Fat depot origin affects fatty acid handling in cultured rat and human preadipocytes

Regional differences in free fatty acid (FFA) handling contribute to diseases associated with particular fat distributions. As cultured rat preadipocytes became differentiated, FFA transfer into preadipocytes increased and was more rapid in single perirenal than in epididymal cells matched for lipid content. Uptake by human omental preadipocytes was greater than uptake by abdominal subcutaneous preadipocytes. Adipose-specific fatty acid binding protein (aP2) and keratinocyte lipid binding protein abundance was higher in differentiated rat perirenal than in epididymal preadipocytes. This interdepot difference in preadipocyte aP2 expression was reflected in fat tissue in older animals. Carnitine palmitoyltransferase 1 activity increased during differentiation and was higher in perirenal than in epididymal preadipocytes, particularly the muscle isoform. Long-chain acyl-CoA levels were higher in perirenal than in epididymal preadipocytes and isolated fat cells. These data are consistent with interdepot differences in fatty acid flux ensuing from differences in fatty acid binding proteins and enzymes of fat metabolism. Heterogeneity among depots results, in part, from distinct intrinsic characteristics of adipose cells. Different depots are effectively separate miniorgans.     

Inhibition of rat perirenal preadipocyte differentiation

The process of adipose differentiation uniquely endows fat cells to accrue triacylglycerols under conditions of nutrient energy surfeit and to release fatty acids during energy deprivation. The object of this investigation was to study influences on this process in perirenal preadipocytes, grown in primary culture or first subculture and derived from male Sprague-Dawley rats, 180-200 g. Supplementation of the culture medium with 1-methyl-3-isobutylxanthine, corticosterone, and insulin induced differentiation in practically all perirenal preadipocytes, as indicated morphologically and by rising glycerophosphate dehydrogenase activity. Appreciable differentiation was induced even in the absence of methylisobutylxanthine. Transforming growth factor beta (1-1000 pM), cachectin (tumour necrosis factor alpha) (1-1000 pM), and basic fibroblast growth factor (0.063-63 nM) inhibited adipose differentiation significantly, almost completely at the higher concentrations. Direct inhibition, rather than a persisting mitogenic effect of fibroblast growth factor, was confirmed using demecolcine (Colcemid). The fact that transforming growth factor beta and cachectin inhibit differentiation in preadipocytes from postpubertal rats suggests that this effect probably also occurs in vivo, thus diverting energy from adipose depots in certain neoplastic and inflammatory states. We propose that the anterior pituitary, through fibroblast growth factor(s), modulates the pool of preadipocytes and other mesenchymal cells. The mitogenic effect would be complemented by a concerted function, inhibition of adipose differentiation, resulting in the retention of a greater number of potentially replicative cells. Then, depending on the subject's nutritional and endocrine status, extrapituitary factors would regulate the specific process of differentiation.     

Diversity of SREBP-1 gene expression in rat adipose tissue depots in response to refeeding after food restriction

The SREBP-1c mRNA level and precursor (microsomal) form of SREBP-1 abundance were significantly higher in epididymal and perirenal than in subcutaneous white adipose tissue of control rats. Moreover, the SREBP-1c mRNA level and an amount of precursor form of SREBP-1 were significantly higher in the epididymal and perirenal white adipose tissue of rats maintained on restricted diet and refed ad libitum for 48 h as compared to the control animals. No significant effects of food restriction/refeeding on SREBP-1c mRNA level and an amount of precursor form of SREBP-1 were found in subcutaneous white adipose tissue. The mature (nuclear) form of SREBP-1 was significantly increased in the epididymal, perirenal and subcutaneous white adipose tissue of the food restricted/refed animals. The activity, protein level and the mRNA abundance of malic enzyme (one of the target genes for SREBP-1) increased significantly in the epididymal, perirenal and subcutaneous white adipose tissue of the food restricted/refed rats as compared to the control animals, however the increase in perirenal and epididymal was higher than in the subcutaneous white adipose tissue. The results presented suggest that SREBP-1c is differently expressed in various rat white adipose tissue depots both under basal (control) and dieting conditions.     

