Tumor Necrosis Factor-α Suppresses Adipocyte-Specific Genes and Activates Expression of Preadipocyte Genes in 3T3-L1 Adipocytes

Nuclear Factor-κB Activation by TNF-α Is Obligatory

  1. Hong Ruan1,
  2. Nir Hacohen1,
  3. Todd R. Golub12,
  4. Luk Van Parijs34 and
  5. Harvey F. Lodish13
  1. 1Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, Massachusetts
  2. 2Dana-Farber Cancer Institute and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts
  3. 3Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts
  4. 4Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts

    Abstract

    Tumor necrosis factor-α (TNF-α) is a contributing cause of the insulin resistance seen in obesity and obesity-linked type 2 diabetes, but the mechanism(s) by which TNF-α induces insulin resistance is not understood. By using 3T3-L1 adipocytes and oligonucleotide microarrays, we identified 142 known genes reproducibly upregulated by at least threefold after 4 h and/or 24 h of TNF-α treatment, and 78 known genes downregulated by at least twofold after 24 h of TNF-α incubation. TNF-α-induced genes include transcription factors implicated in preadipocyte gene expression or NF-κB activation, cytokines and cytokine-induced proteins, growth factors, enzymes, and signaling molecules. Importantly, a number of adipocyte-abundant genes, including GLUT4, hormone sensitive lipase, long-chain fatty acyl-CoA synthase, adipocyte complement-related protein of 30 kDa, and transcription factors CCAAT/enhancer binding protein-α, receptor retinoid X receptor-α, and peroxisome profilerator-activated receptor γ were significantly downregulated by TNF-α treatment. Correspondingly, 24-h exposure of 3T3-L1 adipocytes to TNF-α resulted in reduced protein levels of GLUT4 and several insulin signaling proteins, including the insulin receptor, insulin receptor substrate 1 (IRS-1), and protein kinase B (AKT). Nuclear factor-κB (NF-κB) was activated within 15 min of TNF-α addition. 3T3-L1 adipocytes expressing IκBα-DN, a nondegradable NF-κB inhibitor, exhibited normal morphology, global gene expression, and insulin responses. However, absence of NF-κB activation abolished suppression of >98% of the genes normally suppressed by TNF-α and induction of 60–70% of the genes normally induced by TNF-α. Moreover, extensive cell death occurred in IκBα-DN-expressing adipocytes after 2 h of TNF-α treatment. Thus the changes in adipocyte gene expression induced by TNF-α could lead to insulin resistance. Further, NF-κB is an obligatory mediator of most of these TNF-α responses.

    Footnotes

    • Address correspondence and reprint requests to Professor Harvey F. Lodish, Whitehead Institute for Biomedical Research, 9 Cambridge Center, Room 601, Cambridge, MA 02142. E-mail: lodish{at}wi.mit.edu.

      Received for publication 27 December 2001 and accepted in revised form 18 February 2002.

      ACRP30, adipocyte complement-related protein of 30 kDa; Adm, adrenomedullin; AKT, protein kinase B; AP-1, activator protein 1; Bcl-3, B-cell leukemia/lymphoma-3; CDK, cyclin-dependent kinase; CEBP-α, CCAAT/enhancer binding protein-α; EST, expressed sequence tag; Fra-1, Fos-related antigen-1; GATA-6, GATA-binding protein 6; GFP, green fluorescent protein; HMGP-1C, high mobility group protein-1 isoform C; HSL, hormone-sensitive lipase; IKK, IκB kinase; IKKi, inducible IKK; IL-6, interleukin 6; IR, insulin receptor; IRS-1, IR substrate 1; LPSBP, lipopolysaccharide binding protein; LTR, long terminal repeat; MAPKKK, mitogen-activated protein kinase kinase kinase; MMP-3, matrix metalloproteinase 3; NF-κB, nuclear factor-κB; PAI-1, plasminogen activator inhibitor 1; pMIG, pMSCV-IRES-GFP; pIκBα-DN, pMSCV-IκBα__DN-IRES-GFP; PPAR-γ, peroxisome profilerator-activated receptor γ; RXR, receptor retinoid X receptor-α; Spi2-1, serine protease inhibitor 2-1; TNF, tumor necrosis factor-α; VCAM-1, vascular cell adhesion molecule 1.

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