The induction of brown-like adipocyte development in white adipose tissue (WAT) confers numerous metabolic benefits by decreasing adiposity and increasing energy expenditure. Therefore, WAT browning has gained considerable attention for its potential to reverse obesity and its associated co-morbidities. However, this perspective has been tainted by recent studies identifying the detrimental effects of inducing WAT browning. This review aims to highlight the adverse outcomes of both overactive and underactive browning activity, the harmful side effects of browning agents, as well as the molecular brake-switch system that has been proposed to regulate this process. Developing novel strategies that both sustain the metabolic improvements of WAT browning and attenuate the related adverse side effects is therefore essential for unlocking the therapeutic potential of browning agents in the treatment of metabolic diseases.
Adipocytes, Beige ; cytology ; Adipose Tissue, Brown ; cytology ; metabolism ; Adipose Tissue, White ; cytology ; Aging ; metabolism ; Animals ; Humans

OBJECTIVE: To establish a simple, low-cost and time-saving method for primary culture of mature white adipocytes from mice. METHODS: Mature white adipocytes were isolated from the epididymis and perirenal area of mice for primary culture using a modified mature adipocyte culture method or the ceiling culture method. The morphology of the cultured mature adipocytes was observed using Oil Red O staining, and the cell viability was assessed with CCK8 method. The expression of PPARγ protein in the cells was detected with Western blotting, and the mRNA expressions of CD36, FAS, CPT1A and FABP4 were detected using RT-qPCR. RESULTS: Oil Red O staining showed a good and uniform morphology of the adipocytes in primary culture using the modified culture method, while the cells cultured using the ceiling culture method exhibited obvious morphological changes. CCK8 assay showed no significant difference in cell viability between freshly isolated mature white adipocytes and the cells obtained with the modified culture method. Western blotting showed that the freshly isolated adipocytes and the cells cultured for 72 h did not differ significantly in the expression levels of PPARγ protein (P=0.759), which was significantly lowered in response to treatment with GW9662 (P < 0.001). GW9662 treatment of the cells upregulated mRNA expressions of CD36 (P < 0.001) and CPT1A (P=0.003) and down-regulated those of FAS (P=0.001) and FABP4 (P < 0.001). CONCLUSION We established a convenient and time-saving method for primary culture mature white adipocytes from mice to facilitate further functional studies of mature adipocytes.
Male ; Mice ; Animals ; Adipocytes, White/metabolism* ; PPAR gamma/metabolism* ; RNA, Messenger ; Cell Differentiation ; 3T3-L1 Cells

Adipose tissue inflammation is considered a major contributing factor in the development of obesity-associated insulin resistance and cardiovascular diseases. However, the cause of adipose tissue inflammation is presently unclear. The role of mitochondria in white adipocytes has long been neglected because of their low abundance. However, recent evidence suggests that mitochondria are essential for maintaining metabolic homeostasis in white adipocytes. In a series of recent studies, we found that mitochondrial function in white adipocytes is essential to the synthesis of adiponectin, which is the most abundant adipokine synthesized from adipocytes, with many favorable effects on metabolism, including improvement of insulin sensitivity and reduction of atherosclerotic processes and systemic inflammation. From these results, we propose a new hypothesis that mitochondrial dysfunction in adipocytes is a primary cause of adipose tissue inflammation and compared this hypothesis with a prevailing concept that “adipose tissue hypoxia” may underlie adipose tissue dysfunction in obesity. Recent studies have emphasized the role of the mitochondrial quality control mechanism in maintaining mitochondrial function. Future studies are warranted to test whether an inadequate mitochondrial quality control mechanism is responsible for mitochondrial dysfunction in adipocytes and adipose tissue inflammation.
11-beta-Hydroxysteroid Dehydrogenases ; Adipocytes ; Adipocytes, White ; Adipokines ; Adiponectin ; Adipose Tissue ; Anoxia ; Cardiovascular Diseases ; Homeostasis ; Inflammation ; Insulin Resistance ; Metabolism ; Mitochondria ; Nitric Oxide ; Obesity ; Quality Control