Hormone-sensitive adenylyl cyclase in preadipocytes cultured from adipose tissue: comparison with 3T3-L1 cells and adipocytes

The adenylyl cyclase system of preadipocytes derived from the stromal vascular fraction of perirenal rat fat pads was characterized. Unlike mature adipocytes, preadipocyte adenylyl cyclase was only weakly stimulated by catecholamines and adrenocorticotrophic hormone, but was stimulated by guanine nucleotides. Parathyroid hormone and 2-chloroadenosine also stimulated preadipocyte adenylyl cyclase. The adenylyl cyclase system of preadipocytes resembled that of undifferentiated 3T3-L1 cells. However, agents which induced the differentiation of the 3T3-L1 cell adenylyl cyclase system did not have a similar effect on preadipocytes. A medium (CDM6) which induced some differentiation of preadipocyte adenylyl cyclase was developed. The observations that the adenylyl cyclase system of preadipocytes and undifferentiated 3T3-L1 cells are similar, that preadipocyte adenylyl cyclase can be induced to develop along lines similar to early differentiation of 3T3-L1 cells, and that the adenylyl cyclase system of fully-differentiated 3T3-L1 cells has characteristics intermediate between preadipocytes and adipocytes, suggest that the differentiation of preadipocyte and 3T3-L1 adenyly cyclase in vitro mimics adipose adenylyl cyclase development in vivo. The increased catecholamine and ACTH stimulation, and reduced GTP and adenosine sensitivities of adipocytes compared to preadipocytes suggest that a number of genes affecting adenylyl cyclase-associated regulatory and receptor proteins are coordinately repressed and derepressed during development.     

Comparative investigation of vitamins and their analogues on terminal differentiation, from preadipocytes to adipocytes, of 3T3-L1 cells

1. The effects of 20 kinds of vitamins or their analogues on the growth rate of preadipocytes and the terminal differentiation of preadipocytes to adipocytes was systematically compared in 3T3-L1 cells. 2. The addition of vitamin C markedly increased the growth rate of preadipocytes at over 50 microM. 3. The addition of vitamin K3 slowed down the growth rate at over 0.1 microM. 4. In water soluble vitamins and their analogues tested, the vitamin B6 group and vitamin C significantly stimulated the differentiation, and consequently increased the glycerophosphate dehydrogenase activity and triglyceride accumulation, to a concentration of over 10 microM. 5. Many fat soluble vitamins and their analogues (the vitamin A group, including beta-carotene, the vitamin D group, vitamin E and the vitamin K group) strongly inhibited the adipose conversion of 3T3-L1 cells at microM level.     

Protein factor obtained from rat adipose tissue specifically permits the proliferation of the 3T3-L1 and Ob1771 cell lines

We have found the presence of protein factor in rat adipose tissue which permits the proliferation of 3T3-L1 and Ob1771 preadipocytes cultured in a completely defined serum-free medium containing only progression factors [epidermal growth factor (EGF) and insulin] as growth factors. This mitogenic activity of the protein factor was not detected in various other cell lines, in particular, Swiss 3T3 cells which could proliferate in response to a competent factor [platelet-derived growth factor (PDGF) or fibroblast growth factor (FGF)] in the same serum-free medium. This activity of the factor was heat- and pronase-unstable, and reductant-stable, and the apparent molecular weight of the factor was about 20,000. These results strongly suggest that the protein factor is different from PDGF or FGF and contributes to the formation of new adipocytes by specifically stimulating the proliferation of preadipocytes, acting like competent factor.     

Preadipocyte stimulating factor in rat serum: evidence for a discrete 63 kDa protein that promotes cell differentiation of rat preadipocytes in primary cultures

