Early Stage Of Adipogenesis Research Articles

MiR-26a Inhibits Porcine Adipogenesis by Regulating ACADM and ACSL1 Genes and Cell Cycle Progression

MicroRNAs play essential roles in biological processes by regulating gene expression at the post-transcriptional level. Our previous studies suggested the role of miR-26a in porcine fat accumulation. Here, through gain- and loss-of-function analyses, we first showed that miR-26a increased the proliferation of porcine preadipocytes by promoting cell division and that miR-26a inhibited the preadipocyte differentiation. Next, acyl-CoA dehydrogenase, medium chain (ACADM) was revealed to promote the proliferation and differentiation of preadipocytes for the first time. Then, it was revealed that miR-26a regulates adipogenesis by directly binding to the 3′ untranslated region of ACADM and the long-chain acyl-Co A synthetase 1 (ACSL1) gene, a previously known regulator of adipogenesis. Finally, RNA-sequencing, performed on preadipocytes overexpressing miR-26a, identified 337 differentially expressed genes in the early stage of adipogenesis; among them, nine genes were characterized as potential targets of miR-26a. The 337 genes were mainly involved in Gene Ontology terms related to cell division, indicating that cell cycle progression was also a major event regulated by miR-26a during adipogenesis. We provide novel data for understanding the molecular mechanisms underlying adipogenesis, which will contribute to controlling fat accumulation in animals.

Increased obesogenic action of palmitic acid during early stage of adipogenesis

The functional differences between preadipocytes and fully differentiated mature adipocytes derived from stromal vascular fraction stem cells, as well as primary adipocytes have been analysed by evaluating their response to the obesogenic factor (a saturated fatty acid) and TNF-triggered inflammation. The analysis of single adipocytes shows that the saturated fatty acid (palmitic acid) accumulation is accompanied by inflammation and considerably dependent on the stage of the adipogenesis. In particular, preadipocytes show the exceptional potential for palmitic acid uptake resulting in their hypertrophy and the elevated cellular expression of the inflammation marker (ICAM-1). Our research provides new information on the impact of obesogenic factors on preadipocytes that is important in the light of childhood obesity prevention.

Effect of metabolically divergent pig breeds and tissues on mesenchymal stem cell expression patterns during adipogenesis

BackgroundUnraveling the intricate and tightly regulated process of adipogenesis, involving coordinated activation of transcription factors and signaling pathways, is essential for addressing obesity and related metabolic disorders. The molecular pathways recruited by mesenchymal stem cells (MSCs) during adipogenesis are also dependent on the different sources of the cells and genetic backgrounds of donors, which contribute to the functional heterogeneity of the stem cells and consequently affect the developmental features and fate of the cells.MethodsIn this study, the alteration of transcripts during differentiation of synovial mesenchymal stem cells (SMSCs) derived from fibrous synovium (FS) and adipose synovial tissue (FP) of two pig breeds differing in growth performance (German Landrace (DL)) and fat deposition (Angeln Saddleback (AS)) was investigated. SMSCs from both tissues and breeds were stimulated to differentiate into adipocytes in vitro and sampled at four time points (day 1, day 4, day 7 and day 14) to obtain transcriptomic data.ResultsWe observed numerous signaling pathways related to the cell cycle, cell division, cell migration, or cell proliferation during early stages of adipogenesis. As the differentiation process progresses, cells begin to accumulate intracellular lipid droplets and changes in gene expression patterns in particular of adipocyte-specific markers occur. PI3K-Akt signaling and metabolic pathways changed most during adipogenesis, while p53 signaling and ferroptosis were affected late in adipogenesis. When comparing MSCs from FS and FP, only a limited number of differentially expressed genes (DEGs) and enriched signaling pathways were identified. Metabolic pathways, including fat, energy or amino acid metabolism, were highly enriched in the AS breed SMSCs compared to those of the DL breed, especially at day 7 of adipogenesis, suggesting retention of the characteristic metabolic features of their original source, demonstrating donor memory in culture. In contrast, the DL SMSCs were more enriched in immune signaling pathways.ConclusionsOur study has provided important insights into the dynamics of adipogenesis and revealed metabolic shifts in SMSCs associated with different cell sources and genetic backgrounds of donors. This emphasises the critical role of metabolic and genetic factors as important indications and criteria for donor stem cell selection.

