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Genomic suppression of murine B29/Ig‐β promoter‐driven transgenes
Author(s) -
Vettermann Christian,
Lutz Johannes,
Selg Manuel,
Bösl Michael,
Jäck HansMartin
Publication year - 2006
Publication title -
european journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.272
H-Index - 201
eISSN - 1521-4141
pISSN - 0014-2980
DOI - 10.1002/eji.200636536
Subject(s) - biology , microbiology and biotechnology , transgene , gene , genetically modified mouse , gene expression , progenitor cell , genetics , stem cell
Abstract Immunoglobulin β (Ig‐β) is a critical signal transducer of precursor B cell and B cell receptors. B29, the gene coding for Ig‐β, is switched on in progenitor B cells and expressed until the terminal stage of antibody‐producing plasma cells. Although several cis ‐acting elements and transcription factors required for B29 expression have been characterized in cell lines, the in vivo significance of individual motifs located in the 1.2‐kb promoter region remained unclear. To address whether this region drives B lineage‐specific expression in mice as efficiently as in transfected cell lines, we established transgenic animals carrying the B29 promoter fused to either enhanced green fluorescent protein (EGFP) or the precursor B cell receptor component λ5. Surprisingly, only minimal levels of B29‐derived transcripts were produced in B lymphoid tissues of several independent transgenic lines, and the respective proteins were below the detection limit. In addition, transgenic transcripts were found in testis, kidney and brain. Hence, the 1.2‐kb‐sized B29 promoter does not define a strong, B lineage‐restricted expression unit when randomly integrated into the genome and passed through the murine germ line. Therefore, yet unidentified genomic locus control elements are required to efficiently drive B29 expression in B lymphocytes.