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Complex biallelic IGH rearrangements in IgM‐expressing Z‐138 cell line: Involvement of downstream immunoglobulin class switch recombination
Author(s) -
Guikema Jeroen E. J.,
Fenton James A. L.,
de Boer Conny,
Kleiverda Karin,
Brink Antoinette A. T. P.,
Raap Anton K.,
Estrov Zeev,
Schuuring Ed,
Kluin Philip M.
Publication year - 2005
Publication title -
genes, chromosomes and cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.754
H-Index - 119
eISSN - 1098-2264
pISSN - 1045-2257
DOI - 10.1002/gcc.20132
Subject(s) - immunoglobulin class switching , biology , microbiology and biotechnology , chromosomal translocation , immunoglobulin heavy chain , breakpoint , genetics , enhancer , gene , b cell , antibody , gene expression
Chromosomal translocations involving the immunoglobulin (Ig) receptor loci usually disrupt and silence these loci. On the basis of observations in follicular lymphoma (FL) with downstream Ig heavy chain ( IGH ) class switch recombination (CSR), we hypothesized that downstream CSR‐mediated chromosomal translocations would leave the V(D)J‐Cμ transcription unit intact, thereby still allowing IgM expression from the IGH allele involved in the translocation. To test this hypothesis, we analyzed biallelic IGH translocations in the IgM‐expressing cell line Z‐138 by interphase FISH, DNA fiber–FISH, long‐distance vectorette PCR, and DNA sequencing. One IGH allele was involved in a t(11;14), showing a break in the JH region that juxtaposed the Eμ enhancer and the 3′ Cα enhancers to the cyclin D1 gene. The other IGH allele contained a t(8;14) breakpoint involving the 3′ end of a Sγ region, whereas the reciprocal breakpoint at 8q24 was approximately 40 kb centromeric of MYC . Molecular analysis showed that this IGH allele harbored a normal V(D)J‐Cμ complex, which is responsible for IgM expression. These data show that chromosomal breakpoints such as the t(8;14) can occur in downstream IGH constant regions and do not necessarily interfere with Ig expression. © 2004 Wiley‐Liss, Inc.