Brown fat is a specialized fat depot that can increase energy expenditure and produce heat. After the recent discovery of the presence of active brown fat in human adults and novel transcription factors controlling brown adipocyte differentiation, the field of the study of brown fat has gained great interest and is rapidly growing. Brown fat expansion and/or activation results in increased energy expenditure and a negative energy balance in mice and limits weight gain. Brown fat is also able to utilize blood glucose and lipid and results in improved glucose metabolism and blood lipid independent of weight loss. Prolonged cold exposure and beta adrenergic agonists can induce browning of white adipose tissue. The inducible brown adipocyte, beige adipocyte evolving by thermogenic activation of white adipose tissue have different origin and molecular signature from classical brown adipocytes but share the characteristics of high mitochondria content, UCP1 expression and thermogenic capacity when activated. Increasing browning may also be an efficient way to increase whole brown fat activity. Recent human studies have shown possibilities that findings in mice can be reproduced in human, making brown fat a good candidate organ to treat obesity and its related disorders.
Adipocytes ; Adipocytes, Brown ; Adipose Tissue, Brown* ; Adipose Tissue, White ; Adrenergic beta-Agonists ; Adult ; Animals ; Blood Glucose ; Energy Metabolism ; Glucose ; Hot Temperature ; Humans ; Metabolism ; Mice ; Mitochondria ; Obesity* ; Transcription Factors ; Weight Gain ; Weight Loss

Adipose tissue is a central metabolic organ that controls energy homeostasis of the whole body. White adipose tissue (WAT) stores excess energy in the form of triglycerides, whereas brown adipose tissue (BAT) dissipates energy in the form of heat through mitochondrial uncoupling protein 1 (Ucp1). A newly identified adipose tissue called ‘beige fat’ (BAT-like) is produced through a process called WAT browning. This tissue mainly resides in WAT depots and displays intermediate characteristics of both WAT and BAT. Since the recent discovery of BAT in the human body, along with the identification of molecular targets for BAT activation, stimulating energy expenditure has been considered as a great strategy to treat human obesity and metabolic diseases. Here we summarize recent findings regarding molecular targets and thermogenic small molecules that can stimulate BAT and increase energy expenditure, with an emphasis on possible therapeutic applications in humans.
Adipocytes* ; Adipose Tissue ; Adipose Tissue, Brown ; Adipose Tissue, White ; Energy Metabolism ; Homeostasis ; Hot Temperature ; Human Body ; Humans ; Metabolic Diseases ; Obesity ; Triglycerides

Given that increased thermogenesis in white adipose tissue, also known as browning, promotes energy expenditure, significant efforts have been invested to determine the molecular factors involved in this process. Here we show that HOXC10, a homeobox domain-containing transcription factor expressed in subcutaneous white adipose tissue, is a suppressor of genes involved in browning white adipose tissue. Ectopic expression of HOXC10 in adipocytes suppresses brown fat genes, whereas the depletion of HOXC10 in adipocytes and myoblasts increases the expression of brown fat genes. The protein level of HOXC10 inversely correlates with brown fat genes in subcutaneous white adipose tissue of cold-exposed mice. Expression of HOXC10 in mice suppresses cold-induced browning in subcutaneous white adipose tissue and abolishes the beneficial effect of cold exposure on glucose clearance. HOXC10 exerts its effect, at least in part, by suppressing PRDM16 expression. The results support that HOXC10 is a key negative regulator of the process of browning in white adipose tissue.
Adipocytes ; Adipose Tissue, Brown ; Adipose Tissue, White ; Animals ; Ectopic Gene Expression ; Energy Metabolism ; Genes, Homeobox ; Glucose ; Mice ; Myoblasts ; Thermogenesis ; Transcription Factors

Chronic energy surplus increases body fat, leading to obesity. Since obesity is closely associated with most metabolic complications, pathophysiological roles of adipose tissue in obesity have been intensively studied. White adipose tissue is largely divided into subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT). These two white adipose tissues are similar in their appearance and lipid storage functions. Nonetheless, emerging evidence has suggested that SAT and VAT have different characteristics and functional roles in metabolic regulation. It is likely that there are intrinsic differences between VAT and SAT. In diet-induced obese animal models, it has been reported that adipogenic progenitors in VAT rapidly proliferate and differentiate into adipocytes. In obesity, VAT exhibits elevated inflammatory responses, which are less prevalent in SAT. On the other hand, SAT has metabolically beneficial effects. In this review, we introduce recent studies that focus on cellular and molecular components modulating adipogenesis and immune responses in SAT and VAT. Given that these two fat depots show different functions and characteristics depending on the nutritional status, it is feasible to postulate that SAT and VAT have different developmental origins with distinct adipogenic progenitors, which would be a key determining factor for the response and accommodation to metabolic input for energy homeostasis.
Adipocytes ; Adipogenesis ; Adipose Tissue ; Adipose Tissue, White ; Energy Metabolism ; Hand ; Homeostasis ; Inflammation ; Intra-Abdominal Fat ; Models, Animal ; Nutritional Status ; Obesity ; Stem Cells ; Subcutaneous Fat

