Activation of CCAAT/enhancer-binding protein (C/EBP) alpha expression by C/EBP beta during adipogenesis requires a peroxisome proliferator-activated receptor-gamma-associated repression of HDAC1 at the C/ebp alpha gene promoter

LINC00278 and BRG1: A key regulatory axis in male obesity and preadipocyte adipogenesis

Obesity is a significant public health concern directly associated with adipogenesis. Long non-coding RNAs (lncRNAs) have emerged as critical regulators of adipogenesis. However, the roles of sex-specific lncRNAs in adipose tissue are not well comprehended. In this study, we used lncRNA microarrays to profile lncRNAs expression in visceral adipose tissues from obese and lean individuals, identifying LINC00278 as significantly and exclusively expressed in males. Elevated levels of LINC00278 were associated with higher body mass index (BMI) and non-remission after bariatric surgery in individuals with obesity. Mechanistic studies further revealed that METTL14 regulates the m6A methylation of LINC00278, which in turn binds with BRG1, activating the PPAR-γ2 pathway and promoting adipogenesis. Additionally, adipose-specific LINC00278 knock-in in C57BL/6 J mice resulted in adipocyte enlargement, increased body weight, higher body fat percentage, and impaired glucose metabolism. Treatment with the BRG1 inhibitor, BRM/BRG1 ATP Inhibitor-1, significantly alleviated the obesity phenotype in these mice. Our findings highlight the critical role of LINC00278 in male adipogenesis, suggesting that targeting the LINC00278-BRG1 axis could be a potential therapeutic strategy for managing obesity and related metabolic disorders in males.

A new target for drug repositioning: CEBPα elicits LL-37 expression in a vitamin D-independent manner promoting Mtb clearance

Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis (Mtb) and is a growing public health problem worldwide. Within the innate immune response, we highlight the secretion of the antimicrobial peptide LL-37, which is crucial for Mtb elimination in infected cells. Previous reports have shown that CEBPα activation induces LL-37 independently of its main inducer, vitamin D, under endoplasmic reticulum (ER) stress. In this study, we report that infection with Mtb causes ER stress in pulmonary epithelial cells and macrophages. The stress induces the activation of CEBPα, which in turn promotes the LL-37 expression. Furthermore, the participation of CEBPα is necessary for the correct clearance of Mtb in an in vitro infection model. We identify candidate drugs (mycophenolic acid, indapamide, and glibenclamide) capable of activating CEBPα and promoting LL-37 through in silico assays. The effect of the drugs was corroborated by gene and protein expression analysis. Finally, we observed that treatment with these drugs improves bacterial clearance in infected cells. Our results lead us to suggest CEBPα as a potential therapeutic target as an adjuvant in the standard treatment of tuberculosis, seeking a reduction in treatment time, and thus a lower appearance of drug resistance.

Circ_0011446 Regulates Intramuscular Adipocyte Differentiation in Goats via the miR-27a-5p/FAM49B Axis

Intramuscular fat (IMF), or marbling, is a critical indicator of goat meat quality. Non-coding RNAs play a key role in the formation and deposition of IMF in vertebrates by regulating genes involved in its synthesis, degradation, and transport. The competing endogenous RNA (ceRNA) hypothesis identifies circular RNAs (circRNAs) as natural "sponges" for microRNAs (miRNAs). However, the precise mechanisms of circRNAs in goat IMF remain poorly understood. In the current study, we utilized existing sequencing data to construct a ceRNA regulatory network associated with intramuscular adipogenesis and fat deposition in goats. Our goal was to elucidate the post-transcriptional regulatory mechanism of family with sequence similarity 49 member B (FAM49B). Functionally, FAM49B was found to inhibit the differentiation of intramuscular preadipocytes and to directly interact with miR-27a-5p. Mechanistically, dual-luciferase reporter assays and quantitative real-time PCR (qRT-PCR) confirmed the interaction between circ0011446 and miR-27a-5p. Circ0011446 enhanced the expression of FAM49B mRNA and protein through post-transcriptional regulation. As a ceRNA, circ0011446 competitively binds miR-27a-5p, preventing miR-27a-5p from degrading FAM49B. In conclusion, our findings demonstrate that circ0011446 suppresses goat adipogenic differentiation of intramuscular preadipocytes by regulating the expression of the downstream target gene FAM49B through miR-27a-5p sequestration. This study provides a reference for goat meat quality or livestock breeding.

The first dimeric indole-diterpenoids from a marine-derived Penicillium sp. fungus and their potential for anti-obesity drugs

Obesity has become a worldwide health problem. Seeking natural products with anti-obesity activity from lots of fungi has drawn the attention of pharmacologists. In our study, dipenipenoids A and B (1 and 2), the first dimeric indole-diterpenoids with a rare C-20-C-22' linkage, and their monomers (3 and 4), were isolated from a marine-derived Penicillium sp. CF-06 fungus from Suaeda salsa. The absolute configurations of 1-3 were assigned by the calculated TDDFT ECD method. The structure of 4 was verified by a single-crystal X-ray diffraction method for the first time. Interestingly, 1 and 2 displayed significant effects on the differentiation of 3T3-L1 adipocytes by down-regulating the expression of peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer binding protein alpha (C/EBPα) proteins, while monomers 3 and 4 exhibited no activity. Molecular docking results explained the mechanism that the interaction between dimer 1 and PPARγ was stronger than that between monomer 3 and PPARγ. Our research could provide new insight for the discovery of anti-obesity drugs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-024-00253-x.

Promising role of peroxisome proliferator-activated receptors in respiratory disorders, a review

Several studies indicate various pharmacological and therapeutic effects of peroxisome proliferator-activated receptors (PPARs) in different disorders. The current review describes the influences of PPARs on respiratory, allergic, and immunologic diseases. Various databases, including PubMed, Science Direct, and Scopus, were searched regarding the effect of PPARs on respiratory and allergic disorders from 1990 to 2024. The effects of PPARs stimulation on experimental animal models of respiratory diseases such as asthma, chronic obstructive pulmonary diseases (COPD), pulmonary fibrosis (PF), and lung infections were shown. Therapeutic potential mediated through PPARs has also been demonstrated in lung cancer, lung infections, and allergic and immunologic disorders. However, few clinical studies showed PPARs mediated therapeutic effects on asthma and COPD. The PPARs-mediated effects on various respiratory disorders were shown through antioxidant, immunomodulatory, anti-inflammatory, and other mechanisms. Therefore, this review indicated possible remedy effects mediated by these receptors in treating respiratory, allergic, and immunologic diseases. Moreover, this mechanistic review paves the way for researchers to consider further experimental and clinical studies.

Anti-Obesity Effects of Pleurotus ferulae Water Extract on 3T3-L1 Adipocytes and High-Fat-Diet-Induced Obese Mice

This study offers promising insights into the anti-obesity potential of Pleurotus ferulae, an edible mushroom valued in Asian cuisine for its nutritional benefits. A hot water extract of P. ferulae (PWE) administered to high-fat diet-induced obese mice over an 8-week period significantly reduced their body weight gain and fat accumulation. PWE not only improved the body weight metrics but also positively influenced the serum lipid profile of obese mice by lowering their total cholesterol and low-density lipoprotein cholesterol levels. In vitro studies using 3T3-L1 adipocytes showed that PWE inhibited adipocyte differentiation and lipid accumulation by downregulating key adipogenic transcription factors, particularly PPARγ and C/EBPα, as well as related lipogenic genes involved in fat synthesis and storage, such as Fabp4, Fasn, and Scd1. Chemical analysis revealed that PWE is rich in polysaccharides, which have been associated with various health benefits, including anti-obesity, anti-diabetic, and anti-cancer properties. These findings suggest that the bioactive compounds in PWE may serve as functional food components that could potentially be applied for the prevention and management of obesity and other metabolic disorders.

MicroRNA Nobel Prize: Timely Recognition and High Anticipation of Future Products-A Prospective Analysis

MicroRNAs (miRNAs) maintain cellular homeostasis by blocking mRNAs by binding with them to fine-tune the expression of genes across numerous biological pathways. The 2024 Nobel Prize in Medicine and Physiology for discovering miRNAs was long overdue. We anticipate a deluge of research work involving miRNAs to repeat the history of prizes awarded for research on other RNAs. Although miRNA therapies are included for several complex diseases, the realization that miRNAs regulate genes and their roles in addressing therapies for hundreds of diseases are expected; but with advancement in drug discovery tools, we anticipate even faster entry of new drugs. To promote this, we provide details of the current science, logic, intellectual property, formulations, and regulatory process with anticipation that many more researchers will introduce novel therapies based on the discussion and advice provided in this paper.

