Analysis of mice with single and multiple copies of transgenes reveals a novel arrangement for the lambda5-VpreB1 locus control region.
The murine lambda5-VpreB1 locus encodes two proteins that form part of the pre-B-cell receptor and play a key role in B-lymphocyte development. We have identified a locus control region (LCR) which is responsible for coordinate activation of both genes in pre-B cells. Analysis of mice with single and multiple copies of transgenes shows a clear difference in the expression behavior of the genes depending on the transgene copy number. While expression of both lambda5 and VpreB1 in single- and two-copy integrations requires the presence of a set of DNase I hypersensitive sites located 3' of the lambda5 gene, small fragments containing the genes have LCR activity when arranged in multiple-copy tandem arrays, indicating that additional components of the LCR are located within or close to the genes. The complete LCR is capable of driving efficient copy-dependent expression of a lambda5 gene in pre-B cells even when it is integrated into centomeric gamma-satellite DNA. The finding that activation of expression of the locus by positively acting factors is fully dominant over the silencing effect of heterochromatin has implications for models for chromatin-mediated gene silencing during B-cell development.
Sabbattini
P
P
Gene Regulation and Chromatin Group, MRC Clinical Sciences Centre, Imperial College School of Medicine, Hammersmith Hospital, London W12 0NN, United Kingdom.
Georgiou
A
A
Sinclair
C
C
Dillon
N
N
D000818:Animals; D001402:B-Lymphocytes; D002503:Centromere; D002874:Chromosome Mapping; D003850:Deoxyribonuclease I; D005260:Female; D018628:Gene Dosage; D015870:Gene Expression; D015322:Gene Rearrangement, B-Lymphocyte; D017930:Genes, Reporter; D006570:Heterochromatin; D007147:Immunoglobulin Light Chains; D054444:Immunoglobulin Light Chains, Surrogate; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D007146:Immunoglobulin lambda-Chains / Q000235:genetics*; D019901:Locus Control Region / Q000235:genetics*; D008562:Membrane Glycoproteins / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic; D019076:Transgenes
D006570:Heterochromatin; D007147:Immunoglobulin Light Chains; D054444:Immunoglobulin Light Chains, Surrogate; D007135:Immunoglobulin Variable Region; D007146:Immunoglobulin lambda-Chains; D008562:Membrane Glycoproteins; D003850:Deoxyribonuclease I