title: Myosin IIA is essential for Shigella flexneri cell-to-cell spread.
abstract: A key feature of Shigella pathogenesis is the ability to spread from cell-to-cell post-invasion. This is dependent on the bacteria's ability to initiate de novo F-actin tail polymerisation, followed by protrusion formation, uptake of bacteria-containing protrusion and finally, lysis of the double membrane vacuole in the adjacent cell. In epithelial cells, cytoskeletal tension is maintained by the actin-myosin II networks. In this study, the role of myosin II and its specific kinase, myosin light chain kinase (MLCK), during Shigella intercellular spreading was investigated in HeLa cells. Inhibition of MLCK and myosin II, as well as myosin IIA knockdown, significantly reduced Shigella plaque and infectious focus formation. Protrusion formation and intracellular bacterial growth was not affected. Low levels of myosin II were localised to the Shigella F-actin tail. HeLa cells were also infected with Shigella strains defective in cell-to-cell spreading. Unexpectedly loss of myosin IIA labelling was observed in HeLa cells infected with these mutant strains. This phenomenon was not observed with WT Shigella or with the less abundant myosin IIB isoform, suggesting a critical role for myosin IIA.
authors.affiliation: School of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA, Australia.
authors.forename: Mabel
authors.initials: M
authors.lastname: Lum
authors.forename: Renato
authors.initials: R
authors.lastname: Morona
mesh_terms: D000199:Actins / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D006576:Heterocyclic Compounds, 4 or More Rings / Q000494:pharmacology; D054884:Host-Pathogen Interactions / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008070:Lipopolysaccharides / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism; D024507:Nonmuscle Myosin Type IIA / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D012763:Shigella flexneri / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014774:Virulence / Q000187:drug effects / Q000235:genetics / Q000502:physiology
chemical_list: D000199:Actins; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D006576:Heterocyclic Compounds, 4 or More Rings; D008070:Lipopolysaccharides; D034741:RNA, Small Interfering; D014157:Transcription Factors; C058483:virG protein, Shigella flexneri; C472645:blebbistatin; D009219:Myosin-Light-Chain Kinase; D024507:Nonmuscle Myosin Type IIA
keywords: ML-7; ML-9; MLCK; Shigella flexneri; blebbistatin; myosin IIB