Role of PRIP-1, a novel Ins(1,4,5)P3 binding protein, in Ins(1,4,5)P3-mediated Ca2+ signaling

Authors

  • Kae Harada,

    1. Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science and Station for Collaborative Research, Kyushu University, Fukuoka, Japan
    2. Division of Periodontology, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
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  • Hiroshi Takeuchi,

    1. Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science and Station for Collaborative Research, Kyushu University, Fukuoka, Japan
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  • Masahiro Oike,

    1. Department of Pharmacology, Faculty of Medical Science, Kyushu University, Fukuoka, Japan
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  • Miho Matsuda,

    1. Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science and Station for Collaborative Research, Kyushu University, Fukuoka, Japan
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  • Takashi Kanematsu,

    1. Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science and Station for Collaborative Research, Kyushu University, Fukuoka, Japan
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  • Hitoshi Yagisawa,

    1. Department of Life Science, Graduate School of Science, Himeji Institute of Technology, Hyogo, Japan
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  • Kei-ichi I. Nakayama,

    1. Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
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  • Katsumasa Maeda,

    1. Division of Periodontology, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
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  • Christophe Erneux,

    1. Institute of Interdisciplinary Research (IRIBHN), Free University of Brussels, Campus Erasme, Bldg C, Brussels, Belgium
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  • Masato Hirata

    Corresponding author
    1. Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science and Station for Collaborative Research, Kyushu University, Fukuoka, Japan
    • Professor, Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan.
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Abstract

PRIP-1 was isolated as a novel inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] binding protein with a domain organization similar to phospholipase C-δ1 (PLC-δ1) but lacking the enzymatic activity. Further studies revealed that the pleckstrin homology (PH) domain of PRIP-1 is the region responsible for binding Ins(1,4,5)P3. In this study we aimed to clarify the role of PRIP-1 at the physiological concentration in Ins(1,4,5)P3-mediated Ca2+ signaling, as we had previously used COS-1 cells overexpressing PRIP-1 (Takeuchi et al., 2000, Biochem J 349:357–368). For this purpose we employed PRIP-1 knock out (PRIP-1−/−) mice generated previously (Kanematsu et al., 2002, EMBO J 21:1004–1011). The increase in free Ca2+ concentration in response to purinergic receptor stimulation was lower in primary cultured cortical neurons prepared from PRIP-1−/− mice than in those from wild type mice. The relative amounts of [3H]Ins(1,4,5)P3 measured in neurons labeled with [3H]inositol was also lower in cells from PRIP-1−/− mice. In contrast, PLC activities in brain cortex samples from PRIP-1−/− mice were not different from those in the wild type mice, indicating that the hydrolysis of Ins(1,4,5)P3 is enhanced in cells from PRIP-1−/− mice. In vitro analyses revealed that type1 inositol polyphosphate 5-phosphatase physically interacted with a PH domain of PRIP-1 (PRIP-1PH) and its enzyme activity was inhibited by PRIP-1PH. However, physical interaction with these two proteins did not appear to be the reason for the inhibition of enzyme activity, indicating that binding of Ins(1,4,5)P3 to the PH domain prevented its hydrolyzation. Together, these results indicate that PRIP-1 plays an important role in regulating the Ins(1,4,5)P3-mediated Ca2+ signaling by modulating type1 inositol polyphosphate 5-phosphatase activity through binding to Ins(1,4,5)P3. © 2004 Wiley-Liss, Inc.

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