title: Regulatory elements of the mb-1 gene encoding the Ig-alpha component of the human B-cell antigen receptor.
abstract: The mb-1 gene encodes the Ig-alpha component of the B-cell antigen receptor. It is specifically expressed in pre-B and mature B cells but not in plasma cells losing membrane Ig (mIg) expression. We looked for transcriptional regulatory elements within a 12 kb genomic fragment. A strong promoter activity was found in a 591 bp fragment harboring consensus binding sites for known transcription factors including Ets, EBF/BlyF, LyF1/micro B and Spl. It was able to drive transcription of a reporter gene in the absence of any additional enhancer and was mostly active in B lymphocytes not in plasma cells or T cells. Although no fragment from the mb-1 gene displayed enhancer activity in combination with either the SV40, a Ig VH or a Ig VL promoter, a 1078 bp fragment corresponding to the 5' part of the gene behaved as a strong enhancer in either orientation in constructs driven by the mb-1 promoter itself. Deletions within this fragment allowed to delineate shorter sequences with enhancer activity upstream the first exon. The tissue-restricted, promoter-restricted and stage-specific activity of this 5' flanking region suggests that it is the main regulatory element of the mb-1 gene.
authors.affiliation: Laboratoire d'Immunologie et Immunogénétique, CNRS EP 118 Faculté de Médecine de Limoges, France.
authors.forename: I
authors.initials: I
authors.lastname: Leduc
authors.forename: M
authors.initials: M
authors.lastname: Cogne
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D002051:Burkitt Lymphoma; D051925:CD79 Antigens; D002454:Cell Differentiation / Q000235:genetics; D004742:Enhancer Elements, Genetic; D017353:Gene Deletion; D005803:Genes, Immunoglobulin; D006801:Humans; D019169:Jurkat Cells; D051379:Mice; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000235:genetics; D011401:Promoter Regions, Genetic; D011947:Receptors, Antigen, B-Cell / Q000235:genetics* / Q000276:immunology / Q000378:metabolism*; D012045:Regulatory Sequences, Nucleic Acid / Q000276:immunology*
chemical_list: D015703:Antigens, CD; D051925:CD79 Antigens; C497881:CD79A protein, human; C497882:Cd79a protein, mouse; D011947:Receptors, Antigen, B-Cell