Identification of novel ubiquitous and cell type-specific factors that specifically recognize immunoglobulin heavy chain and kappa light chain promoters.
In a search for novel factors that interact with the octamer element, immunoglobulin kappa light chain (V kappa) and heavy chain VH) gene promoters were compared for binding to nuclear proteins from lymphoid cells. Both promoters showed a similar pattern of bound factors, which was entirely different from that seen with the human immunodeficiency virus, type I promoter. Besides OTF-1 (Oct-1) and OTF-2 (Oct-2), at least three additional complexes were observed. Two of these were functionally analyzed: C1, a slowly migrating complex, which was much more abundant in B cells than in non-lymphoid cells, and C4, which appeared to have ubiquitous distribution. As determined by several methods, the protein(s) forming the C1 complex bound on the V kappa gene to a site that partially covers the octamer element, whereas, surprisingly, in the VH gene a region spanning the TATA box up to the transcriptional initiation site was recognized. The ubiquitous C4 complex was analyzed for the light chain promoter. The protein specifically bound to a site immediately 5' to the octamer. By in vitro transcription analysis, we found that C4 augments the octamer-dependent transcription of the V kappa gene. The activation required binding of OTF-1/OTF-2, and C4 could not stimulate transcription by itself, implying a synergistic interaction. Due to the overlapping binding sites, the effect of C1 by itself could not be clearly separated from the C4 effect. However, the specific interaction of C1 with crucial control elements of light chain and heavy chain promoters strongly suggests a functional role in immunoglobulin gene transcription control.
Franke
S
S
Max-Planck-Institut für Molekulare Genetik, Otto-Warburg Laboratorium, Berlin, Germany.
Scholz
G
G
Scheidereit
C
C
D001402:B-Lymphocytes / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D004247:DNA; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007145:Immunoglobulin kappa-Chains / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic
D004268:DNA-Binding Proteins; D007143:Immunoglobulin Heavy Chains; D007145:Immunoglobulin kappa-Chains; D004247:DNA