Adipocyte最新文献

Background: Mature adipocytes are difficult to study ex vivo, prompting the use of human adipose progenitor cells (hAPCs). However, hAPCs undergo replicative senescence, limiting their utility in long-term studies.

Methods: We inserted human telomerase reverse transcriptase (TERT) into the AAVS1 locus of CD55+ hAPCs derived from abdominal subcutaneous adipose tissue, and characterized the cells before and after adipogenic differentiation.

Results: TERT-hAPCs retained proliferative and adipogenic capacities for over 80 passages, comparable to early-passage wild type hAPCs. Transcriptomic and proteomic analyses confirmed strong adipocyte gene expression. Functionally, TERT-hAPCs responded to insulin and lipolytic stimuli (isoprenaline, dibutyryl cAMP, TNF-α). They adapted well to both 2D and 3D cultures, with improved adipogenesis under spheroid conditions.

Conclusion: Immortalization of CD55+ hAPCs yields cells with stable proliferative and adipogenic capacity across passages. Being cryopreservable and suitable for both 2D and 3D cultures, TERT-hAPCs offer a reliable, reusable model system for adipocyte studies using cells with a consistent genetic background.

Chronic inflammation in obesity can induce complications such as diabetes and cardiovascular disease. Visceral adipose tissue is the main source of inflammation, but it is difficult to regulate effectively. Here, we investigated whether ES suppressed inflammation in eWAT and reduced chronic inflammation in obese individuals. We established a high-fat diet (HFD) model with C57BL/6J mice to measure chronic inflammation in obesity. In addition, the sympathetic nerve activity (SNA) was measured with the electrophysiological technique, the immunostaining and flow cytometry were used to detect the Y1 receptors in macrophage. Finally, the key role of the M1/M2 polarization in white adipose tissues by activating the Y1 receptor was verified by Y1 receptor antagonist BIBP3226. ES reduced the contents of IL-1β, TNF-α, IL-6 and TGF-β in the plasma and the mRNA expression of il-1 and tnfα in eWAT. Also, ES suppressed SNA in eWAT which regulated NPY1R receptor. In addition, ES induced M1/M2 polarization in eWAT via the Y1 receptor. The injection of a Y1 receptor (NPY1R) antagonist BIBP3226 restrained M1/M2 polarization. Further studies revealed that ES regulated sympathetic axons in eWAT to activate the Y1 receptor. This research demonstrates ES reduce chronic inflammation e mechanism is associated with the sympathetic Y1 receptor pathway, which promotes M1/M2 polarization.

Different adipose tissues (AT) have been described, including subcutaneous and visceral tissues (SCAT and VAT). They display different morphological structures, physiological and metabolic functions. Imaging adipocytes in the whole AT was not feasible because of the large adipocyte sizes and the lipid-full content of the droplets that increased the refractive index. Tissue clearing is then required mainly through a delipidation step, which induces also a tissue shrinkage. Our aim was to image in 3D freshly extracted adipocytes and compare them to those within their tissues. Trout ATs were stained with 5DTAF (extracellular matrix) and Nile Red (lipids). After clearing with Histodenz, 3D images were obtained using a confocal microscope, and adipocytes were segmented and measured. In situ, major differences in adipocyte size and shape were observed between the VAT and SCAT. Ex situ, only the size mattered because all cells were round outside their tissues. This method can be applied to other species, such as mice. In situ, adipocyte sphericity was even higher in the SCAT from a Swiss and a C57Bl6. This approach demonstrates that 3D adipocyte imaging with lipid labeling enables accurate morphological characterization, provides insights into depot-specific structural features, and supports optimization of cell isolation protocols.