Deciphering adipose development: Function, differentiation and regulation

The overdevelopment of adipose tissues, accompanied by excess lipid accumulation and energy storage, leads to adipose deposition and obesity. With the increasing incidence of obesity in recent years, obesity is becoming a major risk factor for human health, causing various relevant diseases (including hypertension, diabetes, osteoarthritis and cancers). Therefore, it is of significance to antagonize obesity to reduce the risk of obesity-related diseases. Excess lipid accumulation in adipose tissues is mediated by adipocyte hypertrophy (expansion of pre-existing adipocytes) or hyperplasia (increase of newly-formed adipocytes). It is necessary to prevent excessive accumulation of adipose tissues by controlling adipose development. Adipogenesis is exquisitely regulated by many factors in vivo and in vitro, including hormones, cytokines, gender and dietary components. The present review has concluded a comprehensive understanding of adipose development including its origin, classification, distribution, function, differentiation and molecular mechanisms underlying adipogenesis, which may provide potential therapeutic strategies for harnessing obesity without impairing adipose tissue function.

MicroRNA-21 modulates brown adipose tissue adipogenesis and thermogenesis in a mouse model of polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS), the most common endocrine disorder in premenopausal women, is associated with increased obesity, hyperandrogenism, and altered brown adipose tissue (BAT) thermogenesis. MicroRNAs play critical functions in brown adipocyte differentiation and maintenance. We aim to study the role of microRNA-21 (miR-21) in altered energy homeostasis and BAT thermogenesis in a PCOS mouse model of peripubertal androgen exposure.

METHODS

Three-week-old miR-21 knockout (miR21KO) or wild-type (WT) female mice were treated with dihydrotestosterone (DHT) or vehicle for 90 days. Body composition was determined by EchoMRI. Energy expenditure (EE), oxygen consumption (VO2), carbon dioxide production (VCO2), and respiratory exchange ratio (RER) were measured by indirect calorimetry. Androgen receptor (AR), and markers of adipogenesis, de novo lipogenesis, angiogenesis, extracellular matrix remodeling, and thermogenesis were quantified by RT-qPCR and/or Western-blot.

RESULTS

MiR-21 ablation attenuated DHT-mediated increase in body weight while having no effect on fat or BAT mass. MiR-21 ablation attenuated DHT-mediated BAT AR upregulation. MiR-21 ablation did not alter EE; however, miR21KO DHT-treated mice have reduced VO2, VCO2, and RER. MiR-21 ablation reversed DHT-mediated decrease in food intake and increase in sleep time. MiR-21 ablation decreased some adipogenesis (Adipoq, Pparγ, and Cebpβ) and extracellular matrix remodeling (Mmp-9 and Timp-1) markers expression in DHT-treated mice. MiR-21 ablation abolished DHT-mediated increases in thermogenesis markers Cpt1a and Cpt1b, while decreasing CIDE-A expression.

CONCLUSIONS

Our findings suggest that BAT miR-21 may play a role in regulating DHT-mediated thermogenic dysfunction in PCOS. Modulation of BAT miR-21 levels could be a novel therapeutic approach for the treatment of PCOS-associated metabolic derangements.

White-to-Beige and Back: Adipocyte Conversion and Transcriptional Reprogramming

Obesity has become a pandemic, as currently more than half a billion people worldwide are obese. The etiology of obesity is multifactorial, and combines a contribution of hereditary and behavioral factors, such as nutritional inadequacy, along with the influences of environment and reduced physical activity. Two types of adipose tissue widely known are white and brown. While white adipose tissue functions predominantly as a key energy storage, brown adipose tissue has a greater mass of mitochondria and expresses the uncoupling protein 1 (UCP1) gene, which allows thermogenesis and rapid catabolism. Even though white and brown adipocytes are of different origin, activation of the brown adipocyte differentiation program in white adipose tissue cells forces them to transdifferentiate into "beige" adipocytes, characterized by thermogenesis and intensive lipolysis. Nowadays, researchers in the field of small molecule medicinal chemistry and gene therapy are making efforts to develop new drugs that effectively overcome insulin resistance and counteract obesity. Here, we discuss various aspects of white-to-beige conversion, adipose tissue catabolic re-activation, and non-shivering thermogenesis.

Lipid Storage, Lipolysis, and Lipotoxicity in Obesity

The ratio of free fatty acid (FFA) turnover decreases significantly with the expansion of white adipose tissue. Adipose tissue and dietary saturated fatty acid levels significantly correlate with an increase in fat cell size and number. The G0/G1 switch gene 2 increases lipid content in adipocytes and promotes adipocyte hypertrophy through the restriction of triglyceride (triacylglycerol: TAG) turnover. Hypoxia in obese adipose tissue due to hypertrophic adipocytes results in excess deposition of extracellular matrix (ECM) components. Cluster of differentiation (CD) 44, as the main receptor of the extracellular matrix component regulates cell-cell and cell-matrix interactions including diet-induced insulin resistance. Excess TAGs, sterols, and sterol esters are surrounded by the phospholipid monolayer surface and form lipid droplets (LDs). Once LDs are formed, they grow up because of the excessive amount of intracellular FFA stored and reach a final size. The ratio of FFA turnover/lipolysis decreases significantly with increases in the degree of obesity. Dysfunctional adipose tissue is unable to expand further to store excess dietary lipids, increased fluxes of plasma FFAs lead to ectopic fatty acid deposition and lipotoxicity. Reduced neo-adipogenesis and dysfunctional lipid-overloaded adipocytes are hallmarks of hypertrophic obesity linked to insulin resistance. Obesity-associated adipocyte death exhibits feature of necrosis-like programmed cell death. Adipocyte death is a prerequisite for the transition from hypertrophic to hyperplastic obesity. Increased adipocyte number in obesity has life-long effects on white adipose tissue mass. The positive correlation between the adipose tissue volume and magnetic resonance imaging proton density fat fraction estimation is used for characterization of the obesity phenotype, as well as the risk stratification and selection of appropriate treatment strategies. In obese patients with type 2 diabetes, visceral adipocytes exposed to chronic/intermittent hyperglycemia develop a new microRNAs' (miRNAs') expression pattern. Visceral preadipocytes memorize the effect of hyperglycemia via changes in miRNAs' expression profile and contribute to the progression of diabetic phenotype. Nonsteroidal anti-inflammatory drugs, metformin, and statins can be beneficial in treating the local or systemic consequences of white adipose tissue inflammation. Rapamycin inhibits leptin-induced LD formation. Collectively, in this chapter, the concept of adipose tissue remodeling in response to adipocyte death or adipogenesis, and the complexity of LD interactions with the other cellular organelles are reviewed. Furthermore, clinical perspective of fat cell turnover in obesity is also debated.

Deciphering the interaction between Twist1 and PPARγ during adipocyte differentiation

Obesity, a worldwide epidemic in recent years, is mainly due to the uncontrolled development of adipose tissues, which includes adipocyte hypertrophy and hyperplasia. Adipocyte differentiation is a process involving multiple transcription factor cascades, and the exact mechanism has not yet been defined. As a bHLH transcription factor, Twist1 exerts its activity by forming homo- or heterodimers with other factors. In this study, we showed Twist1 restricts adipogenesis through PPARγ. Expression of various differentiation markers (including PPARγ and adiponectin) and triglyceride-containing lipid droplets were decreased with overexpression of Twist1. Pathway enrichment analysis of RNA-seq data showed that differentially expressed genes (DEGs) caused by Twist1 overexpression were significantly related to lipolysis and PPARγ signaling. This implicates that Twist1 plays important regulatory roles in these processes. ChIP and dual luciferase assays showed that Twist1 could bind either PPARγ or adiponectin promoter to repress their respective transcription or directly to PPARγ protein to regulate its transcriptional activity. Furthermore, Twist1 directly interacted RXRα, which usually forms heterodimer with PPARγ to regulate adipogenesis. Taken together, our results suggest that Twist1 is an inhibitory modulator of adipogenesis and its function is likely through direct interaction with PPARγ protein or its gene promoter.

