance of different cell types in the adult breast. Here, we discuss the key cellular and molecular mechanisms through which pubertal mammary gland development may affect adult mammographic density and cancer risk.

Tyrosol May Prevent Obesity by Inhibiting Adipogenesis in 3T3-L1 Preadipocytes

Tyrosol (TR), a major polyphenol found in extra virgin olive oil (EVOO), exerts several antioxidant effects. However, only scarce evidences are present regarding its activity on adipocytes and obesity. This study evaluated the role of TR in adipogenesis. Murine 3T3-L1 preadipocytes were incubated with TR (300 and 500 μM), and TR administration inhibited adipogenesis by downregulation of several adipogenic factors (leptin and aP2) and transcription factors (C/EBPα, PPARγ, SREBP1c, and Glut4) and by modulation of the histone deacetylase sirtuin 1. After complete differentiation, adipocytes treated with 300 and 500 μM TR showed a reduction of 20% and 30% in lipid droplets, respectively. Intracellular triglycerides were significantly reduced after TR treatment (p < 0.05). Mature adipocytes treated with TR at 300 and 500 μM showed a marked decrease in the inflammatory state and oxidative stress as shown by the modulation of specific biomarkers (TNF, IL6, ROS, and SOD2). TR treatment also acted on the early stage of differentiation by reducing cell proliferation (~40%) and inducing cell cycle arrest during Mitotic Expansion Clonal (first 48 h of differentiation), as shown by the increase in both S1 phase and p21 protein expression. We also showed that TR induced lipolysis by activating the AMPK-ATGL-HSL pathway. In conclusion, we provided evidence that TR reduces 3T3-L1 differentiation through downregulation of adipogenic proteins, inflammation, and oxidative stress. Moreover, TR may trigger adipose tissue browning throughout the induction of the AMPK-ATGL-UCP1 pathway and, subsequently, may have promise as a potential therapeutic agent for the treatment and prevention of obesity.

Effects of SFRP4 overexpression on the production of adipokines in transgenic mice

Secreted frizzled-related protein (SFRP) 4 is an extracellular antagonist of Wnt signalling that regulates adipogenesis, and is highly in the visceral adipose tissue of obese individuals. However, it is still unclear how exactly SFRP4 regulates the secretion of adipokines in the adipose tissue in vivo, an event that is closely related to the pathogenesis of obesity and insulin resistance. In this study, we generated transgenic (Tg) mice overexpressing SFRP4 in the liver and investigated SFRP4 role in adipokine secretion in mice on a regular normal diet. In Tg mice, SFRP4 protein was overexpressed in the liver, as compared to wild-type littermates (non-Tg), and released into the blood. Moreover, the size of adipocytes was smaller in the visceral adipose tissue of Tg mice compared to controls. Additionally, SFRP4 overexpression affected the expression of genes related to adipocyte differentiation, causing the upregulation of adiponectin and glucose transporter 4, and the downregulation of CCAAT/enhancer-binding protein-β, in both visceral and subcutaneous adipose tissue. However, there was no difference in body weight or body composition between Tg and non-Tg mice. In summary, our data showed that SFRP4 overexpression altered adipocyte size and adipokine secretion, possibly affecting adipocyte differentiation, obesity, and glucose metabolism.

Suppression of adipocyte differentiation by low-intensity pulsed ultrasound via inhibition of insulin signaling and promotion of CCN family protein 2

Adipocyte differentiation is regulated by several transcription factors such as the CCAAT/enhancer-binding proteins (C/EBPs) and peroxisome proliferator-activated receptor-γ (PPARγ). Here, we demonstrate that low-intensity pulsed ultrasound (LIPUS) suppressed differentiation into mature adipocytes via multiple signaling pathways. When C3H10T1/2, a mesenchymal stem cell line, was treated with LIPUS (3.0 MHz, 60 mW/cm2 ) for 20 minutes once a day for 4 days during adipogenesis, and both the number of lipid droplets and the gene expression of PPARγ and C/EBPα were significantly decreased. Furthermore, LIPUS treatment decreased the phosphorylation of the insulin receptor and also that of Akt and ERK1/2, which are located downstream of this receptor. Next, we showed that LIPUS suppressed the gene expression of angiotensinogen (AGT), which is an adipokine produced by mature adipocytes, as well as that of angiotensin-converting enzyme 1 (ACE1) and angiotensin receptor type 1 (AT1 R) during adipogenesis of pre-adipogenic 3T3-L1 cells. Next, the translocation of Yes-associated protein (YAP) into the nucleus of 3T3-L1 cells was promoted by LIPUS, leading to upregulation of CCN family protein 2 (CCN2), a cellular communication network factor. Moreover, forced expression of CCN2 in 3T3-L1 cells decreased PPARγ gene expression, but it did not increase alkaline phosphatase and osterix gene expression. Finally, gene silencing of CCN2 in C3H10T1/2 cells diminished the effect of LIPUS on the gene expression of PPARγ and C/EBPα. These findings suggest that LIPUS suppressed adipogenesis through inhibition of insulin signaling and decreased PPARγ expression via increased CCN2 production, resulting in a possible decrease of mature adipocytes.

