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J. Virol., 10 1995, 6335-6341, Vol 69, No. 10
SD Estes, DL Stoler and GR Anderson
Cells exposed to hypoxia undergo substantial changes in gene expression
generally associated with metabolic adaptation and increasing oxygen
delivery. In contrast, responses distinct from those elicited by hypoxia
are induced in anoxic fibroblasts; this includes activation of a set of
VL30 elements. The responses seen in anoxically cultured fibroblasts are
expressed physiologically in vivo during the anaerobic phase of wound
healing. A fundamental question is whether transcriptional regulatory
pathways utilized during anoxia are distinct from those already
characterized for hypoxic cells. We report here the isolation of a 14-bp
sequence within a VL30 retrotransposon promoter which mediates its anoxia
responsiveness. Analyses of the protein complexes binding to this sequence
demonstrated the presence of two distinct inducible DNA binding activities.
The first is present in both hypoxic and anoxic fibroblasts and is
indistinguishable from hypoxia- inducible factor 1. The second activity,
which is present only in anoxic fibroblasts, is a previously
uncharacterized heterodimeric DNA binding activity that appears to arise
via posttranslational modification of an existing complex found in aerobic
cells. These results indicate that the strong VL30 transcriptional
induction seen with anoxia occurs through a mechanism specific to anoxia.
Copyright © 1995, American Society for Microbiology
Anoxic induction of a sarcoma virus-related VL30 retrotransposon is mediated by a cis-acting element which binds hypoxia-inducible factor 1 and an anoxia-inducible factor
Department of Molecular and Cellular Biology, Roswell Park, Cancer Institute, Buffalo, New York 14263, USA.
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