| 1. |
- Dufau, J, et al.
(författare)
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In vitro and ex vivo models of adipocytes
- 2021
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Ingår i: American journal of physiology. Cell physiology. - : American Physiological Society. - 1522-1563 .- 0363-6143. ; 320:5, s. C822-C841
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Tidskriftsartikel (refereegranskat)abstract
- Adipocytes are specialized cells with pleiotropic roles in physiology and pathology. Several types of fat cells with distinct metabolic properties coexist in various anatomically defined fat depots in mammals. White, beige, and brown adipocytes differ in their handling of lipids and thermogenic capacity, promoting differences in size and morphology. Moreover, adipocytes release lipids and proteins with paracrine and endocrine functions. The intrinsic properties of adipocytes pose specific challenges in culture. Mature adipocytes float in suspension culture due to high triacylglycerol content and are fragile. Moreover, a fully differentiated state, notably acquirement of the unilocular lipid droplet of white adipocyte, has so far not been reached in two-dimensional culture. Cultures of mouse and human-differentiated preadipocyte cell lines and primary cells have been established to mimic white, beige, and brown adipocytes. Here, we survey various models of differentiated preadipocyte cells and primary mature adipocyte survival describing main characteristics, culture conditions, advantages, and limitations. An important development is the advent of three-dimensional culture, notably of adipose spheroids that recapitulate in vivo adipocyte function and morphology in fat depots. Challenges for the future include isolation and culture of adipose-derived stem cells from different anatomic location in animal models and humans differing in sex, age, fat mass, and pathophysiological conditions. Further understanding of fat cell physiology and dysfunction will be achieved through genetic manipulation, notably CRISPR-mediated gene editing. Capturing adipocyte heterogeneity at the single-cell level within a single fat depot will be key to understanding diversities in cardiometabolic parameters among lean and obese individuals.
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| 2. |
- Kulyte, A, et al.
(författare)
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MTCH2 in human white adipose tissue and obesity
- 2011
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Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 96:10, s. E1661-E1665
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Tidskriftsartikel (refereegranskat)abstract
- Context:Genome-wide association studies have identified single-nucleotide polymorphisms in approximately 40 loci associated with obesity-related traits. How these loci regulate obesity is largely unknown. One obesity-associated single-nucleotide polymorphism is close to the MTCH2 gene (mitochondrial carrier homolog 2).Objective:The objective of the study was to assess the expression of genes in obesity-associated loci in abdominal sc white adipose tissue (scWAT) in relation to obesity. A more comprehensive expression study was performed on MTCH2.Design:mRNA levels of 66 genes from 40 loci were determined by microarray in scWAT from lean and obese women (n = 30). MTCH2 mRNA was measured by quantitative RT-PCR in lean and obese before and after weight loss in intact adipose pieces and isolated adipocytes, paired samples of scWAT and omental WAT, and primary adipocyte cultures (n = 191 subjects in total). MTCH2 genotypes were compared with mRNA expression in 96 women. MTCH2 protein was examined in scWAT of 38 individuals.Results:Adipose expression of eight genes was significantly associated with obesity; of these, MTCH2 displayed the highest absolute signal. MTCH2 mRNA and protein expression was significantly increased in obese women but was not affected by weight loss. MTCH2 was enriched in isolated fat cells and increased during adipocyte differentiation. There was no cis influence of MTCH2 genotypes on mRNA levels.Conclusion:MTCH2 is highly expressed in human WAT and adipocytes with increased levels in obese women. These results suggest that MTCH2 may play a role in cellular processes underlying obesity.
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| 3. |
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| 4. |
- Dahlman, I, et al.