BACKGROUND: Resveratrol (RSV) is a polyphenolic phytoalexin that has many effects on metabolic diseases such as diabetes and obesity. Given the importance of brown adipose tissue (BAT) for energy expenditure, we investigated the effects of RSV on brown adipocytes. METHODS: For the in vitro study, interscapular BAT was isolated from 7-week-old male Sprague Dawley rats. For the in vivo study, 7-week-old male Otsuka Long Evans Tokushima Fatty (OLETF) rats were divided into four groups and treated for 27 weeks with: standard diet (SD); SD+RSV (10 mg/kg body weight, daily); high fat diet (HFD); HFD+RSV. RSV was provided via oral gavage once daily during the in vivo experiments. RESULTS: RSV treatment of primary cultured brown preadipocytes promoted mitochondrial activity, along with over-expression of estrogen receptor α (ER-α). In OLETF rats, both HFD and RSV treatment increased the weight of BAT and the differentiation of BAT. However, only RSV increased the mitochondrial activity and ER-α expression of BAT in the HFD-fed group. Finally, RSV improved the insulin sensitivity of OLETF rats by increasing the mitochondrial activity of BAT, despite having no effects on white adipocytes and muscles in either diet group. CONCLUSION: RSV could improve insulin resistance, which might be associated with mitochondrial activity of brown adipocyte. Further studies evaluating the activity of RSV for both the differentiation and mitochondrial activity of BAT could be helpful in investigating the effects of RSV on metabolic parameters.
Adipocytes, Brown* ; Adipocytes, White ; Adipose Tissue, Brown ; Animals ; Body Weight ; Diet ; Diet, High-Fat* ; Energy Metabolism ; Estrogen Receptor alpha ; Estrogens ; Humans ; In Vitro Techniques ; Insulin Resistance ; Male ; Metabolic Diseases ; Mitochondria ; Muscles ; Obesity ; Rats ; Rats, Inbred OLETF ; Rats, Sprague-Dawley

Obesity gives vent to many diseases such as type 2 diabetes, hypertension, and hyperlipidemia, being considered as the main causes of mortality and morbidity worldwide. The pathogenesis and pathophysiology of metabolic syndrome can well be understood by studying the molecular mechanisms that control the development and function of adipose tissue. In human body, exist two types of adipose tissue, the white and the brown one, which are reported to play various roles in energy homeostasis. The major and most efficient storage of energy occurs in the form of triglycerides in white adipose tissue while brown adipose tissue actively participates in both basal and inducible energy consumption in the form of thermogenesis. Recent years have observed a rapid and greater interest towards developmental plasticity and therapeutic potential of stromal cells those isolated from adipose tissue. The adipocyte differentiation involves a couple of regulators in the white or brown adipogenesis. Peroxisome proliferators-activated receptor-gamma actively participates in regulating carbohydrate and lipid metabolism, and also acts as main regulator of both white and brown adipogenesis. This review based on our recent research, seeks to highlight the adipocyte differentiation.
Adipocytes ; Adipocytes, Brown ; Adipogenesis ; Adipose Tissue ; Adipose Tissue, Brown ; Adipose Tissue, White ; DNA-Directed DNA Polymerase ; Genes, Homeobox ; Homeostasis ; Human Body ; Humans ; Hyperlipidemias ; Hypertension ; Lipid Metabolism ; Obesity ; Peroxisomes ; Stromal Cells ; Thermogenesis ; Triglycerides

The anti-obesity effects of a hot water extract from wasabi (Wasabia japonica Matsum.) leaves (WLE), without its specific pungent constituents, such as allyl-isothiocyanate, were investigated in high fat-diet induced mice. C57J/BL mice were fed a high-fat diet (control group) or a high-fat diet supplemented with 5% WLE (WLE group). Physical parameters and blood profiles were determined. Gene expression associated with lipid metabolism in liver and white adipose tissue were analyzed. After 120 days of feeding, significantly lower body weight gain, liver weight and epididymal white adipose tissue weight was observed in the WLE group compared to the control group. In liver gene expression within the WLE group, PPARalpha was significantly enhanced and SREBP-1c was significantly suppressed. Subsequent downstream genes controlled by these regulators were significantly suppressed. In epididymal white adipose tissue of the WLE group, expression of leptin, PPARgamma, and C/EBPalpha were significantly suppressed and adiponectin was significantly enhanced. Acox, related to fatty acid oxidization in adipocytes, was also enhanced. Our results demonstrate that the WLE dietary supplement induces mild suppression of obesity in a high-fat diet induced mice, possibly due to suppression of lipid accumulation in liver and white adipose tissue.
Adipocytes ; Adiponectin ; Adipose Tissue, White ; Animals ; Body Weight ; Diet, High-Fat ; Dietary Supplements ; Gene Expression ; Leptin ; Lipid Metabolism ; Liver ; Mice ; Obesity ; PPAR alpha ; PPAR gamma ; Sterol Regulatory Element Binding Protein 1 ; Water