3T3-L1 Adipocytes Research Articles

Cytokines secreted from adipose tissues mediate tumor proliferation and metastasis in triple negative breast cancer

BackgroundObesity is a high-risk factor for development and poor prognosis of triple-negative breast cancer (TNBC), which was considered as a high malignant and poor clinical outcome breast cancer subtype. TNBC proliferation and migration regulated by obesity is complex. Here, we studied effects of cytokines secreted from adipose tissue on development of TNBC.MethodsForty postmenopausal cases by Yuebei People’s Hospital of Shaoguan with stage I/IIA TNBC were enrolled. Cytokine concentrations were examined using ELISA analysis. Proliferation and migration of TNBC cell lines were performed using CCK8 assays and Transwell tests. The Log-rank (Mantel-Cox) test, two-tailed Mann-Whitney U test and two-tailed unpaired t test were performed using GraphPad Prism 8.4.2.ResultsSurvival analysis indicated that obese patients with TNBC had worse disease free survival (DFS) as compared with normal weight group (Hazard Ratio 4.393, 95% confidence interval (CI) of ratio 1.071–18.02, p < 0.05). Obese patients with TNBC had severe insulin resistance and high plasma triglycerides. However, plasma adiponectin concentration was decreased and interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) concentration was increased in obese TNBC patients as compared with the nonobese group. The similar results were found in the cytokine secretion from adipose tissues and insulin-resistant adipocytes. The secretion of adipose tissue from obese TNBC patients could promote proliferation and migration of TNBC cell lines, including MDA-MB-157, MDA-MB-231, MDA-MB-453 and HCC38 cells. These TNBC cell lines co-incubated with insulin-resistant 3T3-L1 adipocytes or supplementing these cytokines medium also exhibited increase of proliferative and migratory capacity.ConclusionTNBC patients with obesity had worse prognosis compared with the normal weight groups. Alteration of cytokines secreted from adipose tissues mediated proliferation and migration of TNBC, leading to tumor progression in TNBC patients with obesity.

Esaxerenone, a selective mineralocorticoid receptor blocker, improves insulin sensitivity in mice consuming high-fat diet

BackgroundEsaxerenone is a novel, non-steroidal selective mineralocorticoid receptor (MR) blocker. MR activation plays a crucial role in the development of cardiovascular and metabolic diseases. In this study, we investigated the effects of esaxerenone on various metabolic parameters in mice. Materials and methodsEsaxerenone (3 mg/kg/day) was orally administered to high-fat diet (HFD)-fed male C57BL/6 mice. Mice fed a normal diet (ND) served as controls. Glucose and insulin tolerance, plasma lipid levels, and transaminase levels were assessed as metabolic parameters. Macrophage accumulation in the adipose tissue was evaluated using histological analysis. 3T3-L1 adipocytes, HepG2 cells, and C2C12 myotubes were used for in vitro experiments. Gene expression and insulin signaling were examined using quantitative RT-PCR and western blotting, respectively. ResultsHFD successfully induced insulin resistance compared with that in ND. Esaxerenone ameliorated insulin resistance (P < 0.05) without altering other metabolic parameters, such as the lipid profile. Esaxerenone administration tended to decrease plasma transaminase levels compared with those in the non-treated group. In the adipose tissue, esaxerenone decreased macrophage accumulation (P < 0.05) and increased the expression levels of adiponectin and PPARγ. Aldosterone significantly decreased the expression levels of PPARγ and adiponectin in 3T3-L1 adipocytes. Furthermore, aldosterone attenuated insulin-induced Akt phosphorylation in 3T3-L1 adipocytes, HepG2 cells, and C2C12 myotubes in a dose-dependent manner (P < 0.01). These effects were ameliorated by pretreatment with esaxerenone. ConclusionEsaxerenone ameliorated insulin resistance in HFD-fed mice. Reduction of inflammation and improvement in insulin signaling may underlie the beneficial effects of esaxerenone.

Hulless barley polyphenol extract inhibits adipogenesis in 3T3-L1 cells and obesity related-enzymes.

