The adaptor protein Shc plays a key role during early B cell development

The adaptor protein Shc is phosphorylated downstream of many cell surface receptors, including Ag and cytokine receptors. However, the role of Shc in B cell development has not been addressed. Here, through conditional expression of a dominant negative Shc mutant and conditional loss of Shc protein expression, we tested a role for Shc during early B lymphopoiesis. We identified a requirement for Shc beginning at the transition from the pre-pro-B to pro-B stage, with a strong reduction in the number of pre-B cells. This developmental defect is due to increased cell death rather than impaired proliferation or commitment to the B lineage. Additional studies suggest a role for Shc in IL-7-dependent signaling in pro-B cells. Shc is phosphorylated in response to IL-7 stimulation in pro-B cells, and pro-B cells from mice with impaired Shc signaling display increased apoptosis. Together, these data demonstrate a critical role for Shc in early B lymphopoiesis with a requirement in early B cell survival. In addition, we also identify Shc as a required player in signaling downstream of the IL-7R in early B cells.