Selection against N-region diversity in immunoglobulin heavy chain variable regions during the development of pre-immune B cell repertoires

1992 ◽  
Vol 4 (5) ◽  
pp. 549-553 ◽  
Author(s):  
L. Carlsson ◽  
C. Övermo ◽  
D. Holmberg
Keyword(s):  
B Cell ◽  
Heavy Chain ◽  
Immunoglobulin Heavy Chain ◽  
Variable Regions

scholarly journals Mouse Lymphoid Cell Line Selected To Have High Immunoglobulin Promoter Activity

2002 ◽  
Vol 22 (5) ◽  
pp. 1460-1473 ◽  
Author(s):  
Dean Tantin ◽  
Phillip A. Sharp
Keyword(s):  
B Cell ◽  
Cell Line ◽  
Heavy Chain ◽  
Lymphoid Cell ◽  
Transcription Initiation ◽  
Promoter Activity ◽  
Immunoglobulin Heavy Chain ◽  
Parental Line ◽  
Lymphoid Cell Line ◽  
Variable Regions

ABSTRACT Immunoglobulin variable region promoters are predominantly B-cell specific, but the molecular basis for this specificity has not been elucidated. To further understand how B-cell-specific immunoglobulin promoter expression is mediated, the murine lymphoid cell line 2017 was engineered to express the green fluorescent protein under the control of an immunoglobulin heavy chain promoter and selected for high activity using multiple rounds of fluorescence-activated cell sorting. Rare clones with intense and stable immunoglobulin promoter activity were isolated. Transient transfection experiments demonstrated that two different immunoglobulin promoters and two other B-cell-specific promoters have higher activities in the selected cell lines relative to the parental line and to the non-cell-type-specific histone H2B promoter. The increased immunoglobulin activity required nucleotide residues downstream of the transcription initiation site which were also important for maximal activity in B cells and which were conserved in other B-cell-specific promoters. Unlike the unselected cells, the 2017 variants also showed activation of their endogenous immunoglobulin heavy chain variable regions.

scholarly journals Rate of replication of the murine immunoglobulin heavy-chain locus: evidence that the region is part of a single replicon.

1987 ◽  
Vol 7 (1) ◽  
pp. 450-457 ◽  
Author(s):  
E H Brown ◽  
M A Iqbal ◽  
S Stuart ◽  
K S Hatton ◽  
J Valinsky ◽  
...  
Keyword(s):  
B Cell ◽  
Cell Line ◽  
Gene Cluster ◽  
Cell Lines ◽  
Heavy Chain ◽  
Dna Content ◽  
Immunoglobulin Heavy Chain ◽  
S Phase ◽  
C Value ◽  
Murine Erythroleukemia

We measured the temporal order of replication of EcoRI segments from the murine immunoglobulin heavy-chain constant region (IgCH) gene cluster, including the joining (J) and diversity (D) loci and encompassing approximately 300 kilobases. The relative concentrations of EcoRI segments in bromouracil-labeled DNA that replicated during selected intervals of the S phase in Friend virus-transformed murine erythroleukemia (MEL) cells were measured. From these results, we calculated the nuclear DNA content (C value; the haploid DNA content of a cell in the G1 phase of the cell cycle) at the time each segment replicated during the S phase. We observed that IgCH genes replicate in the following order: alpha, epsilon, gamma 2a, gamma 2b, gamma 1, gamma 3, delta, and mu, followed by the J and D segments. The C value at which each segment replicates increased as a linear function of its distance from C alpha. The average rate of DNA replication in the IgCH gene cluster was determined from these data to be 1.7 to 1.9 kilobases/min, similar to the rate measured for mammalian replicons by autoradiography and electron microscopy (for a review, see H. J. Edenberg and J. A. Huberman, Annu. Rev. Genet. 9:245-284, 1975, and R. G. Martin, Adv. Cancer Res. 34:1-55, 1981). Similar results were obtained with other murine non-B cell lines, including a fibroblast cell line (L60T) and a hepatoma cell line (Hepa 1.6). In contrast, we observed that IgCh segments in a B-cell plasmacytoma (MPC11) and two Abelson murine leukemia virus-transformed pre-B cell lines (22D6 and 300-19O) replicated as early as (300-19P) or earlier than (MPC11 and 22D6) C alpha in MEL cells. Unlike MEL cells, however, all of the IgCH segments in a given B cell line replicated at very similar times during the S phase, so that a temporal directionality in the replication of the IgCH gene cluster was not apparent from these data. These results provide evidence that in murine non-B cells the IgCH, J, and D loci are part of a single replicon.