Involvement of calcium channels in the regulation of adipogenesis

As an important second messenger in adipocytes, calcium ions (Ca²⁺) are essential in regulating various intracellular signalling pathways that control critical cellular functions. Calcium channels show selective permeability to Ca²⁺ and facilitate Ca²⁺ entry into the cytoplasm, which are normally located in the plasmatic and intracellular membranes. The increase of cytosolic Ca²⁺ modulates a variety of signalling pathways and results in the transcription of target genes that contribute to adipogenesis, a key cellular event includes proliferation and differentiation of adipocyte. In the past decades, the involvement of some Ca²⁺-permeable ion channels, such as Ca²⁺ release-activated Ca²⁺ channels, transient receptor potential channels, voltage-gated calcium channels and others, in adipogenesis has been extensively explored. In the present review, we provided a summary of the expression and contributions of these Ca²⁺-permeable channels in mediating Ca²⁺ influxes that drive adipogenesis. Moreover, we discussed their potentials as future therapeutic targets.

Surface-associated lipid droplets: an intermediate site for lipid transport in human adipocytes?

Adipose tissue plays a major role in regulating whole-body energy metabolism. While the biochemical processes regulating storage and release of excess energy are well known, the temporal organization of these events is much less defined. In this study, we have characterized the presence of small surface-associated lipid droplets, distinct from the central droplet, in primary human adipocytes. Based on microscopy analyses, we illustrate the distribution of mitochondria, endoplasmic reticulum and lysosomes in the vicinity of these specialized lipid droplets. Ultrastructure analysis confirmed the presence of small droplets in intact adipose tissue. Further, CIDEC, known to bind and regulate lipid droplet expansion, clearly localized at these lipid droplets. Neither acute or prolonged stimulation with insulin or isoprenaline, or pharmacologic intervention to suppress lipid flux, affected the presence of these lipid droplets. Still, phosphorylated perilipin and hormone-sensitive lipase accumulated at these droplets following adrenergic stimuli, which supports metabolic activity at these locations. Altogether, we propose these lipid droplet clusters represent an intermediate site involved in lipid transport in primary adipocytes.

The histone methyltransferase Suv39h regulates 3T3-L1 adipogenesis

We discovered a unique expression pattern of two histone methyltransferases Suv39h1 and Suv39h2 during 3T3-L1 adipogenesis, both of which preferentially catalyse the formation of H3K9 dimethylation (H3K9me2) and further H3K9 trimethylation (H3K9me3), a transcriptional repressive mark. The expression of Suv39h1 and Suv39h2 displayed a sharp increase at the early stage of 3T3-L1 differentiation, which peaked after differentiation induction, and then declined towards later stage of differentiation, suggesting a key role for these two histone methyltransferases in adipogenesis. Indeed, inactivating Suv39h1 or Suv39h2 via lentiviral shRNA knockdown inhibited adipogenesis, while overexpressing Suv39h1 promoted adipogenesis. Notably, overexpressing or knocking down Suv39h1 in 3T3-L1 cells was associated with reciprocal changes in the expression of Wnt10a, an anti-adipogenic regulator. Further, Wnt10a knockdown largely prevented the inhibitory effect of Suv39h1 on adipogenesis, indicating Wnt10a as a downstream target mediating Suv39h1’s action in adipogenesis. Mechanistically, our comprehensive approaches involving ChIP, co-immunoprecipitation and pyrosequencing analysis demonstrated that Suv39h1 may regulate Wnt10a expression via H3K9 methylation and interaction with DNA methyltransferase 1 (DNMT1) at the Wnt10a promoter, resulting in altered DNA methylation at the promoter. We conclude that Suv39h promotes adipogenesis by epigenetically down-regulating Wnt10a expression via H3K9me3 and DNA methylation at the Wnt10a promoter.Abbreviated title: Suv39h and 3T3-L1 Adipogenesis

Concentrated nanofat: a modified fat extraction promotes hair growth in mice via the stem cells and extracellular matrix components interaction

Background

Fat graft transplantation seems a promising cell therapy for hair loss. However, impurities in lipoaspirate weaken the treatment effect. Here, we developed the lipoaspirate extraction method then investigate the effect and mechanism on hair growth-promoting in a mouse model.

Methods

Fat graft was prepared into concentrated nanofat (CNF), decellularized CNF (DCNF), and adipose-derived stem cells (ADSCs). They were injected subcutaneously in the back of depilated mice to test the hair promoting effect. Conditioned media (CM) from the adipose extracts were applied to dermal papilla cells (DPCs) to evaluate the cell viability and the anagen related signal.

Results

CNF and a high dose of ADSCs promoted hair growth and induced telogen-to-anagen transition in depilated mice. DCNF and a low dose of ADSCs did not show such effect; however, hair growth was promoted when they were used in combination. In vitro study showed the CNF-CM treated DPCs exhibited increased proliferation, migration, cell cycle progression, and elevated Wnt/β-catenin pathway protein levels compared with the other treatment groups.

Conclusions

CNF has a better effect than ADSCs in hair promotion via activating the DPCs and anagen induction. In this nature complex of stem cells (SCs) and extracellular matrix (ECM), ECM serves a significant supplementary role and amplifies the power of ADSCs. These results supply a theoretical basis on the clinical application of CNF to treat hair loss.

Genomic analysis of worldwide sheep breeds reveals PDGFD as a major target of fat-tail selection in sheep

Background

Fat tail is a unique trait in sheep acquired during domestication. Several genomic analyses have been conducted in sheep breeds from limited geographic origins to identify the genetic factors underlying this trait. Nevertheless, these studies obtained different candidates. The results of these regional studies were easily biased by the breed structures.

