title: The human lambda immunoglobulin enhancer is controlled by both positive elements and developmentally regulated negative elements.
abstract: We have recently reported the localization of the first transcriptional enhancer in the human lambda (lambda) immunoglobulin light chain locus. Enhancer activity was contained on a 1.2 kb SstI fragment, with partial activity retained on a core 111 bp PstI-SstI fragment. This enhancer is located 11.7 kb downstream of C lambda 7, the most 3' lambda constant region gene. Using a chloramphenicol acetyl transferase (CAT) assay system, we have now determined the boundaries of the complete enhancer and find it is two- to four-fold as active as the core fragment in both pre-B and B cell lines. Interestingly, a larger fragment, containing the complete enhancer as well as 5' and 3' flanking sequences has four- to eight-fold reduced activity when tested in pre-B cell lines, but full activity in B cell lines. This suggests the presence of developmentally regulated negative elements flanking the human lambda enhancer which prevent or reduce its activity at a developmentally incorrect time. By using in vivo footprinting we have begun to examine the protein interactions within this enhancer in a more physiologically relevant manner and have identified motifs which are shared with the murine lambda enhancers, as well as motifs unique to the human lambda enhancer.
authors.affiliation: Department of Microbiology and Immunology, University of Miami School of Medicine, FL 33101, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Glozak
authors.forename: B B
authors.initials: BB
authors.lastname: Blomberg
mesh_terms: D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004742:Enhancer Elements, Genetic; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D007146:Immunoglobulin lambda-Chains / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data
chemical_list: D007146:Immunoglobulin lambda-Chains