Anti-Obesity Effect of Lactobacillus acidophilus DS0079 (YBS1) by Inhibition of Adipocyte Differentiation through Regulation of p38 MAPK/PPARγ Signaling.

Obesity is spawned by an inequality between the portion of energy consumed and the quantity of energy expended. Disease entities such as cardiovascular disease, arteriosclerosis, hypertension, and cancer, which are correlated with obesity, influence society and the economy. Suppression of adipogenesis, the process of white adipocyte generation, remains a promising approach for treating obesity. Oil Red O staining was used to differentiate 3T3-L1 cells for screening 20 distinct Lactobacillus species. Among these, Lactobacillus acidophilus DS0079, referred to as YBS1, was selected for further study. YBS1 therapy decreased 3T3-L1 cell development. Triglyceride accumulation and mRNA expression of the primary adipogenic marker, peroxisome proliferator-activated receptor gamma (PPARγ), including its downstream target genes, adipocyte fatty acid binding protein 4 and adiponectin, were almost eliminated. YBS1 inhibited adipocyte differentiation at the early stage (days 0-2), but no significant difference was noted between the mid-stage (days 2-4) and late-stage (days 4-6) development. YBS1 stimulated the activation of p38 mitogen-activated protein kinase (p38 MAPK) during the early stages of adipogenesis; however, this effect was eliminated by the SB203580 inhibitor. The data showed that YBS1 administration inhibited the initial development of adipocytes via stimulation of the p38 MAPK signaling pathway, which in turn controlled PPARγ expression. In summary, YBS1 has potential efficacy as an anti-obesity supplement and requires further exploration.

WRN loss accelerates abnormal adipocyte metabolism in Werner syndrome

BackgroundMetabolic dysfunction is one of the main symptoms of Werner syndrome (WS); however, the underlying mechanisms remain unclear. Here, we report that loss of WRN accelerates adipogenesis at an early stage both in vitro (stem cells) and in vivo (zebrafish). Moreover, WRN depletion causes a transient upregulation of late-stage of adipocyte-specific genes at an early stage.MethodsIn an in vivo study, we generated wrn−/− mutant zebrafish and performed histological stain and Oil Red O staining to assess the fat metabolism. In an in vitro study, we used RNA-seq and ATAC-seq to profile the transcriptional features and chromatin accessibility in WRN depleted adipocytes. Moreover, we performed ChIP-seq to further study the regulatory mechanisms of metabolic dysfunction in WS.ResultsOur findings show that mechanistically WRN deficiency causes SMARCA5 upregulation. SMARCA5 is crucial in chromatin remodeling and gene regulation. Additionally, rescuing WRN could normalize SMARCA5 expression and adipocyte differentiation. Moreover, we find that nicotinamide riboside (NR) supplementation restores adipocyte metabolism in both stem cells and zebrafish models.ConclusionsOur findings unravel a new mechanism for the influence of WRN in the early stage of adipogenesis and provide a possible treatment for metabolic dysfunction in WS. These data provide promising insights into potential therapeutics for ageing and ageing-related diseases.

Cinnamyl Alcohol Attenuates Adipogenesis in 3T3-L1 Cells by Arresting the Cell Cycle.

Cinnamyl alcohol (CA) is an aromatic compound found in several plant-based resources and has been shown to exert anti-inflammatory and anti-microbial activities. However, the anti-adipogenic mechanism of CA has not been sufficiently studied. The present study aimed to investigate the effect and mechanism of CA on the regulation of adipogenesis. As evidenced by Oil Red O staining, Western blotting, and real-time PCR (RT-PCR) analyses, CA treatment (6.25-25 μM) for 8 d significantly inhibited lipid accumulation in a concentration-dependent manner and downregulated adipogenesis-related markers (peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein α (C/EBPα), fatty acid binding protein 4 (FABP4), adiponectin, fatty acid synthase (FAS)) in 3-isobutyl-1-methylxanthine, dexamethasone, and insulin(MDI)-treated 3T3-L1 adipocytes. In particular, among the various differentiation stages, the early stage of adipogenesis was critical for the inhibitory effect of CA. Cell cycle analysis using flow cytometry and Western blotting showed that CA effectively inhibited MDI-induced initiation of mitotic clonal expansion (MCE) by arresting the cell cycle in the G0/G1 phase and downregulating the expression of C/EBPβ, C/EBPδ, and cell cycle markers (cyclin D1, cyclin-dependent kinase 6 (CDK6), cyclin E1, CDK2, and cyclin B1). Moreover, AMP-activated protein kinase α (AMPKα), acetyl-CoA carboxylase (ACC), and extracellular signal-regulated kinase 1/2 (ERK1/2), markers of upstream signaling pathways, were phosphorylated during MCE by CA. In conclusion, CA can act as an anti-adipogenic agent by inhibiting the AMPKα and ERK1/2 signaling pathways and the cell cycle and may also act as a potential therapeutic agent for obesity.

