Cryptosporidium parvum infects human cholangiocytes via sphingolipid-enriched membrane microdomains

Jeremy B. Nelson, Steven P. O'hara, Aaron J. Small, Pamela S. Tietz, Amit K. Choudhury, Richard E. Pagano, Xian Ming Chen, Nicholas F. Larusso

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Abstract

Cryptosporidium parvum attaches to intestinal and biliary epithelial cells via specific molecules on host-cell surface membranes including Gal/GalNAc-associated glycoproteins. Subsequent cellular entry of this parasite depends on host-cell membrane alterations to form a parasitophorous vacuole via activation of phosphatidylinositol 3-kinase (PI-3K)/Cdc42-associated actin remodelling. How C. parvum hijacks these host-cell processes to facilitate its infection of target epithelia is unclear. Using specific probes to known components of sphingolipid-enriched membrane microdomains (SEMs), we detected aggregation of host-cell SEM components at infection sites during C. parvum infection of cultured human biliary epithelial cells (i.e. cholangiocytes). Activation and membrane translocation of acid-sphingomyelinase (ASM), an enzyme involved in SEM membrane aggregation, were also observed in infected cells. Pharmacological disruption of SEMs and knockdown of ASM via a specific small interfering RNA (siRNA) significantly decreased C. parvum attachment (by ∼84%) and cellular invasion (by ∼88%). Importantly, knockdown of ASM and disruption of SEMs significantly blocked C. parvum-induced accumulation of Gal/GalNAc-associated glycoproteins at infection sites by ∼90%. Disruption of SEMs and knockdown of ASM also significantly blocked C. parvum -induced activation of host-cell PI-3K and subsequent accumulation of Cdc42 and actin by up to 75%. Our results suggest an important role of SEMs for C. parvum attachment to and entry of host cells, likely via clustering of membrane-binding molecules and facilitating of C. parvum-induced actin remodelling at infection sites through activation of the PI-3K/Cdc42 signalling pathway.

Original languageEnglish (US)
Pages (from-to)1932-1945
Number of pages14
JournalCellular Microbiology
Volume8
Issue number12
DOIs
StatePublished - Dec 1 2006

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All Science Journal Classification (ASJC) codes

  • Microbiology
  • Immunology
  • Virology

Cite this

Nelson, J. B., O'hara, S. P., Small, A. J., Tietz, P. S., Choudhury, A. K., Pagano, R. E., Chen, X. M., & Larusso, N. F. (2006). Cryptosporidium parvum infects human cholangiocytes via sphingolipid-enriched membrane microdomains. Cellular Microbiology, 8(12), 1932-1945. https://doi.org/10.1111/j.1462-5822.2006.00759.x