Results

To minimize the bias and distinguish the true candidates, we used an extended data set of 968 sheep representing 18 fat-tailed breeds and 14 thin-tailed breeds from around the world, and integrated two statistical tests to detect selection signatures, including Genetic Fixation Index (F_ST) and difference of derived allele frequency (ΔDAF). The results showed that platelet derived growth factor D (PDGFD) exhibited the highest genetic differentiation between fat- and thin-tailed sheep breeds. Analysis of sequence variation identified that a 6.8-kb region within the first intron of PDGFD is likely the target of positive selection and contains regulatory mutation(s) in fat-tailed sheep. Histological and gene expression analyses demonstrated that PDGFD expression is associated with maturation and hemostasis of adipocytes. Further retrospective analysis of public transcriptomic datasets revealed that PDGFD expression is down-regulated during adipogenesis in both human and mouse, and is higher in fat tissues of obese individuals than that in lean individuals.

Conclusions

These results reveal that PDGFD is the predominant factor for the fat tail phenotype in sheep by contributing to adiopogenesis and maintaining the hemostasis of mature adipocytes. This study provides insights into the selection of fat-tailed sheep and has important application to animal breeding, as well as obesity-related human diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-020-07210-9.

Stearoyl-CoA Desaturase-2 in Murine Development, Metabolism, and Disease

Stearoyl-CoA Desaturase-2 (SCD2) is a member of the Stearoyl-CoA Desaturase (SCD) family of enzymes that catalyze the rate-limiting step in monounsaturated fatty acid (MUFA) synthesis. The MUFAs palmitoleoyl-CoA (16:1n7) and oleoyl-CoA (18:1n9) are the major products of SCD2. Palmitoleoyl-CoA and oleoyl-CoA have various roles, from being a source of energy to signaling molecules. Under normal feeding conditions, SCD2 is ubiquitously expressed and is the predominant SCD isoform in the brain. However, obesogenic diets highly induce SCD2 in adipose tissue, lung, and kidney. Here we provide a comprehensive review of SCD2 in mouse development, metabolism, and various diseases, such as obesity, chronic kidney disease, Alzheimer′s disease, multiple sclerosis, and Parkinson′s disease. In addition, we show that bone mineral density is decreased in SCD2KO mice under high-fat feeding conditions and that SCD2 is not required for preadipocyte differentiation or the expression of PPARγ in vivo despite being required in vitro.

Crocetin Isolated from the Natural Food Colorant Saffron Reduces Intracellular Fat in 3T3-L1 Adipocytes

Saffron, as a food colorant, has been displaced by low-cost synthetic dyes. These have unhealthy properties; thus, their replacement with natural food colorants is an emerging trend. Obesity is a worldwide health problem due to its associated comorbidities. Crocetin esters (crocins) are responsible for the red saffron color. Crocetin (CCT) exhibits healthful properties. We aimed to broaden the existing knowledge on the health properties of CCT isolated from saffron, to facilitate its consideration as a healthy natural food colorant in the future. We evaluated the ability of CCT (1 and 5 μM) to reduce lipid accumulation during the differentiation of 3T3-L1 preadipocytes. Intracellular fat was quantified by Oil Red O staining. CTT cytotoxicity was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The number and size of lipid droplets were analyzed using WimLipid software. The expression of adipogenic genes (CCAAT/enhancer-binding protein (C/EBPβ, C/EBPδ, C/EBPα), and peroxisome proliferator-activated receptor γ (PPARγ)) was analyzed using quantitative real-time PCR (qRT-PCR). CCT 5 μM decreased intracellular fat by 22.6%, without affecting viability or lipid droplet generation, via a decrease in C/EBPα expression, implicated in lipid accumulation. Thus, CCT is a potential candidate to be included in dietary therapies aimed at reversing adipose tissue accumulation in obesity.

Oligostilbenes extracts from Iris lactea Pall. var. chinensis (Fisch.) Koidz improve lipid metabolism in HFD/STZ-induced diabetic mice and inhibit adipogenesis in 3T3-L1 cells

The present study investigated the anti-diabetic effects of Oligostilbenes extracts (Olie) from Iris lactea Pall. var. chinensis (Fisch.) Koidz (I. lactea) and the potential mechanisms, in high-fat-diet (HFD)-induced diabetic mice and 3T3-L1 adipocytes. Olie are a group of major active extracts from I. lactea that have been used as nutraceutical because of their antioxidant activity. Six-week Olie treatment improved fasting blood glucose levels, as well as blood lipid profiles in HFD/streptozocin (STZ)-induced diabetic mice, compared with non-treated mice. Olie treatment upregulated the levels of phosphorylated of AMPK and lipolysis-related proteins, while the hepatic expression of ACC and FAS in diabetic mice was inhibited. In cultured 3T3-L1 cells, Olie (2-15 μg/mL) treatment dose-dependently suppressed the differentiation into mature adipocytes and lowered cellular lipid accumulation. Consistently, Olie reduced expression of adipogenic transcription factors including CCAAT/enhancer-binding protein β (C/EBPβ) and peroxisome proliferator-activated receptor γ (PPARγ). In addition, mitochondrial function in 3T3-L1 adipocytes was improved after Olie treatment. Taken together, our findings indicate that a lipid-lowering effect of Olie in HFD/STZ-induced diabetic mice and adipogenesis/ lipogenesis suppressing effect in 3T3-L1 cells, via regulating the expression of lipid metabolism-related proteins.

