Loss- and gain-of-function mutations reveal an important role of BSAP (Pax-5) at the start and end of B cell differentiation

Abstract

Pax-5 codes for the transcription factor BSAP which is expressed throughout B cell development except in terminally differentiated plasma cells. Gene targeting experiments in the mouse revealed a differential dependency of fetal and adult B-lymphopoiesis on this transcription factor. BSAP is required for B-lineage commitment in the fetal liver and for progression beyond an early pro-B cell stage in adult bone marrow. The characterization of Pax-5-deficient pro-B cells demonstrated an important role of BSAP in the regulation of the CD19, mb-1 (Ig α) and N-myc genes as well as in the developmental pathway controlling V(H)-to-D(H)J(H) recombination at the immunoglobulin heavy-chain (IgH) locus...