Hydroxylated polymethoxyflavones reduce the activity of pancreatic lipase, inhibit adipogenesis and enhance lipolysis in 3T3-L1 mouse embryonic fibroblast cells

Hydroxylated polymethoxyflavones (HPMFs) have been shown to possess various anti-disease effects, including against obesity. This study investigates the anti-obesity effects of HPMFs in further detail, aiming to gain understanding of their mechanism of action in this context. The current study demonstrates that two HPMFs; 3′-hydroxy-5,7,4′,5′-tetramethoxyflavone (3′OH-TetMF) and 4′-hydroxy-5,7,3′,5′-tetramethoxyflavone (4′OH-TetMF) possess anti-obesity effects. They both significantly reduced pancreatic lipase activity in a competitive manner as demonstrated by molecular docking and kinetic studies. In cell studies, it was revealed that both of the HPMFs suppress differentiation of 3T3-L1 mouse embryonic fibroblast cells during the early stages of adipogenesis. They also reduced expression of key adipogenic and lipogenic marker genes, namely peroxisome proliferator-activated receptor-gamma (PPARγ), CCAAT/enhancer-binding protein α and β (C/EBP α and β), adipocyte binding protein 2 (aP2), fatty acid synthase (FASN), and sterol regulatory element-binding protein 1 (SREBF 1). They also enhanced the expression of cell cycle genes, i.e., cyclin D1 (CCND1) and C-Myc, and reduced cyclin A2 expression. When further investigated, it was also observed that these HPMFs accelerate lipid breakdown (lipolysis) and enhance lipolytic genes expression. Moreover, they also reduced the secretion of proteins (adipokines), including pro-inflammatory cytokines, from mature adipocytes. Taken together, this study concludes that these HPMFs have anti-obesity effects, which are worthy of further investigation.

Early adipogenesis is repressed through the newly identified FHL2-NFAT5 signaling complex

The LIM-domain-only protein FHL2 is a modulator of signal transduction and has been shown to direct the differentiation of mesenchymal stem cells towards osteoblast and myocyte phenotypes. We hypothesized that FHL2 may simultaneously interfere with the induction of the adipocyte lineage. Therefore, we investigated the role of FHL2 in adipocyte differentiation. For these studies pre-adipocytes isolated from mouse adipose tissue and the 3T3-L1 (pre)adipocyte cell line were applied. We performed FHL2 gain of function and knockdown experiments followed by extensive RNAseq analyses and phenotypic characterization of the cells by oil-red O (ORO) lipid staining. Through affinity-purification mass spectrometry (AP-MS) novel FHL2 interacting proteins were identified. Here we report that FHL2 is expressed in pre-adipocytes and for accurate adipocyte differentiation, this protein needs to be downregulated during the early stages of adipogenesis. More specifically, constitutive overexpression of FHL2 drastically inhibits adipocyte differentiation in 3T3-L1 cells, which was demonstrated by suppressed activation of the adipogenic gene expression program as shown by RNAseq analyses, and diminished lipid accumulation. Analysis of the protein-protein interactions mediating this repressive activity of FHL2 on adipogenesis revealed the interaction of FHL2 with the Nuclear factor of activated T-cells 5 (NFAT5). NFAT5 is an established inhibitor of adipocyte differentiation and its knockdown rescued the inhibitory effect of FHL2 overexpression on 3T3-L1 differentiation, indicating that these proteins act cooperatively. We present a new regulatory function of FHL2 in early adipocyte differentiation and revealed that FHL2-mediated inhibition of pre-adipocyte differentiation is dependent on its interaction with NFAT5. FHL2 expression increases with aging, which may affect mesenchymal stem cell differentiation, more specifically inhibit adipocyte differentiation.