The bile acid induced hepatokine orosomucoid suppresses adipocyte differentiation

Bile acids have recently emerged as key metabolic hormones with beneficial impacts in multiple metabolic diseases. We previously discovered that hepatic bile acid overload distally modulates glucose and fatty acid metabolism in adipose tissues to exert anti-obesity effects. However, the detailed mechanisms that explain the salutary effects of serum bile acid elevation remain unclear. Here, proteomic profiling identified a new hepatokine, Orosomucoid (ORM) that governs liver-adipose tissue crosstalk. Hepatic ORMs were highly induced by both genetic and dietary bile acid overload. To address the direct metabolic effects of ORM, purified ORM proteins were administered during adipogenic differentiation of 3T3-L1 cells and mouse stromal vascular fibroblasts. ORM suppressed adipocyte differentiation and strongly inhibited gene expression of adipogenic transcription factors such as C/EBPβ, KLF5, C/EBPα, and PPARγ. Taken together, our data clearly suggest that bile acid-induced ORM secretion from the liver blocks adipocyte differentiation, potentially linked to anti-obesity effect of bile acids.

Improvement of Aglycone Content in Soy Isoflavones Extract by Free and Immobilized Β-Glucosidase and their Effects in Lipid Accumulation

Soybean is one of the most important commodities in the world, being applied in feed crops and food, pharmaceutical industries in different ways. Soy is rich in isoflavones that in aglycone forms have exhibited significant anti-obesity and anti-lipogenic effects. Obesity is a global problem as several diseases have been related to this worldwide epidemic. The aim of this work was to verify the effect of free and immobilized β-glucosidase, testing Lentikats, and sol-gel as carriers. Moreover, we wanted to examine if the different types of hydrolysis would generate extracts with distinct biological activity concerning lipid accumulation, PPAR-α regulation, and TNF-α, IL-6, and IL-10 concentrations using in vitro assays. Our results show that all formulations of β-glucosidase could hydrolyze soy isoflavones. Thus, after 24 h of incubation, daidzein content increased 2.6-, 10.8-, and 12.2-fold; and genistein content increased 11.7, 11.4, and 11.4 times with the use of free enzyme, Lentikats®, and sol-gel immobilized enzyme, respectively. Moreover, both methodologies for enzyme immobilization led to promising forms of biocatalysts for application in the production of soy extracts rich in isoflavones aglycones, which are expected to bring about health benefits. A mild lipogenic effect was observed for some concentrations of extracts, as well as a slight inhibition in PPAR-α expression, although no significant differences were noticeable in the cytokines TNF-α, IL-10, and IL-6 as compared with the control.

Novel Function of α-Cubebenoate Derived from Schisandra chinensis as Lipogenesis Inhibitor, Lipolysis Stimulator and Inflammasome Suppressor

The efficacy of α-cubebenoate isolated from Schisandra chinensis has been previously studied in three disease areas, namely inflammation, sepsis, and allergy, and its role in other diseases is still being explored. To identify the novel function of α-cubebenoate on lipid metabolism and related inflammatory response, alterations in fat accumulation, lipogenesis, lipolysis, and inflammasome activation were measured in 3T3-L1 preadipocytes and primary adipocytes treated with α-cubebenoate. Lipid accumulation significantly decreased in MDI (3-isobutyl-1-methylxanthine, dexamethasone, and insulin)-stimulated 3T3-L1 adipocytes treated with α-cubebenoate without any significant cytotoxicity. The mRNA levels of peroxisome proliferator-activated receptor (PPAR)γ and CCAAT-enhancer binding protein (C/EBP) α for adipogenesis, as well as adipocyte fatty acid binding protein 2 (aP2) and fatty acid synthetase (FAS) for lipogenesis, were reduced after α-cubebenoate treatment, while cell cycle arrest at G2/M stage was restored in the same group. α-cubebenoate treatment induced glycerol release in primary adipocytes and enhanced expression of lipolytic proteins (HSL, perilipin, and ATGL) expression in MDI-stimulated 3T3-L1 adipocytes. Inflammasome activation and downstream cytokines expression were suppressed with α-cubebenoate treatment, but the expression of insulin receptor signaling factors was remarkably increased by α-cubebenoate treatment in MDI-stimulated 3T3-L1 adipocytes. These results indicate that α-cubebenoate may play a novel role as lipogenesis inhibitor, lipolysis stimulator, and inflammasome suppressor in MDI-stimulated 3T3-L1 adipocytes. Our results provide the possibility that α-cubebenoate can be considered as one of the candidates for obesity management.

Modeling Adipogenesis: Current and Future Perspective

Adipose tissue is contemplated as a dynamic organ that plays key roles in the human body. Adipogenesis is the process by which adipocytes develop from adipose-derived stem cells to form the adipose tissue. Adipose-derived stem cells’ differentiation serves well beyond the simple goal of producing new adipocytes. Indeed, with the current immense biotechnological advances, the most critical role of adipose-derived stem cells remains their tremendous potential in the field of regenerative medicine. This review focuses on examining the physiological importance of adipogenesis, the current approaches that are employed to model this tightly controlled phenomenon, and the crucial role of adipogenesis in elucidating the pathophysiology and potential treatment modalities of human diseases. The future of adipogenesis is centered around its crucial role in regenerative and personalized medicine.

Flavonoids as antiobesity agents: A review

Obesity is a global health problem that affects all age groups in both developing and developed countries. In recent years, the prevalence of overweight and obesity has reached pandemic levels, resulting in a dramatic increase in the incidence of various comorbidities, such as cardiovascular diseases, type 2 diabetes, and cancer, consequently leading to massive health and socioeconomic burdens. Together with lifestyle changes, antiobesity pharmacotherapy is gaining momentum as an adjunctive treatment. However, the available pharmacological approaches have limited use owing to either significant adverse effects or low efficacy. Over the years, natural products have been an important source of lead compounds for drug discovery. Among these, flavonoids are associated with important biological effects and health-promoting activities. In this review, we discuss the modulatory effects of flavonoids on obesity and their potential mechanisms of action. The literature strongly suggests that most common flavonoids demonstrate a pronounced effect on obesity as shown by their ability to lower body weight, fat mass, and plasma triglycerides/cholesterol, both in in vitro and in vivo models. The impact of flavonoids on obesity can be observed through different mechanisms: reducing food intake and fat absorption, increasing energy expenditure, modulating lipid metabolism, or regulating gut microbiota profile. A better understanding of the known antiobesity mechanisms of flavonoids will enable their potential use to treat this medical condition. Therefore, this review focuses on the putative biological mechanisms through which flavonoids may prevent or treat obesity and highlights new perspectives on future pharmacological use.

