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Updated: Jul 23, 2026

Retroviral Infection of Murine Embryonic Stem Cell Derived Embryoid Body Cells for Analysis of Hematopoietic Differentiation
Published on: October 20, 2014
Pax5/BSAP maintains the identity of B cells in late B lymphopoiesis
M Horcher1, A Souabni, M Busslinger
1Research Institute of Molecular Pathology, Vienna Biocenter, Dr. Bohr-Gasse 7, A-1030 Vienna, Austria.
Abstract:
The B lineage commitment factor Pax5 (BSAP) is expressed throughout B cell development. To investigate its late function, we generated a mouse strain carrying a floxed Pax5 allele that was conditionally inactivated by CD19-cre or Mx-cre expression. Pax5 deletion resulted in the preferential loss of mature B cells, inefficient lymphoblast formation, and reduced serum IgG levels. Mature B cells radically changed their gene expression pattern in response to Pax5 inactivation. Most B cell antigens were downregulated on the cell surface, and the transcription of B cell-specific genes was decreased, whereas the expression of non-B lymphoid genes was activated in Pax5-deficient B cells. These data demonstrate that Pax5 is essential for maintaining the identity and function of B cells during late B lymphopoiesis.
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