FAM129B is a cooperative protein that regulates adipogenesis

FAM129B is one of Niban-like proteins described in neoplastic cells and implicated in melanoma cell invasion, but no reports have been published on FAM129B and cell differentiation. We show that FAM129B is early and transiently expressed and crucial for 3T3-F442A adipogenesis. Fam129b is expressed downstream of the early genes Cebpb, Klf4, Klf5 and Srebf1a, but upstream of Pparg2 since knockdown of Fam129b blocked Pparg2 expression and adipose differentiation. Glycogen synthase kinase 3 beta activity, a crucial kinase for adipogenesis, and the ERK1/2 are involved in FAM129B phosphorylation as part of the adipogenic program. Phosphorylated FAM129B is crucial for Pparg2 expression and the lipogenic gene expression downstream of Pparg2, and hence for adipogenesis. Fam129b knockdown reduced adipocyte cluster formation and size, regulating commitment and clonal amplification. In vivo, BAT, inguinal and epidydimal fat expressed Fam129b, suggesting a role in adipose tissue development. We conclude that FAM129B is a cooperative protein that regulates differentiation during the early stages of adipogenesis.

OR23-5 Exploring the Role of PARP7 in Adipogenesis

Abstract Adipogenesis is a complex and tightly regulated process that plays a vital role in multiple aspects of human health. The molecular mechanisms regulating adipogenesis are incompletely understood, although key facets of the signaling and regulatory pathways have been defined. ADP-ribosylation – the process whereby ADP-ribose moieties are covalently transferred from NAD+ to substrate proteins – has been shown to control multiple components of the adipogenic regulatory machinery, including the transcription factor C/EBPb. In order to explore the role of mono(ADP-ribosyl)transferases (MARTs) during adipogenesis, we used an siRNA-mediated knockdown screen in mouse 3T3-L1 preadipocytes to determine which MARTs are required for the differentiation of the preadipocytes into mature adipocytes. This screen identified PARP7 the primary candidate. Using a variety of cell-based and biochemical assays, we have identified key aspects of PARP7's involvement throughout adipogenesis. We observed dynamic localization of PARP7 during adipogenesis, moving from the nucleus in early adipogenesis to the cytosol during mid to late adipogenesis. The requirement for PARP7, as determined by knockdown, was most evident in early stages of adipogenesis. Knockdown of PARP7 was rescued by a PPAR g agonist, suggesting that PARP7 acts before the onset of the later stages of adipogenesis leading to mature adipocytes. Together, these findings led us to hypothesize that PARP7 plays a critical role in the nucleus during early adipogenesis. Preliminary data have revealed that PARP7 binds to C/EBPb, a key "first wave" transcription factor that drives adipogenesis, during a time when C/EBPb is poly(ADP-ribosyl)ated by PARP1 in the nucleus. Ongoing investigations are exploring: (1) the mechanisms by which PARP7 binds to C/EBPb; (2) the impact of PARP7 binding on C/EBPb stability; and (3) the biological outcomes of PARP7-C/EBPb interactions. Collectively, these studies provide an avenue to better understand the role of PARP7 in the regulation of adipogenesis. This work is supported by a grant from the NIH/NIDDK (R01 DK069710) and funds from the Cecil H. and Ida Green Center for Reproductive Biology Sciences Endowment to W.L.K., and a predoctoral fellowship from the American Heart Association to M.S.S. Presentation: Monday, June 13, 2022 12:15 p.m. - 12:30 p.m.

RNA-Seq and lipidomics reveal different adipogenic processes between bovine perirenal and intramuscular adipocytes

