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Title: Gene expression profiling of 3T3-L1 preadipocyte differentiation and neotoralactone-treated HepG2 cells by cDNA microarray
Other Titles: Yong cDNA xin pian yan jiu 3T3-L1 qian zhi fang xi bao fen hua ji xin jue ming nei zhi chu li HepG2 xi bao de ji yin biao da tu pu
用 cDNA 芯片研究 3T3-L1 前脂肪細胞分化及新決明內脂處理 HepG2 細胞的基因表達圖譜
Authors: Au, Tze-shan (歐子辰)
Department: Dept. of Biology and Chemistry
Degree: Master of Philosophy
Issue Date: 2002
Publisher: City University of Hong Kong
Subjects: Cell differentiation
DNA microarrays
Fat cells
Gene expression
Notes: CityU Call Number: QH450.A825 2002
Includes bibliographical references (leaves 95-96)
Thesis (M.Phil.)--City University of Hong Kong, 2002
xix, 99 leaves : ill. (some col.) ; 30 cm.
Type: Thesis
Abstract: Obesity is a prevalent health hazard in developed countries and is connected with many pathological disorders. The cause of obesity is the increase in the number and size of adipocytes, which are associated with the increase of adipocyte differentiation and lipid synthesis respectively. Since the mechanism of adipocyte differentiation is still not very clear, it is very important to investigate the mechanism of adipocyte differentiation and to find new drugs, which can inhibit adipocyte differentiation and lipid synthesis. 3T3-L1 mouse preadipocyte was selected as a standard model to study adipocyte differentiation. With an inducing medium which consists of three kinds of differentiation inducing factors, DEX, MIX and insulin, 3T3-Ll preadipocyte can be induced into mature adipocyte. The roles of individual inducing factors and their different combinations in the differentiation of 3T3-L1 preadipocyte were studied using cell-based assay, flow cytometry and a cDNA microarray containing 1000 mouse genes. The results showed that among the three inducing factors, DEX is the most important one. Removing DEX from the inducing medium significantly decreased the differentiation level of 3T3- L1 preadipocyte. We also found that in the absence of insulin, 3T3-L1 preadipocyte still differentiated well, but the size of the cells was slightly smaller than that of fully induced cells in the presence of all three inducing factors. By comparing the gene expression profiles of 3T3-L1 preadipocytes induced with individual inducing factors and their different combinations, the relationships among individual inducing factors and their different combinations with expression of preadipocyte differentiation related genes were identified. Neotoralactone (NT), a single compound isolated from the seed of Cassia obtusifolia (a traditional Chinese medicine) has been claimed to have weight loss effect. Animal experiments were performed to examine the biological effect of this compound. The results showed that it could decrease the increase rate of body weight of rats fed with high nutrient diet. Then the compound was examined using 3T3-Ll preadipocyte differentiation assays. The results demonstrated that NT has minimal effect on 3T3-L1 preadipocyte differentiations. HepG2 human heptocarcinoma cell line was chosen to be the model system because one of the proposed mechanisms of weight reduction effect of Cassia obtusifolia is the alteration of lipid metabolism primarily taken place in the liver. A high-density cDNA microarray containing about 10,000 human genes and ESTs was used to analyze the gene expression profiles of the HepG2 cells with and without NT treatment. The results displayed that NT regulates a panel of genes related to lipid metabolism and suggested that the mechanism of weight loss effect of NT is alteration of lipid metabolism but not adipocyte differentiation.
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