Coordinated transcriptional control of adipocyte triglyceride lipase (Atgl) by transcription factors Sp1 and peroxisome proliferator–activated receptor γ (PPARγ) during adipocyte differentiation

• DOI: 10.1074/jbc.m117.783043
• Publication Date: 2017-07-19T00:10:12Z
• Authors: Debasish Roy; Kenneth T. Farabaugh; Jing Wu; Alyssa Charrier; Cynthia Smas; Maria Hatzoglou; Kavitha Thirumurugan; David A. Buchner
• Keywords: Adipose triglyceride lipase; Triglyceride lipase

The breakdown of stored fat deposits into its components is a highly regulated process that maintains plasma levels free fatty acids to supply energy cells. Insulin-mediated transcription Atgl, the enzyme mediates rate-limiting step in lipolysis, key point this regulation. Under conditions such as obesity or insulin resistance, Atgl often misregulated, which can contribute overall disease progression. mechanisms by induced during adipogenesis are not fully understood. We utilized computational approaches identify putative transcriptional regulatory elements and then tested effect these factors bind them cultured preadipocytes mature adipocytes. Here we report down-regulated basal factor Sp1 magnitude down-regulation depends on interactions between peroxisome proliferator–activated receptor γ (PPARγ). In adipocytes, when PPARγ abundant, abrogated repression at promoter up-regulated mRNA expression. 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Analysis approximately DNA sequence immediately Genomatix TRANSFAC matrices revealed Sp1-binding minimal (−50 −36 bp). across numerous species, mice humans, suggesting biological function (Fig. 1A). Therefore, test were co-transfected luciferase reporter constructs varying 5′ end deletions vector. overexpression significantly activity all constructs, indicating region (−192 +21) negatively affect 1B). examined predicted selectively mutating five nucleotides (−46 5′-CCGCC-3′ −42), shown Fig. 1C. These mutations completely prevented inhibitory 1D), confirming Atgl. When transfected variable-length promoter-luciferase incubated mithramycin A, inhibitor, 24 h, endogenous −192/+21 −373/+21 containing 1E). demonstrates exerts −50. significance was investigated depletion studies Knockdown lentiviral vector producing shRNA targeting relative 2, B). Conversely, electroporation C D) resulted lower ATGL E F) concomitant reduction medium 2G). treated (10 μm) showed presence absence 2H). 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