Role In Adipocyte Differentiation Research Articles

Effects of mifepristone on adipocyte differentiation in mouse 3T3-L1 cells

BackgroundBoth glucocorticoid receptor and peroxisome proliferator-activated receptor-γ (PPARγ) play a critical role in adipocyte differentiation. Mifepristone is not only an antagonist of the glucocorticoid receptor but also an agonist of PPARγ. Therefore, the present study investigated the effect of mifepristone on adipocyte differentiation.MethodsMouse 3T3-L1 cells were used as a model for adipocyte differentiation. The lipid droplet formation was evaluated with Bodipy493/503 staining and the expression of adipocyte markers [adiponectin and adipocyte fatty acid binding protein-4 (Fabp4)] was evaluated with quantitative PCR and immunoblot analyses for indication of adipocyte differentiation. siRNA and neutralizing antibodies were used to elucidate the molecular mechanism of mifepristone-induced adipocyte differentiation. Luciferase reporter assay was used to examine the effect of mifepristone on the promoter activity of PPAR-response element (PPRE). The DNA microarray analysis was used to characterize the transcriptome of the mifepristone-induced adipocytes. In vivo adipogenic effect of mifepristone was examined in mice.ResultsMifepristone not only enhanced adipocyte differentiation induced by the conventional protocol consisting of insulin, dexamethasone and 3-isobutyl-1-methylxanthine but also induced adipocyte differentiation alone, as evidenced by lipid droplets formation and induction of the expression of adiponectin and Fabp4. These effects were inhibited by an adiponectin-neutralizing antibody and a PPARγ antagonist. Mifepristone activated the promoter activity of PPRE in a manner sensitive to PPARγ antagonist. A principal component analysis (PCA) of DNA microarray data revealed that the mifepristone-induced adipocytes represent some characteristics of the in situ adipocytes in normal adipose tissues to a greater extent than those induced by the conventional protocol. Mifepristone administration induced an increase in the weight of epididymal, perirenal and gluteofemoral adipose tissues.ConclusionsMifepristone alone is capable of inducing adipocyte differentiation in 3T3-L1 cells and adipogenesis in vivo. PPARγ plays a critical role in the mifepristone-induced adipocyte differentiation. Mifepristone-induced adipocytes are closer to the in situ adipocytes than those induced by the conventional protocol. The present study proposes a single treatment with mifepristone as a novel protocol to induce more physiologically relevant adipocytes in 3T3-L1 cells than the conventional protocol.

Silencing ANGPTL8 reduces mouse preadipocyte differentiation and insulin signaling

ANGPTL8, expressed mainly in the liver and adipose tissue, regulates the activity of lipoprotein lipase (LPL) present in the extracellular space and triglyceride (TG) metabolism through its interaction with ANGPTL3 and ANGPTL4. Whether intracellular ANGPTL8 can also exert effects in tissues where it is expressed is uncertain. ANGPTL8 expression was low in preadipocytes and much increased during differentiation. To better understand the role of intracellular ANGPTL8 in adipocytes and assess whether it may play a role in adipocyte differentiation, we knocked down its expression in normal mouse subcutaneous preadipocytes. ANGPTL8 knockdown reduced adipocyte differentiation, cellular TG accumulation and also isoproterenol-stimulated lipolysis at day 7 of differentiation. RNA-Seq analysis of ANGPTL8 siRNA or control siRNA transfected SC preadipocytes on days 0, 2, 4 and 7 of differentiation showed that ANGPTL8 knockdown impeded the early (day 2) expression of adipogenic and insulin signaling genes, PPARγ, as well as genes related to extracellular matrix and NF-κB signaling. Insulin mediated Akt phosphorylation was reduced at an early stage during adipocyte differentiation. This study based on normal primary cells shows that ANGPTL8 has intracellular actions in addition to effects in the extracellular space, like modulating LPL activity. Preadipocyte ANGPTL8 expression modulates their differentiation possibly via changes in insulin signaling gene expression.