Obesity is characterized by excessive lipid accumulation, hypertrophy, and hyperplasia of adipose cells. Hulless barley (Hordeum vulgare L. var. nudum Hook. f.) is the principal crop grown in the Qinghai-Tibet plateau. Polyphenols, the major bioactive compound in hulless barley, possess antioxidant, anti-inflammatory, and antibacterial properties. However, the anti-obesity effect of hulless barley polyphenol (HBP) extract has not been explored. Therefore, the current study assessed the impact of HBP extract on preventing obesity. For this purpose, we evaluated the inhibitory effect of HBP extract against obesity-related enzymes. Moreover, we investigated the effect of HBP extract on adipocyte differentiation and adipogenesis through 3T3-L1 adipocytes. Our results demonstrated that HBP extract could inhibit α-amylase, α-glucosidase (α-GLU), and lipase in a dose-dependent manner. In addition, HBP extract inhibited the differentiation of 3T3-L1 preadipocytes by arresting the cell cycle at the G0/G1 phase. Furthermore, the extract suppressed the expression of adipogenic transcription factors such as peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein α (C/EBPα), regulating fatty acid synthase (FAS), fatty acid-binding protein 4 (FABP4), and adipose triglyceride lipase (ATGL). It was also observed that HBP extract alleviated intracellular lipid accumulation by attenuating oxidative stress. These findings specify that HBP extract could inhibit obesity-related enzymes, adipocyte differentiation, and adipogenesis. Therefore, it is potentially beneficial in preventing obesity.

AMPKβ isoform expression patterns in various adipocyte models and in relation to body mass index.

AMP-activated protein kinase (AMPK) activation is considered a useful strategy for the treatment of type 2 diabetes (T2D). It is unclear whether the expression and/or activity of AMPK in adipocytes is dysregulated in obesity. Also, the expression/activity pattern of AMPKβ isoforms, which are targets for AMPK activators, in adipocytes remains elusive. In this study we show that the two AMPKβ isoforms make roughly equal contributions to AMPK activity in primary human and mouse adipocytes, whereas in cultured 3T3-L1 adipocytes of mouse origin and in primary rat adipocytes, β1-associated activity clearly dominates. Additionally, we found that obesity is not associated with changes in AMPK subunit expression or kinase activity in adipocytes isolated from subcutaneous adipose tissue from individuals with various BMI.

Adipocyte-Derived Extracellular Vesicles Promote Prostate Cancer Cell Aggressiveness by Enabling Multiple Phenotypic and Metabolic Changes.

Background: In recent decades, obesity has widely emerged as an important risk factor for prostate cancer (PCa). Adipose tissue and PCa cells have been shown to orchestrate a complex interaction network to support tumor growth and evolution; nonetheless, the study of this communication has only been focused on soluble factors, although increasing evidence highlights the key role of extracellular vesicles (EVs) in the modulation of tumor progression. Methods and Results: In the present study, we found that EVs derived from 3T3-L1 adipocytes could affect PC3 and DU145 PCa cell traits, inducing increased proliferation, migration and invasion. Furthermore, conditioning of both PCa cell lines with adipocyte-released EVs resulted in lower sensitivity to docetaxel, with reduced phosphatidylserine externalization and decreased caspase 3 and PARP cleavage. In particular, these alterations were paralleled by an Akt/HIF-1α axis-related Warburg effect, characterized by enhanced glucose consumption, lactate release and ATP production. Conclusions: Collectively, these findings demonstrate that EV-mediated crosstalk exists between adipocytes and PCa, driving tumor aggressiveness.

