Indispensable functions of ABL and PDGF receptor kinases in epithelial adherence of attaching/effacing pathogens under physiological conditions.
Enteropathogenic Escherichia coli (EPEC) and Citrobacter rodentium are attaching-and-effacing (A/E) pathogens that cause intestinal inflammation and diarrhea. The bacteria adhere to the intestinal epithelium, destroy microvilli, and induce actin-filled membranous pedestals but do not invade the mucosa. Adherence leads to activation of several host cell kinases, including FYN, n-SRC, YES, ABL, and ARG, phosphorylation of the bacterial translocated intimin receptor, and actin polymerization and pedestal formation in cultured cells. However, marked functional redundancy appears to exist between kinases, and their physiological importance in A/E pathogen infections has remained unclear. To address this question, we employed a novel dynamic in vitro infection model that mimics transient and short-term interactions in the intestinal tract. Screening of a kinase inhibitor library and RNA interference experiments in vitro revealed that ABL and platelet-derived growth factor (PDGF) receptor (PDGFR) kinases, as well as p38 MAP kinase, have unique, indispensable roles in early attachment of EPEC to epithelial cells under dynamic infection conditions. Studies with mutant EPEC showed that the attachment functions of ABL and PDGFR were independent of the intimin receptor but required bacterial bundle-forming pili. Furthermore, inhibition of ABL and PDGFR with imatinib protected against infection of mice with modest loads of C. rodentium, whereas the kinases were dispensable for high inocula or late after infection. These results indicate that ABL and PDGFR have indispensable roles in early A/E pathogen attachment to intestinal epithelial cells and for in vivo infection with limiting inocula but are not required for late intimate bacterial attachment or high inoculum infections.
Department of Medicine, University of California, San Diego, La Jolla, California;
Carolin F
CF
Manthey
Department of Medicine, University of California, San Diego, La Jolla, California;
Christine B
CB
Calabio
Department of Medicine, University of California, San Diego, La Jolla, California;
Anna
A
Wosinski
Department of Medicine, University of California, San Diego, La Jolla, California;
Elaine M
EM
Hanson
Division of Gastroenterology, British Columbia Children's Hospital, Child and Family Research Institute, and University of British Columbia, Vancouver, British Columbia, Canada; and.
Bruce A
BA
Vallance
Department of Physics, University of California, San Diego, La Jolla, California;
Alex
A
Groisman
Division of Gastroenterology and Nutrition, Department of Pediatrics, Mattel Children's Hospital and David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California.
Martín G
MG
Martín
Department of Medicine, University of California, San Diego, La Jolla, California; Moores Cancer Center, University of California, San Diego, La Jolla, California;
Jean Y J
JY
Wang
Department of Medicine, University of California, San Diego, La Jolla, California; leckmann@ucsd.edu.
Lars
L
Eckmann
D000818:Animals; D001422:Bacterial Adhesion / Q000502:physiology*; D002460:Cell Line; D054308:Enteropathogenic Escherichia coli / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D004847:Epithelial Cells / Q000502:physiology*; D004927:Escherichia coli Infections / Q000382:microbiology; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D016374:Oncogene Proteins v-abl / Q000235:genetics / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017479:Receptors, Platelet-Derived Growth Factor / Q000235:genetics / Q000378:metabolism*
D016374:Oncogene Proteins v-abl; D047428:Protein Kinase Inhibitors; C099852:PDGF receptor tyrosine kinase; D017479:Receptors, Platelet-Derived Growth Factor
intestinal epithelium; kinase signaling; microbial pathogenesis