Reversion of B Cell Commitment upon Loss of Pax5 Expression

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Science  05 Jul 2002:
Vol. 297, Issue 5578, pp. 110-113
DOI: 10.1126/science.1067518

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The transcription factor Pax5 is essential for initiating B cell lineage commitment, but its role in maintaining commitment is unknown. Using conditional Pax5 inactivation in committed pro-B cells, we demonstrate that Pax5 is required not only to initiate its B lymphoid transcription program, but also to maintain it in early B cell development. As a consequence of Pax5 inactivation, previously committed pro-B cells regained the capacity to differentiate into macrophages in vitro and to reconstitute T cell development in vivo in RAG2 −/− mice. Hence, Pax5 expression is continuously required to maintain B cell lineage commitment, because its loss converts committed pro-B cells into hematopoietic progenitors with multilineage potential.

  • * These authors contributed equally to this work.

  • Present address: Department of Biochemistry, Institute of Medical Biology, University of Tromsø, N-9037 Tromsø, Norway.

  • To whom correspondence should be addressed: E-mail: busslinger{at}

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