Identification of a Novel Long Non-Coding RNA G8110 That Modulates Porcine Adipogenic Differentiation and Inflammatory Responses

Long non-coding RNAs (lncRNAs) have been extensively studied, and their crucial roles in adipogenesis, lipid metabolism, and gene expression have been revealed. However, the exact regulatory or other mechanisms by which lncRNAs influence the functioning of mesenteric adipose tissue (MAT) remain largely unknown. In this paper, we report the identification of a new lncRNA, named G8110, from the MAT of Bama pigs. The coordinated expression levels of lncRNA G8110 and NFE2L1 were significantly decreased in the MAT of obese Bama pigs compared with those in the MAT of lean pigs. Using a bone mesenchymal stem cell adipogenic differentiation model, we found that lncRNA G8110 played a role in adipocyte differentiation by positively regulating NFE2L1. We also found that lncRNA G8110 inhibited the formation of intracellular lipid synthesis, promoted lipid metabolism, and inhibited the expression of inflammatory cytokines. Our findings regarding lipid synthesis may further promote the role of lncRNAs in driving adipose tissue remodeling and maintaining metabolic health.

Genetic polymorphism of Pro12Ala in type 2 diabetes mellitus: Role in inflammation linked to Insulin resistance.

Peroxisome Proliferator-Activated Receptor gamma 2 (PPARγ2) belongs to nuclear receptor superfamily and plays a role in adipocyte differentiation and inflammation. Evidences suggest that inflammatory processes hold key to insulin resistance and PPARγ2 has also been implicated. PPARγ2 exhibits gene polymorphism. The Ala allele of Pro12Ala polymorphism (rs1801282) is associated with a reduced risk for insulin resistance. We attempted the study in overweight and obese males to generate evidences linking insulin resistance, inflammatory mediators, and gene polymorphism of PPARγ2 in overweight and obese males. The conventional biochemical parameters were estimated using established methods. Adiponectin and Haptoglobin were quantitated by ELISA, whereas Ferritin and hs-CRP were by chemi-luminescence. Indices of insulin sensitivity /Insulin resistance were computed based on established formulae. Gene analysis was based on PCR and RFLP. Appropriate statistical analysis was enabled to project gene polymorphism.The heterozygous variant (CG) was around 8 and 38 percent respectively in overweight and obese males. The G Allele was 3.89% and 18.82%. The wild type and heterozygous variant of PPARγ2 depicted significance with haptoglobin, whereas adiponectin showed significance in the wild type. Chi-square test was performed to assess the relation between polymorphic genotypes and ferritin emerged significant. Indices of insulin resistance showed different characteristics with wild type and heterozygous variant ofPPARγ2 gene polymorphism. The inflammatory mediators (hs-CRP, Ferritin, Haptoglobin and adiponectin) exhibited variegated characteristics with the wild type and heterozygous variant of PPARγ2, thus pointing to the nexus among insulin resistance, inflammation, and adipocyte differentiation.

Glutamine Production by Glul Promotes Thermogenic Adipocyte Differentiation Through Prdm9-Mediated H3K4me3 and Transcriptional Reprogramming.

Thermogenic adipocytes have been extensively investigated due to their energy dissipating property and therapeutic potential for obesity and diabetes. Besides serving as fuel sources, accumulating evidence suggests that intermediate metabolites play critical roles in multiple biological processes. However, their role in adipocyte differentiation and thermogenesis remains unexplored. Here, we report that human and mouse obesity is associated with marked downregulation of glutamine synthetase (Glul) expression and activity in thermogenic adipose tissues. Glul is robustly upregulated during brown adipocyte (BAC) differentiation and in brown adipose tissue (BAT) upon cold exposure and Cl316,243 stimulation. Further genetic, pharmacologic, or metabolic manipulations of Glul and glutamine levels reveal that glutamine cell-autonomously stimulates BAC differentiation and function, BAT tissue remodeling, and improves systemic energy homeostasis in mice. Mechanistically, glutamine promotes transcriptional induction of adipogenic and thermogenic gene programs through histone modification-mediated chromatin remodeling. Among all the glutamine-regulated writer and eraser genes responsible for histone methylation and acetylation, only Prdm9, a histone lysine methyltransferase, is robustly induced during BAC differentiation. Importantly, Prdm9 inactivation by shRNA knockdown or a selective inhibitor attenuates glutamine-triggered adipogenic and thermogenic induction. Further, Prdm9 gene transcription is regulated by glutamine through the recruitment of C/EBPb to its enhancer region. This work reveals glutamine as a novel activator of thermogenic adipocyte differentiation and uncovers an unexpected role of C/EBPb-Prdm9-mediated H3K4me3 and transcriptional reprogramming in adipocyte differentiation and thermogenesis.