ABSTRACT Adipogenesis involves complex interactions between transcription and metabolic signalling. Exploration of the developmental characteristics of intramuscular adipocyte will provide targets for enhancing beef cattle marbling without increasing obesity. Few reports have compared bovine perirenal and intramuscular adipocyte transcriptomes using the combined analysis of transcriptomes and lipid metabolism to explore differences in adipogenic characteristics. We identified perirenal preadipocytes (PRA) and intramuscular preadipocytes (IMA) in Qinchuan cattle. We found that IMA were highly prolific in the early stages of adipogenesis, while PRA shows a stronger adipogenic ability in the terminal differentiation. Bovine perirenal and intramuscular adipocytes were detected through the combined analysis of the transcriptome and metabolome. More triglyceride was found to be upregulated in perirenal adipocytes; however, more types and amounts of unsaturated fatty acids were detected in intramuscular adipocytes, including eicosapentaenoic acid (20:5 n-3; EPA) and docosahexaenoic acid (22:6 n-3; DHA). Furthermore, differentially expressed genes in perirenal and intramuscular adipocytes were positively correlated with the eicosanoid, phosphatidylcholine (PC), phosphatidyl ethanolamine (PE), and sphingomyelin contents. Associated differential metabolic pathways included the glycerolipid and glycerophospholipid metabolisms. Our research findings provide a basis for the screening of key metabolic pathways or genes and metabolites involved in intramuscular fat production in cattle.

1396-P: Critical Cellular Functions That Mediate the Early Stages of Adipogenesis Are Directly Influenced by 14-3-3zeta and Its Interactome

Aim: We previously discovered that 14-3-3-zeta (14-3-3ζ) was essential for adipocyte differentiation. Although 14-3-3ζ scaffold is not a transcription factor (TF) , it undergoes nuclear translocation during adipogenesis. Considering its diverse interactome, we hypothesized that 14-3-3ζ anchors, nucleates and regulates essential transcriptional complexes required for adipogenesis. Methods: 3T3-L1 pre-adipocytes were modified by CRISPR-Cas9 to express a TAP (Flag-HA) -tagged 14-3-3ζ protein. At 48 first hours of adipogenesis, nuclear TAP-14-3-3-ζ complexes were purified to identify and annotate the 14-3-3ζ interactome by MS and Gene Ontology. Highly enriched proteins functions were assessed for their roles in adipogenesis using pharmacological inhibitors or siRNA. In parallel, chromatin accessibility was assessed by ATAC-Seq from control or 14-3-3ζ-depleted 3T3-L1 cells during early adipogenesis. Results: We found that the 14-3-3ζ nuclear interactome during the early stages of adipogenesis was significantly enriched with 133 proteins, including CEBP-β, an early adipogenic TF. According to GO analysis, proteins within the 14-3-3ζ interactome were primarily associated (FDR ≤ 0.01) with histone H2B ubiquitination, DNA unwinding for replication, DNA hypermethylation and ribosome assembly. Pharmacological inhibition or depletion by siRNA of these proteins significantly dampened adipocyte differentiation. Principal component analysis of ATAC-seq results revealed that samples from 14-3-3ζ-depleted cells differed from controls in term of whole chromatin accessibility, and DESeq2 identified nearly 3400 (p<0.05) differentially accessible regions of open chromatin following 14-3-3ζ depletion. Conclusion: These results reveal that via critical protein interactions, 14-3-3ζ has essential roles in chromatin accessibility, DNA replication, and mRNA translation, which are crucial events for the early adipogenesis. Disclosure S.A.Rial: None. A.Alkhoury: None. G.Lavoie: None. P.Roux: None. T.M.Durcan: None. A.Martinez-sanchez: None. G.E.Lim: None. Funding Natural Sciences and Engineering Research Council of Canada (NSERC) ; Canada Research Chairs (CRC) ; Fonds de recherche du Québec-Nature and Technologies (FRQNT)

A chromatin accessibility landscape during early adipogenesis of human adipose-derived stem cells

ABSTRACT Obesity has become a serious global public health problem; a deeper understanding of systemic change of chromatin accessibility during human adipogenesis contributes to conquering obesity and its related diseases. Here, we applied the ATAC-seq method to depict a high-quality genome‐wide time-resolved accessible chromatin atlas during adipogenesis of human adipose-derived stem cells (hASCs). Our data indicated that the chromatin accessibility drastic dynamically reformed during the adipogenesis of hASCs and 8 h may be the critical transition node of adipogenesis chromatin states from commitment phase to determination phase. Moreover, upon adipogenesis, we also found that the chromatin accessibility of regions related to anti-apoptotic, angiogenic and immunoregulatory gradually increased, which is beneficial to maintaining the health of adipose tissue (AT). Finally, the chromatin accessibility changed significantly in intronic regions of peroxisome proliferator‐activated receptor γ during adipogenesis, and these regions were rich in transcription factors binding motifs that were exposed for further regulation. Overall, we systematically analysed the complex change of chromatin accessibility occurring in the early stage of adipogenesis and deepened our understanding of human adipogenesis. Furthermore, we also provided a good reference data resource of genome‐wide chromatin accessibility for future studies on human adipogenesis.

