Characterization of the joining chain (J-chain) promoter.
A 300 b.p. promoter from the mouse joining chain (J-chain) gene was studied with regard to functional activity and protein/DNA interactions. The promoter only stimulated expression of a chloramphenicol-acetyl-transferase (CAT) reporter gene when an enhancer was present in the construct, regardless of whether the construct was transfected into cell lines that did or did not express an endogenous J-chain. Furthermore, deletion mutants lacking the 5' portion of the promoter were transcribed at a higher rate than the intact promoter in both J-chain positive and J-chain negative B-cell lines but not in untransformed B lymphocytes stimulated by lipopolysaccharide, indicating the presence of a negative control element in the 5' portion of the J-chain promoter active in tumour cells only. The octamer element in the J-chain promoter was found to bind Oct proteins, albeit with a low affinity. The penta-deca (p.d.) element in the J-chain promoter bound proteins in extracts from untransformed B cells but not in the tested cell lines. The protein binding to the J-chain p.d. element did not compete efficiently with a p.d. element from the SP6 kappa promoter. A protein binding to the 5' portion of the J-chain was expressed in some cell lines but not in others; neither a negative nor a positive correlation to J-chain expression could be seen. It was concluded that the J-chain promoter is equivalent to a kappa promoter and that differentiation-specific J-chain expression is governed by distal, positive control elements located outside the analysed region.
Sigvardsson
M
M
Immunology Unit, Lund University, Sweden.
Olsson
L
L
Högbom
E
E
Leanderson
T
T
D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D001483:Base Sequence; D015152:Blotting, Northern; D002460:Cell Line; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D007144:Immunoglobulin J-Chains / Q000235:genetics / Q000378:metabolism*; D007145:Immunoglobulin kappa-Chains / Q000235:genetics / Q000378:metabolism; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D016385:TATA Box; D014162:Transfection
D004268:DNA-Binding Proteins; D007144:Immunoglobulin J-Chains; D007145:Immunoglobulin kappa-Chains