Novel control motif cluster in the IgH delta-gamma 3 interval exhibits B cell-specific enhancer function in early development.
The majority of the human Ig heavy chain (IgH) constant (C) region locus has been cloned and mapped. An exception is the region between C delta and C gamma 3, which is unstable and may be a recombination hot spot. We isolated a pBAC clone (pHuIgH3'delta-gamma 3) that established a 52-kb distance between C delta and C gamma 3. Sequence analysis identified a high number of repeat elements, explaining the instability of the region, and an unusually large accumulation of transcription factor-binding motifs, for both lymphocyte-specific and ubiquitous transcription activators (IKAROS, E47, Oct-1, USF, Myc/Max), and for factors that may repress transcription (Delta EF1, Gfi-1, E4BP4, C/EBP beta). Functional analysis in reporter gene assays revealed the importance of the C delta-C gamma 3 interval in lymphocyte differentiation and identified independent regions capable of either enhancement or silencing of reporter gene expression and interaction with the IgH intron enhancer E mu. In transgenic mice, carrying a construct that links the beta-globin reporter to the novel delta-gamma 3 intron enhancer (E delta-gamma 3), transgene transcription is exclusively found in bone marrow B cells from the early stage when IgH rearrangement is initiated up to the successful completion of H and L locus recombination, resulting in Ab expression. These findings suggest that the C delta-C gamma 3 interval exerts regulatory control on Ig gene activation and expression during early lymphoid development.
Mundt
C A
CA
Laboratory of Developmental Immunology, The Babraham Institute, Babraham, Cambridge, United Kingdom.
Nicholson
I C
IC
Zou
X
X
Popov
A V
AV
Ayling
C
C
Brüggemann
M
M
D020816:Amino Acid Motifs; D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism; D001482:Base Composition; D001665:Binding Sites / Q000235:genetics / Q000276:immunology; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D004742:Enhancer Elements, Genetic / Q000276:immunology*; D018985:Epitopes, B-Lymphocyte / Q000235:genetics* / Q000378:metabolism; D020868:Gene Silencing / Q000276:immunology; D006801:Humans; D007127:Immunoglobulin Constant Regions / Q000235:genetics* / Q000378:metabolism; D007143:Immunoglobulin Heavy Chains / Q000235:genetics* / Q000378:metabolism; D019169:Jurkat Cells; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D012091:Repetitive Sequences, Nucleic Acid; D013234:Stem Cells / Q000276:immunology / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014407:Tumor Cells, Cultured
D018985:Epitopes, B-Lymphocyte; D007127:Immunoglobulin Constant Regions; D007143:Immunoglobulin Heavy Chains; D014157:Transcription Factors