Affiliation:
1. Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
Abstract
ABSTRACT
The bacterial pathogen
Listeria monocytogenes
causes foodborne illnesses resulting in gastroenteritis, meningitis, or abortion.
Listeria
induces its internalization into some human cells through interaction of the bacterial surface protein InlB with the host receptor tyrosine kinase Met. InlB-dependent entry requires localized polymerization of the host actin cytoskeleton. The signal transduction pathways that act downstream of Met to regulate actin filament assembly or other processes during
Listeria
uptake remain incompletely characterized. Here, we demonstrate important roles for the human serine/threonine kinases mTOR and protein kinase C-α (PKC-α) in InlB-dependent entry. Experiments involving RNA interference (RNAi) indicated that two multiprotein complexes containing mTOR, mTORC1 and mTORC2, are each needed for efficient internalization of
Listeria
into cells of the human cell line HeLa. InlB stimulated Met-dependent phosphorylation of mTORC1 or mTORC2 substrates, demonstrating activation of both mTOR-containing complexes. RNAi studies indicated that the mTORC1 effectors 4E-BP1 and hypoxia-inducible factor 1α (HIF-1α) and the mTORC2 substrate PKC-α each control
Listeria
uptake. Genetic or pharmacological inhibition of PKC-α reduced the internalization of
Listeria
and the accumulation of actin filaments that normally accompanies InlB-mediated entry. Collectively, our results identify mTOR and PKC-α to be host factors exploited by
Listeria
to promote infection. PKC-α controls
Listeria
entry, at least in part, by regulating the actin cytoskeleton downstream of the Met receptor.
Funder
University of Otago Research Committee
Otago School of Medical Sciences Dean's bequest fund
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
21 articles.
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