Proto-oncogene FAM83A contributes to casein kinase 1–mediated mitochondrial maintenance and white adipocyte differentiation

Family with sequence similarity 83 A (FAM83A) is a newly discovered proto-oncogene that has been shown to play key roles in various cancers. However, the function of FAM83A in other physiological processes is not well known. Here, we report a novel function of FAM83A in adipocyte differentiation. We used an adipocyte-targeting fusion oligopeptide (FITC-ATS-9R) to deliver a FAM83A-sgRNA/Cas9 plasmid to knockdown Fam83a (ATS/sg-FAM83A) in white adipose tissue in mice, which resulted in reduced white adipose tissue mass, smaller adipocytes, and mitochondrial damage that was aggravated by a high-fat diet. In cultured 3T3-L1 adipocytes, we found loss or knockdown of Fam83a significantly repressed lipid droplet formation and downregulated the expression of lipogenic genes and proteins. Furthermore, inhibition of Fam83a decreased mitochondrial ATP production through blockage of the electron transport chain, associated with enhanced apoptosis. Mechanistically, we demonstrate FAM83A interacts with casein kinase 1 (CK1) and promotes the permeability of the mitochondrial outer membrane. Furthermore, loss of Fam83a in adipocytes hampered the formation of the TOM40 complex and impeded CK1-driven lipogenesis. Taken together, these results establish FAM83A as a critical regulator of mitochondria maintenance during adipogenesis.

Standardized pectolinarin rich-Cirsium setidens Nakai extract attenuates bisphenol A-induced the 3T3-L1 adipocytes differentiation and obese C57BL/6J mice via the suppression of adipogenesis-related transcription factors

Endocrine-disrupting chemicals (EDCs), called obesogens, play an important role in obesity by mimicking or disrupting bioidentical hormones. In this study, we determined the obesogenic effect of bisphenol A (BPA) and evaluated the anti-obesogenic effects of a standardized Cirsium setidens Nakai ethanolic extract (CNE) as a functional food ingredient on the lipid accumulation and expression of key adipogenic transcription factors (ATFs) in 3 T3-L1 adipocytes and C57BL/6J mice. The underlying mechanism of the obesogenic effect of BPA was confirmed using the peroxisome proliferator-activated receptor γ (PPARγ) antagonist, GW9662. In addition, the anti-obesogenic effects of CNE were confirmed by measuring the lipid accumulation, reactive oxygen species (ROS) production, body and adipose tissue weights, and the adipogenesis- and lipogenesis-related proteins in BPA-induced 3T3-L1 adipocytes and obese mice. These findings indicate that CNE could potentially be used as a promising natural means to prevent BPA-induced obesity and obesity-related metabolic diseases.

Halophila beccarii extract ameliorate glucose uptake in 3T3-L1 adipocyte cells and improves glucose homeostasis in streptozotocin-induced diabetic rats

The regulation of carbohydrate metabolizing enzymes is an effective way of reducing blood glucose levels and improving glycogen synthesis during the management of type 2 diabetes. The present investigation was conducted to explain the detailed mechanism with which a Seagrass, Halophila beccarii extract (HBE) enhances the glucose uptake in the 3T3-L1 adipocyte cell culture system in invitro. HBE stimulates the glucose uptake by the translocation of glucose transporter 4 (GLUT4) on to plasma cell membrane through induction of insulin receptor substrate 1 (IRS-1)/protein kinase B (Akt) signaling pathways. To assess the effect of HBE on T2DM, we used invivo experimental diabetes rat models induced with streptozotocin (STZ) to perform oral GTT and ITT. Furthermore, we assessed the enzymatic profile of Glycolysis, Pentose phosphate pathway, and gluconeogenesis from liver tissue homogenate. After long-term exposure with HBE, our results confirmed, that HBE improves the glucose uptake in 3T3-L1 cell lines by up-regulation of glucose transporter type 4 (GLUT4) through uptake of glucose by the adipocytes. The resulting data indicated that HBE had a great potentiality in preventing diabetes and maintaining glucose homeostasis through improving glucose uptake. The present data also showed that HBE with its insulin mimetic activity activates glycogen synthesis and enhances glucose utilization by regulating the carbohydrate metabolic enzymes. The similarity between HBE and insulin indicates that the HBE follows the mechanisms same as the insulin signaling pathway to show the antidiabetic activity.

Toll-like Receptor 7 (TLR7) Is Expressed in Adipocytes and the Pharmacological TLR7 Agonist Imiquimod and Adipocyte-Derived Cell-Free Nucleic Acids (cfDNA) Regulate Adipocyte Function.

