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  • The EMBO Journal (2003) 22, 4677 - 4688
  • doi:10.1093/emboj/cdg457

Amplification of receptor signalling by Ca2+ entry-mediated translocation and activation of PLCbig gamma2 in B lymphocytes

Motohiro Nishida1, Kenji Sugimoto2, Yuji Hara1,3, Emiko Mori1,3, Takashi Morii2, Tomohiro Kurosaki4 and Yasuo Mori1,3

  1. Division of Molecular and Cellular Physiology, Center for Integrative Bioscience, Okazaki National Research Institutes, Okazaki, Aichi 444-8585, Japan
  2. Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan
  3. Institute of Advanced Energy, Kyoto University, and PRESTO, Japan Science and Technology Corporation, Uji, Kyoto 611-0011, Japan
  4. Department of Molecular Genetics, Institute for Liver Research, Kansai Medical University, and Laboratory for Lymphocyte Differentiation, RIKEN Research Center for Allergy and Immunology, Moriguchi 570-8506, Japan

Correspondence to:

Yasuo Mori, E-mail: moriy@nips.ac.jp

Received 17 March 2003; Accepted 23 July 2003; Revised 22 July 2003

In non-excitable cells, receptor-activated Ca2+ signalling comprises initial transient responses followed by a Ca2+ entry-dependent sustained and/or oscillatory phase. Here, we describe the molecular mechanism underlying the second phase linked to signal amplification. An in vivo inositol 1,4,5-trisphosphate (IP3) sensor revealed that in B lymphocytes, receptor-activated and store-operated Ca2+ entry greatly enhanced IP3 production, which terminated in phospholipase Cgamma2 (PLCgamma2)-deficient cells. Association between receptor-activated TRPC3 Ca2+ channels and PLCgamma2, which cooperate in potentiating Ca2+ responses, was demonstrated by co-immunoprecipitation. PLCgamma2-deficient cells displayed diminished Ca2+ entry-induced Ca2+ responses. However, this defect was canceled by suppressing IP3-induced Ca2+ release, implying that IP3 and IP3 receptors mediate the second Ca2+ phase. Furthermore, confocal visualization of PLCgamma2 mutants demonstrated that Ca2+ entry evoked a C2 domain-mediated PLCgamma2 translocation towards the plasma membrane in a lipase-independent manner to activate PLCgamma2. Strikingly, Ca2+ entry-activated PLCgamma2 maintained Ca2+ oscillation and extracellular signal-regulated kinase activation downstream of protein kinase C. We suggest that coupling of Ca2+ entry with PLCgamma2 translocation and activation controls the amplification and co-ordination of receptor signalling.

  • Keywords:

    • Ca2+ influx,
    • C2 domain,
    • PLCgamma2,
    • signal amplification,
    • TRPC