title: Complex regulation of the immunoglobulin mu heavy-chain gene enhancer: microB, a new determinant of enhancer function.
abstract: The B-lymphocyte-specific activity of the immunoglobulin mu heavy-chain gene enhancer has been attributed to the octamer motif (ATTTGCAT) present within the enhancer that binds a B-cell-specific factor designated NF-A2/OTF-2. However, significant residual enhancer activity even after deletion of this element has suggested the presence of a second critical functional determinant. We have used deletion and mutational analyses to define an element, microB (TTTGGGGAA), that is essential for B-cell-specific enhancer activity in S194 myeloma cells in the absence of the octamer. Transfection analysis in a panel of lymphoid cell lines suggests that the presence of either microB or octamer leads to considerable enhancer activity in cell lines representing later stages of B-cell differentiation, whereas both elements are needed for function in cell lines representing earlier stages. Furthermore, in contrast to the results in pre-B-cell lines, both microB and octamer elements function independently in certain T-cell lines in which the mu enhancer is active.
authors.affiliation: Rosenstiel Basic Medical Sciences Research Center, Waltham, Massachusetts.
authors.forename: B
authors.initials: B
authors.lastname: Nelsen
authors.forename: T
authors.initials: T
authors.lastname: Kadesch
authors.forename: R
authors.initials: R
authors.lastname: Sen
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology; D001483:Base Sequence; D002460:Cell Line; D002872:Chromosome Deletion; D003001:Cloning, Molecular; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D005803:Genes, Immunoglobulin; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007148:Immunoglobulin mu-Chains / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D015345:Oligonucleotide Probes; D010957:Plasmids; D015183:Restriction Mapping; D014162:Transfection
chemical_list: D007143:Immunoglobulin Heavy Chains; D007148:Immunoglobulin mu-Chains; D015345:Oligonucleotide Probes