Inhibition of transcription factors belonging to the rel/NF-kappa B family by a transdominant negative mutant.
The KBF1 factor, which binds to the enhancer A located in the promoter of the mouse MHC class I gene H-2Kb, is indistinguishable from the p50 DNA binding subunit of the transcription factor NF-kappa B, which regulates a series of genes involved in immune and inflammatory responses. The KBF1/p50 factor binds as a homodimer but can also form heterodimers with the products of other members of the same family, like the c-rel and v-rel (proto)oncogenes. The dimerization domain of KBF1/p50 is contained between amino acids 201 and 367. A mutant of KBF1/p50 (delta SP), unable to bind to DNA but able to form homo- or heterodimers, has been constructed. This protein reduces or abolishes in vitro the DNA binding activity of wild-type proteins of the same family (KBF1/p50, c- and v-rel). This mutant also functions in vivo as a trans-acting dominant negative regulator: the transcriptional inducibility of the HIV long terminal repeat (which contains two potential NF-kappa B binding sites) by phorbol ester (PMA) is inhibited when it is co-transfected into CD4+ T cells with the delta SP mutant. Similarly the basal as well as TNF or IL1-induced activity of the MHC class I H-2Kb promoter can be inhibited by this mutant in two different cell lines. These results constitute the first formal demonstration that these genes are regulated by members of the rel/NF-kappa B family.
Unité de Biologie Moléculaire du Gène, U.277 Inserm-U.A. 535 CNRS, Paris, France.
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D000818:Animals; D001483:Base Sequence; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D002460:Cell Line; D002872:Chromosome Deletion; D004742:Enhancer Elements, Genetic; D005799:Genes, Dominant; D016325:HIV Long Terminal Repeat; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000235:genetics; D052002:NF-kappa B p50 Subunit; D020572:Oncogene Proteins v-rel; D010703:Phorbol Esters / Q000494:pharmacology; D015682:Retroviridae Proteins, Oncogenic / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*; D014162:Transfection
D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; C489548:NFKB1 protein, human; D020572:Oncogene Proteins v-rel; D010703:Phorbol Esters; D015682:Retroviridae Proteins, Oncogenic; D014157:Transcription Factors