In primary cultures of rat preadipocytes (PA) isolated from epididymal or perirenal depots, rat serum is more effective than other animal sera (fetal calf, newborn calf, human, horse, rabbit, cat, sheep, goat, dog, pig) in promoting adipogenic conversion, biochemical differentiation, and mitogenesis. Only mouse serum is comparable to rat serum. This activity is attributable to a specific growth factor (preadipocyte stimulating factor, PSF). An assay for PSF in rat serum was devised using PA from perirenal fat of 3-month-old Fischer 344 rats grown first to confluence in FCS for 8 days and then for the next 3 days in test serum, followed by measurement of triglyceride (TG) and glycerol-3-phosphate dehydrogenase (GPDH). Rat serum induces dose-dependent rapid cell division, which coincides with accumulation of TG and increase of GPDH; for routine quantitation, TG is assayed. The biochemical characteristics of PSF in serum are as follows: stable at 4 degrees C for up to 1 year; inactivated at 100 degrees C (80% loss, 30 min) but stable at 56 degrees C for 1 hr; stable at pH 2-12; non-dialyzable; completely resistant to pepsin, trypsin, and chymotrypsin but destroyed by pronase and subtilisn; stable to DTT and periodate; and m.w. between 68 kDa (Sephacryl-300) and 58 kDa (Sephacryl-300 in 5 M urea). PSF activity is greater in serum from Wistar than from Fischer 344 rats, while activity of serum from Zucker obese (fa/fa) rats is at least as great as that from Wistar rats and, like serum of rats made obese by feeding a high-fat, high-carbohydrate diet, is not suppressed. PSF activity is not due to insulin, insulin-like growth factor-1 (IGF-1), growth hormone, glucocorticoids, or combinations of these hormones. PSF activity was not seen with a number of growth factors including colony-stimulating factor (CSF-1), GM-CSF, interleukins 1, 2, and 3, neuroleukin, tumor necrosis factor, and others. PSF is distinct from the low molecular weight (4-8 kDa) differentiation factor present in rat serum, FCS, and human serum that promotes the adipogenic conversion and cellular differentiation of 3T3-L1, 3T3-F442A, and Ob17 cells. PSF appears to be a new differentiation factor for rat preadipocytes, has properties suggestive of a highly glycosylated protein, and may be highly species specific.     

Compensatory growth of adipose tissue after partial lipectomy: involvement of serum factors

The regulation of body weight/fat was studied by investigating mechanisms for compensatory adipose tissue growth after removal of bilateral epididymal fat pads from male adult Wistar rats. Food intake during the first 4 weeks and energy expenditure on Days 8-10 postsurgery were not different between lipectomized and sham operated rats. During Days 29-31 post surgery, a small (2.4%) but significant (P < 0.05) increase in heat production per metabolic body size was detected in lipectomized as compared with sham operated rats. The carcass composition of lipectomized and sham operated rats was not significantly different 16 weeks after surgery. The compensatory growth was fat pad-specific: mesenteric, retroperitoneal, and inguinal fat pads, but not perirenal fat pads, were heavier in lipectomized rats than in sham operated rats as early as 4 weeks postsurgery. Examination of fat cell size distribution in the compensating pads indicated a shift toward larger cells in retroperitoneal fat, but not in inguinal fat of lipectomized as compared with sham operated rats. Serum from lipectomized rats, but not media conditioned by exposure to retroperitoneal fat pads from lipectomized rats, stimulated proliferation of preadipocytes in vitro more than that from sham operated rats. Thus, compensatory adipose tissue growth after lipectomy may be mediated, in part, by blood-borne factors that are derived from tissues other than adipose tissue.     

Aortic carboxypeptidase-like protein is regulated by transforming growth factor beta in 3T3-L1 preadipocytes

Adipogenesis is characterized by early remodeling of the extracellular matrix, allowing preadipocytes to adopt a more spherical shape and optimize lipid accumulation as they mature. Aortic carboxypeptidase-like protein (ACLP), found in collagen-rich tissues including adipose tissue, is expressed in 3T3-L1 and 3T3-F442A preadipocytes, and is downregulated during adipogenesis. We now report that ACLP is found in medium conditioned by 3T3-L1 preadipocytes. Transforming growth factor (TGF) beta, a known modulator of fibrillar matrix protein production, increased ACLP expression by 2.4+/-0.4-fold (mean+/-SE; n=3) in 3T3-L1 preadipocytes, through a mechanism that requires p42/44 MAPK activity. Addition of TGFbeta to differentiation medium, which inhibits adipogenesis, raised ACLP levels in 3T3-L1 cells. However, sustained expression of ACLP in stable clones of 3T3-L1 or 3T3-F442A preadipocytes did not interfere with adipogenesis.     

