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Mol. Cell. Biol., 12 1997, 6970-6981, Vol 17, No. 12
PL Jones, D Ping and JM Boss
Manganese superoxide dismutase (MnSOD), a tumor necrosis factor (TNF)-
inducible reactive oxygen-scavenging enzyme, protects cells from TNF-
mediated apoptosis. To understand how MnSOD is regulated, transient
transfections of promoter-reporter gene constructions, in vitro DNA binding
assays, and in vivo genomic footprint (IVGF) analysis were carried out on
the murine MnSOD gene. The results of this analysis identified a 238-bp
region of intron 2 that was responsive to TNF and interleukin-1beta (IL-1).
This TNF response element (TNFRE) had the properties of a traditional
enhancer element that functioned in an orientation- and
position-independent manner. IVGF of the TNFRE revealed TNF- and
IL-1-induced factor occupancy of sites that could bind NF-kappaB and C/EBP.
The 5' portion of the TNFRE bound C/EBP-beta in vitro and was both
necessary and sufficient for TNF responsiveness with the MnSOD promoter or
with a heterologous promoter when in an upstream position. The 3' end of
the TNFRE bound both NF-kappaB and C/EBP but was not necessary for TNF
responsiveness with the MnSOD promoter. However, this 3' portion of the
TNFRE was required for the TNFRE to function as a downstream enhancer with
a heterologous promoter. These data functionally separate the MnSOD TNFRE
into a region responsible for TNF activation and one that mediates
induction when it is downstream of a promoter.
Copyright © 1997, American Society for Microbiology
Tumor necrosis factor alpha and interleukin-1beta regulate the murine manganese superoxide dismutase gene through a complex intronic enhancer involving C/EBP-beta and NF-kappaB
Department of Microbiology and Immunology, Emory University School of Medicine, Emory University, Atlanta, Georgia 30322, USA.
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