A novel pathway to enhance adipocyte differentiation of 3T3-L1 cells by up-regulation of lipocalin-type prostaglandin D synthase mediated by liver X receptor-activated sterol regulatory element-binding protein-1c.
Lipocalin-type prostaglandin (PG) D synthase (L-PGDS) is expressed in adipocytes and is proposed to be involved in the regulation of glucose tolerance and atherosclerosis in type 2 diabetes, because L-PGDS gene knock-out mice show abnormalities in these functions. However, the role of L-PGDS and the regulation mechanism governing its gene expression in adipocytes remain unclear. Here, we applied small interference RNA of L-PGDS to mouse 3T3-L1 cells and found that it suppressed differentiation of these cells into adipocytes. Reporter analysis of the mouse L-PGDS promoter demonstrated that a responsive element for liver receptor homolog-1 (LRH-1) at -233 plays a critical role in preadipocytic 3T3-L1 cells. Moreover, we identified two sterol regulatory elements (SREs) at -194 to be cis-elements for activation of L-PGDS gene expression in adipocytic 3T3-L1 cells. L-PGDS mRNA was induced in response to synthetic liver X receptor agonist, T0901317, through activation of the expression of SRE-binding protein-1c (SREBP-1c) in the adipocytic 3T3-L1 cells. The results of electrophoretic mobility shift assay and chromatin immunoprecipitation assay revealed that LRH-1 and SREBP-1c bound to their respective binding elements in the promoter of L-PGDS gene. Small interference RNA-mediated suppression of LRH-1 or SREBP-1c decreased L-PGDS gene expression in preadipocytic or adipocytic 3T3-L1 cells, respectively. These results indicate that L-PGDS gene expression is activated by LRH-1 in preadipocytes and by SREBP-1c in adipocytes. Liver X receptor-mediated up-regulation of L-PGDS through activation of SREBP-1c is a novel path-way to enhance adipocyte differentiation.
Fujimori
Ko
K
Department of Molecular Behavioral Biology, Osaka Bioscience Institute, 6-2-4 Furuedai, Suita, Osaka 565-0874, Japan.
Aritake
Kosuke
K
Department of Molecular Behavioral Biology, Osaka Bioscience Institute, 6-2-4 Furuedai, Suita, Osaka 565-0874, Japan.
Urade
Yoshihiro
Y
Department of Molecular Behavioral Biology, Osaka Bioscience Institute, 6-2-4 Furuedai, Suita, Osaka 565-0874, Japan. Electronic address: uradey@obi.or.jp.
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology* / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D047369:Chromatin Immunoprecipitation; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D006845:Hydrocarbons, Fluorinated; D019746:Intramolecular Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D054834:Lipocalins; D000071518:Liver X Receptors; D051379:Mice; D008969:Molecular Sequence Data; D057093:Orphan Nuclear Receptors; D012333:RNA, Messenger / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D051780:Sterol Regulatory Element Binding Protein 1 / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology; D015854:Up-Regulation; D005466:Fluorocarbons; D000096926:Benzenesulfonamides
D004268:DNA-Binding Proteins; D006845:Hydrocarbons, Fluorinated; D019746:Intramolecular Oxidoreductases; D054834:Lipocalins; D000071518:Liver X Receptors; D057093:Orphan Nuclear Receptors; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D051780:Sterol Regulatory Element Binding Protein 1; D013449:Sulfonamides; C423915:T0901317; D005466:Fluorocarbons; D000096926:Benzenesulfonamides; C022466:prostaglandin R2 D-isomerase