Obesity is a global health concern that promotes chronic low-grade inflammation, leading to insulin resistance, a key factor in many metabolic diseases. Angiotensin 1-7 (Ang 1-7), a component of the renin-angiotensin system (RAS), exhibits anti-inflammatory effects in obesity and related disorders, though its mechanisms remain unclear. In this study, we examined the effect of Ang 1-7 on inflammation of white adipose tissue (WAT) in dietary-induced obese mice. Monocyte chemoattractant protein-1 (MCP-1) produced by white adipocytes and tumour necrosis factor-α (TNF-α) produced by macrophages are pro-inflammatory cytokines and interact to form a pathogenic loop to exacerbate obesity-induced inflammation. We found that Ang 1-7 reduced MCP-1 and TNF-α gene expressions and the number of crown-like structures, which are histological hallmarks of the pro-inflammatory process, in visceral epididymal WAT (eWAT) and reduced circulating MCP-1 and TNF-α levels, accompanied by improvement in insulin resistance, in dietary-induced obese mice. Furthermore, Ang 1-7 reduced MCP-1 and TNF-α secretions in 3T3-L1 white adipocytes and RAW 264.7 macrophages, respectively, which are in vitro experimental models mimicking obesity condition. Our results suggest that Ang 1-7 directly acts on WAT to mitigate obesity-induced inflammation. Thus, this study provides novel insights into the underlying mechanism of anti-obesity effects of Ang 1-7.

The expression of CAPG (capping actin protein, gelsolin-like) is upregulated in visceral white adipose tissue of high-fat diet -fed mice; however, its impact on adipocyte functionality remains unclear. We observed upregulated CAPG expression in the epididymal adipose tissue of high-fat diet-fed mice. To investigate the impact of CAPG on adipocyte differentiation and function, we generated a Capg knockdown 3T3-L1 cell line and induced adipogenic differentiation to mature adipocytes. Adipogenesis was assessed via Oil Red O and BODIPY staining, revealing that Capg knockdown markedly suppressed adipogenesis. Western blot analysis demonstrated that CAPG depletion reduced PPARγ expression. Additionally, Western blot analysis revealed that Capg knockdown significantly enhanced lipid utilization in adipocytes. ELISA and qPCR results further demonstrated that Capg knockdown effectively attenuated inflammatory responses in adipocytes. In conclusion, CAPG promotes adipogenesis and inflammatory responses, suggesting that targeted inhibition of CAPG may represent a potential therapeutic strategy for obesity-associated adipose tissue dysfunction.

Melanin-concentrating hormone signalling pathways in the central nervous system are of significant clinical interest in treating appetite, sleep, and mood disorders. However, with the additional discovery of active MCH signalling pathways in peripheral tissues, knowing the degree to which cellular context influence MCH receptor function is increasingly important. In this study, we discovered MCH-mediated signalling responses that demonstrated bell-shaped dose response curves in multiple assays using both pre- and post-adipocyte 3T3-L1 models. MCH facilitated cell adhesion in pre-adipocytes, increased both the number and size of lipid droplets and inhibited lipolysis in adipocytes, with a maximum effective dose at 1 nM MCH. We hypothesize that the concentration of MCH cells are exposed to influences G protein bias at MCHR1 and/or signal switching to an unidentified pathway. Furthermore, this study elucidates the importance of hormone concentration when measuring GPCR signalling pathways in cell culture and tissue models.

Sequestration of free fatty acids (FFA) inside white adipose tissue (WAT) may reduce plasma FFA levels and prevent lipotoxicity in other organs. However, it is poorly understood how WAT responds to this metabolic stress. As albumin promotes FFA release from WAT, and thus albumin deficiency should promote FFA sequestration, we studied albumin knockout (Alb^-/-) mice and their wildtype (WT) littermates (eight-week-old males). Transmission electron microscopy and molecular analyses were used for characterization. There was no significant difference between genotypes for WAT mass, adipocyte size or triacylglycerol (TAG) content. No signs of cell death were observed in Alb^-/- adipocytes, suggesting a tolerance to the metabolic challenge. Alb^-/- adipocytes exhibited a lower density of caveolae with smaller invagination depths, indicating a potential adaptation to reduce FFA transport. A significantly higher abundance of micro-lipid droplets was observed in Alb^-/- mice, which may result from a rapid substrate cycle with high lipolysis and re-esterification. In support of the ultrastructural phenotype, lipidomic analysis also demonstrated a significant difference between Alb^-/- and WT for TAG composition. Our results showed that when no albumin is present to facilitate FFA mobilization, WAT can chronically adapt to protect the adipocytes in both morphological and molecular manners.