The Extract of Arctium lappa L. Fruit (Arctii Fructus) Improves Cancer-Induced Cachexia by Inhibiting Weight Loss of Skeletal Muscle and Adipose Tissue

Background: Cachexia induced by cancer is a systemic wasting syndrome and it accompanies continuous body weight loss with the exhaustion of skeletal muscle and adipose tissue. Cancer cachexia is not only a problem in itself, but it also reduces the effectiveness of treatments and deteriorates quality of life. However, effective treatments have not been found yet. Although Arctii Fructus (AF) has been studied about several pharmacological effects, there were no reports on its use in cancer cachexia. Methods: To induce cancer cachexia in mice, we inoculated CT-26 cells to BALB/c mice through subcutaneous injection and intraperitoneal injection. To mimic cancer cachexia in vitro, we used conditioned media (CM), which was CT-26 colon cancer cells cultured medium. Results: In in vivo experiments, AF suppressed expression of interleukin (IL)-6 and atrophy of skeletal muscle and adipose tissue. As a result, the administration of AF decreased mortality by preventing weight loss. In adipose tissue, AF decreased expression of uncoupling protein 1 (UCP1) by restoring AMP-activated protein kinase (AMPK) activation. In in vitro model, CM increased muscle degradation factors and decreased adipocytes differentiation factors. However, these tendencies were ameliorated by AF treatment in C2C12 myoblasts and 3T3-L1 cells. Conclusion: Taken together, our study demonstrated that AF could be a therapeutic supplement for patients suffering from cancer cachexia.

Suppression of MKL1 promotes adipocytic differentiation and reduces the proliferation of myxoid liposarcoma cells

Myxoid liposarcoma (MLS) is thought to occur due to defective adipocytic differentiation in mesenchymal stem cells. A promising strategy for MLS treatment is the prevention of sarcomagenesis by promoting the terminal differentiation of MLS cells into adipocytes. Previous studies have reported that the suppression of megakaryoblastic leukemia 1 (MKL1) expression induces adipocytic differentiation in preadipocyte cell lines. The present study aimed to investigate the effects of MKL1 suppression on MLS cells. In the present study, MKL1 knockdown was demonstrated to promote the adipocytic differentiation of an MLS-derived cell line, designated 1955/91, under adipogenic conditions. This suggests that therapeutic targeting of the MKL1-associated molecular pathway has potential as a promising method of MLS treatment. However, the induction of adipogenesis by MKL knockdown was incomplete, and Oil Red O staining indicated that intracellular lipid droplets were only sporadically generated. Conversely, MKL1 knockdown reduced the growth of the MLS cells. As adipocytic differentiation in vitro requires cellular confluence, the decreased growth rate of the MLS cells following MKL1 knockdown could be attributed to the incomplete induction of adipogenesis. Translocated in liposarcoma-CCAAT/enhancer-binding protein homologous protein (TLS-CHOP) is an MLS-specific oncoprotein that is thought to play key roles in sarcomagenesis and the suppression of adipocytic differentiation. However, the results of western blotting analyses suggest that TLS-CHOP has limited effects on MKL1 expression in MLS cells and that MKL1 knockdown hardly affects TLS-CHOP expression. Thus, it is postulated that the inhibitory effect of TLS-CHOP on adipogenesis is not associated with MKL1 expression. However, MKL1 and the molecular pathway involving MKL1 appear to be attractive targets for the differentiation therapy of MLS.

Licorice extract suppresses adipogenesis through regulation of mitotic clonal expansion and adenosine monophosphate-activated protein kinase in 3T3-L1 cells

Licorice, the root of Glycyrrhiza glabra, has been observed to possess an anti-obesity effect. Previous research has suggested that licorice acetone extract (LE) has an influence on mitotic clonal expansion (MCE) and adenosine monophosphate-activated protein kinase (AMPK), which play a key role in regulating adipogenesis. This study sought further insight into the molecular mechanism of LE's anti-obesity effect using 3T3-L1 adipocytes in vitro. LE inhibited 3T3-L1 adipogenesis, and the inhibitory effect of LE on adipogenesis was most significant in the early stage of adipogenic differentiation. LE inhibited the protein expression of cyclins and cyclin-dependent kinases in the MCE stage and arrested cells in the G1 phase of the cell cycle. Furthermore, it activated AMPK via phosphorylation. Moreover, the expression levels of lipid metabolism-related genes were regulated by LE. These findings suggest the anti-obesity effect of LE via MCE and AMPK regulation. PRACTICAL APPLICATIONS: Although the anti-obesity effects of licorice have been studied, the application of functional food-related anti-obesity effects of licorice has been less than that of other extracts. The present study increases the reliability of the anti-obesity effect of licorice by suggesting a new mechanism of action and expands the application of functional foods related to the anti-obesity effect of licorice. A new mechanistic insight will not only improve the scientific knowledge but will also help to predict the side effects of licorice's anti-obesity application.