Endosome-localized Toll-like receptors (TLRs) 3 and 9 are expressed and functionally active in adipocytes. The functionality and role of TLR7 in adipocyte biology and innate immunity of adipose tissue (AT) is poorly characterized. We analyzed TLR7 mRNA and protein expression in murine 3T3-L1 and primary adipocytes, in co-cultures of 3T3-L1 adipocytes with murine J774A.1 monocytes and in human AT. The effects of TLR7 agonists imiquimod (IMQ) and cell-free nucleic acids (cfDNA) on adipokine concentration in cell-culture supernatants and gene expression profile were investigated. We found that TLR7 expression is strongly induced during adipocyte differentiation. TLR7 gene expression in adipocytes and AT stroma-vascular cells (SVC) seems to be independent of TLR9. IMQ downregulates resistin concentration in adipocyte cell-culture supernatants and modulates gene expression of glucose transporter Glut4. Adipocyte-derived cfDNA reduces adiponectin and resistin in cell-culture supernatants and potentially inhibits Glut4 gene expression. The responsiveness of 3T3-L1 adipocytes to imiquimod is preserved in co-culture with J774A.1 monocytes. Obesity-related, adipocyte-derived cfDNA engages adipocytic pattern recognition receptors (PRRs), modulating AT immune and metabolic homeostasis during adipose inflammation.

Anti-inflammatory and Insulin Signaling Phenotype Induced by Repeated Lipopolysaccharide Stimulation in 3T3-L1 Adipocytes.

Lipopolysaccharide (LPS) is thought to be a causative agent of type 2 diabetes, because it has been shown that a single LPS stimulation in vitro induces chronic inflammation and reduces insulin signaling in adipocytes. However, oral LPS administration prevents type 2 diabetes, and this effect does not correspond to a single LPS adipocyte stimulation. In this study, the response of adipocytes to single and repeated stimulation with LPS was examined. 3T3-L1 cells were differentiated into adipocytes and stimulated with LPS once or thrice every 24 h. The expression levels of inflammatory and anti-inflammatory factors and insulin sensitivity-related factors were measured. Single stimulation with LPS increased the mRNA and protein expression of inflammatory factors (interleukin-6 and monocyte chemotactic protein 1), but this increase was inhibited by repeated stimulation. In contrast, the mRNA expression levels of anti-inflammatory factors (proliferator-activated receptor γ and peroxisome proliferator-activated receptor gamma coactivator1 α) were increased by repeated LPS stimulation. Additionally, the mRNA expression levels of insulin sensitivity-related factors (glucose transporter type 4, insulin receptor, insulin receptor substrate 1 and thymoma viral proto-oncogene 2) in adipocytes were increased upon repeated LPS stimulation. Repetitive LPS stimulation, unlike single stimulation of adipocytes, upregulates anti-inflammatory and insulin signaling-related factors.

Taste 2 Receptor Is Involved in Differentiation of 3T3-L1 Preadipocytes

Expression of taste 2 receptor (T2R) genes, also known as bitter taste receptor genes, has been reported in a variety of tissues. The white adipose tissue of mice has been shown to express Tas2r108, Tas2r126, Tas2r135, Tas2r137, and Tas2r143, but the function of T2Rs in adipocytes remains unclear. Here, we show that fasting and stimulation by bitter compounds both increased Tas2r expression in mouse white adipose tissue, and serum starvation and stimulation by bitter compounds both increased the expression of Tas2r genes in 3T3-L1 adipocytes, suggesting that T2Rs have functional roles in adipocytes. RNA sequencing analysis of 3T3-L1 adipocytes stimulated by epicatechin, the ligand of Tas2r126, suggested that this receptor may play a role in the differentiation of adipocytes. Overexpression of Tas2r126 in 3T3-L1 preadipocytes decreases fat accumulation after induction of differentiation and reduces the expression of adipogenic genes. Together, these results indicate that Tas2r126 may be involved in adipocyte differentiation.

