title: Negative regulation of DsbA-L gene expression by the transcription factor Sp1.
abstract: Disulfide-bond A oxidoreductase-like protein (DsbA-L) possesses beneficial effects such as promoting adiponectin multimerization and stability, increasing insulin sensitivity, and enhancing energy metabolism. The expression level of DsbA-L is negatively correlated with obesity in mice and humans, but the underlying mechanisms remain unknown. To address this question, we generated reporter gene constructs containing the promoter sequence of the mouse DsbA-L gene. Deletion analysis showed that the proximal promoter of mouse DsbA-L is located between -186 and -34 bp relative to the transcription start site. In silico analysis identified a putative Sp1 transcription factor binding site in the first intron of the DsbA-L gene. Electrophoretic mobility shift assay and chromatin immunoprecipitation analysis indicated that Sp1 bound to this intron region in vitro and in intact cells. Overexpression of Sp1 or suppressing Sp1 expression by siRNA reduced or increased DsbA-L promoter activity, respectively. The binding activity of Sp1 was gradually decreased during 3T3-L1 cell differentiation and was significantly increased in adipose tissues of obese mice. Our results identify Sp1 as an inhibitor of DsbA-L gene transcription, and the Sp1-mediated inhibition of DsbA-L gene expression may provide a mechanism underlying obesity-induced adiponectin downregulation and insulin resistance.
authors.affiliation: Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Clinical Center for Diabetes, Shanghai, China.
authors.forename: Qichen
authors.initials: Q
authors.lastname: Fang
authors.affiliation: Department of Medicine, Medical School of Soochow University, Suzhou, China.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Yang
authors.affiliation: Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Clinical Center for Diabetes, Shanghai, China.
authors.forename: Huating
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Clinical Center for Diabetes, Shanghai, China.
authors.forename: Wenxiu
authors.initials: W
authors.lastname: Hu
authors.affiliation: Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, Second Xiangya Hospital, Central South University, Changsha, China.
authors.forename: Lihui
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Clinical Center for Diabetes, Shanghai, China.
authors.forename: Shan
authors.initials: S
authors.lastname: Jiang
authors.affiliation: Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Clinical Center for Diabetes, Shanghai, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Dong
authors.affiliation: Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Clinical Center for Diabetes, Shanghai, China.
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Song
authors.affiliation: Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Clinical Center for Diabetes, Shanghai, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Developmental Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX.
authors.forename: Shuo
authors.initials: S
authors.lastname: Chen
authors.affiliation: Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, Second Xiangya Hospital, Central South University, Changsha, China Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX.
authors.forename: Feng
authors.initials: F
authors.lastname: Liu
authors.affiliation: Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Clinical Center for Diabetes, Shanghai, China wpjia@sjtu.edu.cn.
authors.forename: Weiping
authors.initials: W
authors.lastname: Jia
mesh_terms: D041721:3T3-L1 Cells; D052242:Adiponectin / Q000378:metabolism; D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D002454:Cell Differentiation / Q000235:genetics; D003198:Computer Simulation; D015536:Down-Regulation; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation; D005982:Glutathione Transferase / Q000235:genetics* / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D007438:Introns / Q000235:genetics; D051379:Mice; D009765:Obesity / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D016329:Sp1 Transcription Factor / Q000378:metabolism*
chemical_list: D052242:Adiponectin; D016329:Sp1 Transcription Factor; D005982:Glutathione Transferase; C568627:glutathione transferase kappa, mouse