1alpha,25-Dihydroxyvitamin D hydroxylase in adipocytes

High vitamin D intake is associated with reduced insulin resistance. Expression of extra-renal 1alpha,25-dihydroxyvitamin D hydroxylase (1alpha-hydroxylase) has been reported in several tissues and contributes to local synthesis of 1alpha,25-dihydroxyvitamin D(3) (1,25(OH)(2)D) from the substrate 25-hydroxyvitamin D (25OHD). Expression and dietary regulation of 1alpha-hydroxylase in tissues associated with energy metabolism, including adipose tissue, has not been assessed. Male Wistar rats were fed a high calcium (1.5%) and high vitamin D (10,000IU/kg) or a low calcium (0.25%), low vitamin D (400IU/kg) with either a high fat (40% energy) or high sucrose (66% energy) dietary background for 14 weeks. Expression of 1alpha-hydroxylase, assessed by real time PCR, was detected in adipose tissue and did not differ with dietary level of calcium and vitamin D. 1alpha-Hydroxylase mRNA was also detected in 3T3-L1 preadipocytes and 25OHD treatment at 10nM levels induced 1,25(OH)(2)D responsive gene, CYP24, and this response was reduced in the presence of the p450 inhibitor, ketoconazole. In addition, (3)H 25OHD was converted to (3)H 1,25(OH)(2)D in intact 3T3-L1 preadipocytes. Cumulatively, these results demonstrate that 1alpha-hydroxylase is expressed in adipose tissue and is functional in cultured adipocytes. Thus, the capacity for local production may play a role in regulating adipocyte growth and metabolism.     

Blueberry Peel Extracts Inhibit Adipogenesis in 3T3-L1 Cells and Reduce High-Fat Diet-Induced Obesity

This study examined the anti-obesity effect and mechanism of action of blueberry peel extracts (BPE) in 3T3-L1 cells and high-fat diet (HFD)-induced obese rats. The levels of lipid accumulation were measured, along with the changes in the expression of genes and proteins associated with adipocyte differentiation in 3T3-L1 cells. Evidenced by Oil-red O staining and triglyceride assay, BPE dose-dependently inhibited lipid accumulation at concentrations of 0, 50, and 200 µg/ml. BPE decreased the expression of the key adipocyte differentiation regulator C/EBPβ, as well as the C/EBPα and PPARγ genes, during the differentiation of preadipocytes into adipocytes. Moreover, BPE down-regulated adipocyte-specific genes such as aP2 and FAS compared with control adipocytes. The specific mechanism mediating the effects of BP revealed that insulin-stimulated phosphorylation of Akt was strongly decreased, and its downstream substrate, phospho-GSK3β, was downregulated by BPE treatment in 3T3-L1 cells. Together, these data indicated that BP exerted anti-adipogenic activity by inhibiting the expression of PPARγ and C/EBPβ and the Akt signaling pathway in 3T3-L1 adipocytes. Next, we investigated whether BP extracts attenuated HFD-induced obesity in rats. Oral administration of BPE reduced HFD-induced body weight gain significantly without affecting food intake. The epididymal or perirenal adipose tissue weights were lower in rats on an HFD plus BPE compared with the tissue weights of HFD-induced obese rats. Total cholesterol and triglyceride levels in the rats fed BPE were modestly reduced, and the HDL-cholesterol level was significantly increased in HFD plus BP-fed rats compared with those of HFD-fed rats. Taken together, these results demonstrated an inhibitory effect of BP on adipogenesis through the down-regulation of C/EBPβ, C/EBPα, and PPARγ and the reduction of the phospho-Akt adipogenic factor in 3T3-L1 cells. Moreover, BPE reduced body weight gain and inhibited fat accumulation in an HFD-induced animal model of obesity.     

Phoenixin-14 stimulates differentiation of 3T3-L1 preadipocytes via cAMP/Epac-dependent mechanism

Phoenixin-14 (PNX) is a newly discovered peptide produced by proteolytic cleavage of the small integral membrane protein 20 (Smim20). Previous studies showed that PNX is involved in controlling reproduction, pain, anxiety and memory. Furthermore, in humans, PNX positively correlates with BMI suggesting a potential role of PNX in controlling fat accumulation in obesity. Since the influence of PNX on adipose tissue formation has not been so far demonstrated, we investigated the effects of PNX on proliferation and differentiation of preadipocytes using 3T3-L1 and rat primary preadipocytes. We detected Smim20 and Gpr173 mRNA in 3T3-L1 preadipocytes as well as in rat primary preadipocytes. Furthermore, we found that PNX peptide is produced and secreted from 3T3-L1 and rat primary adipocytes. PNX increased 3T3-L1 preadipocytes proliferation and viability. PNX stimulated the expression of adipogenic genes (Pparγ, C/ebpβ and Fabp4) in 3T3-L1 adipocytes. 3T3-L1 preadipocytes differentiated in the presence of PNX had increased lipid content. Stimulation of cell proliferation and differentiation by PNX was also confirmed in rat preadipocytes. PNX failed to induce AKT phosphorylation, however, PNX increased cAMP levels in 3T3-L1 cells. Suppression of Epac signalling attenuated PNX-induced Pparγ expression without affecting cell proliferation. Our data show that PNX stimulates differentiation of 3T3-L1 and rat primary preadipocytes into mature adipocytes via cAMP/Epac-dependent pathway. In conclusion our data shows that phoenixin promotes white adipogenesis, thereby may be involved in controlling body mass regulation.     