Discrimination of Dendropanax morbifera via HPLC fingerprinting and SNP analysis and its impact on obesity by modulating adipogenesis- and thermogenesis-related genes

Dendropanax morbifera (DM), a medicinal plant, is rich in polyphenols and commonly used to treat cancer, inflammation, and thrombosis. However, to date, no study has been conducted on DM regarding the enormous drift of secondary metabolites of plants in different regions of the Republic of Korea and their effects on antiobesity, to explore compounds that play an important role in two major obesity-related pathways. Here, we present an in-depth study on DM samples collected from three regions of the Republic of Korea [Jeju Island (DMJ), Bogildo (DMB), and Jangheung (DMJG)]. We used high-performance liquid chromatography (HPLC) and multivariate component analyses to analyze polyphenol contents (neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, and rutin), followed by discrimination of the samples in DMJG using single nucleotide polymorphism and chemometric analysis. In silico and in vitro evaluation of major compounds found in the plant extract on two major anti-obesity pathways (adipogenesis and thermogenesis) was carried out. Furthermore, two extraction methods (Soxhlet and ultrasound-assisted extraction) were used to understand which method is better and why. Upon quantifying plant samples in three regions with the polyphenols, DMJG had the highest content of polyphenols. The internal transcribed region (ITS) revealed a specific gel-based band for the authentication of DMJG. PCA and PLS-DA revealed the polyphenol's discriminative power of the region DMJG. The anti-obesity effects of plant extracts from the three regions were related to their polyphenol contents, with DMJG showing the highest effect followed by DMJ and DMB. Ultrasound-assisted extraction yielded a high number of polyphenols compared to that of the Soxhlet method, which was supported by scanning electron microscopy. The present work encourages studies on plants rich in secondary metabolites to efficiently use them for dietary and therapeutic purposes.

Gadolinium-based contrast agents suppress adipocyte differentiation in 3T3-L1 cells

Gadolinium-based contrast agents (GBCAs) are widely used in magnetic resonance imaging (MRI) to improve the sensitivity and enhance diagnostic performance. GBCAs are mostly eliminated from the body through the kidney after administration; however small amounts of gadolinium are retained in the brain and other tissues. Although there is increasing concern about the adverse health effects of gadolinium, the cellular effects of GBCAs remains poorly understood. Here, we elucidated the potential cytotoxicity of the GBCAs Omniscan and Gadovist in 12 different cell lines, especially 3T3-L1 adipocyte cell line. Omniscan and Gadovist treatments significantly increased intracellular gadolinium levels in 3T3-L1 cells in a time- and dose-dependent manner. Additionally, Omniscan and Gadovist treatments downregulated the expression of adipocyte differentiation markers, including peroxisome proliferator-activated receptor γ (PPARG), adiponectin (ADIPOQ), and fatty acid-binding protein (FABP4), in 3T3-L1 cells, especially during early differentiation (day 0-2). Moreover, histological analysis using Oil red O staining showed that gadolinium chloride (GdCl₃) treatment suppressed lipid droplet accumulation and the expression of adipocyte differentiation markers. Overall, the results showed that Omniscan and Gadovist treatment suppressed adipocyte differentiation in 3T3-L1 cells, contributing to the understanding of the potential toxic effects of GBCA exposure.

Identification of DDX5 as an indispensable activator of the glucocorticoid receptor in adipocyte differentiation

The expression of CCAAT/enhancer-binding protein (C/EBP) family members and peroxisome proliferator-activated receptor γ (PPAR γ) is essential for the differentiation of pre-adipocyte 3T3-L1 cells into mature adipocytes induced by a combined stimulation with dexamethasone, 3-isobutyl-1-methylxanthine and insulin (DMI). We herein demonstrated that the RNA helicase DDX5, the expression of which was induced by DMI, played an important role in the adipocyte differentiation of 3T3-L1 cells. The DMI-induced accumulation of lipid droplets and expression of adipocyte markers in 3T3-L1 cells were significantly inhibited by the knockdown of DDX5. The knockdown of DDX5 interfered with the expressional induction of C/EBPδ, which was the first to be induced in the transcription factor cascade, and inhibited the subsequent expression of the other transcription factors, C/EBPβ, PPARγ and C/EBPα. DDX5 interacted with the glucocorticoid receptor (GR), which induced the expression of C/EBPδ. The knockdown of DDX5 failed to induce the nuclear translocation of GR, suggesting the essential role of DDX5 in the early stage of adipocyte differentiation. Furthermore, the reconstitution of DDX5, but not the DDX5 mutant (K144N) lacking RNA helicase activity, restored DMI-induced GR activation and adipocyte differentiation in 3T3-L1 cells in which DDX5 was knocked down, confirming that the RNA helicase activity of DDX5 is essential for adipogenesis. Collectively, these results revealed for the first time that DDX5 is necessary for GR activation and plays an essential role in early adipocyte differentiation.

Histone modifications in fat metabolism and obesity

The World Health Organization (WHO) has identified the obesity epidemic as one of the leading causes of overall morbidity and mortality. Obesity affects individual health, and quality of life and has negative long-term economic implications on society and the entire country. In recent years, studies on histone modifications in fat metabolism and obesity have received great attention. Processes such as methylation, histone modification, chromatin remodeling, and microRNA expression are mechanisms in epigenetic regulation. These processes play a particularly important role in cell development and differentiation through gene regulation. In this chapter, we discuss the types of histone modifications in adipose tissue under different conditions, the role of histone modifications in adipose tissue development, and the relationship between histone modifications and biosynthesis in the body. In addition, the chapter provides detailed information on histone modifications in obesity, the relationship between histone modifications and food consumption status, and the role of histone modifications in overweight and obesity.

Anmyungambi Decoction Ameliorates Obesity through Activation of Non-Shivering Thermogenesis in Brown and White Adipose Tissues

Obesity is a burden to global health. Non-shivering thermogenesis of brown adipose tissue (BAT) and white adipose tissue (WAT) is a novel strategy for obesity treatment. Anmyungambi (AMGB) decoction is a multi-herb decoction with clinical anti-obesity effects. Here, we show the effects of AMGB decoction using high-fat diet (HFD)-fed C57BL6/J mice. All four versions of AMGB decoction (100 mg/kg/day, oral gavage for 28 days) suppressed body weight gain and obesity-related blood parameters in the HFD-fed obese mice. They also inhibited adipogenesis and induced lipolysis in inguinal WAT (iWAT). Especially, the AMGB-4 with 2:1:3:3 composition was the most effective; thus, further studies were performed with the AMGB-4 decoction. The AMGB-4 decoction displayed a dose-dependent body weight gain suppression. Serum triglyceride, total cholesterol, and blood glucose decreased as well. In epididymal WAT, iWAT, and BAT, the AMGB-4 decoction increased lipolysis markers. Additionally, the AMGB-4 decoction-fed mice showed an increased non-shivering thermogenic program in BAT and iWAT. Excessive reactive oxygen species (ROS) and suppressed antioxidative factors induced by the HFD feeding were also altered to normal levels by the AMGB-4 decoction treatment. Overall, our study supports the clinical use of AMGB decoction for obesity treatment by studying its mechanisms. AMGB decoction alleviates obesity through the activation of the lipolysis-thermogenesis program and the elimination of pathological ROS in thermogenic adipose tissues.

Spermine Suppresses Adipocyte Differentiation and Exerts Anti-Obesity Effects In Vitro and In Vivo

Endogenous polyamines such as putrescine (Put), spermidine (Spd), and spermine (Spm) affect adipocyte differentiation. In this study, we investigated the effect of exogenously supplemented polyamines on mouse adipocyte differentiation and anti-obesity actions in vitro and in vivo. The preadipocyte cell line, 3T3-L1, was cultured with Put, Spd, or Spm, and lipid accumulation in the cells was measured by Oil Red O staining. Lipid accumulation was significantly suppressed by Spm. Suppression of CCAAT/enhancer binding protein α mRNA by Spm suggested that the decreased lipid accumulation was due to delaying the cell differentiation. The body weight and fat of obese mice induced with a high-fat diet were reduced by oral ingestion of Spm. In conclusion, oral supplementation of Spm has the ability to prevent obesity through inhibition of adipocyte differentiation.

