| First Author | Brauweiler A | Year | 2001 |
| Journal | J Immunol | Volume | 167 |
| Issue | 1 | Pages | 204-11 |
| PubMed ID | 11418650 | Mgi Jnum | J:120515 |
| Mgi Id | MGI:3706718 | Doi | 10.4049/jimmunol.167.1.204 |
| Citation | Brauweiler A, et al. (2001) Partially distinct molecular mechanisms mediate inhibitory FcgammaRIIB signaling in resting and activated B cells. J Immunol 167(1):204-11 |
| abstractText | FcgammaRIIB functions as an inhibitory receptor to dampen B cell Ag receptor signals and immune responses. Accumulating evidence indicates that ex vivo B cells require the inositol 5-phosphatase, Src homology domain 2-containing inositol 5-phosphatase (SHIP), for FcgammaRIIB-mediated inhibitory signaling. However, we report here that LPS-activated primary B cells do not require SHIP and thus differ from resting B cells. SHIP-deficient B cell blasts display efficient FcgammaRIIB-dependent inhibition of calcium mobilization as well as Akt and extracellular signal-related protein kinase phosphorylation. Surprisingly, FcgammaRIIB-dependent degradation of phosphatidylinositol 3,4,5-trisphosphate and conversion into phosphatidylinositol 3,4-bisphosphate occur in SHIP-deficient B cell blasts, demonstrating the function of an additional inositol 5-phosphatase. Further analysis reveals that while resting cells express only SHIP, B cell blasts also express the recently described inositol 5-phosphatase, SHIP-2. Finally, data suggest that both SHIP-2 and SHIP can mediate downstream biologic consequences of FcgammaRIIB signaling, including inhibition of the proliferative response. |
