title: Differential pp40I kappa B-beta inhibition of DNA binding by rel proteins.
abstract: Regulation of gene expression by members of the NF-kappa B/rel transcription factor family is a central component of signal transduction pathways utilized by many cellular processes, including lymphocyte activation, embryonic development, and oncogenesis. The members of the NF-kappa B/rel transcription factor family are regulated by association with a family of inhibitor (I kappa B) proteins (I kappa B) proteins. To address the importance of the association between rel and I kappa B proteins for oncogenesis by rel proteins, we characterized rel-I kappa B interactions in chicken embryo fibroblasts (CEF) infected with retroviral vectors encoding the avian c-rel (p68c-rel), v-rel (p59v-rel), and I kappa B-beta (pp40I kappa B-beta) proteins. In these experiments, the p59v-rel:pp40I kappa B-beta ratio in coinfected CEF was nearly identical to the p59v-rel:pp40I kappa B-beta ratio in v-rel-transformed cells. The avian I kappa B-beta protein, pp40I kappa B-beta, was able to associate with both the nononcogenic p68c-rel and the oncogenic p59v-rel. Association of p68c-rel with pp40I kappa B-beta in coinfected CEF resulted in inhibition of the DNA-binding activity of p68c-rel. Anti-pp40I kappa B-beta serum was able to restore DNA binding to p68c-rel in the presence of high levels of pp40I kappa B-beta, indicating that pp40I kappa B-beta functions in a trans-acting manner to inhibit DNA binding by p68c-rel. In contrast, sequence-specific DNA binding by the oncogenic v-rel protein, p59v-rel, was not abolished by pp40I kappa B-beta in coinfected CEF. Anti-pp40I kappa B-beta serum did not immunoprecipitate the p59v-rel-DNA adduct or alter the electrophoretic mobility of the p59v-rel-DNA adduct, consistent with the idea that pp40I kappa B-beta and DNA are competitive inhibitors for the same or overlapping domains on rel proteins. Internal v-rel-derived sequences were identified that are responsible for loss of pp40I kappa B-beta-mediated inhibition of DNA binding by p59v-rel. Loss of pp40I kappa B-beta-mediated inhibition of DNA binding by recombinant v/c-rel proteins was not sufficient for oncogenic activation of c-rel. Instead, removal of C-terminal c-rel-derived sequences in addition to loss of pp40I kappa B-beta-mediated inhibition of DNA binding was required for oncogenic activation of c-rel. These results demonstrate the presence of an interaction between internal and C-terminal regions of the c-rel protein that is important for the ability of c-rel to regulate the proliferation of lymphoid cells.
authors.affiliation: Department of Biochemistry, University of Missouri-Columbia 65211.
authors.forename: J A
authors.initials: JA
authors.lastname: Diehl
authors.forename: T A
authors.initials: TA
authors.lastname: McKinsey
authors.forename: M
authors.initials: M
authors.lastname: Hannink
mesh_terms: D000818:Animals; D001483:Base Sequence; D001717:Birds; D002472:Cell Transformation, Viral; D002642:Chick Embryo; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology; D015972:Gene Expression Regulation, Neoplastic; D020672:I-kappa B Proteins; D008969:Molecular Sequence Data; D020572:Oncogene Proteins v-rel; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D020569:Proto-Oncogene Proteins c-rel; D012190:Retroviridae / Q000235:genetics*; D015682:Retroviridae Proteins, Oncogenic / Q000235:genetics / Q000378:metabolism*; D013154:Spleen / Q000166:cytology; D013329:Structure-Activity Relationship; D051841:Transcription Factor RelB; D014157:Transcription Factors
chemical_list: D004279:DNA, Viral; D004268:DNA-Binding Proteins; C083487:I kappa B beta protein; D020672:I-kappa B Proteins; D020572:Oncogene Proteins v-rel; D011518:Proto-Oncogene Proteins; D020569:Proto-Oncogene Proteins c-rel; D015682:Retroviridae Proteins, Oncogenic; D014157:Transcription Factors; D051841:Transcription Factor RelB