1,3,5,8-Tetrahydroxyxanthone suppressed adipogenesis via activating Hedgehog signaling in 3T3-L1 adipocytes

In this study, we investigated the effect of 1,3,5,8-tetrahydroxyxanthone (THX) on the adipogenesis of 3T3-L1 adipocytes. THX, a xanthone isolated from Gentianella acuta, inhibited lipid accumulation in 3T3-L1 adipocytes and reduced the protein levels of the key adipogenic transcriptional factors, peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα), in a dose-dependent manner. In addition, THX enhanced the transcriptional activity of Gli1 known as the key indicator of Hedgehog (Hh) signaling activity and increased the expression of Gli1 and its upstream regulator Smo. The Smo activator SAG exerted the similar effect with THX on regulating Gli1, Smo, PPARγ and C/EBPα expression, which led to the suppression of fat formation in 3T3-L1 adipocytes. Furthermore, we found that the inhibitory effect of THX on adipogenesis was derived from regulation of the early stage of adipogenesis. These results suggest that THX suppresses the differentiation of adipocyte through Hh signaling and may be considered as a potent agent for the prevention of obesity.

The Role of Transcription Factor PPAR-γ in the Pathogenesis of Psoriasis, Skin Cells, and Immune Cells

The peroxisome proliferator-activated receptor PPAR-γ is one of three PPAR nuclear receptors that act as ligand-activated transcription factors. In immune cells, the skin, and other organs, PPAR-γ regulates lipid, glucose, and amino acid metabolism. The receptor translates nutritional, pharmacological, and metabolic stimuli into the changes in gene expression. The activation of PPAR-γ promotes cell differentiation, reduces the proliferation rate, and modulates the immune response. In the skin, PPARs also contribute to the functioning of the skin barrier. Since we know that the route from identification to the registration of drugs is long and expensive, PPAR-γ agonists already approved for other diseases may also represent a high interest for psoriasis. In this review, we discuss the role of PPAR-γ in the activation, differentiation, and proliferation of skin and immune cells affected by psoriasis and in contributing to the pathogenesis of the disease. We also evaluate whether the agonists of PPAR-γ may become one of the therapeutic options to suppress the inflammatory response in lesional psoriatic skin and decrease the influence of comorbidities associated with psoriasis.

MiR-23b Promotes Porcine Preadipocyte Differentiation via SESN3 and ACSL4

Genetic improvement of pork quality is one of the hot topics in pig germplasm innovation. Backfat thickness and intramuscular fat content are important indexes of meat quality. MiRNAs are becoming recognized as a crucial regulator of adipose development. Therefore, it is crucial to understand how miR-23b regulates fat metabolism at the molecular level. In the present study, Oil Red O staining, and Western blot were used to evaluate the effect of miR-23b on the differentiation of porcine preadipocytes. Dual-luciferase reporter gene assay, pulldown, and RIP were used to reveal the mechanism of miR-23b regulating cell differentiation. The findings demonstrated that miR-23b promotes the expression of adipogenic factors and increases the content of lipid droplets, thus promoting the differentiation of preadipocytes. Further research found that miR-23b can directly bind to the 3’UTR of SESN3 to regulate adipogenic differentiation. In addition, it was speculated that miR-23b controls cell differentiation by positively regulating the expression of ACSL4 in other ways. Here, we demonstrate that miR-23b promotes the differentiation of porcine preadipocytes by targeting SESN3 and promoting the expression of ACSL4. The present study is meaningful to the improvement of pork quality and the development of animal husbandry.

Gestational and lactational exposure to the emergent alternative plasticizer 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH) impairs lipid metabolism to a greater extent than the commonly used Di(2-ethylhexyl) phthalate (DEHP) in the adult rat mammary gland

Due to their endocrine disruption properties, phthalate plasticizers such as di(2-ethylhexyl) phthalate (DEHP) can affect the hormone-dependent development of the mammary gland. Over the past few years, DEHP has been partially replaced by 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH) which also have potential endocrine disrupting properties. The goal of the present study is to understand the impact of a gestational and lactational exposure to DEHP and DINCH on mammary gland development using Sprague-Dawley rats. Both plasticizers altered the adipocytes of the mammary gland fat pad of adult progeny, as demonstrated by a decrease in their size, folding of their membrane and modulations of the lipid profiles. DEHP treatments decreased the expression of Rxrα and Scd1 at the low and high dose, respectively, but did not affect any of the other genes studied. DINCH modulation of lipid metabolism could be observed at puberty by a decreased expression of genes implicated in triglyceride synthesis, lipid transport and lipolysis, but by an increased expression of genes of the β-oxidation pathway and of genes involved in lipid storage and fatty acid synthesis at adulthood, compared to control and DEHP-treated rats. A strong upregulation of different inflammatory markers was observed following DINCH exposure only. Together, our results indicate that a gestational and lactational exposure to DINCH has earlier and more significant effects on lipid homeostasis, adipogenesis and the inflammatory state of the adult mammary gland than DEHP exposure. The long-term consequence of these effects on mammary gland health remained to be determined.

Effect of expression of PPARG, DNM2L, RRAD, and LINGO1 on broiler chicken breast muscle satellite cell function

Disorders affecting the breast muscle of modern commercial broiler chickens have increased in recent years. Wooden Breast (WB) myopathy is characterized by a palpably hard breast muscle with increased fat deposition. WB is a metabolic disorder with lipid accumulation considered to be a primary causal factor. The adult myoblasts, satellite cells, are a partially differentiated stem cell population and primarily function in muscle growth and regeneration. The satellite cells also express adipogenic genes. The objective of this study was to determine the expression of the adipogenic genes PPARG, DNM2L, RRAD, and LINGO1 in commercial Ross 708 (708) and Randombred (RBch) satellite cells. RBch satellite cells are from commercial 1995 broilers before WB and 708 broilers are a modern commercial line. In general, expression of these genes was different between the 708 and RBch satellite cells during proliferation and differentiation. Expression of PPARG and RRAD were both significantly increased during both proliferation and differentiation in the 708 cells (P ≤ 0.05). Knocking down the expression of these genes with small interfering RNAs did not greatly affect either proliferation or differentiation. Lipid accumulation was affected by the knockdown of these genes with significant line effects from 48 h of proliferation through 72 h of differentiation. In general, 708 satellite cells had higher lipid levels. Knockdown treatment effect was specific to each gene. The results demonstrate that lipid biosynthesis has been affected in breast muscle satellite cells which may contribute to the increased lipid deposition in modern day commercial broiler chickens.

Biogenic Phytochemicals Modulating Obesity: From Molecular Mechanism to Preventive and Therapeutic Approaches

The incidence of obesity and over bodyweight is emerging as a major health concern. Obesity is a complex metabolic disease with multiple pathophysiological clinical conditions as comorbidities are associated with obesity such as diabetes, hypertension, cardiovascular disorders, sleep apnea, osteoarthritis, some cancers, and inflammation-based clinical conditions. In obese individuals, adipocyte cells increased the expression of leptin, angiotensin, adipocytokines, plasminogen activators, and C-reactive protein. Currently, options for treatment and lifestyle behaviors interventions are limited, and keeping a healthy lifestyle is challenging. Various types of phytochemicals have been investigated for antiobesity potential. Here, we discuss pathophysiology and signaling pathways in obesity, epigenetic regulations, regulatory mechanism, functional ingredients in natural antiobesity products, and therapeutic application of phytochemicals in obesity.

Tamarixetin Abrogates Adipogenesis Through Inhibiting p300/CBP-Associated Factor Acetyltransferase Activity in 3T3-L1 Preadipocyte Cells

Tamarixetin (TX) is an O-methylated flavonoid naturally derived from quercetin. TX has bioactive properties; however, whether it shows antilipogenic activity remains unknown. Therefore, in the present study, we aimed to determine the antilipogenic effects of TX using 3T3-L1 adipocytes. The 3T3-L1 adipocytes were cultured in a differentiation medium with or without TX. Lipid accumulation was diminished and the mRNA expression of lipogenesis-related genes was decreased following TX treatment. We found that TX exhibited antilipogenic effects by inhibiting the expression of p300/CBP-associated factor (pCAF), a histone acetyltransferase, as confirmed by pCAF knockdown. Furthermore, TX inhibited both pCAF expression and its activity, thereby reducing the total acetylation level of nonhistone and histone proteins. Finally, TX decreased the expression of CCAAT/enhancer-binding protein alpha and beta (CEBPα and CEBPβ), and peroxisome proliferator-activated receptor γ along with pCAF expression during adipogenesis of 3T3-L1 cells in a time-dependent manner. Collectively, our findings suggest that TX is a potent antilipogenic agent derived from natural products and may be used as a pCAF inhibitor.

