Identification of lipid droplet-associated proteins in the formation of macrophage-derived foam cells using microarrays
INTERNATIONAL JOURNAL OF MOLECULAR MEDICINE
Authors: Li, Hang; Song, Yue; Li, Fanfan; Zhang, Lijun; Gu, Yu; Zhang, Liying; Jiang, Lina; Dong, Wenpeng; Ye, Jing; Li, Qing
Abstract
A large number of macrophage-derived foam cells stores excessive neutral lipids in intracellular droplets, and plays a major role during the development of atherosclerosis. The formation and catabolism of intracellular lipid droplets (LDs) are regulated by LD-associated proteins, a group of proteins which are located on the surface of LDs and regulate the formation, morphology and lipolysis of LDs. In order to illustrate the function of LD-associated proteins during the process of atherosclerosis, the foam cell model is induced by oxidized low-density lipoprotein (ox-LDL) in macrophages originated from the THP-1 cell line, and cDNA microarrays are used to monitor the gene expression profiles of LD-associated proteins. Gene expression data show that 2% of changed genes are lipid binding genes during the transformation of foam cells. The major candidate genes, the cell death-inducing DFF45-like effector (CIDE) family and Perilipin, Adipophilin, and TIP47 (PAT) family, have different alterations during the formation of foam cells. CIDEB, CIDEC, Adipophilin, S3-12 and LSDP5 were up-regulated, while TIP47 was down-regulated. There was no significant change in CIDEA and Perilipin. These results were confirmed by real-time PCR and immunoblotting. This study presents a comprehensive analysis of the gene expression of LD-associated proteins during the differentiation of human foam cells, which may play an important role in the process of atherosclerosis.
Female Nur77-Deficient Mice Show Increased Susceptibility to Diet-Induced Obesity
PLOS ONE
Authors: Perez-Sieira, Sonia; Martinez, Gloria; Porteiro, Begona; Lopez, Miguel; Vidal, Anxo; Nogueiras, Ruben; Dieguez, Carlos
Abstract
Adipose tissue is essential in the regulation of body weight. The key process in fat catabolism and the provision of energy substrate during times of nutrient deprivation or enhanced energy demand is the hydrolysis of triglycerides and the release of fatty acids and glycerol. Nur77 is a member of the NR4A subfamily of nuclear receptors that plays an important metabolic role, modulating hepatic glucose metabolism and lipolysis in muscle. However, its endogenous role on white adipose tissue, as well as the gender dependency of these mechanisms, remains largely unknown. Male and female wild type and Nur77 deficient mice were fed with a high fat diet (45% calories from fat) for 4 months. Mice were analyzed in vivo with the indirect calorimetry system, and tissues were analyzed by real-time PCR and Western blot analysis. Female, but not male Nur77 deficient mice, gained more weight and fat mass when compared to wild type mice fed with high fat diet, which can be explained by decreased energy expenditure. The lack of Nur77 also led to a decreased pHSL/HSL ratio in white adipose tissue and increased expression of CIDEA in brown adipose tissue of female Nur77 deficient mice. Overall, these findings suggest that Nur77 is an important physiological modulator of lipid metabolism in adipose tissue and that there are gender differences in the sensitivity to deletion of the Nur77 signaling. The decreased energy expenditure and the actions of Nur77 on liver, muscle, brown and white adipose tissue contribute to the increased susceptibility to diet-induced obesity in females lacking Nur77.