The Receptor Tyrosine Kinase c-Met Promotes Lipid Accumulation in 3T3-L1 Adipocytes.

The receptor tyrosine kinase c-Met is elaborated in embryogenesis, morphogenesis, metabolism, cell growth, and differentiation. JNJ38877605 (JNJ) is an inhibitor of c-Met with anti-tumor activity. The c-Met expression and its role in adipocyte differentiation are unknown. Here, we investigated the c-Met expression and phosphorylation, knockdown (KD) effects, and pharmacological inhibition of c-Met by JNJ on fat accumulation in murine preadipocyte 3T3-L1 cells. During 3T3-L1 preadipocyte differentiation, strikingly, c-Met expression at the protein and mRNA levels and the protein phosphorylation on Y1234/1235 and Y1349 is crucial for inducing its kinase catalytic activity and activating a docking site for signal transducers were increased in a time-dependent manner. Of note, JNJ treatment at 20 μM that strongly inhibits c-Met phosphorylation without altering its total expression resulted in less lipid accumulation and triglyceride (TG) content with no cytotoxicity. JNJ further reduced the expression of adipogenic regulators, including CCAAT/enhancer-binding protein-α (C/EBP-α), peroxisome proliferator-activated receptor-γ (PPAR-γ), fatty acid synthase (FAS), acetyl CoA carboxylase (ACC), and perilipin A. Moreover, JNJ treatment increased cAMP-activated protein kinase (AMPK) and liver kinase B-1 (LKB-1) phosphorylation but decreased ATP levels. Significantly, KD of c-Met suppressed fat accumulation and triglyceride (TG) quantity and reduced the expression of C/EBP-α, PPAR-γ, FAS, ACC, and perilipin A. Collectively, the present results demonstrate that c-Met is a novel, highly conserved mediator of adipogenesis regulating lipid accumulation in murine adipocytes.

Metastasis suppressor 1 interacts with protein tyrosine phosphatase receptor-δ to regulate adipogenesis.

Adipogenesis is a finely controlled process and its dysfunction may contribute to metabolic disorders such as obesity. Metastasis suppressor 1 (MTSS1) is a player in tumorigenesis and metastasis of various types of cancers. To date, it is not known whether and how MTSS1 plays a role in adipocyte differentiation. In the current study, we found that MTSS1 was upregulated during adipogenic differentiation of established mesenchymal cell lines and primary cultured bone marrow stromal cells. Gain-of-function and loss-of-function experiments uncovered that MTSS1 facilitated adipocyte differentiation from mesenchymal progenitor cells. Mechanistic explorations revealed that MTSS1 bound and interacted with FYN, a member of Src family of tyrosine kinases (SFKs), and protein tyrosine phosphatase receptor-δ (PTPRD). We demonstrated that PTPRD was capable of inducing the differentiation of adipocytes. Overexpression of PTPRD attenuated the impaired adipogenesis induced by the siRNA targeting MTSS1. Both MTSS1 and PTPRD activated SFKs by suppressing the phosphorylation of SFKs at Tyr530 and inducing the phosphorylation of FYN at Tyr419. Further investigation showed that MTSS1 and PTPRD were able to activate FYN. Collectively, our study has for the first time unraveled that MTSS1 plays a role in adipocyte differentiation in vitro through interacting with PTPRD and thereby activating SFKs such as FYN tyrosine kinase.

NF-κB-inducing kinase maintains mitochondrial efficiency and systemic metabolic homeostasis

NF-κB-inducing kinase (NIK) is an essential upstream inducer of noncanonical NF-κB signaling and a critical regulator of immunity and inflammation. Our recent work has demonstrated that NIK regulates mitochondrial respiration and adaptive metabolic responses in cancer and innate immune cells. However, it is not clear whether NIK also has roles in regulating systemic metabolism. In this study, we demonstrate that NIK has local and systemic effects on developmental and metabolic processes. Our findings show that NIK-deficient mice exhibit reduced adiposity, as well as elevated energy expenditure both basally, and under the stress of a high-fat diet. Moreover, we identify NF-κB-independent and -dependent functions for NIK in white adipose tissue metabolism and development. Specifically, we found that in an NF-κB-independent manner NIK is required for maintaining mitochondrial fitness, as NIK-deficient adipocytes have impaired mitochondrial membrane potential and spare respiratory capacity. In addition to mitochondrial exhaustion, NIK-deficient adipocytes and ex vivo adipose tissue exhibit a compensatory upregulation of glycolysis to meet bioenergetic demands. Finally, while NIK regulation of mitochondrial metabolism in preadipocytes is NF-κB-independent, we demonstrate that NIK has a complementary role in adipocyte differentiation that requires activation of RelB and the noncanonical NF-κB pathway. Collectively, these data demonstrate that NIK has critical roles in local and systemic development and metabolism. Our findings establish NIK as an important regulator of organelle, cell, and systemic metabolic homeostasis, suggesting that metabolic dysfunction may be an important and unappreciated component of immune disorders and inflammatory diseases arising from NIK deficiency.

