Show simple item record

dc.contributor.authorSaleque, Shireen
dc.identifier.citationSource: Dissertation Abstracts International, Volume: 61-02, Section: B, page: 7720.;Advisors: Barbara K. Birshtein.
dc.description.abstractExpression and rearrangement of the murine immunoglobulin heavy chain (IgH) locus are regulated by an intronic enhancer, Emu, and a 3' regulatory region, consisting of four enhancers (Calpha3'E, 3'alphaE(hs1.2), hs3 and hs4). Genomic Southern and DNA sequence analysis of the 3' regulatory region revealed that a ∼25kb segment of DNA commencing at Calpha3'E and terminating at hs3 possessed a quasi-dyad symmetry, with 3'alphaE(hs1,2) at its center. Additionally, Calpha3'E, like 3'alpha(hs1,2) and hs3, but unlike hs4 which lies outside this dyad structure, exhibited DNase I hypersensitivity and transcriptional activity in plasma cell lines. These results led to a model in which the dyad structure of the 3' regulatory region was involved in co-ordinate regulation of the enhancers Calpha3'E, 3'alphaE(hs1,2) and hs3.;To test this hypothesis and assess the function of the 3' IgH enhancers in their native context, I utilized a naturally occurring deletion of two of these enhancers, hs3A and hs1,2 in a pre-B cell line, 70Z/3. mu expression in 70Z/3 was found to be comparable to that in a pre-B cell line with an intact 3'' region, indicating that hs3A and hs1,2 were not essential for mu expression at this stage. Furthermore, a 70Z/3-plastnacytoma fusion hybrid exhibited substantially elevated levels of mu RNA and protein relative to its pre-B parent and comparable to that observed in a number of mu-producing spleen cell hybridomas. Additionally, the hybrid cell line underwent spontaneous class switching in culture to IgG1 at a frequency comparable to most hybridomas. These results indicated that Calpha3'EE/hs3A and hs1,2 were not essential for high levels of IgH expression or for spontaneous class switching in a plasma cell line and implied a redundancy of enhancer function in the IgH locus at this stage.;Further analysis of the enhancer elements also led to the identification of a transcription factor Yin-Yang 1 (YY1) binding site in hs3, that is regulated in response to LPS, an in vitro switching stimulus. Mutation of the YY1 binding site in hs3 resulted in a 30--50% decrease in the activity of hs3 in a plasma cell line.;These studies have led to a more detailed delineation of the structure of the mouse 3' regulatory region, its role in influencing the various processes involved in heavy chain production, and identification of a new regulator of the 3' enhancers.
dc.publisherProQuest Dissertations & Theses
dc.subjectMolecular biology.
dc.titleStructure, function and regulation of IgH 3' enhancers

Files in this item


There are no files associated with this item.

This item appears in the following Collection(s)

Show simple item record