Mouse Embryonic Fibroblast Adipogenic Potential: A Comprehensive Transcriptome Analysis

Our understanding of adipose tissue has progressed from an inert tissue for energy storage to be one of the largest endocrine organs regulating metabolic homoeostasis through its ability to synthesize and release various adipokines that regulate a myriad of pathways. The field of adipose tissue biology is growing due to this association with various chronic metabolic diseases. An important process in the regulation of adipose tissue biology is adipogenesis, which is the formation of new adipocytes. Investigating adipogenesis in vitro is currently a focus for identifying factors that might be utilized in clinically. A powerful tool for such work is high-throughput sequencing which can rapidly identify changes at gene expression level. Various cell models exist for studying adipogenesis and has been used in high-throughput studies, yet little is known about transcriptome profile that underlies adipogenesis in mouse embryonic fibroblasts. This study utilizes RNA-sequencing and computational analysis with DESeq2, gene ontology, protein–protein networks, and robust rank analysis to understand adipogenesis in mouse embryonic fibroblasts in-depth. Our analyses confirmed the requirement of mitotic clonal expansion prior to adipogenesis in this cell model and highlight the role of Cebpa and Cebpb in regulating adipogenesis through interactions of large numbers of genes.

CEBPβ binding directly to the promoter region drives CEBPɑ transcription and improves FABP4 transcriptional activity in adipose tissue of yak (Bos grunniens)

Fatty acid binding protein 4 (FABP4) was crucial to fatty acid uptake and intracellular transport. However, the mechanisms regulating yak (Bos grunniens) FABP4 transcription were not determined. In the current study, predominant expression levels of yak FABP4 were identified in subcutaneous fat and longissimus dorsi muscles by quantitative real-time polymerase chain reactions (qPCR). The CCAAT/enhancer binding protein alpha (CEBPα) and myocyte enhancer factor 2A (MEF2A), as transcriptional activator or repressor in the promoter region of FABP4, were confirmed by both site-directed mutagenesis experiment and chromatin immunoprecipitation assay. Additionally, molecular mechanisms of CEBPɑ regulation were analyzed to explore the transcriptional regulatory property of FABP4, which indicated that transcriptional activity of CEBPɑ depended on CCAAT/ enhancer binding protein beta (CEBPβ) transcription factor. Our results demonstrated that CEBPβ binding directly to the promoter region drove CEBPɑ transcription, improving yak FABP4 transcriptional activity in adipocytes. This mechanism expanded the information on the transcriptional regulatory network of adipogenesis.

A mix of chlorogenic and caffeic acid reduces C/EBPß and PPAR-γ1 levels and counteracts lipid accumulation in macrophages

PURPOSE

Chlorogenic acid (CGA) and caffeic acid (CA) are bioactive compounds in whole grains, berries, apples, some citrus fruits and coffee, which are hypothesized to promote health-beneficial effects on the cardiovascular system. This study aimed to evaluate the capacity of CGA and CA to reduce lipid accumulation in macrophages, recognized as a critical stage in the progression of atherosclerosis. Furtherly, the modulation of CCAAT/enhancer-binding protein β (C/EBPβ) and peroxisome proliferator-activated receptor- γ1 (PPAR-γ1), as transcription factors involved in lipid metabolism, was evaluated.

METHODS

THP-1-derived macrophages were treated for 24 h with 0.03, 0.3, 3 and 30 μM of CGA and CA, tested alone or in combination, and a solution of oleic/palmitic acid (500 μM, 2:1 ratio). Lipid storage was assessed spectrophotometrically through fluorescent staining of cells with Nile red. C/EBPβ and PPAR-γ1 mRNA and protein levels were evaluated by RT-PCR and enzyme-linked immunosorbent assay, respectively.

RESULTS

The mix of CGA + CA (1:1 ratio) reduced lipid accumulation at all concentrations tested, except for the highest one. The greatest effect ( - 65%; p < 0.01) was observed at the concentration of 0.3 μM for each compound. The same concentration significantly (p < 0.01) downregulated C/EBPβ and PPAR-γ1 gene expression and reduced their protein levels at 2 h and 24 h, respectively.

CONCLUSION

The results indicate that the capacity of CGA + CA mix to reduce lipid storage in macrophages is mediated by a reduction in the expression of transcription factors C/EBPβ and PPAR-γ1.

A Short S-Equol Exposure Has a Long-Term Inhibitory Effect on Adipogenesis in Mouse 3T3-L1 Cells

In the search for new drugs against obesity, the chronic disease that threatens human health worldwide, several works have focused on the study of estrogen homologs because of the role of estrogen receptors (ERs) in adipocyte growth. The isoflavone equol, an ERβ agonist, has shown beneficial metabolic effects in in vivo and in vitro assays; however, additional studies are required to better characterize its potential for body weight control. Here, we showed that the treatment of 3T3-L1 cells with 10 μM of S-equol for the first three days of the adipocyte differentiation protocol was able to prevent cells becoming semi-rounded and having a lipid droplet formation until the seventh day of culture; moreover, lipid accumulation was reduced by about 50%. Congruently, S-equol induced a reduction in mRNA expression of the adipogenic markers C/EBPα and PPARγ, and adipokines secretion, mainly Adiponectin, Leptin, Resistin, and MCP-1, while the release of PAI-1 was augmented. Moreover, it also reduced the expression of ERα and attenuated the subexpression of ERβ associated with adipogenesis. Altogether, our data suggested that S-equol binding to ERβ affects the transcriptional program that regulates adipogenesis and alters adipocyte functions. Future efforts will focus on studying the impact of S-equol on ER signaling pathways.

Estrogen receptor alpha regulates the expression of adipogenic genes genetically and epigenetically in rat bone marrow-derived mesenchymal stem cells

Regulation of the efficacy of epigenetic modifiers is regarded as an important control mechanism in the determination and differentiation of stem cell fate. Studies are showing that the effect of estrogen is important in the differentiation of mesenchymal stem cells (MSCs) into adipocytes, osteocytes, and chondrocytes. Activation of certain transcription factors and epigenetic modifications in related genes play an active role in the initiation and completion of adipogenic differentiation. Understanding the role of estrogen in diseases such as obesity, which increases with the onset of menopause, will pave the way for more effective use of estrogen as a therapeutic option. Demonstration of the differentiation tendencies of MSCs change in the presence/absence of estrogen, especially the evaluation of reversible epigenetic changes, will provide valuable information for clinical applications. In this study, the effect of estrogen on the expression of genes involved in adipogenic differentiation of MSCs and accompanying epigenetic modifications was investigated. Our results showed that estrogen affects the expression of adipogenesis-related transcription factors such as PPARy, C/EBPα and Adipsin. In addition, after estrogen treatment, increased accumulation of estrogen receptor alpha (ERα) and repressive epigenetic markers such as H3K27me2 and H3K27me3 were observed on the promoter of given transcription factors. By using co-immunoprecipitation experiments we were also able to show that ERα physically interacts with the zeste homolog 2 (EZH2) H3K27 methyltransferase in MSCs. We propose that the increase of H3K27me2 and H3K27me3 markers on adipogenic genes upon estrogen treatment may be mediated by the direct interaction of ERα and EZH2. Taken together, these findings suggest that estrogen has a role as an epigenetic switcher in the regulation of H3K27 methylation leading to suppression of adipogenic differentiation of MSC.

Mechanism of the fungal-like particles in the inhibition of adipogenesis in 3T3-L1 adipocytes

The dynamic ability of adipocytes in adipose tissue to store lipid in response to changes in the nutritional input and inflammatory elicitors has a major impact on human health. Previously, we established laminarin-coated beads or LCB as an inflammatory elicitor for adipocytes. However, it was not clear whether LCB inhibits lipid accumulation in adipocytes. Here, we show that LCB acts in the early stage of adipogenesis through both interleukin-1 receptor-associated kinases (IRAK) and spleen tyrosine kinase (SYK) pathways, resulting in the activation of the AMP-activated protein kinase (AMPK) and nuclear factor-κB (NF-κB) complexes, which subsequently cause cell cycle arrest, downregulation of the key transcription factors and enzymes responsible for adipogenesis, inhibition of adipogenesis, and stimulation of an inflammatory response. While LCB could effectively block lipid accumulation during the early stage of adipogenesis, it could stimulate an inflammatory response at any stage of differentiation. Additionally, our results raise a possibility that toll-like receptor 2 (TLR2) and C-type lectin domain family 7 member A (CLEC7A/Dectin-1) might be potential β-glucan receptors on the fat cells. Together, we present the mechanism of LCB, as fungal-like particles, that elicits an inflammatory response and inhibits adipogenesis at the early stage of differentiation.