Suppression of Adipogenesis and Fat Accumulation by Vitexin Through Activation of Hedgehog Signaling in 3T3-L1 Adipocytes.

Many studies have demonstrated that adipogenesis is associated with obesity, and the Hedgehog (Hh) signaling pathway regulates adipogenesis and obesity. Following the screening study of the chemical library evaluating the effect of vitexin on Gli1 transcriptional activity, vitexin was chosen as a candidate for antiadipogenic efficacy. Vitexin significantly reduced lipid accumulation and suppressed C/EBPα (CCAAT/enhancer-binding protein α) and PPARγ (peroxisome proliferator-activated receptor γ) expression, which are known as key adipogenic factors in the early stages of adipogenesis by activating Hh signaling. Furthermore, Hh inhibitor GANT61 reversed the effect of AMP-activated protein kinase (AMPK) activator AICAR (5-aminoimidazole-4-carboxamide ribonucleotide), indicating that Hh signaling is an upstream regulator of AMPK in 3T3-L1 cells. Vitexin suppressed adipogenesis by regulating Hh signaling and phosphorylation of AMPK, leading to the inhibition of fat formation. These results suggest that vitexin can be considered a potent dietary agent in alleviating lipid accumulation and obesity.

Zebrafish obesogenic test identifies anti-adipogenic fraction in Moringa oreifera leaf extracts.

The zebrafish obesogenic test (ZOT) is a powerful tool for identifying anti‐adipogenic compounds for in vivo screening. In our previous study, we found that Moringa oleifera (MO) leaf powder suppressed the accumulation of visceral adipose tissue (VAT) in ZOT. MO demonstrates a wide range of pharmacological effects; however, little is known about its functional constituents. To identify the anti‐adipogenic components of MO leaves, we prepared extracts using different extraction methods and tested the obtained extracts and fractions using ZOT. We found that the dichloromethane extract and its hexane:EtOAc = 8:2 fraction reduced VAT accumulation in young zebrafish fed a high‐fat diet. We also performed gene expression analysis in the zebrafish VAT and found that CCAAT/enhancer‐binding protein beta and CCAAT/enhancer‐binding protein delta (associated with early stages of adipogenesis) gene expression was downregulated after fraction 2 administration. We identified a new MO fraction that suppressed VAT accumulation by inhibiting early adipogenesis using the ZOT. Phenotype‐driven zebrafish screening is a reasonable strategy for identifying bioactive components in natural products.

MRNA m5C controls adipogenesis by promoting CDKN1A mRNA export and translation

ABSTRACT 5-Methylcytosine (m5C) is a type of RNA modification that exists in tRNAs and rRNAs and was recently found in mRNA. Although mRNA m5C modification has been reported to regulate diverse biological process, its function in adipogenesis remains unknown. Here, we demonstrated that knockdown of NOL1/NOP2/Sun domain family member 2 (NSUN2), a m5C methyltransferase, increased lipid accumulation of 3T3-L1 preadipocytes through accelerating cell cycle progression during mitotic clonal expansion (MCE) at the early stage of adipogenesis. Mechanistically, we proved that NSUN2 directly targeted cyclin-dependent kinase inhibitor 1A (CDKN1A) mRNA, a key inhibitory regulator of cell cycle progression, and upregulated its protein expression in an m5C-dependent manner. Further study identified that CDKN1A was the target of Aly/REF export factor (ALYREF), a reader of m5C modified mRNA. Upon NSUN2 deficiency, the recognition of CDKN1A mRNA by ALYREF was suppressed, resulting in the decrease of CDKN1A mRNA shuttling from nucleus to cytoplasm. Thereby, the translation of CDKN1A was reduced, leading to the acceleration of cell cycle and the promotion of adipogenesis. Together, these findings unveiled an important function and mechanism of the m5C modification on adipogenesis by controlling cell cycle progression, providing a potential therapeutic target to prevent obesity.

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

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

Ginsenoside F2 Suppresses Adipogenesis in 3T3-L1 Cells and Obesity in Mice via the AMPK Pathway.

