BCR targets cyclin D2 via Btk and the p85alpha subunit of PI3-K to induce cell cycle progression in primary mouse B cells.

The p85alpha subunit of PI3-K and Btk are two crucial components of the B-cell receptor (BCR) signalling pathway. In the present study, we showed that primary splenic B cells from p85alpha null and xid (Btk-deficient) mice fail to induce cyclin D2 expression and enter early G1, but not S phase of the cell cycle in response to BCR engagement. Furthermore, these Btk or p85alpha null B cells displayed increased cell death compared with wild type following BCR engagement.