Cryptosporidium parvum invasion of biliary epithelia requires host cell tyrosine phosphorylation of cortactin via c-Src

Xian-Ming Chen, Bing Q. Huang, Patrick L. Splinter, Hong Cao, Guan Zhu, Mark A. McNiven, Nicholas F. Larusso

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Background & Aims: Cryptosporidium parvum invasion of epithelia requires polymerization of host cell actin at the attachment site. We analyzed the role of host cell c-Src, a cytoskeleton-associated protein tyrosine kinase, in C. parvum invasion of biliary epithelia. Methods: In vitro models of biliary cryptosporidiosis using a human biliary epithelial cell line were used to assay the role of c-Src signaling pathway in C. parvum invasion. Results: c-Src and cortactin, an actin-binding protein and a substrate for c-Src, were recruited to the parasite-host cell interface during C. parvum invasion. Tyrosine phosphorylation of cortactin in infected cells was also detected. Inhibition of host cell c-Src significantly blocked C. parvum-induced accumulation and tyrosine phosphorylation of cortactin and actin polymerization at the attachment sites, thereby inhibiting C. parvum invasion of biliary epithelial cells. A triple mutation of tyrosine of cortactin in the epithelia also diminished C. parvum invasion. In addition, proteins originating from the parasite were detected within infected cells at the parasite-host cell interface. Antiserum against C. parvum membrane proteins blocked accumulation of c-Src and cortactin and significantly decreased C. parvum invasion. No accumulation of the endocytosis-related proteins, dynamin 2 and clathrin, was found at the parasite-host cell interface; also, inhibition of dynamin 2 did not block C. parvum invasion. Conclusions: C. parvum invasion of biliary epithelial cells requires host cell tyrosine phosphorylation of cortactin by a c-Src-mediated signaling pathway to induce actin polymerization at the attachment site, a process associated with microbial secretion but independent of host cell endocytosis.

Original languageEnglish
Pages (from-to)216-228
Number of pages13
Issue number1
Publication statusPublished - Jul 1 2003
Externally publishedYes


All Science Journal Classification (ASJC) codes

  • Gastroenterology

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