Insertion of the IgH locus 3 ' regulatory palindrome in expression vectorswarrants sure and efficient expression in stable B cell transfectants

We have explored the effect of inserting 3' immunoglobulin heavy chain (IgH ) locus transcriptional regulatory elements in stable expression vectors dr iven by a heavy chain variable gene promoter (pVH). A cassette was construc ted, associating three enhancer elements from the palindromic part of the 3 ' IgH regulatory region, namely C alpha 3'/hs3 reverse, alpha 3'E/hs1-2 and hs3. As regard to stable expression, this cassette carried some features o f a locus control region (LCR) and conferred expression to an associated ca r reporter gene in the majority of B cells having integrated the transgene. The palindromic cassette was inserted in an expression vector carrying Ig light chain coding sequences. In this construct, transcription driven by a pVH promoter/E mu cassette upstream of the transcription initiation site wa s boosted by the palindromic cassette located downstream of the coding sequ ence. This potent expression plasmid mimicking the architecture of endogeno us Ig loci, definitely manifested a potent stimulatory activity for stable transcription, outscoring conventional ubiquitous or B-cell specific expres sion vectors. (C) 1998 Elsevier Science B.V. All rights reserved.