Negative Regulation of Disulfide-bond A Oxidoreductase-like Protein (DsbA-L) Gene Expression by the Transcription Factor Sp1

  1. Weiping Jia1
  1. 1Department 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 200233, China
  2. 2Department of Medicine, Medical School of Soochow University, Suzhou 215006, China
  3. 3Department of Pharmacology,
  4. 4Department of Developmental Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229, United States
  5. 5Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China.
  1. Corresponding author: Weiping Jia, E-mail: wpjia{at}sjtu.edu.cn

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 to -34 bp relative to the transcription start site. In silico analysis identified a putative Sp1 transcription factor binding site in the first intron of 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 cells 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 down-regulation and insulin resistance.

  • Received February 3, 2014.
  • Accepted July 6, 2014.

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This Article

  1. Diabetes