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J. Exp. Med.,
Volume 188, Number 7, October 5, 1998 1333-1342
By

§
§
From the * Amgen Institute, Toronto, Ontario, Canada M5G 2C1; the Ship is an Src homology 2 domain containing inositol polyphosphate 5-phosphatase which has
been implicated as an important signaling molecule in hematopoietic cells. In B cells, Ship becomes associated with Fc
Department of Medical
Biophysics and the § Department of Immunology, University of Toronto, Ontario, Canada M5G 2M9;
and the
Ontario Cancer Institute, Toronto, Ontario, Canada M5G 2M9
receptor IIB (Fc
RIIB), a low affinity receptor for the Fc portion of
immunoglobulin (Ig)G, and is rapidly tyrosine phosphorylated upon B cell antigen receptor
(BCR)-Fc
RIIB coligation. The function of Ship in lymphocytes was investigated in Ship
/
recombination-activating gene (Rag)
/
chimeric mice generated from gene-targeted Ship
/
embryonic stem cells. Ship
/
Rag
/
chimeras showed reduced numbers of B cells and an
overall increase in basal serum Ig. Ship
/
splenic B cells displayed prolonged Ca2+ influx,
increased proliferation in vitro, and enhanced mitogen-activated protein kinase (MAPK) activation in response to BCR-Fc
RIIB coligation. These results demonstrate that Ship plays an
essential role in Fc
RIIB-mediated inhibition of BCR signaling, and that Ship is a crucial negative regulator of Ca2+ flux and MAPK activation.
receptor IIB inhibitory signal;
signal transduction;
B
cell antigen receptor signaling;
gene targeting
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