Immunoglobulin heavy-chain enhancer is required to maintain transfected gamma 2A gene expression in a pre-B-cell line

1990 ◽  
Vol 10 (3) ◽  
pp. 1076-1083
Author(s):  
B Porton ◽  
D M Zaller ◽  
R Lieberson ◽  
L A Eckhardt
Keyword(s):  
B Cell ◽  
Cell Lines ◽  
Heavy Chain ◽  
Gene Activation ◽  
Immunoglobulin Heavy Chain ◽  
Transcription Unit ◽  
Enhancer Activity ◽  
Igh Genes ◽  
High Level

The immunoglobulin heavy-chain (IgH) enhancer serves to activate efficient and accurate transcription of cloned IgH genes when introduced into B lymphomas or myelomas. The role of this enhancer after gene activation, however, is unclear. The endogenous IgH genes in several cell lines, for example, have lost the IgH enhancer by deletion and yet continue to be expressed. This might be explained if the role of the enhancer were to establish high-level gene transcription but not to maintain it. Alternatively, other enhancers might lie adjacent to endogenous IgH genes, substituting their activity for that of the lost IgH enhancer. To address both of these alternatives, we searched for enhancer activity within the flanking regions of one of these IgH enhancer-independent genes and designed an experiment that allowed us to consider separately the establishment and maintenance of expression of a transfected gene. For the latter experiment we generated numerous pre-B cell lines stably transformed with a gamma 2a gene. In this gene, the IgH enhancer lay at a site outside the heavy-chain transcription unit, between DH and JH gene segments. After expression of the transfected gene was established, selective conditions were chosen for the outgrowth of subclones that had undergone D-J joining and thus IgH enhancer deletion. Measurements of gamma 2a expression before and after enhancer deletion revealed that the enhancer was required for maintenance of expression of the transfected gene. The implication of this finding for models of enhancer function in endogenous genes is discussed.

Pi, a pre-B-cell-specific enhancer element in the immunoglobulin heavy-chain enhancer

1993 ◽  
Vol 13 (10) ◽  
pp. 5957-5969
Author(s):  
T A Libermann ◽  
D Baltimore
Keyword(s):  
B Cell ◽  
Heavy Chain ◽  
Mutational Analysis ◽  
Protein S ◽  
Immunoglobulin Heavy Chain ◽  
Chain Gene ◽  
Cell Stage ◽  
Enhancer Activity ◽  
Enhancer Element ◽  
Light Chain Gene

We have identified a new immunoglobulin heavy-chain enhancer element, designated pi, between the microE2 and microE3 elements. The pi enhancer element is transcriptionally active primarily during early stages of B-cell development but becomes virtually inactive during B-cell maturation at about the stage of immunoglobulin kappa light-chain gene rearrangement. Mutational analysis suggests that the pi element is crucial for immunoglobulin heavy-chain enhancer activity at the pre-B-cell stage but is almost irrelevant for enhancer activity at the mature B-cell or plasma-cell stage. The activity of the pi enhancer element correlates with the presence of an apparently pre-B-cell-specific protein-DNA complex. The similarity of the pi site to recognition sequences for members of the ets gene family suggests that the protein(s) interacting with the pi site most likely are ets-related transcription factors.

A second B cell-specific enhancer 3' of the immunoglobulin heavy-chain locus

Nature ◽  
1990 ◽  
Vol 344 (6262) ◽  
pp. 165-168 ◽  
Author(s):  
Sven Pettersson ◽  
Graham P. Cook ◽  
Marianne Brüggemann ◽  
Gareth T. Williams ◽  
Michael S. Neuberger
Keyword(s):  
B Cell ◽  
Heavy Chain ◽  
Immunoglobulin Heavy Chain ◽  
Chain Locus ◽  
Heavy Chain Locus

scholarly journals Changes in Locus-specific V(D)J Recombinase Activity Induced by Immunoglobulin Gene Products during B Cell Development

1997 ◽  
Vol 185 (4) ◽  
pp. 609-620 ◽  
Author(s):  
Andrei Constantinescu ◽  
Mark S. Schlissel
Keyword(s):  
B Cells ◽  
B Cell ◽  
Heavy Chain ◽  
Light Chain ◽  
Immunoglobulin Heavy Chain ◽  
Cell Development ◽  
B Cell Development ◽  
Allelic Exclusion ◽  
Chain Locus ◽  
Heavy Chain Locus

The process of V(D)J recombination is crucial for regulating the development of B cells and for determining their eventual antigen specificity. Here we assess the developmental regulation of the V(D)J recombinase directly, by monitoring the double-stranded DNA breaks produced in the process of V(D)J recombination. This analysis provides a measure of recombinase activity at immunoglobulin heavy and light chain loci across defined developmental stages spanning the process of B cell development. We find that expression of a complete immunoglobulin heavy chain protein is accompanied by a drastic change in the targeting of V(D)J recombinase activity, from being predominantly active at the heavy chain locus in pro-B cells to being exclusively restricted to the light chain loci in pre-B cells. This switch in locus-specific recombinase activity results in allelic exclusion at the immunoglobulin heavy chain locus. Allelic exclusion is maintained by a different mechanism at the light chain locus. We find that immature, but not mature, B cells that already express a functional light chain protein can undergo continued light chain gene rearrangement, by replacement of the original rearrangement on the same allele. Finally, we find that the developmentally regulated targeting of V(D)J recombination is unaffected by enforced rapid transit through the cell cycle induced by an Eμ-myc transgene.

Sign in / Sign up

Export Citation Format

Share Document