Interleukin-15 stimulates adiponectin secretion by 3T3-L1 adipocytes: evidence for a skeletal muscle-to-fat signaling pathway

Interleukin-15 (IL-15) is a cytokine which is highly expressed in skeletal muscle tissue, and which has anabolic effects on skeletal muscle protein dynamics both in vivo and in vitro. Additionally, administration of IL-15 to rats and mice inhibits white adipose tissue deposition. To determine if the action of IL-15 on adipose tissue is direct, the capacity of cultured murine 3T3-L1 preadipocytes and adipocytes to respond to IL-15 was examined. IL-15 administration inhibited lipid accumulation in differentiating 3T3-L1 preadipocytes, and stimulated secretion of the adipocyte-specific hormone adiponectin by differentiated 3T3-L1 adipocytes. The latter observation constitutes the first report of a cytokine or growth factor which stimulates adiponectin production. IL-15 mRNA expression by cultured 3T3-L1 adipogenic cells and C2C12 murine skeletal myogenic cells was also examined. Quantitative real-time PCR indicated IL-15 mRNA was expressed by C2C12 skeletal myogenic cells, and was upregulated more than 10-fold in differentiated skeletal myotubes compared to undifferentiated myoblasts. In contrast, 3T3-L1 cells expressed little or no IL-15 mRNA at either the undifferentiated preadipocyte or differentiated adipocyte stages. These findings provide support for the hypothesis that IL-15 functions in a muscle-to-fat endocrine axis which modulates fat:lean body composition and insulin sensitivity.     

Ketone body synthesis from leucine by adipose tissue from different sites in the rat

Leucine is catabolized to ketone bodies in adipose tissue, but the contribution of this output to overall ketone metabolism is not known. The intent of the present study was to determine the capacity of different adipose tissues to synthesize ketone bodies from leucine. The amino acid was readily converted into acetoacetate in epididymal, perirenal, and omental fat tissues. In rats fed ad libitum, the rate of acetoacetate synthesis in omental fat (about 2 mumol g tissue-1h-1) was at least 8 times higher than in epididymal or perirenal fat. In omental fat, the rates of acetoacetate formation from alpha-ketoisocaproic acid were 47-55% lower than from leucine at all concentrations examined. There was no significant synthesis of beta-hydroxybutyrate from leucine or alpha-ketoisocaproic acid. After oxidative decarboxylation, a greater proportion (about three-fourths) of leucine in omental fat was metabolized to acetoacetate than to CO2 production through the Krebs cycle. Although addition of glucose, pyruvate, or carnitine did not affect the production of acetoacetate, fasting for 24 h stimulated acetoacetate synthesis from leucine and alpha-ketoisocaproic acid in omental fat. The high rate of leucine conversion to acetoacetate in omental fat was related to high activities of leucine aminotransferase and branched-chain alpha-keto acid dehydrogenase. Moreover, protein content and cytochrome c oxidase activity of omental mitochondria were, respectively, 13 and 12 times higher than in epididymal mitochondria. In contrast, fat content of epididymal adipose tissue was 21 times that of omental adipose tissue. Epididymal depot consisted of 2.0% protein and 75.8% fat, whereas omental depot contains 17.2% protein and 3.6% fat, resembling that of liver and muscle. The results suggest that the high ketogenic capacity of omental fat stems in part from an augmented mitochondrial mass and high activity of branched-chain alpha-keto acid dehydrogenase.     