The Important Role of m6A-Modified circRNAs in the Differentiation of Intramuscular Adipocytes in Goats Based on MeRIP Sequencing Analysis.

Intramuscular fat contributes to the improvement of goat meat quality. N6-Methyladenosine (m6A)-modified circular RNAs play important roles in adipocyte differentiation and metabolism. However, the mechanisms by which m6A modifies circRNA before and after differentiation of goat intramuscular adipocytes remain poorly understood. Here, we performed methylated RNA immunoprecipitation sequencing (MeRIP-seq) and circRNA sequencing (circRNA-seq) to determine the distinctions in m6A-methylated circRNAs during goat adipocyte differentiation. The profile of m6A-circRNA showed a total of 427 m6A peaks within 403 circRNAs in the intramuscular preadipocytes group, and 428 peaks within 401 circRNAs in the mature adipocytes group. Compared with the intramuscular preadipocytes group, 75 peaks within 75 circRNAs were significantly different in the mature adipocytes group. Furthermore, the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of intramuscular preadipocytes and mature adipocytes showed that the differentially m6A-modified circRNAs were enriched in the PKG signaling pathway, endocrine and other factor-regulated calcium reabsorption, lysine degradation, etc. m6A-circRNA-miRNA-mRNA interaction networks predicted the potential m6A-circRNA regulation mechanism in different goat adipocytes. Our results indicate that there is a complicated regulatory relationship between the 12 upregulated and 7 downregulated m6A-circRNAs through 14 and 11 miRNA mediated pathways, respectively. In addition, co-analysis revealed a positive association between m6A abundance and levels of circRNA expression, such as expression levels of circRNA_0873 and circRNA_1161, which showed that m6A may play a vital role in modulating circRNA expression during goat adipocyte differentiation. These results would provide novel information for elucidating the biological functions and regulatory characteristics of m6A-circRNAs in intramuscular adipocyte differentiation and could be helpful for further molecular breeding to improve meat quality in goats.

Monoacylglycerol O-acyltransferase 1 lowers adipocyte differentiation capacity in vitro but does not affect adiposity in mice.

Monoacylglycerol O-acyltransferase 1 (Mogat1), a lipogenic enzyme that converts monoacylglycerol to diacylglycerol, is highly expressed in adipocytes and may regulate lipolysis by re-esterifying fatty acids released during times when lipolytic rates are low. However, the role of Mogat1 in regulating adipocyte fat storage during differentiation and diet-induced obesity is relatively understudied. Here, adipocyte-specific Mogat1 knockout mice were generated and subjected to a high-fat diet to determine the effects of Mogat1 deficiency on diet-induced obesity. Mogat1 floxed mice were also used to develop preadipocyte cell lines wherein Mogat1 could be conditionally knocked out to study adipocyte differentiation in vitro. In preadipocytes, it was found that Mogat1 knockout at the onset of preadipocyte differentiation prevented the accumulation of glycerolipids and reduced the differentiation capacity of preadipocytes. However, the loss of adipocyte Mogat1 did not affect weight gain or fat mass induced by a high-fat diet in mice. Furthermore, loss of Mogat1 in adipocytes did not affect plasma lipid or glucose concentrations or insulin tolerance. These data suggest Mogat1 may play a role in adipocyte differentiation in vitro but not adipose tissue expansion in response to nutrient overload in mice.

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.

