Published online
doi:10.1083/jcb.200702050
The Journal of Cell Biology, Vol. 177, No. 2, 317-328
The Rockefeller University Press, 0021-9525 $30.00
© Chung et al.
Coupling Ca2+ store release to Icrac channel activation in B lymphocytes requires the activity of Lyn and Syk kinases
S. Clare Chung1,
Andre Limnander2,3,
Tomohiro Kurosaki4,5,
Arthur Weiss2,3, and
Juan I. Korenbrot1
1 Department of Physiology, 2 Department of Medicine, and 3 Howard Hughes Medical Institute, School of Medicine, University of California, San Francisco, San Francisco, CA 94143
4 Department of Molecular Genetics, Institute for Liver Research, Kansai Medical University, and 5 Laboratory for Lymphocyte Differentiation, RIKEN Research Center for Allergy and Immunology, Moriguchi 570-8506, Japan
Correspondence to Juan I. Korenbrot: juan.korenbrot{at}ucsf.edu
Activation of the B cell receptor complex in B lymphocytes causes Ca2+ release from intracellular stores, which, in turn, activates ion channels known as Icrac. We investigated the mechanisms that link Ca2+ store release to channel gating in DT40 B lymphocyte cell lines genetically manipulated to suppress the expression of several tyrosine kinases: Btk, Lyn, Syk, and the Blnk adaptor molecule. The simultaneous but not the independent suppression of Lyn and Syk expression prevents the activation of Icrac without interfering with thapsigargin-sensitive Ca2+ store release. Icrac activation by Ca2+ is reversed in mutant cells by the homologous expression of the missing kinases. Pharmacological inhibition of kinase activity by LavendustinA and PP2 cause the same functional deficit as the genetic suppression of enzyme expression. Biochemical assays demonstrate that kinase activity is required as a tonic signal: targets must be phosphorylated to link Ca2+ store release to Icrac gating. The action of kinases on Icrac activation does not arise from control of the expression level of the stromal interaction molecule 1 and Orai1 proteins.
Abbreviations used in this paper: BCR, B cell receptor; IP3, inositol 1,4,5-trisphosphate; STIM1, stromal interaction molecule 1; TG, thapsigargin.

CiteULike
Complore
Connotea
Del.icio.us
Digg
Facebook
Reddit
Technorati
Twitter What's this?
This article has been cited by other articles:
-
Zhu, P., Liu, X., Treml, L. S., Cancro, M. P., Freedman, B. D.
(2009). Mechanism and Regulatory Function of CpG Signaling via Scavenger Receptor B1 in Primary B Cells. J. Biol. Chem.
284: 22878-22887
[Abstract]
[Full Text]
-
Lyubchenko, T., Nielsen, J. P., Miller, S. M., Liubchenko, G. A., Holers, V. M.
(2009). Role of initial protein phosphorylation events and localized release-activated calcium influx in B cell antigen receptor signaling. J. Leukoc. Biol.
85: 298-309
[Abstract]
[Full Text]
-
Kannan, S., Audet, A., Huang, H., Chen, L.-j., Wu, M.
(2008). Cholesterol-Rich Membrane Rafts and Lyn Are Involved in Phagocytosis during Pseudomonas aeruginosa Infection. J. Immunol.
180: 2396-2408
[Abstract]
[Full Text]
-
Chung, S.C., Limnander, A., Kurosaki, T., Weiss, A., Korenbrot, J.I.
(2007). Coupling Ca2+ store release to Icrac channel activation in B lymphocytes requires the activity of Lyn and Syk kinases. JGP
129: i1-i1
[Full Text]