Myosin light chain kinase plays an essential role in S. flexneri dissemination.
Shigella flexneri, the causitive agent of bacillary dysentery, has been shown to disseminate in colonic epithelial cells via protrusions that extend from infected cells and are endocytosed by adjacent cells. This phenomenon occurs in the region of the eukaryotic cell's adherens junctions and is inhibited by pharmacological reagents or host cell mutations that completely disrupt the junctional complex. In this study, inhibitors of the myosin light chain kinase (MLCK) were shown to dramatically decrease intercellular spread of S. flexneri but to have no inhibitory effect on bacterial entry, multiplication or actin-based motility within the host cell. Furthermore, cell-to-cell spread of Listeria monocytogenes, another bacterial pathogen that uses an actin-based mechanism to move within the eukaryotic cytoplasm and to spread from cell to cell, was not affected by the MLCK inhibitors, indicating that (1) the inhibition of S. flexneri cell-to-cell spread in treated cells is not due to a complete break down of cell-cell contacts, which was subsequently confirmed by confocal microscopy, and (2) MLCK plays a role in a S. flexneri-specific mechanism of dissemination. Myosin has been shown to play a role in a variety of membrane-based phenomena. The work presented here suggests that activation of this molecule via phosphorylation by MLCK, at the very least participates in the formation of the bacteria-containing protrusion, and could also contribute to the endocytosis of this structure by neighboring cells.
Rathman
M
M
Unité de Pathogénie Microbienne Moléculaire, INSERM U389 and Station Centrale de Microscopie Electronique, Institut Pasteur, 75724 Paris Cedex 15, France.
de Lanerolle
P
P
Ohayon
H
H
Gounon
P
P
Sansonetti
P
P
D000199:Actins / Q000276:immunology / Q000378:metabolism; D022005:Adherens Junctions / Q000737:chemistry / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D015153:Blotting, Western; D018938:Caco-2 Cells; D015820:Cadherins / Q000032:analysis; D016764:Cell Polarity; D022081:Cell Surface Extensions / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008089:Listeria monocytogenes / Q000502:physiology; D008565:Membrane Proteins / Q000032:analysis; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D009068:Movement; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism; D010750:Phosphoproteins / Q000032:analysis; D012763:Shigella flexneri / Q000502:physiology* / Q000648:ultrastructure; D019311:Staurosporine / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D062826:Zonula Occludens-1 Protein
D000199:Actins; D015820:Cadherins; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D010750:Phosphoproteins; D013449:Sulfonamides; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; C017967:W 7; D009219:Myosin-Light-Chain Kinase; D009218:Myosins; D019311:Staurosporine