Cinnamon extract improves abnormalities in glucose tolerance by decreasing Acyl-CoA synthetase long-chain family 1 expression in adipocytes

We previously demonstrated that cinnamon extract (CE) alleviates streptozotocin-induced type 1 diabetes in rats. The present study aimed to elucidate the detailed molecular target of cinnamon in cultured adipocytes and epididymal adipose tissue of type 2 diabetes model mice. Two-dimensional gel electrophoresis was employed to determine the molecular target of cinnamon in adipocytes. The function of Acyl-CoA synthetase long-chain family-1 (ACSL1), a molecular target of cinnamon that was identified in this study, was further investigated in 3T3-L1 adipocytes using specific inhibitors. Type 2 diabetes model mice (KK-Ay/TaJcl) were used to investigate the effect of CE on glucose tolerance, ACSL1 expression, and related signal molecules in vivo. CE decreased ACSL1 mRNA and protein expression in 3T3-L1 adipocytes but increased glucose uptake and AMPK signaling activation; moreover, a similar effect was observed with an ACSL1 inhibitor. CE improved glucose tolerance and downregulated ACSL1 in mice adipose tissue in vivo. ACSL1 was demonstrated as a molecular target of CE in type 2 diabetes both in a cell culture system and diabetic mouse model.

O054 A novel hyaluronic acid hydrogel as an extracellular matrix to improve adipose tissue graft survival in autologous transfer for breast cancer reconstruction

Abstract Introduction Adipose tissue transfer is used for correcting breast contour defects after cancer surgery. Graft survival can be as poor as 15% at four years follow-up. Hyaluronic acid (HA) hydrogels can be used to suspend adipocytes to aid survival. Methods A unique HA gel with cross-linked aldehyde and hydrazine groups allowing self-healing around cells after injection was engineered. The gel's rheology and degradation properties in vitro were characterised. 3T3-L1, murine and human adipocytes were encapsulated within HA hydrogel, with survival and gene expression interrogated. A murine animal model underwent subcutaneous injection of primary murine adipocytes mixed with HA gel, with survival and gene expression examined. Results The novel HA hydrogel can be degraded by tissue hyaluronidases in 4–5 days. Self-healing occurred in 30 minutes and the gel is robust enough to be injected through a needle. 3T3-L1, murine and human adipocytes were encapsulated within HA hydrogel and showed a &amp;lt;15% deduction in survival compared to control. Mature adipocyte gene expression markers compared to control showed no difference. Primary murine adipocytes injected in vivo showed no difference in survival at higher gel volumes compared to control. Conclusion The novel engineered HA hydrogel has suitable mechanical characteristics for injection and can support adipocyte survival in vitro and in vivo and is ready for a pilot human trial. Take-home message Our novel HA gel can support adipocytes in vivo and in vitro, and offers a potential method for augmentation of adipose tissue transfer.

Novel soybean peptide iglycin ameliorates insulin resistance of high-fat diet fed C57BL/6J mice and differentiated 3T3L1 adipocytes with improvement of insulin signaling and mitochondrial function

Soy consumption has been associated with potential health benefits in reducing chronic diseases. These physiological functions have been attributed to soy proteins or more commonly to bioactive peptides. Thus, more studies are required to identify these bioactive peptides, and elucidate their biological mechanisms of action. In the present study, a novel peptide iglycin was purified from soybean seeds with a molecular mass of 3.88 kDa. Thereafter, iglycin reduced fasting blood glucose and restored insulin sensitivity of C57BL/6J mice on a high-fat diet with increased phosphorylation of insulin receptor substrate 1 (IRS1) and AKT in adipose tissue. Furthermore, it improved glucose uptake, induced translocation of intracellular GLUT4 to plasma membrane and activation of insulin signaling in adipocytes under insulin-resistant condition. In addition, it decreased reactive oxygen species production, lipid peroxidation and inhibited adipocyte apoptosis with improved mitochondrial function as evidenced by up-regulation of succinate dehydrogenase activity, mitochondrial membrane potential and intracellular ATP store. These data suggested that iglycin ameliorated insulin resistance via activation of insulin signaling, which was associated with inhibition of oxidative stress, adipocyte apoptosis, and improvement of mitochondrial function.

