ABSTRACT
Rehmannia glutinosa, a Traditional Chinese Medicine (TCM), has been used to increase physical strength. Here, we report that Rehmannia glutinosa extract (RE) inhibits adipocyte differentiation and adipogenesis. RE impairs differentiation of 3T3-L1 preadipocytes in a dose-dependent manner. At the molecular level, treatment with RE inhibits expression of the key adipocyte differentiation regulator C/EBPbeta, as well as C/EBPalpha and the terminal marker protein 422/aP2, during differentiation of preadipocytes into adipocytes. Additionally, RE inhibits the mitotic clonal expansion (MCE) process of adipocyte differentiation, and RE prevents localization of C/EBPbeta to the centromeres. RE also prevents high fat diet (HFD) induced weight gain and adiposity in rats. Taken together, our results indicate that Rehmannia glutinosa extract inhibits preadipocyte differentiation and adipogenesis in cultured cells and in rodent models of obesity.
Subject(s)
Adipocytes/drug effects , Adipogenesis/drug effects , CCAAT-Enhancer-Binding Protein-alpha/antagonists & inhibitors , CCAAT-Enhancer-Binding Protein-beta/antagonists & inhibitors , Obesity/prevention & control , Plant Extracts/pharmacology , 3T3-L1 Cells , Adipocytes/metabolism , Adipogenesis/genetics , Animals , CCAAT-Enhancer-Binding Protein-alpha/analysis , CCAAT-Enhancer-Binding Protein-alpha/metabolism , CCAAT-Enhancer-Binding Protein-beta/analysis , CCAAT-Enhancer-Binding Protein-beta/metabolism , Centromere/chemistry , Centromere/metabolism , Diet , Disease Models, Animal , Fats/administration & dosage , Fats/adverse effects , Fatty Acid-Binding Proteins/antagonists & inhibitors , Fatty Acid-Binding Proteins/metabolism , Male , Mice , Mitosis/drug effects , Obesity/chemically induced , Obesity/metabolism , Rats , Rats, Sprague-DawleyABSTRACT
Glucose and insulin stimulate leptin gene expression in vitro and in vivo. To identify cis-elements that are responsible for the glucose and insulin effects, mouse 3T3-L1 adipocytes were transiently transfected with reporter constructs with serial deletions in mouse ob gene promoter. The cis-elements were identified with Gel mobility shift assays (GMSA), DNase I footprint assays and PCR mediated site-directed mutation assays. Transient transfections detected a negative cis-acting element, a glucose-responsive element (GLRE), and an insulin-responsive element (IRE) in the region from -1 719 bp to -1 452 bp of mouse ob gene. This region does not contain any known GLRE or IRE. GMSA identified a DNA binding protein which specifically binds a native probe prepared from mouse ob gene promoter (-1 719 bp/-1 452 bp), and the binding was repressed by glucose or insulin. DNase I footprint assays and PCR mediated site-directed mutations assays identified that the binding motif AGCAAAA, spanning -1 698 bp to -1 692 bp of the mouse ob gene promoter, was responsible for the effects of glucose and insulin on ob gene expression. These studies suggest that a negative cis-acting element is located between -1 719 bp and -1 452 bp of the mouse ob gene promoter, and glucose and insulin simulate mouse ob gene expression by repressing the binding of a transcription factor to this element. This element, AGCAAAA, spanning -1 698 bp to -1 692 bp is a novel GLRE and IRE.