Comparative transcriptome analysis of longissimus dorsi tissues with different intramuscular fat contents from Guangling donkeys

BackgroundDonkey meat has low fat and high protein contents and is rich in various unsaturated fatty acids and trace elements that are beneficial to human digestion and absorption. IMF (intramuscular fat), also known as marbling, is an important indicator of the lean meat to fat ratio, which directly affects the tenderness and juiciness of the meat. At present, the underlying molecular variations affecting IMF content among donkey breeds are unclear. The Guangling donkey is an indigenous species in China. This study explored candidate regulatory genes that affect IMF content in Guangling donkeys. The IMF content of the longissimus dorsi muscle in 30 Guangling donkeys was measured. Six donkeys of similar age were selected according to age factors and divided into two groups, the high (H) and low (L) fat groups, according to their IMF content.ResultsRNA-seq technology was used to compare the muscle transcriptome between the two groups. More than 75.0% of alternative splicing (AS) events were of the skipped exon (SE) type. A total of 887 novel genes were identified; only 386 novel genes were aligned to the annotation information of various databases. Transcriptomics analysis revealed 167 differentially expressed genes (DEGs), of which 64 were upregulated and 103 were downregulated between the H and L groups. Gene ontology analysis showed that the DEGs were enriched in multiple biological processes and pathways that are related to adipocyte differentiation, lipid synthesis, and neutral lipid metabolism. KEGG pathway analysis suggested that arachidonic acid metabolism, the HIF-1 signalling pathway, fructose and mannose metabolism, glycerophospholipid metabolism, and the AMPK signalling pathway were involved in lipid deposition. In addition, a gene–gene interaction network was constructed that revealed that the DEGs, including SCD, LEPR, CIDEA, DLK1, DGAT2, ITGAL, HMOX1, WNT10B, and DGKA, had significant roles in adipocyte differentiation and adipogenesis. The selected DEGs were further validated by qRT–PCR.ConclusionThis study improves the in-depth understanding of gene regulation and protein expression regarding IMF deposition and lays a basis for subsequent molecular breeding studies in Guangling donkeys.

Regulatory roles of fibronectin and integrin α5 in reorganization of the actin cytoskeleton and completion of adipogenesis.

Cellular differentiation is characterized by changes in cell morphology that are largely determined by actin dynamics. We previously showed that depolymerization of the actin cytoskeleton triggers the differentiation of preadipocytes into mature adipocytes as a result of inhibition of the transcriptional coactivator activity of megakaryoblastic leukemia 1 (MKL1). The extracellular matrix (ECM) influences cell morphology via interaction with integrins, and reorganization of the ECM is associated with cell differentiation. Here we show that interaction between actin dynamics and ECM rearrangement plays a key role in adipocyte differentiation. We found that depolymerization of the actin cytoskeleton precedes disruption and degradation of fibrillar fibronectin (FN) structures at the cell surface after the induction of adipogenesis in cultured preadipocytes. A FN matrix suppressed both reorganization of the actin cytoskeleton into the pattern characteristic of adipocytes and terminal adipocyte differentiation, and these inhibitory effects were overcome by knockdown of integrin α5 (ITGα5). Peroxisome proliferator-activated receptor γ was required for down-regulation of FN during adipocyte differentiation, and MKL1 was necessary for the expression of ITGα5. Our findings suggest that cell-autonomous down-regulation of FN-ITGα5 interaction contributes to reorganization of the actin cytoskeleton and completion of adipocyte differentiation.

Verification of Candidate SNP Effects Reveals Two QTLs on BTA7 for Beef Marbling in Two Japanese Black Cattle Populations

In our previous study, we used genome resequencing to detect all candidate polymorphisms within a quantitative trait loci (QTL) region for beef marbling reported previously at 10–30 Mbp on bovine chromosome 7, and we selected 6044 polymorphisms as candidate quantitative trait nucleotides (QTNs). In the present study, we aimed to identify quantitative trait genes (QTGs) and QTNs in this QTL region by verifying the effect of SNPs on beef marbling in two Japanese Black cattle populations using a Dynamic Array integrated fluidic circuit. In total, 96 selected SNPs were genotyped in 441 and 529 animals in Hyogo and Miyazaki cattle populations, respectively. The most significant p-values were detected in a SNP in a splice region of ALDH7A1 (SNP93_ALDH7A1; p = 3.46 × 10−5) in Hyogo cattle and a missense polymorphism of intercellular adhesion molecule-1 (ICAM1) (SNP37_ICAM1; p = 3.33 × 10−4) in Miyazaki cattle. Interestingly, SNP93_ALDH7A1 was not significant (p = 0.459) in Miyazaki cattle, and SNP37_ICAM1 showed a weakly significant association (p = 0.043) in Hyogo cattle. Thus, each population would likely have different QTGs and QTNs for beef marbling in the QTL region. In the Hyogo population, it was not possible to determine the accurate range of the linkage disequilibrium (LD) block in LD block analysis because of a strong LD structure throughout the assessed region. In Miyazaki cattle, however, an LD block containing SNP37_ICAM1 had a range of 15.8–16.1 Mbp, suggesting that QTNs would be located within this region. The functions of 19 genes in the LD block were investigated. ICAM1 is known to play an important role in adipocyte differentiation; given this function and the effect of amino acid substitution, SNP37_ICAM1 was identified as a promising candidate QTN for beef marbling. Further research on the effect of SNP37_ICAM1 on adipocyte differentiation is expected to provide insights into the mechanism underlying beef marbling formation.