Thiazolidinediones exhibit different effects on preadipocytes isolated from rat mesenteric fat tissue and cell line 3T3-L1 cells derived from mice

The effects of PPAR-gamma agonists, thiazolidinediones (TZDs), on preadipocytes isolated from rat mesenteric adipose tissue and murine cell line 3T3-L1 were compared using an in vitro cell culture system. After each cell formed a confluent monolayer under appropriate medial conditions, pioglitazone or troglitazone was applied at 10 microM to each medium for cell maturation. We observed morphological changes in each cell, especially the accumulation of lipid droplets in the cytoplasm, during the culture periods. At the end of culture, DNA content, triglyceride (TG) content and glycerol-3-phosphate dehydrogenase (GPDH) activity were determined. Adiponectin concentrations in each culture medium were also measured during appropriate experimental periods. Application of TZDs increased the DNA content, TG accumulation and GPDH activity in the 3T3-L1 cells but not in the mesenteric adipocytes. Although TG accumulation was unchanged, the number of lipid particles was decreased and the size of lipid particles in the mesenteric adipocytes was increased by TZD application. Although the TZDs increased adiponectin release from the 3T3-L1 cells, adiponectin release from mesenteric adipocytes was suppressed (P<0.05). Thus, the effects of TZDs differed between the primary culture of mesenteric adipose cells and the line cell culture of 3T3-L1 cells. The source of adipocytes is an important factor in determining the action of TZDs in vitro, and particular attention should be paid when evaluating the effect of PPAR-gamma agonists on adipose tissues.     

Regulation of haptoglobin gene expression in 3T3-L1 adipocytes by cytokines, catecholamines, and PPARgamma

Factors which regulate expression of the haptoglobin (acute phase reactant) gene in adipocytes have been examined using 3T3-L1 cells. Haptoglobin expression was observed by Northern blotting in each of the major white adipose tissue depots of mice (epididymal, subcutaneous, mesenteric, and perirenal) and in interscapular brown fat. Expression occurred in mature adipocytes, but not in the stromal-vascular fraction. In 3T3-L1 cells, haptoglobin mRNA was detected from day 4 after the induction of differentiation into adipocytes. Lipopolysaccharide and the cytokines, TNFalpha and interleukin-6, resulted in substantial increases in haptoglobin mRNA in 3T3-L1 adipocytes; the increase (7-fold) was highest with TNFalpha. Increases in haptoglobin mRNA level were also induced by dexamethasone, noradrenaline, isoprenaline, and a beta3-adrenoceptor agonist. In contrast, haptoglobin mRNA was reduced by nicotinic acid and the PPARgamma agonist, rosiglitazone. RT-PCR showed that the haptoglobin gene was expressed in human adipose tissue (subcutaneous, omental). It is concluded that haptoglobin gene expression in adipocytes is stimulated by inflammatory cytokines, glucocorticoids, and the sympathetic system, while activation of the PPARgamma nuclear receptor is strongly inhibitory.     

Troglitazone activates TRPV1 and causes deacetylation of PPARγ in 3T3-L1 cells

Published research suggests that activation of transient receptor potential vanilloid subfamily 1 (TRPV1) enhances the expression and deacetylation of peroxisome proliferator-activated receptor gamma (PPARγ) to cause browning of white adipose tissue. Here, we show that TRPV1 activation by capsaicin significantly prevents high fat diet-induced obesity in mice. This is associated with an increase in the expression and deacetylation of PPARγ in the epididymal fat of these mice. Consistent with the TRPV1 activation in vivo, overexpression of TRPV1 enhanced the PPARγ and other thermogenic genes in cultured 3T3-L1 preadipocytes. To determine the interaction between TRPV1 and PPARγ signaling, we analyzed the effect of Troglitazone (Trog; a thiazolidinedione derivative and an agonist of PAARγ) treatment on cultured 3T3-L1 cells. Trog enhanced the expression of TRPV1, PPARγ and thermogenic proteins in undifferentiated 3T3-L1 cells but not in differentiated cells. Acute application of Trog stimulated a robust Ca²⁺ influx into 3T3-L1 cells and TRPV1 inhibition by capsazepine prevented this. More interestingly, Trog or capsaicin treatment caused the deacetylation of PPARγ in 3T3-L1 cells and inhibition of TRPV1 or Sirtuin 1 - prevented this. Our data suggest a novel effect of Trog to induce PPARγ deacetylation by activating TRPV1. This research has a significant implication on the role of TRPV1 and PPARγ signaling in the browning of white adipose tissue.