Inositol 1,4,5-trisphosphate receptor regulates replication, differentiation, infectivity and virulence of the parasitic protist Trypanosoma cruzi

Authors

  • Muneaki Hashimoto,

    Corresponding author
    • Department of Molecular and Cellular Parasitology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan
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    • M. Hashimoto and M. Enomoto equally contributed to this work.
  • Masahiro Enomoto,

    1. Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Saitama, Japan
    2. Division of Signaling Biology, Ontario Cancer Institute, Toronto, ON, Canada
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    • M. Hashimoto and M. Enomoto equally contributed to this work.
  • Jorge Morales,

    1. Department of Molecular and Cellular Parasitology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan
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  • Nagomi Kurebayashi,

    1. Department of Pharmacology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan
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  • Takashi Sakurai,

    1. Department of Pharmacology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan
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  • Tetsuo Hashimoto,

    1. Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
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  • Takeshi Nara,

    Corresponding author
    • Department of Molecular and Cellular Parasitology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan
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  • Katsuhiko Mikoshiba

    Corresponding author
    1. Calcium Oscillation Project, International Cooperative Research Project and Solution-Oriented Research for Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
    • Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Saitama, Japan
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For correspondence. E-mail muneaki@juntendo.ac.jp; Tel. (+81) 3 5802 1043; Fax (+81) 3 5800 0476;

E-mail tnara@juntendo.ac.jp; Tel. (+81) 3 5802 1043; Fax (+81) 3 5800 0476;

E-mail mikosiba@brain.riken.jp; Tel. (+81) 48 467 9745; Fax (+81) 48 467 9744.

Summary

In animals, inositol 1,4,5-trisphosphate receptors (IP3Rs) are ion channels that play a pivotal role in many biological processes by mediating Ca2+ release from the endoplasmic reticulum. Here, we report the identification and characterization of a novel IP3R in the parasitic protist, Trypanosoma cruzi, the pathogen responsible for Chagas disease. DT40 cells lacking endogenous IP3R genes expressing T. cruzi IP3R (TcIP3R) exhibited IP3-mediated Ca2+ release from the ER, and demonstrated receptor binding to IP3. TcIP3R was expressed throughout the parasite life cycle but the expression level was much lower in bloodstream trypomastigotes than in intracellular amastigotes or epimastigotes. Disruption of two of the three TcIP3R gene loci led to the death of the parasite, suggesting that IP3R is essential for T. cruzi. Parasites expressing reduced or increased levels of TcIP3R displayed defects in growth, transformation and infectivity, indicating that TcIP3R is an important regulator of the parasite's life cycle. Furthermore, mice infected with T. cruzi expressing reduced levels of TcIP3R exhibited a reduction of disease symptoms, indicating that TcIP3R is an important virulence factor. Combined with the fact that the primary structure of TcIP3R has low similarity to that of mammalian IP3Rs, TcIP3R is a promising drug target for Chagas disease.

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