| First Author | Al-Alwan M | Year | 2010 |
| Journal | J Immunol | Volume | 184 |
| Issue | 12 | Pages | 6961-9 |
| PubMed ID | 20495066 | Mgi Jnum | J:161306 |
| Mgi Id | MGI:4457973 | Doi | 10.4049/jimmunol.0904176 |
| Citation | Al-Alwan M, et al. (2010) Bam32/DAPP1 promotes B cell adhesion and formation of polarized conjugates with T cells. J Immunol 184(12):6961-9 |
| abstractText | B cell Ag receptors function in both signaling activation of Ag-specific cells and in collecting specific Ag for presentation to T lymphocytes. Signaling via PI3K is required for BCR-mediated activation and Ag presentation functions; however, the relevant downstream targets of PI3K in B cells are incompletely defined. In this study, we have investigated the roles of the PI3K effector molecule Bam32/DAPP1 in BCR signaling and BCR-mediated Ag presentation functions. In mouse primary B cells, Bam32 was required for efficient activation of the GTPase Rac1 and downstream signaling to JNK, but not activation of BLNK, phospholipase C gamma2, or calcium responses. Consistent with a role of this adaptor in Rac-mediated cytoskeletal rearrangement, Bam32 was required for BCR-induced cell adhesion and spreading responses on ICAM-1 or fibronectin-coated surfaces. The function of Bam32 in promoting Rac activation and adhesion required tyrosine 139, a known site of phosphorylation by Lyn kinase. After BCR crosslinking by Ag, Bam32-deficient B cells are able to carry out the initial steps of Ag endocytosis and processing, but show diminished ability to form Ag-specific conjugates with T cells and polarize F-actin at the B-T interface. As a result, Bam32-deficient B cells were unable to efficiently activate Ag-specific T cells. Together, these results indicate that Bam32 serves to integrate PI3K and Src kinase signaling to promote Rac-dependent B cell adhesive interactions important for Ag presentation function. |
