Jae-beom Kim

Adipocyte determination and differentiation-dependent factor 1 (ADD1) is a member of the basic helix-loop-helix leucine zipper (bHLH-LZ) family of transcription factors that binds to two distinct DNA sequences and has been associated with both adipocyte development and cholesterol homeostasis (where it has been termed SREBP1). To investigate the biological role of ADD1, we expressed wild-type and dominant negative forms of this protein with retroviral vectors in preadipocytes and nonadipogenic c

The ability to regulate specific genes of energy metabolism in response to fasting and feeding is an important adaptation allowing survival of intermittent food supplies. However, little is known about transcription factors involved in such responses in higher organisms. We show here that gene expression in adipose tissue for adipocyte determination differentiation dependent factor (ADD) 1/sterol regulatory element binding protein (SREBP) 1, a basic-helix-loop-helix protein that has a dual DNA-b

Adipose differentiation is an important part of the energy homeostasis system of higher organisms. Recent data have suggested that this process is controlled by an interplay of transcription factors including PPARgamma, the C/EBPs, and ADD1/SREBP1. Although these factors interact functionally to initiate the program of differentiation, there are no data concerning specific mechanisms of interaction. We show here that the expression of ADD1/SREBP1 specifically increases the activity of PPARgamma

OBJECTIVE: Tissue inflammation is a key factor underlying insulin resistance in established obesity. Several models of immuno-compromised mice are protected from obesity-induced insulin resistance. However, it is unanswered whether inflammation triggers systemic insulin resistance or vice versa in obesity. The purpose of this study was to assess these questions. RESEARCH DESIGN AND METHODS: We fed a high-fat diet (HFD) to wild-type mice and three different immuno-compromised mouse models (lympho

Adipocyte determination- and differentiation-dependent factor 1 (ADD1), a member of the basic helix-loop-helix (bHLH) family of transcription factors, has been associated with both adipocyte differentiation and cholesterol homeostasis (in which case it has been termed SREBP1). Using PCR-amplified binding analysis, we demonstrate that ADD1/SREBP1 has dual DNA sequence specificity, binding to both an E-box motif (ATCACGTGA) and a non-E-box sequence previously shown to be important in cholesterol m

In obesity, adipocyte hypertrophy and proinflammatory responses are closely associated with the development of insulin resistance in adipose tissue. However, it is largely unknown whether adipocyte hypertrophy per se might be sufficient to provoke insulin resistance in obese adipose tissue. Here, we demonstrate that lipid-overloaded hypertrophic adipocytes are insulin resistant independent of adipocyte inflammation. Treatment with saturated or monounsaturated fatty acids resulted in adipocyte hy

Liver X receptors (LXRs) are nuclear hormone receptors that regulate cholesterol and fatty acid metabolism in liver tissue and in macrophages. Although LXR activation enhances lipogenesis, it is not well understood whether LXRs are involved in adipocyte differentiation. Here, we show that LXR activation stimulated the execution of adipogenesis, as determined by lipid droplet accumulation and adipocyte-specific gene expression in vivo and in vitro. In adipocytes, LXR activation with T0901317 prim

Lipids are essential metabolites, which function as energy sources, structural components and signalling mediators. Most cells are able to convert carbohydrates into fatty acids, which are often converted into neutral lipids for storage in the form of lipid droplets. Accumulating evidence suggests that lipogenesis plays a crucial role not only in metabolic tissues for systemic energy homoeostasis but also in immune and nervous systems for their proliferation, differentiation and even pathophysio

Adiponectin plays a key role in the regulation of the whole-body energy homeostasis by modulating glucose and lipid metabolism. Although obesity-induced reduction of adiponectin expression is primarily ascribed to a transcriptional regulation failure, the underlying mechanisms are largely undefined. Here we show that DNA hypermethylation of a particular region of the adiponectin promoter suppresses adiponectin expression through epigenetic control and, in turn, exacerbates metabolic diseases in

Glucose-6-phosphate dehydrogenase (G6PD) produces cellular NADPH, which is required for the biosynthesis of fatty acids and cholesterol. Although G6PD is required for lipogenesis, it is poorly understood whether G6PD in adipocytes is involved in energy homeostasis, such as lipid and glucose metabolism. We report here that G6PD plays a role in adipogenesis and that its increase is tightly associated with the dysregulation of lipid metabolism and insulin resistance in obesity. We observed that the

Osteogenesis is a complex process associated with dramatic changes in gene expression. To elucidate whether modifications in chromatin structure are involved in osteoblast differentiation, we examined the expression levels of histone deacetylases (HDACs) and the degree of histone acetylation at the promoter regions of osteogenic genes. During osteogenesis, total HDAC enzymatic activity was decreased with significant reduction in HDAC1 expression. Consistently, recruitment of HDAC1 to the promote

We describe a sensitive mRNA profiling technology, PMAGE (for "polony multiplex analysis of gene expression"), which detects messenger RNAs (mRNAs) as rare as one transcript per three cells. PMAGE incorporates an improved ligation-based method to sequence 14-nucleotide tags derived from individual mRNA molecules. One sequence tag from each mRNA molecule is amplified onto a separate 1-micrometer bead, denoted as a polymerase colony or polony, and about 5 million polonies are arrayed in a flow cel

ABSTRACT Firmicutes and Bacteroidetes, 2 major phyla of gut microbiota, are involved in lipid and bile acid metabolism to maintain systemic energy homeostasis in host. Recently, accumulating evidence has suggested that dietary changes promptly induce the alteration of abundance of both Firmicutes and Bacteroidetes in obesity and its related metabolic diseases. Nevertheless, the metabolic roles of Firmicutes and Bacteroidetes on such disease states remain unclear. The aim of this study was to det