A dissection of enhancer function within the immunoglobulin heavy chain locus, using transgenes and the transcription factor BSAP.
Item
-
Title
-
A dissection of enhancer function within the immunoglobulin heavy chain locus, using transgenes and the transcription factor BSAP.
-
Identifier
-
AAI3063797
-
identifier
-
3063797
-
Creator
-
Alaie-Petrillo, Adrienne Simin.
-
Contributor
-
Adviser: Laurel A. Eckhardt
-
Date
-
2002
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Biology, Molecular | Health Sciences, Immunology
-
Abstract
-
Five enhancers within the immunoglobulin heavy chain (IgH) locus serve to regulate transcription of the IgH genes in a stage-specific manner. In Ig-secreting cells, four 3' enhancers (hs3a, hs1,2, hs3b, hs4) can drive IgH gene expression in the absence of the intronic enhancer (Emu). BSAP (B&barbelow;-cell-s&barbelow;pecific a&barbelow;ctivating p&barbelow;rotein) is a transcription factor expressed in pro-B, pre-B, and surface Ig-positive cells but not in Ig-secreting cells. BSAP was shown to repress the 3 ' enhancer element hs1,2 in transient transfection assays. It was suggested, therefore, that BSAP suppresses 3' IgH enhancer function through much of B cell development, releasing this region of enhancers from suppression only when surface Ig+ cells are activated to differentiate into Ig-secreting cells. To test this hypothesis, we introduced a BSAP-expressing vector into an Emu-deficient Ig-secreting plasmacytoma. Since Emu is not available to compensate for loss of 3' enhancer function in this cell line, BSAP expression should result in a dramatic decrease in IgH gene expression if BSAP is indeed a repressor of 3 'IgH enhancer function. We found, however, that ectopic expression of BSAP in this Ig-secreting cell line had very little effect on IgH gene expression. We conclude, therefore, that ectopically expressed BSAP, on its own, is not capable of repressing, in a global fashion, the 3' IgH enhancer region when produced within an established plasmacytoma.;Three of the four IgH 3' enhancers (hs 1,2, hs3b, hs4), were shown to function as a l&barbelow;ocus c&barbelow;ontrol r&barbelow;egion (LCR), in that they directed tissue-specific, insertion site-independent, and copy number-dependent expression of their linked transgene in stable transfections. However, recent studies failed to confirm these earlier findings, observing instead, only partial-LCR like activity. None of the research to date examined the IgH 3' enhancers' ability to function as an LCR while in their native orientation and spacing as the enhancers span too large a distance to be mimicked in conventional cloning vectors. Using b&barbelow;acterial a&barbelow;rtificial c&barbelow;hromosome technology (BAC), we tested whether the 3' enhancers, in their native orientation and spacing, could direct insertion site-independent, copy-number dependent expression. We found that the IgH 3' enhancers do not display classical LCR behavior.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
