Clonal deletion of autoreactive B cells is crucial for the prevention of autoimmunity, but the signaling mechanisms that regulate this checkpoint remain undefined. Here we characterize a previously unrecognized Ca2+-driven pathway for activation of the kinase Erk, which was proapoptotic and biochemically distinct from Erk activation induced by diacylglycerol (DAG). This pathway required protein kinase C-δ (PKC-δ) and the guanine nucleotide-exchange factor RasGRP and depended on the concentration of the Ca2+ sensor STIM1, which controls the magnitude of Ca2+ entry. Developmental regulation of these proteins was associated with selective activation of the pathway in B cells prone to negative selection. This checkpoint was impaired in PKC-δ-deficient mice, which developed B cell autoimmunity. Conversely, overexpression of STIM1 conferred a competitive disadvantage to developing B cells. Our findings establish Ca 2+-dependent Erk signaling as a critical proapoptotic pathway that mediates the negative selection of B cells.
|Original language||English (US)|
|Number of pages||9|
|State||Published - May 2011|
Bibliographical noteFunding Information:
We thank the Sandler-Moore Mass Spectrometry Core Facility at the University of California at San Francisco (funded by the Sandler Family Foundation, the Gordon and Betty Moore Foundation and the National Cancer Institute of the US National Institutes of Health (P30 CA82103)) for assistance in protein identification; the Flow Cytometry Core Facility at the Department of Pathology and Diabetes Center of the University of California at San Francisco for assistance; G. Koretzky (University of Pennsylvania) for the pEF-Flag-hDGK-ζ plasmid; A. Roque for assistance with animal husbandry; H. Phee and M. Hermiston for critical reading of the manuscript and suggestions; B. Au-Yeung and H. Wang for help with tail-vein injections; and members of the Weiss laboratory for discussions. Supported by the Howard Hughes Medical Institute and the Sidney Kimmel Foundation (J.P.R.).