Premium
Role of initial protein phosphorylation events and localized release‐activated calcium influx in B cell antigen receptor signaling
Author(s) -
Lyubchenko Taras,
Nielsen J. Paul,
Miller Sara M.,
Liubchenko Ganna A.,
Holers V. Michael
Publication year - 2009
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1189/jlb.0308193
Subject(s) - biology , microbiology and biotechnology , phosphorylation , receptor , signal transduction , calcium , antigen , immunology , biochemistry , medicine
An increase in intracellular calcium concentration is one of the major initial steps in B cell activation following antigen receptor (BCR) ligation. We show herein that in C57BL/6 murine B lymphocytes and in model cell lines, BCR‐mediated calcium ion (Ca 2+ ) influx occurs via highly selective Ca 2+ release‐activated channels, and stromal interaction molecule 1 (STIM1) plays an important role in this pathway. We also demonstrate the temporal relation between Ca 2+ ‐dependent signaling events and formation of the immune synapse. Our data indicate that cytoplasmic Ca 2+ levels in areas adjacent to the immune synapse differ from those in the rest of the cytoplasm. Finally, a comparison of phosphorylation patterns of BCR‐triggered signaling proteins in the presence or absence of Ca 2+ revealed the unanticipated finding that initial BCR‐triggered, Ca 2+ ‐dependent tyrosine phosphorylation events involve predominantly Ca 2+ released from intracellular stores and that influx‐derived Ca 2+ is not essential. This suggests a different role for this phase of Ca 2+ influx.