Inhibition of STAT3 enhances UCP1 expression and mitochondrial function in brown adipocytes

Extensive studies have shown that the increasing brown adipose tissue (BAT) mass/activity possesses a strong ability to prevent obesity and its related complications. The Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signal pathway is known to play a role in adipocyte differentiation and development. However, its impact on thermogenic properties of mature brown adipocytes has not yet been clarified. Nifuroxazide (NFX), a potent inhibitor of STAT3, has received widespread attention due to its alternative anti-tumor and anti-inflammatory effects. Herein, we report that NFX induces lipolysis with subsequent downregulation of ACCα and FAS, while ATGL and pHSL levels are elevated in mature brown adipocytes. Furthermore, NFX treatment promotes the mitochondrial respiration of mature brown adipocytes, as evidenced by increased expression of thermogenic transcriptional factors and mitochondrial content. In addition, it also alleviates the IL-6 and TNFα inhibition on brown thermogenic programming via suppressing the STAT3/NF-κB/IL-6 signaling pathway. In general, these findings suggest that the blockade of the JAK/STAT3 pathway by NFX has a pro-thermogenic effect on mature brown adipocytes which opens new perspectives for NFX repurposing and potential therapeutic route to counteract obesity and related metabolic disorders.

Anti-adipogenic β-sitosterol and lupeol from Moringa oleifera suppress adipocyte differentiation through regulation of cell cycle progression.

Triterpenes and phytosterols enriched herbal formulations are known for glucose regulation and lipid metabolism. In this study, triterpenes and phytosterols from Moringa oleifera stem bark have been tested for their role in adipocyte differentiation. Chromatographic analysis revealed a wide range of phenolics, highlighting the presence of flavonoids (kaempferol, quercetin, and rutin), terpenoids (lupeol), and phytosterol (stigmasterol, β-sitosterol). Lupeol and β-sitosterol reduced cell viability in a dose-dependent manner showcasing increased G1 phase cell accumulation while reducing other cell cycle phases (S and G2 /M) and significant lowering of intracellular lipid accumulation. Additionally, lupeol (35.37% at 32 μM) and β-sitosterol (42.97% at 16 μM) inhibited reactive oxygen species generation and increased glucose uptake in adipocytes. Collectively, our results indicate that lupeol and β-sitosterol efficaciously attenuated adipogenesis via a controlled cell cycle progression and enhanced glucose uptake in adipocytes. PRACTICAL APPLICATIONS: Active components of Moringa oleifera effectively regulate adipocyte differentation suggest that it can be good medicial supllement for control of obesity.

Understanding the adipose tissue acetylome in obesity and insulin resistance

Obesity is a widely prevalent pathology with a high exponential growth worldwide. Altered lipid accumulation by adipose tissue is one of the main causes of obesity and exploring lipid homeostasis in this tissue may represent a source for the identification of possible therapeutic targets. The study of the proteome and the post-translational modifications of proteins, specifically acetylation due to its involvement in energy metabolism, may be of great interest to understand the molecular mechanisms involved in adipose tissue dysfunction in obesity. The objective of this study was to characterize the subcutaneous and omental adipose tissue acetylome in conditions of obesity and insulin resistance and to describe the importance of acetylation of key molecules in adipose tissue to use them as therapeutic targets. The results describe for the first time the acetylome of subcutaneous and omental adipose tissue under physiological and physiopathological conditions such as obesity and insulin resistance. New evidence showed different acetylation patterns between two main depots and highlight the molecular complexity of adipose tissue. Results showed changes in FABP4 acetylation in subcutaneous fat in relation to insulin resistance, thus unveiling a potential marker of depot-specific dysfunctional expansion in obesity-associated metabolic disease. Furthermore, it is shown that the acetylation of FABP4 affects its function, modulating the capacity of differentiation in adipocytes. In conclusion, this study demonstrates a profound, depot-specific alteration of adipose tissue acetylome, wherein the acetylation of FABP4 may play a key role in adipocyte differentiation and lipid accumulation.