Evaluation of Polyphenol Content and Antioxidant Capacity of Aqueous Extracts from Eight Medicinal Plants from Reunion Island: Protection against Oxidative Stress in Red Blood Cells and Preadipocytes

Background—Medicinal plants are traditionally used as infusions or decoctions for their antioxidant, anti-inflammatory, hypolipidemic and anti-diabetic properties. Purpose—The aim of the study was to define the polyphenol composition and to assess the antioxidant capacity of eight medicinal plants from Reunion Island referred to in the French Pharmacopeia, namely Aphloia theiformis, Ayapana triplinervis, Dodonaea viscosa, Hubertia ambavilla, Hypericum lanceolatum, Pelargonium x graveolens, Psiloxylon mauritianum and Syzygium cumini. Methods—Polyphenol content was assessed by biochemical assay and liquid chromatography coupled to mass spectrometry. Antioxidant capacity was assessed by measuring DPPH reduction and studying the protective effects of herbal preparation on red blood cells or preadipocytes exposed to oxidative stress. Results—Polyphenol content ranged from 25 to 143 mg gallic acid equivalent (GAE)/L for infusions and 35 to 205 mg GAE/L for decoctions. Liquid chromatography coupled to mass spectrometry analysis showed the presence of major bioactive polyphenols, such as quercetin, chlorogenic acid, procyanidin and mangiferin. Antioxidant capacity assessed by different tests, including DPPH and Human red blood cell (RBC) hemolysis of herbal preparations, demonstrated a dose-dependent effect whatever the extraction procedure. Our data suggest that decoction slightly improved polyphenol extraction as well as antioxidant capacity relative to the infusion mode of extraction (DPPH test). However, infusions displayed a better protective effect against oxidative stress-induced RBC hemolysis. Conclusion—Traditional preparations of medicinal plant aqueous extracts (infusions and decoctions) display antioxidant properties that limit oxidative stress in preadipocytes and red blood cells, supporting their use in the context of metabolic disease prevention and treatment.

Anti-adipogenic effect of Lactobacillus fermentum MG4231 and MG4244 through AMPK pathway in 3T3-L1 preadipocytes

This study evaluated the anti-adipogenic effects and mechanisms underlying the action of Lactobacillus fermentum MG4231 and MG4244 strains on adipogenesis and lipid accumulation in 3T3-L1 preadipocytes. Treatment with cell-free extracts (CFEs) from the two strains reduced lipid accumulation and intracellular triglyceride production in 3T3-L1 adipocytes by more than 50%. The inhibitory effects of L. fermentum on lipid accumulation were mediated by the downregulation of FAS and aP2 resulting from the inhibition of PPARγ and C/EBPα gene expression. Moreover, AMPK and HSL phosphorylation was upregulated by CFE treatment. These results indicated that the anti-adipogenic and lipolysis activities of L. fermentum strains were caused by increased AMPK and HSL phosphorylation. Both strains displayed high leucine arylamidase and β-galactosidase enzymatic activity, with excellent adhesion to epithelial cells. Therefore, we identified L. fermentum as potential new probiotics for the prevention of obesity.

An unbiased lipidomics approach identifies key lipid molecules as potential therapeutic targets of Dohongsamul-tang against non-alcoholic fatty liver diseases in a mouse model of obesity

ETHNOPHARMACOLOGICAL RELEVANCE

Dohongsamul-tang (DST) is a traditional herbal formula used to promote the blood circulation and inhibit inflammation, and also widely has been used in the treatment of patients with chronic liver diseases in Korea and China.

AIM OF THE STUDY

This study aimed to investigate the effect of DST on regulation of lipid metabolism of chronic liver diseases in mouse model of non-alcoholic fatty liver diseases (NAFLD).

MATERIALS AND METHODS

In this study, we evaluated the effect of DST on high-fat and high-cholesterol diet (HFHC, 40% fat and 1% cholesterol)-induced NAFLD, and applied unbiased lipidomics using ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC/Q-TOF MS) coupled with multivariate analysis.

RESULTS

DST improved hepatic morphology and reduced levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT). In addition, DST inhibited hepatic lipid accumulation through the downregulation of C/EBPα, PPARγ, and pAMPK. To further elucidate the effect of DST on hepatic lipid metabolism, we applied UPLC/Q-TOF MS-based lipidomics. The score plots of partial least squares-discriminant analysis (PLS-DA) showed that DST changed the lipid metabolic pattern of high-fat and high-cholesterol diet (HFHC) mice. Twenty-two lipid metabolites were selected as biomarkers regulated by DST and pathway analysis revealed that sphingolipid metabolism and glycerophospholipid metabolism were associated with the effect of DST on NAFLD. Among the 22 selected biomarkers, 14 were phospholipids, and DST significantly reversed the increased expression of lysophospholipase 3 (LYPLA3) and neuropathy target esterase (NTE), which are key enzymes in glycerophospholipid metabolism. Given that alterations in sphingolipids and phospholipids can have effects on apoptosis and insulin resistance (IR), we subsequently investigated changes in the expression of apoptosis-related proteins, including Bcl-2-associated X protein (Bax) and B-cell lymphoma 2 (Bcl2), and IR-related markers after DST treatment. We accordingly found that the ratio of Bax to Bcl-2 expression, a maker of apoptosis, was also elevated in HFHC mice and reduced by DST treatment. In addition, DST enhanced hepatic insulin signaling by upregulating the expression of insulin receptor substrate 1 (IRS-1) and phospho-protein kinase B (pAKT), and oral glucose tolerance test (OGTT) analysis indicated that this herbal preparation also ameliorated systemic IR.