CXCR7, an alternative receptor for the inflammatory chemokine SDF-1, is involved in cell proliferation and migration. Recent studies have reported that CXCR7 also plays a role in adipose tissue. However, evidence regarding the role of CXCR7 and its ligands in adipocyte differentiation is limited. In this study, we aimed to elucidate changes in CXCR7 expression during adipocyte differentiation and the role of the SDF-1/CXCR7/CXCR4 axis in adipogenesis using recombinant SDF-1, the CXCR7 ligand CCX771, and small interfering RNAs. The results indicated that the levels of SDF-1 and its receptors, CXCR7 and CXCR4, decreased during the early stages of adipogenesis. Treatment with recombinant SDF-1 and CCX771 inhibited adipogenesis and lipid accumulation by inducing β-arrestin2, Wnt expression, and AKT phosphorylation and downregulating C/EBPα, PPARγ, and FABP4 expression. In contrast, knockdown of SDF-1 and CXCR7 in preadipocytes downregulated the β-arrestin2/Wnt and AKT pathway, leading to the induction of adipogenesis. Meanwhile, knockdown of CXCR4 had no significant effect. In mice, basal gene expression levels of SDF-1 and CXCR7 were higher in the stromal vascular fraction compared to mature adipocytes and were significantly upregulated by a high-fat diet. Our results provide new insights into the local role of the SDF-1-CXCR7 axis in adipocytes and offer additional benefits for the prevention of obesity-related metabolic disorders.

Obesity and type 2 diabetes mellitus are global public health challenges. Activating thermogenic adipose tissues, such as brown adipose tissue and beige adipose tissue, could be a promising strategy to combat obesity and consequently obesity-related diabetes. Both peroxisome proliferator-activated receptor-γ (PPARγ) and retinoid X receptor γ (RXRγ) play significant roles in the regulation of adipogenic differentiation. However, the underlying mechanisms and interactions between these receptors during adipogenic differentiation remain unclear. In this study, we conducted a comprehensive analysis of a transcriptome sequencing dataset sourced from the GEO database, encompassing samples of white and brown adipose tissues from 15 healthy individuals. Our findings reveal that RXRγ expression is significantly elevated in brown adipose tissue relative to white adipose tissue (p = 0.041). Furthermore, co-immunoprecipitation assays validated that RXRγ can be co-precipitated with PPARγ. Subsequent luciferase assays demonstrated that the interaction between RXRγ and PPARγ significantly enhances the transcriptional activity of uncoupling protein 1 (UCP1) compared to the overexpression of PPARγ alone (3.4-fold vs. 1.5-fold, p < 0.001). Notably, in human preadipocytes, the co-overexpression of RXRγ with PPARγ resulted in a significant increase in UCP1 transcriptional activity compared to the overexpression of PPARγ alone (3.4-fold vs. 2.0-fold, p < 0.05). In summary, our findings suggest that RXRγ serves as a novel cofactor for PPARγ, promoting the browning of adipose tissue through the upregulation of UCP1 transcription.

Cachexia is a complex syndrome that is often associated with cancer. Chemotherapy, one of the main cancer treatments, worsens weight loss in cancer-induced cachexia. In this context, it is thought that fat loss precedes muscle loss, and that alterations in adipose tissue are associated with tumours. However, the effect of cancer treatment on adipose tissue is not well understood. This study aimed to evaluate the impact of chemotherapy alone on mature 3T3-L1 adipocytes to identify the mechanisms contributing to adipose tissue alteration. The murine cell line 3T3-L1, a model of mature adipocytes, was used in this study. After differentiation, cells were treated for 48 h with a chemotherapy cocktail called FLOT composed of 5-fluorouracil, leucovorin, oxaliplatin and docetaxel at two concentrations (FLOT 1X and 0.1X). The control group was treated with the vehicle of the chemotherapy cocktail. Viability, mitochondrial function and dynamics, lipid metabolism, and cellular stress were also evaluated. FLOT 1X chemotherapy significantly reduced viability of mature 3T3-L1 cells and inhibited lipid accumulation. Interestingly, while FLOT 1X treatment downregulated lipogenesis markers, FLOT 0.1X treatment upregulated some of them. Although, the treatment showed no effect on mitochondrial respiration or density, it significantly increased expression of oxidative stress and inflammation markers in adipocytes.This in vitro study provides the first evidence of FLOT chemotherapy's direct effects on healthy mature adipocytes. The results demonstrate significant treatment-induced reductions in cell viability along with dysregulation of both lipogenic and lipolytic pathways. These findings elucidate previously unrecognized mechanisms underlying adipose tissue dysfunction in cancer cachexia.