Artemisia scoparia promotes adipogenesis in the absence of adipogenic effectors

OBJECTIVE

Extracts of Artemisia scoparia (SCO) have antidiabetic properties in mice and enhance adipogenesis in vitro, but the underlying mechanisms are unknown. Thiazolidinediones, including rosiglitazone (ROSI), are pharmacological activators of peroxisome proliferator-activated receptor gamma that also promote adipogenesis. The aim of this study was to examine adipogenic pathways responsible for SCO-mediated adipogenesis and identify potential differences between SCO and ROSI in the ability to promote adipocyte development.

METHODS

The ability of SCO or ROSI to promote adipogenesis in 3T3-L1 cells following systematic omission of the common triad of adipogenic effectors dexamethasone, 1-methyl-3-isobutylxanthine (MIX), and insulin was examined. Adipogenesis was assessed by both neutral lipid quantitation and adipocyte marker gene expression.

RESULTS

The results demonstrate that SCO and ROSI promote adipogenesis and increase the expression of several peroxisome proliferator-activated receptor gamma target genes involved in lipid accumulation in the absence of MIX. However, ROSI can enhance adipogenesis in the absence of MIX and insulin and differentially regulates adipogenic and lipid metabolism genes as compared with SCO.

CONCLUSIONS

These data demonstrate the adipogenic capabilities of SCO are similar but not identical to ROSI, thereby warranting further research into SCO as a promising source of therapeutic compounds in the treatment of metabolic disease states.

HDAC inhibitor Trichostatin A suppresses adipogenesis in 3T3-L1 preadipocytes

Background and purpose: Obesity is becoming a major global health issue and is mainly induced by the accumulation of adipose tissues mediated by adipogenesis, which is reported to be regulated by peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT enhancer-binding protein α (C/EBPα). Trichostatin A (TSA) is a novel histone deacetylase inhibitor (HDACI) that was recently reported to exert multiple pharmacological functions. The present study will investigate the inhibitory effect of TSA on adipogenesis, as well as the underlying mechanism.

Methods: The adipogenesis of 3T3-L1 cells was induced by stimulation with a differentiation cocktail (DMI) medium for 8 days. MTT assay was used to measure the cell viability and Oil Red O staining was used to evaluate the adipogenesis of 3T3-L1 cells. The total level of triglyceride and released glycerol were detected to evaluate the lipolysis during 3T3-L1 adipogenesis. The expression levels of Leptin, fatty acid-binding protein 4 (FABP4), and sterol regulatory element-binding protein (SREBP1C) were determined by qRT-PCR. qRT-PCR assay was utilized to detect the expression levels of PPARγ and C/EBPα in 3T3-L1 cells. A high-fat diet (HFD) was used to construct an obese mice model, followed by the treatment with TSA. HE staining was conducted to evaluate the pathological state of adipose tissues. Body weights and the weights of adipose tissues were recorded to evaluate the anti-obesity property of TSA.

Results: Firstly, the promoted lipid accumulation induced by DMI incubation was significantly reversed by the treatment with TSA in a dose-dependent manner. The elevated expression levels of Leptin, FABP4, SREBP1C, PPARγ, and C/EBPα induced by the stimulation with DMI incubation were dramatically inhibited by the introduction of TSA, accompanied by the upregulation of phosphorylated AMP-activated protein kinase (p-AMPK). Secondly, the inhibitory effect of TSA against the expression level of PPARγ and lipid accumulation was greatly abolished by an AMPK inhibitor. Lastly, the increased body weights and visceral adipocyte tissue weight, as well as the enlarged size of adipocytes induced by HFD were pronouncedly reversed by the administration of TSA.

Conclusion: TSA inhibited adipogenesis in 3T3-L1 preadipocytes by activating the AMPK pathway.

Epigenetic effects induced by the ectopic expression of Pax7 in 3T3-L1

Although skeletal muscle cells and adipocytes are derived from the same mesoderm, they do not transdifferentiate in vivo and are strictly distinct at the level of gene expression. To elucidate some of the regulatory mechanisms underlying this strict distinction, Pax7, a myogenic factor, was ectopically expressed in 3T3-L1 adipose progenitor cells to perturb their adipocyte differentiation potential. Transcriptome analysis showed that ectopic expression of Pax7 repressed the expression of some adipocyte genes and induced expression of some skeletal muscle cell genes. We next profiled the epigenomic state altered by Pax7 expression using H3K27ac, an activating histone mark, and H3K27me3, a repressive histone mark, as indicators. Our results show that ectopic expression of Pax7 did not result in the formation of H3K27ac at loci of skeletal muscle-related genes, but instead resulted in the formation of H3K27me3 at adipocyte-related gene loci. These findings suggest that the primary function of ectopic Pax7 expression is the formation of H3K27me3, and muscle gene expression results from secondary regulation.

Gene promoter polymorphisms in boar spermatozoa differing in freezability

Single nucleotide polymorphisms (SNPs) in the 5'-flanking regulatory regions of genes could affect their expression levels. This is a follow-up study aimed to identify polymorphic variants in the 5'-flanking regulatory regions of genes expressed in boar spermatozoa, and to predict the interactions of such variants with transcription factors (TFs) on the gene promoter activity, using bioinformatics. Five and six boars were classified as having good and poor semen freezability (GSF and PSF, respectively) according to post-thaw (PT) assessment of sperm motility and membrane integrity characteristics. The 5'-flanking region sequences of the 14 genes (FOS, NFATC3, EAF2, FGF-14, BAMBI, RAB33B, CKS2, LARS2, SLC25A16, ACADM, CPT2, CCT3, DTD2 and CCDC85A) were PCR amplified and analyzed by Sanger sequencing method. A total of 32 polymorphic variants were identified in the 5'-flanking regions of the genes, including 4 insertion/deletion (indel) polymorphisms, and 8 unknown (novel) SNPs. Multiple sequence alignment analysis revealed a 26-bp indel variant in the 5'-flanking region of the LARS2 gene, which showed greater protein expression in spermatozoa from boars of the PSF group. It was found that 17 polymorphic variants, observed in the differentially expressed (DE) genes, showed significant allele frequency differences between the GSF and PSF groups. Polymorphic variants in the 5'-flanking regulatory regions of the genes contributed to the decrease or increase in the binding affinity for different testis-specific TFs, such as SMAD1, NF-1, FOXMI, RXRA, STAT4 and C/EBPβ. This study provides more insights into the mechanisms responsible for variations in transcriptional activity in promoters of genes expressed in boar spermatozoa. The allelic variants are promising genetic markers for predicting the freezability of boar spermatozoa.

TRPA1 Agonist Cinnamaldehyde Decreases Adipogenesis in 3T3-L1 Cells More Potently than the Non-agonist Structural Analog Cinnamyl Isobutyrate

The cinnamon-derived bioactive aroma compound cinnamaldehyde (CAL) has been identified as a promising antiobesity agent, inhibiting adipogenesis and decreasing lipid accumulation in vitro as well as in animal models. Here, we investigated the antiadipogenic effect of cinnamyl isobutyrate (CIB), another cinnamon-derived aroma compound, in comparison to CAL in 3T3-L1 adipocyte cells. In a concentration of 30 μM, CIB reduced triglyceride (TG) and phospholipid (PL) accumulation in 3T3-L1 pre-adipocytes by 21.4 ± 2.56 and 20.7 ± 2.05%, respectively. CAL (30 μM), in comparison, decreased TG accumulation by 37.5 ± 1.81% and PL accumulation by 28.7 ± 1.83%, revealing the aldehyde to be the more potent antiadipogenic compound. The CIB- and CAL-mediated inhibition of lipid accumulation was accompanied by downregulation of essential adipogenic transcription factors PPARγ, C/EBPα, and C/EBPβ on gene and protein levels, pointing to a compound-modulated effect on adipogenic signaling cascades. Coincubation experiments applying the TRPA-1 inhibitor AP-18 demonstrated TRPA1 dependency of the CAL, but not the CIB-induced antiadipogenic effect.

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.

