53 research outputs found
Interaction of the v-rel protein with an NF-kappa B DNA binding site
The avian reticuloendotheliosis virus T contains within its genome the oncogene rel. The expression of this gene is responsible for the induction of lymphoid tumors in birds. Recently, the rel gene was shown to be related to the p50 DNA binding subunit of the transcription factor complex NF-kappa B. Binding sites for the NF-kappa B complex are found in the enhancer regions of a number of genes, including the immunoglobulin kappa gene and the human immunodeficiency virus long terminal repeat. In this communication we identify an activity from avian reticuloendotheliosis virus T-transformed avian lymphoid cells that binds in an electrophoretic-mobility-shift assay to an NF-kappa B binding site from the kappa enhancer. This activity contains proteins immunologically related to rel, as detected by polyclonal and monoclonal antibodies directed against v-rel. In a DNA affinity precipitation assay using the NF-kappa B site from the human immunodeficiency virus long terminal repeat, v-rel and several other proteins were identified. These data suggest that oncogenic transformation by v-rel is the result of an altered pattern of gene expression
The Avian Transcription Factor c-Rel is Expressed in Lymphocyte Precursor Cells and Antigen-Presenting Cells During Thymus Development
Transcription factors of the Rel/NF-κB family are widely involved in the immune system. In this
study, we investigate the in vivo expression of the avian protein c-Rel in the T-cell lineage during
thymus development. The majority of thymocytes do not express the c-Rel protein. However,
lymphocyte precursor cells that colonize the thymus express the c-Rel protein shortly after their
homing in the organ and before they begin to differentiate, c-Rel is also detected in different
subsets of,antigen-presenting cells such as epithelial cells, dendritic cells, and macrophages. In
vitro studies have shown that Rel/NF-κB proteins are sequestered in an inactive form in the
cytoplasm by interaction with the IκBα inhibitory protein. By immunocytochemistry, we show
that in vivo c-Rel is localized in the cytoplasm of antigen-presenting cells but in both the
cytoplasm and nucleus of lymphocyte precursor cells. The cytoplasmic localization of c-Rel in
antigen-presenting cells correlates with a high expression of IκBα, whereas the nuclear
localization of c-Rel in lymphocyte precursor cells correlates with a much lower expression of
IκBα. These results suggest that c-Rel might be constitutively activated in lymphocyte precursor
cells
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