A calcium-dependent protein kinase regulates Plasmodium ookinete access to the midgut epithelial cell

Authors

  • Tomoko Ishino,

    1. Department of Medical Zoology, Mie University School of Medicine, Edobashi, Tsu, Mie 514-0001, Japan; CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.
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  • Yuki Orito,

    1. Department of Medical Zoology, Mie University School of Medicine, Edobashi, Tsu, Mie 514-0001, Japan; CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.
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  • Yasuo Chinzei,

    1. Department of Medical Zoology, Mie University School of Medicine, Edobashi, Tsu, Mie 514-0001, Japan; CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.
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  • Masao Yuda

    Corresponding author
    1. Department of Medical Zoology, Mie University School of Medicine, Edobashi, Tsu, Mie 514-0001, Japan; CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.
      *E-mail m-yuda@doc.medic.mie-u.ac.jp; Tel. (+81) 59 231 5013; Fax (+81) 59 231 5215.
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*E-mail m-yuda@doc.medic.mie-u.ac.jp; Tel. (+81) 59 231 5013; Fax (+81) 59 231 5215.

Summary

Plasmodium parasites are fertilized in the mosquito midgut and develop into motile zygotes, called ookinetes, which invade the midgut epithelium. Here we show that a calcium-dependent protein kinase, CDPK3, of the rodent malarial parasite (Plasmodium berghei) is produced in the ookinete stage and has a critical role in parasite transmission to the mosquito vector. Targeted disruption of the CDPK3 gene decreased ookinete ability to infect the mosquito midgut by nearly two orders of magnitude. Electron microscopic analyses demonstrated that the disruptant ookinetes could not access midgut epithelial cells by traversing the layer covering the cell surface. An in vitro migration assay showed that these ookinetes lack the ability to migrate through an artificial gel, suggesting that this defect caused their failure to access the epithelium. In vitro migration assays also suggested that this motility is induced in the wild type by mobilization of intracellular stored calcium. These results indicate that a signalling pathway involving calcium and CDPK3 regulates ookinete penetration of the layer covering the midgut epithelium. Because humans do not possess CDPK family proteins, CDPK3 is a good target for blocking malarial transmission to the mosquito vector.

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