Early function of Pax5 (BSAP) before the pre-B cell receptor stage of B lymphopoiesis

Abstract

The formation of the pre-B cell receptor (BCR) corresponds to an important checkpoint in B cell development that selects pro-B (pre-BI) cells expressing a functionally rearranged immunoglobulin μ (Igμ) heavy chain protein to undergo the transition to the pre-B (pre-BII) cell stage. The pre- BCR contains, in addition to Igμ, the surrogate light chains λ5 and VpreB and the signal transducing proteins Igα and Igβ. The absence of one of these pre-BCR components is known to arrest B cell development at the pre-BI cell stage. Disruption of the Pax5 gene, which codes for the B cell-specific activator protein (BSAP), also blocks adult B lymphopoiesis at the pre-BI cell stage. Moreover, expression of..