(författare)
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Adipose tissue pathways involved in weight loss of cancer cachexia
- 2010
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Ingår i: British Journal of Cancer. - : Springer Science and Business Media LLC. - 0007-0920 .- 1532-1827. ; 102:10, s. 1541-8
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The regulatory gene pathways that accompany loss of adipose tissue in cancer cachexia are unknown and were explored using pangenomic transcriptome profiling. METHODS: Global gene expression profiles of abdominal subcutaneous adipose tissue were studied in gastrointestinal cancer patients with (n=13) or without (n=14) cachexia. RESULTS: Cachexia was accompanied by preferential loss of adipose tissue and decreased fat cell volume, but not number. Adipose tissue pathways regulating energy turnover were upregulated, whereas genes in pathways related to cell and tissue structure (cellular adhesion, extracellular matrix and actin cytoskeleton) were downregulated in cachectic patients. Transcriptional response elements for hepatic nuclear factor-4 (HNF4) were overrepresented in the promoters of extracellular matrix and adhesion molecule genes, and adipose HNF4 mRNA was downregulated in cachexia. CONCLUSIONS: Cancer cachexia is characterised by preferential loss of adipose tissue; muscle mass is less affected. Loss of adipose tissue is secondary to a decrease in adipocyte lipid content and associates with changes in the expression of genes that regulate energy turnover, cytoskeleton and extracellular matrix, which suggest high tissue remodelling. Changes in gene expression in cachexia are reciprocal to those observed in obesity, suggesting that regulation of fat mass at least partly corresponds to two sides of the same coin.
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| 5. |
- Ehrlund, A, et al.
(författare)
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Transcriptional Dynamics During Human Adipogenesis and Its Link to Adipose Morphology and Distribution
- 2017
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 66:1, s. 218-230
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Tidskriftsartikel (refereegranskat)abstract
- White adipose tissue (WAT) can develop into several phenotypes with different pathophysiological impact on type 2 diabetes. To better understand the adipogenic process, the transcriptional events that occur during in vitro differentiation of human adipocytes were investigated and the findings linked to WAT phenotypes. Single-molecule transcriptional profiling provided a detailed map of the expressional changes of genes, enhancers, and long noncoding RNAs, where different types of transcripts share common dynamics during differentiation. Common signatures include early downregulated, transient, and late induced transcripts, all of which are linked to distinct developmental processes during adipogenesis. Enhancers expressed during adipogenesis overlap significantly with genetic variants associated with WAT distribution. Transiently expressed and late induced genes are associated with hypertrophic WAT (few but large fat cells), a phenotype closely linked to insulin resistance and type 2 diabetes. Transcription factors that are expressed early or transiently affect differentiation and adipocyte function and are controlled by several well-known upstream regulators such as glucocorticosteroids, insulin, cAMP, and thyroid hormones. Taken together, our results suggest a complex but highly coordinated regulation of adipogenesis.
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| 6. |
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| 7. |
- Kulyte, A, et al.
(författare)
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Additive effects of microRNAs and transcription factors on CCL2 production in human white adipose tissue
- 2014
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 63:4, s. 1248-1258
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Tidskriftsartikel (refereegranskat)abstract
- Adipose tissue inflammation is present in insulin-resistant conditions. We recently proposed a network of microRNAs (miRNAs) and transcription factors (TFs) regulating the production of the proinflammatory chemokine (C-C motif) ligand-2 (CCL2) in adipose tissue. We presently extended and further validated this network and investigated if the circuits controlling CCL2 can interact in human adipocytes and macrophages. The updated subnetwork predicted that miR-126/-193b/-92a control CCL2 production by several TFs, including v-ets erythroblastosis virus E26 oncogene homolog 1 (avian) (ETS1), MYC-associated factor X (MAX), and specificity protein 12 (SP1). This was confirmed in human adipocytes by the observation that gene silencing of ETS1, MAX, or SP1 attenuated CCL2 production. Combined gene silencing of ETS1 and MAX resulted in an additive reduction in CCL2 production. Moreover, overexpression of miR-126/-193b/-92a in different pairwise combinations reduced CCL2 secretion more efficiently than either miRNA alone. However, although effects on CCL2 secretion by co-overexpression of miR-92a/-193b and miR-92a/-126 were additive in adipocytes, the combination of miR-126/-193b was primarily additive in macrophages. Signals for miR-92a and -193b converged on the nuclear factor-κB pathway. In conclusion, TF and miRNA-mediated regulation of CCL2 production is additive and partly relayed by cell-specific networks in human adipose tissue that may be important for the development of insulin resistance/type 2 diabetes.
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