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Acid Sphingomyelinase Promotes Cellular Internalization of Clostridium perfringens Iota-Toxin

Masahiro Nagahama1, Masaya Takehara2, Kazuaki Miyamoto3

  • 1Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan. nagahama@ph.bunri-u.ac.jp.

Toxins
|May 23, 2018
PubMed

Clostridium perfringens iota-toxin is a binary actin-ADP-ribosylating toxin composed of the enzymatic component Ia and receptor binding component Ib. Ib binds to a cell surface receptor, forms Ib oligomer in lipid rafts, and associates with Ia. The Ia-Ib complex then internalizes by endocytosis. Here, we showed that acid sphingomyelinase (ASMase) facilitates the cellular uptake of iota-toxin. Inhibitions of ASMase and lysosomal exocytosis by respective blockers depressed cell rounding induced by iota-toxin. The cytotoxicity of the toxin increased in the presence of Ca2+ in extracellular fluids. Ib entered target cells in the presence but not the absence of Ca2+. Ib induced the extracellular release of ASMase in the presence of Ca2+. ASMase siRNA prevented the cell rounding induced by iota-toxin. Furthermore, treatment of the cells with Ib resulted in the production of ceramide in cytoplasmic vesicles. These observations showed that ASMase promotes the internalization of iota-toxin into target cells.

Keywords:
C. perfringens iota-toxinacid sphingomyelinasemembrane repair

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