CONCLUSIONS

This study suggested that DST might have an effect on NAFLD by regulating the metabolism of lipids such as phospholipids and sphingolipids and demonstrated that lipidomic profiling is useful to investigate the therapeutic effects of herbal decoctions from traditional Korean and Chinese medicine.

Vanadium-protein complex inhibits human adipocyte differentiation through the activation of β-catenin and LKB1/AMPK signaling pathway

Obesity is a common disease over the world and is tightly associated with diabetes mellitus, cardiovascular and cancer disease. Although our previous study showed that the synthetic vanadium-protein (V-P) complex had a better effect on antioxidant and antidiabetic, the relative molecular mechanisms are still entirely unknown. Hence, we investigated the effect of the synthetic V-P complex on adipocyte differentiation (adipogenesis) using human preadipocytes to clarify its molecular mechanisms of action. The primary human preadipocytes were cultured with and without V-P complex during adipocyte differentiation. The cell proliferation, lipid accumulation, and the protein expression of transcription factors and related enzymes were determined for the differentiated human preadipocytes. In this study, the 20 μg/mL of V-P complex reduced the lipid and triglyceride (TG) content by 74.47 and 57.39% (p < 0.05), respectively, and down-regulated the protein expressions of peroxisome proliferator-activated receptor-γ (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), sterol regulatory element-binding protein 1 (SREBP-1) and fatty acid synthase (FAS). Additionally, the V-P complex significantly up-regulated the protein levels of total β-catenin (t-β-catenin), nuclear β-catenin (n-β-catenin), phosphorylated adenosine monophosphate-activated protein kinase alpha (p-AMPKα) and liver kinase B1 (p-LKB1). These showed that the inhibitory effect of V-P complex on human adipogenesis was mediated by activating Wnt/β-catenin and LKB1/AMPK-dependent signaling pathway. Therefore, the synthetic V-P complex could be considered as a candidate for prevention and treatment of obesity.

Insights into the potential benefits of black soybean (Glycine max L.) polyphenols in lifestyle diseases

Black soybean (Glycine max L.), a cultivar containing abundant polyphenols in its seed coat such as anthocyanins and flavan-3-ols, has been reported to possess various health benefits toward lifestyle diseases. In this review article, the safety evaluation of polyphenol-rich black soybean seed coat extract (BE) and absorption of BE polyphenols are summarized. Additionally, we describe the antioxidant activity of BE polyphenols and their ability to induce antioxidant enzymes. The health benefits of BE and its polyphenols, such as anti-obesity and anti-hyperglycemic activities through the activation of AMP-activated protein kinase and translocation of glucose transporter 4, respectively, are also discussed. Furthermore, we found that black soybean polyphenols were involved in the improvement of vascular function. These emerging data require further investigation in scientific studies and human trials to evaluate the prevention of lifestyle diseases using black soybean polyphenols.

Sinensol-C Isolated from Spiranthes sinensis Inhibits Adipogenesis in 3T3-L1 Cells through the Regulation of Adipogenic Transcription Factors and AMPK Activation

Obesity is an abnormal medical condition caused by accumulation of body fat that presents negative health impacts. Adipocyte hyperplasia, also known as adipogenesis, is one of the major manifestations of obesity. In the present study, we isolated six phenanthrene derivatives (compounds 1–6) from the ethyl acetate fraction of Spiranthes sinensis and investigated their anti-adipogenic activity. We found that among the six phenanthrene derivatives, compound 6 (sinensol-C) exhibited strong inhibitory activity against intracellular lipid accumulation in 3T3-L1 adipocytes, with an IC₅₀ value of 12.67 μM. Sinensol-C remarkably suppressed the accumulation of lipid droplets and adipogenesis, via down-regulation of adipogenic transcription factors, including peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding protein α (C/EBPα), sterol regulatory element binding protein-1 (SREBP-1c), fatty acid synthase (FAS), and fatty acid binding protein 4 (FABP4), during adipocyte differentiation in 3T3-L1 cells. In addition, treatment with sinensol-C significantly increased the adenosine monophosphate-activated protein kinase (AMPK) activity in 3T3-L1 cells. Taken together, these data strongly suggest that sinensol-C regulates adiogenesis via down-regulation of adipogenic transcription factors and up-regulation of AMPK. Furthermore, this is the first study that demonstrates that sinensol-C has the capacity to modulate adipogenesis.

Inhibitory effects of compounds from the roots of Potentilla longifolia on lipid accumulation

Potentilla longifolia is a kind of Chaoyao medicine, which is a branch of traditional Chinese medicine. The plant is often referred to as ganyancao or ganyearmcao, which means that it has a significant therapeutic effect on liver inflammation. In previous experiments, we found that a water extract of ganyearmcao inhibited lipid accumulation. In the present study, we isolated one new (ganyearmcaoone A, 1) and eight known compounds (2–9) from a water extract of the dried roots of ganyearmcao; all of the compounds were isolated for the first time from this medicinal plant. We elucidated the chemical structures of these compounds using comprehensive analyses of HR-ESI-MS and 1D, 2D NMR. We evaluated the inhibitory effects of the nine compounds on lipid accumulation in 3T3-L1 cells; we did so using photographic and quantitative assessments of the lipid content with oil red O staining and by measuring triglyceride levels. Compared with the control, compounds 6 and 9 significantly inhibited differentiation of 3T3-L1 cells and lipid accumulation. Compound 1 showed potential inhibitory effects on lipid accumulation. Molecular docking results indicated that compounds 6 and 9 may efficiently bind to AMPK and its downstream kinase (SCD1), thereby inhibiting lipid accumulation. Our results demonstrate that ganyearmcao and its components may play an important role in treating diseases related to lipid accumulation in the future.

