Localized glucose and water influx facilitates Cryptosporidium parvum cellular invasion by means of modulation of host-cell membrane protrusion.
Dynamic membrane protrusions such as lamellipodia and filopodia are driven by actin polymerization and often hijacked by intracellular microbes to enter host cells. The overall rate of membrane protrusion depends on the actin polymerization rate and the increase of localized cell volume. Although the signaling pathways involving actin polymerization are well characterized, the molecular mechanisms regulating local cell volume associated with membrane protrusion are unclear. Cryptosporidium parvum, an intracellular parasite, depends on host-cell membrane protrusion to accomplish cell entry and form the parasitophorous vacuole. Here, we report that C. parvum infection of cholangiocytes recruits host-cell SGLT1, a Na+/glucose cotransporter, and aquaporin 1 (AQP1), a water channel, to the attachment site. SGLT1-dependent glucose uptake occurs at the attachment site. Concordantly, the region of attachment displays localized water influx that is inhibited by either suppression of AQP1 by means of AQP1-small interfering RNA (siRNA) or inhibition of SGLT1 by a specific pharmacologic inhibitor, phlorizin. Inhibition of SGLT1 does not affect actin accumulation but decreases the membrane protrusion at the attachment site. Moreover, functional inhibition of host-cell AQP1 and SGLT1 hampers C. parvum invasion of cholangiocytes. Thus, glucose-driven, AQP-mediated localized water influx is involved in the membrane protrusion during C. parvum cellular invasion, phenomena that may also be relevant to the mechanisms of cell membrane protrusion in general.
Chen
Xian-Ming
XM
Center for Basic Research in Digestive Diseases, Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
O'Hara
Steven P
SP
Huang
Bing Q
BQ
Splinter
Patrick L
PL
Nelson
Jeremy B
JB
LaRusso
Nicholas F
NF
D000199:Actins / Q000378:metabolism*; D000818:Animals; D051398:Aquaporin 1; D020346:Aquaporins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D001789:Blood Group Antigens; D002460:Cell Line; D022081:Cell Surface Extensions / Q000378:metabolism* / Q000469:parasitology; D016785:Cryptosporidium parvum / Q000378:metabolism* / Q000648:ultrastructure; D005947:Glucose / Q000378:metabolism; D006790:Host-Parasite Interactions; D006801:Humans; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051379:Mice; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009004:Monosaccharide Transport Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism*; D010695:Phlorhizin / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000494:pharmacology; D051269:Sodium-Glucose Transporter 1; D014867:Water / Q000378:metabolism
C496020:AQP1 protein, human; D000199:Actins; C496021:Aqp1 protein, mouse; D020346:Aquaporins; D001789:Blood Group Antigens; D008562:Membrane Glycoproteins; D009004:Monosaccharide Transport Proteins; D034741:RNA, Small Interfering; C495674:SLC5A1 protein, human; C495675:Slc5a1 protein, mouse; D051269:Sodium-Glucose Transporter 1; D014867:Water; D051398:Aquaporin 1; D010695:Phlorhizin; D005947:Glucose