Open AccessCryptosporidium parvum infects human cholangiocytes via sphingolipid‐enriched membrane microdomains
Author(s) -
Nelson Jeremy B.,
O’Hara Steven P.,
Small Aaron J.,
Tietz Pamela S.,
Choudhury Amit K.,
Pagano Richard E.,
Chen XianMing,
LaRusso Nicholas F.
Publication year - 2006
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/j.1462-5822.2006.00759.x
Subject(s) - cryptosporidium parvum , biology , microbiology and biotechnology , cdc42 , actin , gene knockdown , sphingolipid , small interfering rna , cell membrane , membrane glycoproteins , pseudopodia , lipid raft , glycoprotein , sphingomyelin , cell , membrane , signal transduction , biochemistry , transfection , apoptosis , gene
Summary 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.