Rapid desensitization of B-cell receptor by a dithiol-reactive protein tyrosine phosphatase inhibitor: uncoupling of membrane IgM from syk inhibits signals leading to Ca2+ mobilization

Immunology Letters
Z RozsnyayJ Gergely

Abstract

B-cell antigen receptor (BCR)-mediated calcium response can be blocked by phenylarsine oxide (PAO), a dithiol group-reactive protein tyrosine phosphatase inhibitor. We have examined the mechanism of this inhibition in BL41 Burkitt lymphoma cells. PAO-dependent inhibition is not restricted to the BCR-mediated functions, as evidenced by the failure of the same cells to mobilize Ca2+ in response to CD19 cross-linking. In contrast, calcium response induced by a putative syk activator, H2O2, exhibited only a moderate sensitivity to PAO, demonstrating that PAO did not cause general suppression of all the functions leading to Ca2+ mobilization. BCR cross-linking or H2O2 treatment leads to the induction of almost complete non-responsiveness for the reciprocal stimulation. Since BCR cross-linking did not generate non-responsiveness to H2O2 in the presence of PAO, and PAO-treated cells remained responsive to syk activation by H2O2, we suppose that PAO may inhibit BCR-mediated signal transduction events upstream of syk activation. This assumption was supported by additional data, indicating that PAO was able to modulate functions of at least 2 different protein tyrosine kinase enzymes involved in BCR-mediated signaling. PAO induced rapid ...Continue Reading

References

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Citations

Mar 16, 2019·Immunological Reviews·Mark J ShlomchikFlorian Weisel
Apr 11, 2019·Molecular Neurobiology·Geir BjørklundSalvatore Chirumbolo

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