In Vitro Evaluation of Clinical Candidates of γ-Secretase Inhibitors: Effects on Notch Inhibition and Promoting Beige Adipogenesis and Mitochondrial Biogenesis

PURPOSE

Inhibition of Notch signaling has been recently demonstrated to promote beige adipocyte biogenesis. However, most γ-secretase inhibitors (GSIs) used to achieve pharmacological inhibition of Notch signaling are at the basic research or preclinical stage, limiting the translation of fundamental findings into clinical practice. This present study aimed to evaluate the potential of several clinical candidates of GSIs as browning agents for the treatment of obesity.

METHODS

Seven GSIs that are clinical candidates for the treatment of Alzheimer's disease or cancer were selected and their impacts on Notch inhibition as well as promoting beige biogenesis were compared using in vitro culture of 3T3-L1 preadipocytes.

RESULTS

Four compounds (i.e.RO4929097, PF-03084014, LY3039478, and BMS-906024) that efficiently inhibited the expression of Notch target genes in 3T3-L1 preadipocytes were identified. Moreover, these compounds were optimized for dose-dependent effects at three gradient concentrations (0.5, 1, and 10 μM) to promote beige adipogenesis and mitochondrial biogenesis in 3T3-L1 preadipocytes without causing severe cytotoxicity.

CONCLUSIONS

Our findings not only highlight the potential of cross-therapeutic application of these GSIs for obesity treatment via inhibition of γ-secretase-mediated processing of Notch signaling, but also provide important experimental evidence to support further design and development of clinically translatable Notch-inhibiting drug delivery systems.

White Adipose Tissue as a Site for Islet Transplantation

Although islet transplantation is recognized as a useful cellular replacement therapy for severe diabetes, surgeons face difficulties in islet engraftment. The transplant site is a pivotal factor that influences the engraftment. Although the liver is the current representative site for clinical islet transplantation, it is not the best site because of limitations in immunity, inflammation, and hypoxia. White adipose tissue, including omentum, is recognized as a useful candidate site for islet transplantation. Its effectiveness has been evaluated in not only various basic and translational studies using small and large animals but also in some recent clinical trials. In this review, we attempt to shed light on the characteristics and usefulness of white adipose tissue as a transplant site for islets.

White Adipose Tissue as a Site for Islet Transplantation

Although islet transplantation is recognized as a useful cellular replacement therapy for severe diabetes, surgeons face difficulties in islet engraftment. The transplant site is a pivotal factor that influences the engraftment. Although the liver is the current representative site for clinical islet transplantation, it is not the best site because of limitations in immunity, inflammation, and hypoxia. White adipose tissue, including omentum, is recognized as a useful candidate site for islet transplantation. Its effectiveness has been evaluated in not only various basic and translational studies using small and large animals but also in some recent clinical trials. In this review, we attempt to shed light on the characteristics and usefulness of white adipose tissue as a transplant site for islets.

Macrophage plays important role in cortisol and serotonin induced adipogenesis in vitro

Psychological stress is an important cause to induce various metabolic disorders such as obesity, type II diabetes, and cardiovascular disorders by affecting the visceral adipose tissue. Pathophysiology of these diseases is often accompanied by the hyperactive immune system. The hyperactive immune system causes immune cells to infiltrate in the adipose tissue to increase the severity of metabolic disorders and to affect the levels of stress associated hormones, such as cortisol and serotonin. Cortisol and serotonin, alone or together, could regulate several aspects of the metabolic and immunological deregulations by manipulating the lipid accumulation or adipogenesis in cells. During adipogenesis, macrophages are recruited. Previous reports from the Aich laboratory established the roles of cortisol and serotonin to influence adipogenesis in pre-adipocytes 3T3-L1 in the presence and absence of macrophages. In the current study, we reported the role of macrophage RAW264.7, especially its polarized states, on differentiated murine adipocytes 3T3-L1 in the presence or absence of cortisol and serotonin. The current study also compares the differential role of macrophage recruitment on pre- and differentiated adipocytes.

Adipogenic effects of prenatal exposure to bisphenol S (BPS) in adult F1 male mice

Bisphenol S (BPS) has been increasingly used as a substitute for bisphenol A (BPA), a known endocrine disruptor. Early-life exposure to BPA affects fetal development and the risk of obesity in adolescence and adulthood. However, the effects of fetal exposure BPS in later life are unknown. This study aimed to investigate the effects of prenatal BPS exposure on adiposity in adult F1 mice. Pregnant C57BL/6 N mice were exposed to BPS (0, 0.05, 0.5, 5, and 50 mg/kg/d) via drinking water from gestation day 9 until delivery. Thereafter, two groups of offspring (6 weeks old) were either administered a standard diet (STD) or a high-fat diet (HFD) for 4 weeks until euthanasia. The body weight and gonadal white adipose tissue (gWAT) mass were determined, and the energy expenditure for the adiposity phenotype was computed especially for male mice, followed by histological analysis of the gWAT. Thereafter, the expression levels of adipogenic marker genes (Pparg, Cebpa, Fabp4, Lpl, and Adipoq) were analyzed in the gWAT via reverse-transcription PCR analysis. BPS-exposed male mice displayed apparent gWAT hypertrophy, consistent with the significant increase in adipocyte size in the gWAT and upregulation of Pparg and its direct target genes among HFD mice in comparison with the control mice. These results suggest that prenatal BPS exposure potentially increases the susceptibility to HFD-induced adipogenesis in male adult mice.