MED19 Regulates Adipogenesis and Maintenance of White Adipose Tissue Mass by Mediating PPARγ-Dependent Gene Expression

The Mediator complex relays regulatory signals from gene-specific transcription factors to the basal transcriptional machinery. However, the role of individual Mediator subunits in different tissues remains unclear. Here, we demonstrate that MED19 is essential for adipogenesis and maintenance of white adipose tissue (WAT) by mediating peroxisome proliferator-activated receptor gamma (PPARγ) transcriptional activity. MED19 knockdown blocks white adipogenesis, but not brown adipogenesis or C2C12 myoblast differentiation. Adipose-specific MED19 knockout (KO) in mice results in a striking loss of WAT, whitening of brown fat, hepatic steatosis, and insulin resistance. Inducible adipose-specific MED19 KO in adult animals also results in lipodystrophy, demonstrating its requirement for WAT maintenance. Global gene expression analysis reveals induction of genes involved in apoptosis and inflammation and impaired expression of adipose-specific genes, resulting from decreased PPARγ residency on adipocyte gene promoters and reduced association of PPARγ with RNA polymerase II. These results identify MED19 as a crucial facilitator of PPARγ-mediated gene expression in adipose tissue.

Absence of AGPAT2 impairs brown adipogenesis, increases IFN stimulated gene expression and alters mitochondrial morphology

BACKGROUND

Biallelic loss of function variants in AGPAT2, encoding 1-acylglycerol-3-phosphate O-acyltransferase 2, cause congenital generalized lipodystrophy type 1, a disease characterized by near total loss of white adipose tissue and metabolic complications. Agpat2 deficient (Agpat2^-/-) mice completely lacks both white and interscapular brown adipose tissue (iBAT). The objective of the present study was to characterize the effects of AGPAT2 deficiency in brown adipocyte differentiation.

METHODS

Preadipocytes obtained from newborn (P0.5) Agpat2^-/- and wild type mice iBAT were differentiated into brown adipocytes, compared by RNA microarray, RT-qPCR, High-Content Screening (HCS), western blotting and electron microscopy.

RESULTS

1) Differentiated Agpat2^-/- brown adipocytes have fewer lipid-laden cells and lower abundance of Pparγ, Pparα, C/ebpα and Pgc1α, both at the mRNA and protein levels, compared those to wild type cells. Prmd16 levels were equivalent in both, Agpat2^-/- and wild type, while Ucp1 was only induced in wild type cells, 2) These differences were not due to lower abundance of preadipocytes, 3) Differentiated Agpat2^-/- brown adipocytes are enriched in the mRNA abundance of genes participating in interferon (IFN) type I response, whereas genes involved in mitochondrial homeostasis were decreased, 4) Mitochondria in differentiated Agpat2^-/- brown adipocytes had altered morphology and lower mass and contacting sites with lipid droplets concomitant with lower levels of Mitofusin 2 and Perlipin 5.

CONCLUSION

AGPAT2 is necessary for normal brown adipose differentiation. Its absence results in a lower proportion of lipid-laden cells, increased expression of interferon-stimulated genes (ISGs) and alterations in mitochondrial morphology, mass and fewer mitochondria to lipid droplets contacting sites in differentiated brown adipocytes.

Molecular Mechanism of Stem Cell Differentiation into Adipocytes and Adipocyte Differentiation of Malignant Tumor

Adipogenesis is the process through which preadipocytes differentiate into adipocytes. During this process, the preadipocytes cease to proliferate, begin to accumulate lipid droplets, and develop morphologic and biochemical characteristics of mature adipocytes. Mesenchymal stem cells (MSCs) are a type of adult stem cells known for their high plasticity and capacity to generate mesodermal and nonmesodermal tissues. Many mature cell types can be generated from MSCs, including adipocyte, osteocyte, and chondrocyte. The differentiation of stem cells into multiple mature phenotypes is at the basis for tissue regeneration and repair. Cancer stem cells (CSCs) play a very important role in tumor development and have the potential to differentiate into multiple cell lineages. Accumulating evidence has shown that cancer cells can be induced to differentiate into various benign cells, such as adipocytes, fibrocytes, osteoblast, by a variety of small molecular compounds, which may provide new strategies for cancer treatment. Recent studies have reported that tumor cells undergoing epithelial-to-mesenchymal transition can be induced to differentiate into adipocytes. In this review, molecular mechanisms, signal pathways, and the roles of various biological processes in adipose differentiation are summarized. Understanding the molecular mechanism of adipogenesis and adipose differentiation of cancer cells may contribute to cancer treatments that involve inducing differentiation into benign cells.

The lncRNA RP11-142A22.4 promotes adipogenesis by sponging miR-587 to modulate Wnt5β expression

Emerging evidence suggests that long noncoding RNAs (lncRNAs) play essential roles in the regulation of gene expression. However, the functional contributions of lncRNAs to adipogenesis remain largely unexplored. In this study, we investigated global changes in the expression patterns of lncRNAs in visceral adipose tissue and identified RP11-142A22.4 as a significantly upregulated lncRNA. In isolated preadipocytes, knockdown of RP11-142A22.4 inhibited differentiation and reduced C/EBP-α and PPAR-γ expression. Investigations of the underlying mechanisms revealed that RP11-142A22.4 contains a functional miR-587 binding site. Mutation of the binding sites for RP11-142A22.4 in miR-587 abolished the interaction, as indicated by a luciferase reporter assay. Furthermore, RP11-142A22.4 affected the expression of miR-587 and its target gene Wnt5β. Overexpression of miR-587 blocked the inhibitory effect of RP11-142A22.4 on preadipocyte differentiation. Moreover, the downregulation of miR-587 restored preadipocyte differentiation upon inhibition by RP11-142A22.4 silencing. Our results suggest that RP11-142A22.4 can control adipocyte differentiation via the miR-587/Wnt5β signaling pathway and serve as a potential target for obesity treatments.

Differential impacts of late gestational over-and undernutrition on adipose tissue traits and associated visceral obesity risk upon exposure to a postnatal high-fat diet in adolescent sheep

We hypothesized that late gestation malnutrition differentially affects expandability of adipose tissues to predispose for early postnatal visceral adiposity. Twin-lambs born to dams fed HIGH (150%/110% of required energy/protein, respectively), NORM (100% of requirements) or LOW (50% of NORM) diets during the last trimester were used. Postnatally, lambs were raised on moderate (CONV) or high-carbohydrate-high-fat (HCHF) diets. Adipose tissues were sampled at autopsy at 6 months of age (~puberty) to characterize cellularity, adipocyte cross-sectional area and gene expression patterns. HIGH and LOW compared to NORM lambs had reduced intrinsic (under CONV diet) cellularity in subcutaneous and mesenteric (particularly LOW), and reduced obesity-induced (under HCHF diet) hyperplasia in subcutaneous, mesenteric and perirenal (particularly HIGH) adipose tissues. This corresponded with more pronounced HCHF diet-induced hypertrophy in mesenteric (particularly LOW), perirenal (particularly HIGH) and subcutaneous (particularly HIGH) adipose tissues, and tissue-specific reductions in mRNA expressions for lipid metabolism, angiogenesis and adipose development. Gene expression for inflammation and lipid metabolism markers were increased and decreased, respectively, in HCHF lambs (HCHF lambs became obese) in all tissues. Both prenatal over- and undernutrition predisposed for abdominal adiposity and extreme perirenal hypertrophy due to reduced intrinsic (observed under CONV diet) cellularity and impaired ability of subcutaneous, mesenteric and perirenal adipose tissues to expand by hyperplasia rather than hypertrophy on an obesogenic (HCHF) diet.

MicroRNA-27a/b-3p and PPARG regulate SCAMP3 through a feed-forward loop during adipogenesis

MicroRNAs (miRNA) modulate gene expression through feed-back and forward loops. Previous studies identified miRNAs that regulate transcription factors, including Peroxisome Proliferator Activated Receptor Gamma (PPARG), in adipocytes, but whether they influence adipogenesis via such regulatory loops remain elusive. Here we predicted and validated a novel feed-forward loop regulating adipogenesis and involved miR-27a/b-3p, PPARG and Secretory Carrier Membrane Protein 3 (SCAMP3). In this loop, expression of both PPARG and SCAMP3 was independently suppressed by miR-27a/b-3p overexpression. Knockdown of PPARG downregulated SCAMP3 expression at the late phase of adipogenesis, whereas reduction of SCAMP3 mRNA levels increased PPARG expression at early phase in differentiation. The latter was accompanied with upregulation of adipocyte-enriched genes, including ADIPOQ and FABP4, suggesting an anti-adipogenic role for SCAMP3. PPARG and SCAMP3 exhibited opposite behaviors regarding correlations with clinical phenotypes, including body mass index, body fat mass, adipocyte size, lipolytic and lipogenic capacity, and secretion of pro-inflammatory cytokines. While adipose PPARG expression was associated with more favorable metabolic phenotypes, SCAMP3 expression was linked to increased fat mass and insulin resistance. Together, we identified a feed-forward loop through which miR-27a/b-3p, PPARG and SCAMP3 cooperatively fine tune the regulation of adipogenesis, which potentially may impact whole body metabolism.

