ABSTRACT: Obesity is often associated with a low-grade systemic inflammation state that contributes to the development of insulin resistance and atherosclerotic complications. This is usually coupled with increased macrophage infiltration in the adipose tissue and a defect in adipocyte differentiation that results in accumulation of hypertrophic fat cells characterized by a deregulated pattern of adipokine expression. Here we show that knockdown of histone demethylase lsd1 in 3T3-L1 preadipocytes results in defective adipogenesis and derepression of an inflammatory program in these cells.
Project description:Obesity is often associated with a low-grade systemic inflammation state that contributes to the development of insulin resistance and atherosclerotic complications. This is usually coupled with increased macrophage infiltration in the adipose tissue and a defect in adipocyte differentiation that results in accumulation of hypertrophic fat cells characterized by a deregulated pattern of adipokine expression. Here we show that knockdown of histone demethylase lsd1 in 3T3-L1 preadipocytes results in defective adipogenesis and derepression of an inflammatory program in these cells. The dataset consists of four sample groups: [1] 3T3-L1 preadipocytes (passage 19) transfected with a control scrambled siRNA at 24h after transfection (siC.24h), [2] 3T3-L1 preadipocytes (p.19) transfected with a siRNA directed against LSD1 at 24h after transfection (siLsd1.24h), [3] 3T3-L1 preadipocytes (p.21) transfected with a control scrambled siRNA at 48h after transfection (siC.48h), and [4] 3T3-L1 preadipocytes (p.21) transfected with a siRNA directed against LSD1 at 48h after transfection (siLsd1.48h). The 24h sample groups (siC.24h and siLsd1.24h) consist of two biological replicate samples; the 48h sample groups (siC.48h and siLsd1.48h) consist of three biological replicate samples. Each sample was hybridized to a separate array, for a total of ten arrays.
Project description:Bivalent H3K4me3 and H3K27me3 chromatin domains in embryonic stem cells keep active developmental regulatory genes expressed at very low levels and poised for activation. Here, we show an alternative and previously unknown bivalent modified histone signature in lineage-committed mesenchymal stem cells and preadipocytes that pairs H3K4me3 with H3K9me3 to maintain adipogenic master regulatory genes (Cebpa and Pparg) expressed at low levels yet poised for activation when differentiation is required. We show lineage-specific gene-body DNA methylation recruits H3K9 methyltransferase SETDB1 which methylates H3K9 immediately downstream of transcription start sites marked with H3K4me3 to establish the bivalent domain. At the Cebpa locus, this prevents transcription factor C/EBPβ binding, histone acetylation, and further H3K4me3 deposition and is associated with pausing of RNA polymerase II, which limits Cebpa gene expression and adipogenesis. We used microarrays to detail the global programme of gene expression in 3T3-L1 preadipocytes and 10Th1lf mesenchymal stem cells and identified up-regulated genes upon knockdown of SETDB1, MBD1, and MCAF1. SETDB1, MBD1, or MCAF1 was knocked-down in 3T3-L1 preadipocytes and 10Thalf mesenchymal stem cells for RNA extraction and hybridization on Affymetrix microarrays. Small interfering RNAs (siRNA) targeting to Setdb1, Mbd1, or Mcaf1 was transfected to 3T3-L1 preadipocytes or 10Thalf mesenchymal stem cells.
Project description:Adipose tissues are closely related to physiological functions and pathological conditions in most organs. Although differentiated 3T3-L1 preadipocytes have been used for in vitro adipose studies, the difference in cellular characteristics of adipogenic differentiation in two-dimensional (2D) culture and three-dimensional (3D) culture remain unclear. In this study, we evaluated gene expression patterns using RNA sequencing and metabolic functions using an extracellular flux analyzer in 3T3-L1 preadipocytes with and without adipogenic induction in 2D culture and 3D culture. In 2D culture, 565 up-regulated genes and 391 down-regulated genes were identified as differentially expressed genes (DEGs) by adipogenic induction of 3T3-L1 preadipocytes, whereas only 69 up-regulated genes and 59 down-regulated genes were identified as DEGs in 3D culture. Ingenuity Pathway Analysis (IPA) revealed that genes associated with lipid metabolism were identified as 2 out of the top 3 causal networks related to diseases and function in 3D spheroids, whereas only one network related to lipid metabolism was identified within the top 9 of these causal networks in the 2D planar cells, suggesting that adipogenic induction in the 3D culture condition exhibits a more adipocyte-specific gene expression pattern in 3T3-L1 preadipocytes. Real-time metabolic analysis revealed that the metabolic capacity shifted from glycolysis to mitochondrial respiration in differentiated 3T3-L1 cells in the 3D culture condition but not in those in the 2D cultured condition, suggesting that adipogenic differentiation in 3D culture induces a metabolic phenotype of well-differentiated adipocytes. Consistently, expression levels of mitochondria-encoded genes including mt-Nd6, mt-Cytb, and mt-Co1 were significantly increased by adipogenic induction of 3T3-L1 preadipocytes in 3D culture compared with those in 2D culture. Taken together, the findings suggest that induction of adipogenesis in 3D culture provides a more adipocyte-specific gene expression pattern and enhances mitochondrial respiration, resulting in more adipocyte-like cellular properties.
Project description:Adipogenic differentiation and metabolic adaptation are initiated through transcriptional and epigenetic reprogramming. In particular, dynamic changes in histone modifications may play central roles in the rearrangement of gene expression patterns. LSD1 (KDM1) protein, encoded by aof2 gene, is a histone demethylase, which is involved in transcriptional regulation. Since the enzymatic activity of LSD1 is FAD (flavin adenine dinucleotide)-dependent, its effects on gene expression may be influenced by FAD availability. To address the importance of histone demethylation in adipogenic differentiation and function, we performed cDNA microarray in LSD1-deficient 3T3-L1 cells as well as in the cells treated with LSD1 inhibitor tranylcypromine (TC). FAD-synthesizing enyme, riboflavin kinase (RFK) -deficient cells were also subjected to the microarray analysis. 3T3-L1 preadipocytes were transfected with aof2- or rfk- specific siRNA or control siRNA (siGL3) . 24 hours later, cells were subjected to adipogenic induction. 24 hours later, cells were harvested for total RNA extraction. For the TC treatment, TC was added to the adipogenic induction medium.
Project description:Adipogenic differentiation and metabolic adaptation are initiated through transcriptional and epigenetic reprogramming. In particular, dynamic changes in histone modifications may play central roles in the rearrangement of gene expression patterns. BHC80 protein, encoded by phf21a gene, is a part of LSD1 histone demethylase complex and is essential for the demethylation activity. To address the importance of histone demethylation in adipogenic differentiation and function, we performed cDNA microarray in BHC80-deficient 3T3-L1 cells 3T3-L1 preadipocytes were transfected with either BHC80-specific siRNA or control siRNA (siGL3). 24 hours later, cells were subjected to adipogenic induction. 24 hours later, cells were harvested for total RNA extraction.
Project description:DNA methylation plays a crucial role in the regulation of gene transcription. In this study, using MeDIP-seq experiment, we report the mapping of DNA methylation in undifferentiated 3T3-L1 cells (preadipocytes). Examination of DNA methylation pattern in undifferentiated 3T3-L1 cells (preadipocytes)