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.

Secondary Metabolites in the Dendrobium heterocarpum Methanolic Extract and Their Impacts on Viability and Lipid Storage of 3T3-L1 Pre-Adipocytes

Although many natural products have proven their potential to regulate obesity through the modulation of adipocyte biology, none of them has yet been approved for clinical use in obesity therapy. This work aims to isolate valuable secondary metabolites from an orchid species (Dendrobium heterocarpum) and evaluate their possible roles in the growth and differentiation of 3T3-L1 pre-adipocytes. Six compounds were isolated from the orchid’s methanolic extracts and identified as amoenylin (1), methyl 3-(4-hydroxyphenyl) propionate (2), 3,4-dihydroxy-5,4’-dimethoxybibenzyl (3), dendrocandin B (4), dendrofalconerol A (5), and syringaresinol (6). Among these phytochemicals, compounds 2, 3, and 6 exhibited lower effects on the viability of 3T3-L1 cells, offering non-cytotoxic concentrations of ≲ 10 µM. Compared to others tested, compound 3 was responsible for the maximum reduction of lipid storage in 3T3-L1 adipocytes (IC50 = 6.30 ± 0.10 µM). A set of protein expression studies unveiled that compound 3 at non-cytotoxic doses could suppress the expression of some key transcription factors in adipocyte differentiation (i.e., PPARγ and C/EBPα). Furthermore, this compound could deactivate some proteins involved in the MAPK pathways (i.e., JNK, ERK, and p38). Our findings prove that D. heterocarpum is a promising source to explore bioactive molecules capable of modulating adipocytic growth and development, which can potentially be assessed and innovated further as pharmaceutical products to defeat obesity.

IL-25 directly modulates adipocyte function and inflammation through the regulation of adiponectin.

This study aimed to investigate the direct role of IL-25 in modulating adipocyte function during homeostasis and low-grade inflammation induced by lipopolysaccharide (LPS). The 3T3-L1 preadipocyte cell lines and primary cultures of adipose-derived stromal vascular precursor cells of wild-type and IL-17RB-deficient mice were used to determine the direct function of IL-25. The expression of IL-17RB in differentiating adipocyte was determined using real-time PCR and flow cytometry analysis. The effect of IL-25 on lipid accumulation, triglyceride content, lipolysis, glucose uptake, and adipokine expression in the mature adipocytes was evaluated. IL-25 modulating the expression of inflammatory cytokines in adipocytes induced by low dose LPS was determined using real-time PCR and ELISA. The receptor for IL-25 was up-regulated during adipocyte differentiation and IL-25 directly modulated adipocyte function by reducing lipid accumulation and triglyceride concentration and enhancing lipolysis without affecting an insulin-stimulated glucose uptake. Interestingly, IL-25 induced adiponectin secretion through the PI3K/AKT signaling pathway. In 3T3-L1 adipocytes under low-grade inflammation, IL-25 attenuated the expression of IL-6 and CCL5 through the induction of adiponectin. Our studies suggest that IL-25 directly regulates adipocyte function by maintaining the adiponectin level during homeostasis and by alleviating inflammatory response through the regulation of adiponectin during low-grade inflammation in adipocytes.

Crateva unilocularis Buch-Ham leaf extract improves glucose metabolism via regulation of insulin secretion and sensitivity in vitro and in vivo

