Possible role of calmodulin in the secretion of Entamoeba histolytica electron-dense granules containing collagenase

Authors

  • M. de L. Muñoz,

    Corresponding author
    1. Department of Genetics and Molecular Biology, Centro de Investigación y de Estudios Avanzados (CINVESTAV) del IPN, Apartado Postal 14-740, México, DF 07000 México.
    • *For correspondence, Tel. (5) 7540200; Fax (5) 5866564.

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  • M. A. Moreno,

    1. Department of Genetics and Molecular Biology, Centro de Investigación y de Estudios Avanzados (CINVESTAV) del IPN, Apartado Postal 14-740, México, DF 07000 México.
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  • J. N. Pérez-Garcia,

    1. Department of Genetics and Molecular Biology, Centro de Investigación y de Estudios Avanzados (CINVESTAV) del IPN, Apartado Postal 14-740, México, DF 07000 México.
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  • G. R. Tovar,

    1. Department of Genetics and Molecular Biology, Centro de Investigación y de Estudios Avanzados (CINVESTAV) del IPN, Apartado Postal 14-740, México, DF 07000 México.
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  • V. I. Hernandez

    1. Department of Genetics and Molecular Biology, Centro de Investigación y de Estudios Avanzados (CINVESTAV) del IPN, Apartado Postal 14-740, México, DF 07000 México.
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Summary

Entamoeba histolytica cells secrete electron-dense granules (EDGs) that have collagenase activity. To study the possible involvement of calmodulin (CaM) on EDG secretion, the effect of several CaM antagonists (TFP, R24571, W-7, W-5, dibucaine and DL-propranolol) was tested on this cellular function. Except for W-5 and dibucaine, the rest of these compounds inhibited EDG secretion. Transmission electron microscopy of collagen-activated trophozoites showed numerous EDGs located in or near the surface membrane. In contrast, trophozoites incubated with TFP showed no EDGs. Protein kinase C inhibitors (H-7, ML-9) had no effect on EDG secretion, suggesting that CaM antagonists acted by selectively inhibiting CaM. These results suggest that a CaM-dependent process is involved in EDG secretion.

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