As a growing but non-infectious epidemic, obesity is a common cause of several comorbidities. GTPase-activating protein SH3 domain-binding protein 1 (G3BP1) is a central regulator of stress‑granule assembly that has significant implications in metabolic disorders. This article aims to explore the functional mechanism of G3BP1 in obesity, both in vitro and in vivo. Functional assays were used to detect cellular phenotypes. Reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) and western blotting were also used to test metastasis-, phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signalling- and Wnt/β-catenin signalling-related genes. Oil‑red‑O staining and haematoxylin and eosin (H&E) staining were used to estimate lipid deposition. RT-qPCR, western blotting, and immunofluorescence staining were used to determine adipocyte differentiation and lipid metabolism. The TOPFlash/FOPFlash reporter assay was used to identify β-catenin activity. In a murine model fed a high-fat diet (HFD, 60% fat), body weight was measured prior to the detection of adipokine levels by enzyme‑linked immunosorbent assay (ELISA), triacylglycerol (TG) concentration using an assay kit, and adipogenic marker genes by western blotting. G3BP1 knockdown inhibited proliferation, migration, invasion, and adipogenesis, and induced cell cycle arrest in 3T3-L1 preadipocytes, and decreased body weight and adipogenesis and fat accumulation in obese mice. G3BP1 activated Wnt/β-catenin and PI3K/AKT pathways. LY294002 (PI3K inhibitor) and SC3036 (PI3K activator) reversed the in vitro effects of G3BP1 or silenced G3BP1 on preadipocyte invasion. G3BP1 may promote preadipocyte proliferation, migration, invasion, and adipogenesis to promote the progression of obesity, which might be relevant to the PI3K/AKT pathway.
In vitro modelling of adipose tissue (AT) commonly employs 2D systems, which do not fully capture the complexity of AT, lacking cell-cell interactions and extracellular matrix (ECM) remodelling. Despite the innovations in 3D culture systems offering physiologically relevant AT platforms, the field lacks consensus and cross-protocol method comparison. We performed a comparative analysis of three scaffold-free spheroid-generation techniques: Ultra Low Attachment plates (ULA), Hanging Drops (HD), and Microwell Culture Plates (MCP), utilizing human AT-derived mesenchymal stromal cells. Each method produced viable spheroids of similar size and morphology within 48 hours. However, MCP demonstrated greater uniformity and a significant increase in mass density when compared to ULA and HD. Adipogenic media increased spheroid size in ULA and MCP, but not in HD spheroids. Notably, the diameter of ULA spheroids was 2- and 6-times larger compared to HD and MCP ones, respectively, regardless of adipogenic induction. Gene expression analysis indicated that all techniques led to PPARγ and ADIPOQ expression during adipogenesis. All methods supported adipocyte differentiation, as evidenced by lipid droplet accumulation, PLIN1, CD36, and HSL expression, and ECM rearrangement. These findings suggest that all the described techniques constitute a robust platform for producing adipogenesis-competent spheroids, while method-specific differences suggest an application-dependent choice.
Lipedema and obesity are chronic, frequently progressive disorders that can present with increased adipose-tissue volume, functional impairment and reduced quality of life. Although often approached as differential diagnoses, they frequently coexist and may aggravate one another. This narrative review addresses how lipedema and obesity interact biologically and clinically and what evidence supports a staged interdisciplinary approach to diagnosis and management. Obesity is increasingly conceptualized as an adiposity-based chronic disease characterized by excess adipose, abnormal adipose-tissue distribution or dysfunction, and associated medical or functional impairment. Obesity can impair lymphatic morphology and function, whereas lymphatic dysfunction may promote subcutaneous adipose-tissue expansion and fibrosis. Literature was identified through iterative PubMed searches and focused supplementary searches in Embase and the Cochrane Library. Publications were selected purposively for their relevance to predefined clinical and mechanistic domains; no systematic screening or formal risk-of-bias assessment was performed. This review synthesizes clinical overlap, biological evidence, diagnostic implications, and staged management for predominantly adult women with suspected or confirmed lipedema, including those with coexisting overweight or obesity. The proposed framework is intended to support clinical reasoning rather than serve as a formal guideline.
Perivascular adipose tissue (PVAT) is recognized as the functional fourth layer of the vasculature. Unlike non-PVAT depots, PVAT is continuously exposed to haemodynamic forces, potentially altering the morphometry of its adipocytes. While transcriptomics studies have identified diverse adipocyte populations, characterizing these cells remains difficult because their inherent fragility limits standard antibody-based phenotyping. Autofluorescence has emerged as a label-free alternative for characterizing cellular heterogeneity. However, autofluorescence-based characterization of PVAT adipocytes remains unexplored, and it is unknown if these cells exhibit distinct profiles reflecting their specific anatomical location. This study aimed to define the autofluorescence profiles of PVAT and non-PVAT adipocytes. Using Sprague-Dawley rats (n = 6), we assessed intrinsic fluorescence in adipocytes from PVATs of thoracic and abdominal aorta, and from mesenteric arteries alongside phenotype-matched non-PVAT counterparts: interscapular brown, subcutaneous, and retroperitoneal tissues. Using optimized methods to maintain adipocyte integrity, we demonstrate that thoracic and intrascapular exhibit similar autofluorescence profiles. In contrast, PVAT sites mesenteric and abdominal diverge across the yellow, red, and violet channels compared with non-PVAT depots, retroperitoneal and subcutaneous. In conclusion, PVAT and non-PVAT adipocytes exhibit depot-specific spectral patterns, with higher autofluorescence observed in PVAT cells, validating autofluorescence as a marker-independent approach for identifying adipocyte differences.
Factors limiting fat cell expandability remain scarcely explored, and comprehensive functional comparisons of adipose depots in humans are limited. In the present study, we collected visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) paired-samples from 22 patients with obesity undergoing elective Roux-en-Y gastric bypass surgery. Whole tissue samples were used to determine adipocyte cell size using a coulter counter and gene expression levels using bulk mRNA sequencing. Isolated adipocytes from the same tissue samples were used to functionally assess glucose uptake using glucose tracer assay, and lipolysis by measuring glycerol release. Western blotting was used to determine Caveolin 1 levels in adipocytes. The relationship between COL3A1 expression and systemic health outcomes was assessed using data from the Adipose Tissue Knowledge Portal. We found that SAT adipocytes were larger in size, displayed higher basal lipolysis and higher lipolysis-related gene expression than VAT adipocytes. Isoprenaline-induced lipolytic responsiveness, as well as basal and insulin-stimulated glucose uptake were higher in VAT than in SAT adipocytes. SAT displayed higher levels of extracellular matrix components associated with cellular flexibility and higher cellular Caveolin 1 levels than VAT. Further, we identified subcutaneous adipose tissue COL3A1 as a potential contributor to insulin resistance in obesity, positively associated with BMI, HOMA-IR and adipocyte size. In summary, our findings underscore distinct metabolic properties of subcutaneous and visceral adipocytes in obesity, with SAT adipose tissue exhibiting characteristics that possibly promote greater cellular expandability.