Long noncoding RNA XIST regulates brown preadipocytes differentiation and combats high-fat diet induced obesity by targeting C/EBP\u03b1

BackgroundActivation of brown adipose tissue (BAT) increases energy expenditure, which makes it an attractive therapeutic strategy for obesity. LncRNAs play an important role in adipocyte differentiation and regulation. Here we assessed the effect of lncRNA XIST on brown preadipocytes differentiation and metabolic regulation.MethodsXIST expression levels were detected in human perirenal (peri-N) and subcutaneous adipose tissues (sub-Q), brown preadipocytes and 3T3-L1 preadipocytes. XIST overexpression and knockdown experiments were performed in brown preadipocytes. XIST overexpression mouse model was established by plasmid injection through tail vein.ResultsIn human adipose tissues, XIST expression was significantly higher in female than in male individuals. In vitro, XIST expression was significantly up-regulated during brown adipocyte differentiation. XIST knockdown inhibited differentiation of brown preadipocytes, while overexpression of XIST promotes brown preadipocytes to fully differentiation. RNA Binding Protein Immunoprecipitation (RIP) experiment revealed that XIST could directly bind to C/EBPα. In vivo, XIST overexpression prevents high-fat diet induced obesity and improves metabolic dysorder in male mice.ConclusionOur results suggest that XIST combats obesity through BAT activation at least partly by combination with transcription factor C/EBPα.

High expression of P4HA3 in obesity: a potential therapeutic target for type 2 diabetes.

The aims of the present study were to evaluate the expression of prolyl 4-hydroxylase subunit alpha 3 (P4HA3) in adipocytes and adipose tissue and to explore its effect on obesity and type 2 diabetes mellitus (T2DM). We initially demonstrated that P4HA3 was significantly upregulated in the subcutaneous adipose tissue of obesity and T2DM patients, and its functional roles in adipocyte differentiation and insulin resistance were investigated using in vitro and in vivo models. The knockdown of P4HA3 inhibited adipocyte differentiation and improved insulin resistance in 3T3-L1 cells. In C57BL/6J db/db mice fed with a high fat diet (HFD), silencing P4HA3 significantly decreased fasting blood glucose and triglycerides (TG) levels, with concomitant decrease of body weight and adipose tissue weight. Further analysis showed that P4HA3 knockdown was correlated with the augmented IRS-1/PI3K/Akt/FoxO1 signaling pathway in the adipose and hepatic tissues of obese mice, which could improve hepatic glucose homeostasis and steatosis of mice. Together, our study suggested that the dysregulation of P4HA3 may contribute to the development of obesity and T2DM.

3T3-L1 세포에서 김치유산균 Weissella koreensis DB1 추출물의 지방분화 억제효과

Weissella koreensis (W. koreensis) DB1 with high-ornithine-producing capacity was isolated from kimchi and shows the anti-adipogenic activity via its production of ornithine. This study was carried out the effects of W. koreensis DB1 cell extracts on the inhibition of adipogenesis in 3T3-L1 cells. MTT results showed that 0-0.75 μg/mL W. koreensis DB1 cell extracts had no significant effect on cell vability. The cell extracts of W. koreensis DB1 at non-cytotoxic concentrations significantly suppressed the differentiated 3T3-L1 cells by decreasing triglyceride level and intracellular lipid accumulation compared to that associated with the untreated control group. The major transcriptional factors involved in adipocyte differentiation, such as peroxisome proliferator-activated receptorγ (PPARγ), CCAAT/enhancer-binding proteinα (C/EBPα), and sterol regulatory element-binding transcription factor-1c (SREBP-1c), were down-regulated by the cell extracts of W. koreensis DB1 treatments compared with the untreated control group. Furthermore, the expressions of lipogenesis-related enzymes including acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) genes were also decreased by the cell extracts of W. koreensis DB1 treatment. Accordingly, these results indicate that the cell extracts of W. koreensis DB1 treatment inhibited the adipogenesis and lipogenesis of 3T3-L1 cells, suggesting a protective role in adipocyte differentiation.