Ginsenoside F2 (GF2) is a protopanaxdiol saponin from Panax ginseng leaves and possesses many potential pharmacological properties. GF2 may prevent obesity by directly binding to the peroxisome proliferator-activated receptor-γ (PPARγ) and inhibiting adipocyte differentiation. However, the mechanism by which GF2 alleviates obesity is unknown. We therefore explored the anti-adipogenesis and anti-obesity effects of GF2 in vitro and in vivo. GF2 inhibited differentiation and reduced the triglyceride (TG) content of 3T3-L1 preadipocytes in the early stage of adipogenesis. Administration of GF2 (50 and 100 mg/kg) to obese mice for 4 weeks reduced the body weight gain, weight of adipose tissues, adipocyte size, and total cholesterol, TG, and AST levels in serum. RNA sequencing and real-time quantitative PCR indicated that GF2 decreased the expression levels of adipokines, including PPARγ, fatty acid synthase, and adiponectin. KEGG enrichment and western blot analyses demonstrated that GF2 accelerated the phosphorylation of AMPK and ACC in vitro and in vivo. Moreover, GF2 promoted the biosynthesis of mitochondria in 3T3-L1 adipocytes and increased the expression of antioxidant enzymes such as SOD and GSH-Px in the liver of obese mice. Therefore, GF2 suppressed adipogenesis and obesity by regulating the expression of adipokines and activating the AMPK pathway. Hence, the findings suggest that GF2 may have potential therapeutic implications to treat obesity.

The dose-dependent pteryxin-mediated molecular mechanisms in suppressing adipogenesis in vitro

Abstract The aim was to perform an in-depth characterization of pteryxin in the anti-obesity related molecular mechanisms using 3T3-L1 preadipocytes. Cells were treated with pteryxin 20 (PTX20) or 50 (PTX50) μg/mL during cell differentiation or maintenance period. Pteryxin dose-dependently suppressed adipogenic gene network. PTX20 downregulated key lipogenic genes suppressing fatty acid synthesis allotting the anti-adipogenesis in the late adipocyte formation stage. PTX50 downregulated adipogenesis related genes, and accelerated lipolytic activity by repressing the adipocyte size marker gene, MEST. In addition to Wnt5a, PTX50 suppressed adipocyte differentiation through TGF-β/Smad3 signaling pathway with the maximum adiposity inhibition in the early stage of adipogenesis and regulated the carbohydrate metabolism. Pteryxin regulated phosphorylation of ERK1/2 and AMPK, and decreased p38 MAPK to repress the mature adipocyte formation. Overall, we have demonstrated the anti-adipogenic characteristics of pteryxin consistent to its dose. PTX50 may serve as a potential candidate to ameliorate adiposity and improve the carbohydrate metabolism.

Rifampicin impairs adipogenesis by suppressing NRF2-ARE activity in mice fed a high-fat diet

Prolonged treatment with rifampicin (RFP), a first-line antibacterial agent used in the treatment of drug-sensitive tuberculosis, may cause various side effects, including metabolic disorders. The nuclear factor (erythroid-derived 2)-like 2 (NFE2L2, also known as NRF2) plays an essential regulatory role in cellular adaptive responses to stresses via the antioxidant response element (ARE). Our previous studies discovered that NRF2 regulates the expression of CCAAT-enhancer-binding protein β (Cebpb) and peroxisome proliferator-activated receptor gamma (Pparg) in the process of adipogenesis. Here, we found that prolonged RFP treatment in adult male mice fed a high-fat diet developed insulin resistance, but reduced fat accumulation and decreased expression of multiple adipogenic genes in white adipose tissues. In 3 T3-L1 preadipocytes, RFP reduced the induction of Cebpb, Pparg and Cebpa at mRNA and protein levels in the early and/or later stage of hormonal cocktail-induced adipogenesis. Mechanistic investigations demonstrated that RFP inhibits NRF2-ARE luciferase reporter activity and expression of NRF2 downstream genes under normal culture condition and in the early stage of adipogenesis in 3 T3-L1 preadipocytes, suggesting that RFP can disturb adipogenic differentiation via NRF2-ARE interference. Taken together, we demonstrate a potential mechanism that RFP impairs adipose function by which RFP likely inhibits NRF2-ARE pathway and thereby interrupts its downstream adipogenic transcription network.