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Infect. Immun., Jul 1997, 2570-2575, Vol 65, No. 7
LM Palmer, TJ Reilly, SJ Utsalo and MS Donnenberg
Human renal epithelial cells are capable of internalizing Escherichia coli
regardless of whether the bacteria are isolated from individuals with
pyelonephritis or from healthy volunteers. In this study, we investigated
the role of host cell tyrosine kinase activity in internalization. We found
that internalization of both fecal and pyelonephritis isolates is blocked
by tyrosine kinase inhibitors. We found increased intensity of two
tyrosine-phosphorylated proteins, with relative mobilities of approximately
123,000 and 110,000, in Western blots of extracts from human renal
epithelial cells infected with E. coli. The increased intensity of these
tyrosine-phosphorylated proteins was observed only in the Triton
X-100-insoluble fraction, suggesting that these proteins could be
associated with the cytoskeleton. Increased tyrosine phosphorylation of
these proteins upon E. coli infection was observed in both transformed and
primary human renal epithelial cells and in cells infected with several
different strains of E. coli isolated from the feces of healthy individuals
or from the blood or urine of patients with pyelonephritis. The increased
tyrosine phosphorylation of these proteins required live bacteria and was
blocked by tyrosine kinase inhibition but not by protein synthesis
inhibitors or cytochalasin D. These experiments establish a strong link
between E. coli internalization and host cell signaling through tyrosine
kinases in human kidney cells and provide evidence that specific proteins
are involved in these processes.
Copyright © 1997, American Society for Microbiology
Internalization of Escherichia coli by human renal epithelial cells is associated with tyrosine phosphorylation of specific host cell proteins
Department of Medicine, University of Maryland School of Medicine, Baltimore 21201, USA.
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