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  • The EMBO Journal (2005) 24, 510 - 520
  • doi:10.1038/sj.emboj.7600555

Published online: 20 January 2005

Positive and negative regulation of EAAT2 by NF-kappaB: a role for N-myc in TNFalpha-controlled repression

Raquel Sitcheran1, Pankaj Gupta2, Paul B Fisher2,3 and Albert S Baldwin1,4

  1. Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, NC, USA
  2. Department of Pathology, College of Physicians and Surgeons, Columbia University Medical Center, New York, NY, USA
  3. Departments of Neurosurgery and Urology, College of Physicians and Surgeons, Columbia University Medical Center, New York, NY, USA
  4. Department of Biology, University of North Carolina at Chapel Hill, NC, USA

Correspondence to:

Albert S Baldwin, 22-000 Lineberger Comprehensive Cancer Center, CB#7295, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7295, USA. Tel.: +1 919 966 3652; Fax: +1 919 966 0444; E-mail: abaldwin@med.unc.edu or jhall@med.unc.edu

Received 21 June 2004; Accepted 21 December 2004

The glutamate transporter gene, EAAT2/GLT-1, is induced by epidermal growth factor (EGF) and downregulated by tumor necrosis factor alpha (TNFalpha). While TNFalpha is generally recognized as a positive regulator of NF-kappaB-dependent gene expression, its ability to control transcriptional repression is not well characterized. Additionally, the regulation of NF-kappaB by EGF is poorly understood. Herein, we demonstrate that both TNFalpha-mediated repression and EGF-mediated activation of EAAT2 expression require NF-kappaB. We show that EGF activates NF-kappaB independently of signaling to IkappaB. Furthermore, TNFalpha can abrogate IKKbeta- and p65-mediated activation of EAAT2. Our results suggest that NF-kappaB can intrinsically activate EAAT2 and that TNFalpha mediates repression through a distinct pathway also requiring NF-kappaB. Consistently, we find that N-myc is recruited to the EAAT2 promoter with TNFalpha and that N-myc-binding sites are required for TNFalpha-mediated repression. Moreover, N-myc overexpression inhibits both basal and p65-induced activation of EAAT2. Our data highlight the remarkable specificity of NF-kappaB activity to regulate gene expression in response to diverse cellular signals and have implications for glutamate homeostasis and neurodegenerative disease.

  • Keywords:

    • EAAT2,
    • EGF,
    • N-myc,
    • NF-kappaB,
    • TNFalpha