This study was undertaken to examine the regulation of leptin production from human adipocytes by tumor necrosis factor-alpha (TNFalpha). Adipocytes were isolated from adipose tissue obtained during bariatric surgical procedures (17 women and 3 men; body mass index, 52.5 +/- 2.4 kg/m2; age, 40 +/- 3 yr) and cultured in suspension. Leptin release from sc adipocytes was inhibited 17.7 +/- 5.2% (P...

In adipocytes, lipolysis is a highly regulated process involving hormonal signals, lipid droplet-associated proteins, and lipases. The discovery of new lipid droplet-associated proteins added complexity to the current model of lipolysis. In this study, we used cultured human adipocytes to demonstrate that fat-specific protein 27 (FSP27), an abundantly expressed protein in adipocytes, regulates ...

Lipid overload in obesity and type 2 diabetes is associated with adipocyte dysfunction, inflammation, macrophage infiltration, and decreased fatty acid oxidation (FAO). Here, we report that the expression of carnitine palmitoyltransferase 1A (CPT1A), the rate-limiting enzyme in mitochondrial FAO, is higher in human adipose tissue macrophages than in adipocytes and that it is differentially expr...

The hexosamine signaling pathway has been shown to serve a nutrient-sensing function. We have previously shown that overexpression of the rate-limiting enzyme for hexosamine synthesis (glutamine-fructose-6-phosphate amidotransferase) in adipose tissue of transgenic mice results in skeletal muscle insulin resistance and altered regulation of leptin and adiponectin. To dissect the pathways by whi...

A significant epidemiological association between obesity and pancreatic ductal adenocarcinoma (PDAC) has previously been described, as well as a correlation between the degree of pancreatic steatosis, PDAC risk and prognosis. The underlying mechanisms are still not completely known.After co-culture of 3T3-L1 adipocytes and MiaPaCa2 with an in vitro transwell system we observed the appearance o...

Hormone-sensitive lipase (HSL) is presumed to be essential for lipolysis, which is defined as the mobilization of free fatty acids from adipocytes. In the present study, we investigated the effects of various lipolytic hormones on the lipolysis in adipocytes derived from mouse embryonic fibroblasts (MEF adipocytes) prepared from HSL-deficient mice (HSL-/-). HSL-/- MEF differentiated into mature...

The growth and aging of 3T3-L1 adipocytes were investigated in a synchronized tissue-culture system. We systematically characterized several major aspects of adipocyte metabolism and functions as variables of cell age. We found that terminal differentiation of 3T3-L1 cells is followed by a near-linear hypertrophic growth (increase in triglyceride content) of the cultured adipocytes throughout a...

Activation of inflammatory signaling pathways links obesity with metabolic disorders. TLR4-mediated activation of MAPKs and NF-κB are 2 such pathways implicated in obesity-induced inflammation. Apolipoprotein A-I (apoA-I) exerts anti-inflammatory effects on adipocytes by effluxing cholesterol from the cells via the ATP binding cassette transporter A1 (ABCA1). It is not known if these effects in...

The activity and turnover of dihydrolipoamide dehydrogenase (E3), the common component of the three 2-oxoacid dehydrogenase complexes, were measured during the differentiation of 3T3-L1 preadipocytes into 3T3-L1 adipocytes. The specific activity of E3 increased approx. 3-4-fold in 3T3-L1 adipocytes differentiated under a regimen of insulin, dexamethasone and 3-isobutyl-1-methylxanthine for 48 h...

The stress protein heat shock protein 60 (Hsp60) induces secretion of proinflammatory mediators from murine adipocytes. This study aimed to study Hsp60 as a mediator of adipose tissue inflammation and skeletal muscle cell (SkMC) insulin sensitivity and to quantify plasma Hsp60 concentrations in lean and obese individuals. Regulation of Hsp60 release and Hsp60-induced cytokine secretion and sign...