Determination of Fat Accumulation Reduction by Edible Fatty Acids and Natural Waxes In Vitro

Natural edible waxes mixed with plant oils, containing high levels of unsaturated fatty acids (FAs), are known as oleogels. Oleogels are used for replacing saturated FAs in animal-derived food with unsaturated FAs. However, the health effects of edible waxes are not yet clearly defined. The purpose of this study was to investigate the effect of FAs and natural waxes on the adipogenesis in 3T3-L1 cells. The 3T3-L1 cells were differentiated and treated with FAs and waxes. These FAs [Palmitic acid (PA), Stearic acid (SA), Oleic acid (OA), Linoleic acid (LA), and Alpha-linolenic acid (ALA)] and waxes [beeswax (BW) and carnauba wax (CW)] were prepared at varying concentrations, and cell toxicity, triglyceride accumulation, lipid droplets size, and distribution inside of cells were determined. Adipogenic gene expression including PPARγ, FASN, C/EBPα, SREBP-1, and CPT-1 was determined. Results showed that increasing the concentration of FAs and waxes led to a decrease in the adipocyte cells viability and metabolic performance. SA showed the highest level of triglyceride accumulation (p<0.05), whereas ALA showed the lowest (p<0.05). Both BW and CW at 3.0 ppm showed significantly higher lipid accumulation than in the control and other groups (p<0.05). ALA had significantly downregulated adipogenic gene expression levels, excluding those of CPT-1, compared to the other treatment groups (p<0.05). Moreover, BW demonstrated similar adipogenic gene expression levels as ALA compared to CW. Consequently, ALA and BW may have health benefits by reducing adipogenesis and can be used in processed meat.

Mechanisms involved in the activation of C/EBPα by small activating RNA in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is generally accompanied by high mortality and low cure rate. CCAAT enhancer-binding proteins (CEBPs) are transcriptional regulators that play a key role in maintaining liver function. Altered expression of C/EBPα and C/EBPβ occurs in many tumours including HCC. saRNAs are small double-stranded RNAs that enhance target gene expression at the transcriptional level. In this report, we activate CEPBA with saRNAs and suppress CEBPB with siRNAs in cells that represent three different degrees of HCC. We performed functional assays to investigate the effects of enhancing C/EBPα and its downstream targets, p21 and albumin across these lines. We also used Mass-spectrometry (MS) subsequent to a ChIP pull-down assay to characterise the components of the protein complex involved in regulating saRNA function. Putative saRNA interacting protein candidates that were identified by MS were knocked-down with siRNAs to investigate its impact on saRNA activity. We confirmed CEBPA-saRNA decreased proliferation and migration in the differentiated lines (HepG3/Hep3B). The undifferentiated line (PLCPRF5) showed saRNA-induced increase in CEBPA but with no loss in proliferation. This effect was reversed when CEBPB was suppressed with CEBPB-siRNA. When interrogating saRNA mode of action; three saRNA interacting proteins, CTR9, HnRNPA2/B1 and DDX5 were identified by MS. Targeted knock-down of these two proteins (by siRNA) abrogated saRNA activity. This study provides insight into how different HCC lines are affected by CEBPA-saRNAs and that endogenous abundance of CEBPB and saRNA accessory proteins may dictate efficacy of CEBPA-saRNA when used in a therapeutic context.

Suppressive Role of Boron on Adipogenic Differentiation and Fat Deposition in Human Mesenchymal Stem Cells

Over the past years, adipose tissue has become an invaluable source of mesenchymal stem cells (MSCs) due to development of improved isolation methodologies. In a recent work, our group established a primary culture of human adipose-derived stem cells (hADSCs), which were characterized for their stem cell characteristics in detail and studied their myogenic differentiation potential in presence of boron. In the current study, we focused on the effects of a boron-containing compound, sodium pentaborate pentahydrate (NaB), on the adipogenic differentiation of hADSCs. Incorporation of boron in various chemical derivates has been a novel interest in drug-discovery attempts due to increasing number of reports on their anticancer, antibacterial, antiviral, and antifungal activities. In this report, a striking suppressive activity of boron on adipogenic differentiation of hADSCs is observed in a dose-dependent manner. Higher concentrations of NaB (20, 50, and 100 μg/mL (68, 170 and 340 μM)) resulted in a progressive decrease of lipid deposition, suppressed master regulators of adipogenesis transcriptional programming at the mRNA and protein levels, while having no evident cytotoxicity on the cells. The findings of this study are encouraging to undertake further investigations on potential beneficial effects boron in terms of its impact on normal and dysfunctional adipose biology. In that respect, these results pave the path to evaluate boron-based compounds in prevention and treatment of obesity which is a modern age pandemic that is predominant worldwide and found in strong association with comorbidities, including type 2 diabetes, hypertension, cardiovascular disease, cancers, and others."

Adipocytes spectrum - From homeostasia to obesity and its associated pathology

Firstly identified by anatomists, the fat tissue is nowadays an area of intense research due to increased global prevalence of obesity and its associated diseases. Histologically, there are four types of fat tissue cells which are currently recognized (white, brown, beige, and perivascular adipocytes). Therefore, in this study we are reviewing the most recent data regarding the origin, structure, and molecular mechanisms involved in the development of adipocytes. White adipocytes can store triglycerides as a consequence of lipogenesis, under the regulation of growth hormone or leptin and adiponectin, and release fatty acids resulted from lipolysis, under the regulation of the sympathetic nervous system, glucocorticoids, TNF-α, insulin, and natriuretic peptides. Brown adipocytes possess a mitochondrial transmembrane protein thermogenin or UCP1 which allows heat generation. Recently, thermogenic, UCP positive adipocytes have been identified in the subcutaneous white adipose tissue and have been named beige adipocytes. The nature of these cells is still controversial, as current theories are suggesting their origin either by transdifferentiation of white adipocytes, or by differentiation from an own precursor cell. Perivascular adipocytes surround most of the arteries, exhibiting a supportive role and being involved in the maintenance of intravascular temperature. Thoracic perivascular adipocytes resemble brown adipocytes, while abdominal ones are more similar to white adipocytes and, consequently, are involved in obesity-induced inflammatory reactions. The factors involved in the regulation of adipose stem cells differentiation may represent potential pathways to inhibit or to divert adipogenesis. Several molecules, such as pro-adipogenic factors (FGF21, BMP7, BMP8b, and Cox-2), cell surface proteins or receptors (Asc-1, PAT2, P2RX5), and hypothalamic receptors (MC4R) have been identified as the most promising targets for the development of future therapies. Further investigations are necessary to complete the knowledge about adipose tissue and the development of a new generation of therapeutic tools based on molecular targets.

Murine models of sleep apnea: functional implications of altered macrophage polarity and epigenetic modifications in adipose and vascular tissues

Obstructive sleep apnea (OSA) is a highly prevalent disease across the lifespan, is characterized by chronic intermittent hypoxia and sleep fragmentation, and has been independently associated with substantial cardiometabolic morbidity. However, the reversibility of end-organ morbidity with treatment is not always apparent, suggesting that both tissue remodeling and epigenetic mechanisms may be operationally involved. Here, we review the cumulative evidence focused around murine models of OSA to illustrate the temporal dependencies of cardiometabolic dysfunction and its reversibility, and more particularly to discuss the critical contributions of tissue macrophages to adipose tissue insulin resistance and vascular atherogenesis. In addition, we describe initial findings potentially implicating epigenetic alterations in both the emergence of the cardiometabolic morbidity of OSA, and in its reversibility with treatment. We anticipate that improved understanding of macrophage biology and epigenetics in the context of intermittent hypoxia and sleep fragmentation will lead to discovery of novel therapeutic targets and improved cardiovascular and metabolic outcomes in OSA.