Crateva unilocularis Buch-Ham has traditionally been used in Nepal for the treatment and prevention of diabetes. However, scientific verification through studies on the preventive effect of C. unilocularis on diabetes has not been done properly. In this study we investigated the effect of C. unilocularis leaf extract (CULE) on glucose uptake and insulin resistance. The effect of CULE on glucose uptake in an in vivo system was measured using zebrafish. In the cell-free system, enzymes activities related to diabetes were measured. Moreover, in the cell-cultured system, RIN-m5F pancreatic beta cells, 3T3-L1 adipocytes, and L6 myotubes were used to measure the effect of CULE on insulin secretion and glucose metabolism. CULE effectively enhanced glucose uptake in zebrafish larvae, and inhibited the activity of dipeptidyl peptidase-IV (DPP-IV) and protein tyrosine phosphatase-1B (PTP-1B) enzymes related to insulin secretion and insulin signaling activation. Also, CULE significantly increased insulin secretion with suppression of NO production in RIN-m5F pancreatic beta cells. In L6 myotubes and TNF-α-induced insulin resistance model of 3T3-L1 adipocytes, CULE significantly increased glucose uptake and immunofluorescence staining of glucose transporter (GLUT)4 protein. Furthermore, the regulatory response of glucose metabolism by CULE was a close correlation with the activation of insulin signaling (IRβ, PI3K, AKT) and 5′-AMP-activated protein kinase (AMPK)α and the reduction of p38 mitogen-activated protein kinase (MAPK) in TNF-α-induced insulin resistance model of 3T3-L1 adipocytes. Thus, our results suggest that CULE may act as a potential agent for the prevention and treatment of metabolic syndrome associated with type 2 diabetes.

Different Seasonal Collections of Ficus carica L. Leaves Diversely Modulate Lipid Metabolism and Adipogenesis in 3T3-L1 Adipocytes.

Due to the high prevalence of obesity and type 2 diabetes, adipogenesis dysfunction and metabolic disorders are common features in the elderly population. Thus, the identification of novel compounds with anti-adipogenic and lipolytic effects is highly desirable to reduce diabetes complications. Plants represent an important source of bioactive compounds. To date, the antidiabetic potential of several traditional plants has been reported, among which Ficus carica L. is one of the most promising. Considering that plant metabolome changes in response to a number of factors including seasonality, the aim of this study was to evaluate whether Ficus carica leaves extracts collected in autumn (FCa) and spring (FCs) differently modulate lipid metabolism and adipogenesis in 3T3-L1 adipocytes. The 1H-NMR profile of the extracts showed that FCs have a higher content of caffeic acid derivatives, glucose, and sucrose than FCa. In contrast, FCa showed a higher concentration of malic acid and furanocoumarins, identified as psoralen and bergapten. In vitro testing showed that only FCa treatments were able to significantly decrease the lipid content (Ctrl vs. FCa 25 μg/mL, 50 μg/mL and 80 μg/mL; p < 0.05, p < 0.01 and p < 0.001, respectively). Furthermore, FCa treatments were able to downregulate the transcriptional pathway of adipogenesis and insulin sensitivity in 3T3-L1 adipocytes. In more detail, FCa 80 μg/mL significantly decreased the gene expression of PPARγ (p < 0.05), C/EBPα (p < 0.05), Leptin (p < 0.0001), adiponectin (p < 0.05) and GLUT4 (p < 0.01). In conclusion, this study further supports an in-depth investigation of F. carica leaves extracts as a promising source of active compounds useful for targeting obesity and diabetes.

EFR3 and phosphatidylinositol 4-kinase IIIα regulate insulin-stimulated glucose transport and GLUT4 dispersal in 3T3-L1 adipocytes.

Insulin stimulates glucose transport in muscle and adipocytes. This is achieved by regulated delivery of intracellular glucose transporter (GLUT4)-containing vesicles to the plasma membrane where they dock and fuse, resulting in increased cell surface GLUT4 levels. Recent work identified a potential further regulatory step, in which insulin increases the dispersal of GLUT4 in the plasma membrane away from the sites of vesicle fusion. EFR3 is a scaffold protein that facilitates localization of phosphatidylinositol 4-kinase type IIIα to the cell surface. Here we show that knockdown of EFR3 or phosphatidylinositol 4-kinase type IIIα impairs insulin-stimulated glucose transport in adipocytes. Using direct stochastic reconstruction microscopy, we also show that EFR3 knockdown impairs insulin stimulated GLUT4 dispersal in the plasma membrane. We propose that EFR3 plays a previously unidentified role in controlling insulin-stimulated glucose transport by facilitating dispersal of GLUT4 within the plasma membrane.