The Chlamydia type III effector TarP alters the dynamics and organization of host cell focal adhesions

Abstract

29The human pathogen Chlamydia trachomatis targets epithelial cells lining the genital mucosa. 30We observed that infection of various cell types, including fibroblasts and epithelial cells resulted 31 in the formation of unusually stable focal adhesions that resisted disassembly induced by the 32 myosin II inhibitor, blebbistatin. Super-resolution microscopy revealed in infected cells the 33 vertical displacement of paxillin and FAK from the signaling layer of focal adhesions; while 34 vinculin remained in its normal position within the force transduction layer. The candidate type III 35 effector TarP which localized to focal adhesions during infection and when expressed 36 ectopically, was sufficient to mimic both the reorganization and blebbistatin-resistant 37 phenotypes. These effects of TarP, including its localization to focal adhesions required 38 interaction with the host protein vinculin through a specific domain at the C-terminus of TarP. 39The consequence of Chlamydia-stabilized focal adhesions was restricted cell motility and 40 enhanced attachment to the extracellular matrix. Thus, via a novel mechanism, Chlamydia 41 inserts TarP within focal adhesions to alter their organization and dynamics. 48attachment to the extracellular matrix, and their assembly and turnover are exquisitely regulated 49 at multiple levels, by kinases, phosphatases, protein-protein interactions, internalization of 50 components, and degradation (Borradori and Sonnenberg, 1999; Geiger et al., 2001; Rosenblatt 51 et al., 2001; Zaidel-Bar et al., 2007). Disruption of one or more of these regulatory processes 52 alters the adhesion dynamics and properties of the cells. 53One strategy employed by bacteria to neutralize exfoliation relies on the precise 54 targeting of one or more components of the focal adhesion proteome. The best-characterized 55 example is that of Shigella, which neutralizes epithelial extrusion to colonize the epithelium 56 efficiently (Kim et al., 2009). It does so by delivering the OspE effector by the type III secretion 57 system (T3SS). This protein reinforces host cell adherence to the basement membrane by 58 interacting with integrin-linked kinase (ILK), a serine/threonine kinase that is part of the focal 59 adhesome (Kim et al., 2009; Zaidel-Bar et al., 2007). A consequence of the OspE-ILK 60 interaction is an increased surface expression of β1-integrin, which in turn promotes focal 61 adhesion (FA) assembly. In addition, the OspE-ILK complex stabilizes the focal adhesions (FAs) 62 by reducing phosphorylation of focal adhesion kinase (FAK) at a functionally important Tyr397 63 residue and of paxillin. Inhibition of both phosphorylation events has been shown to induce FA 64 disassembly (Kim et al., 2009). Interestingly, some EPEC and EHEC strains, as well as 65 Citrobacter rodentium possess the effector EspO, which shares strong homology with OspE 66 (reviewed in Vossenkämper, Macdonald and Marchès, 2011; Morita-Ishihara et al., 2013). As 67 such, it is conceivable that these pathogens also reinforce ...

Differential expression of groEL-1, incB, pyk-F, tal, hctA and omcB genes during Chlamydia trachomatis developmental cycle

“…Furthermore, another study assessing the effects of Chlamydia type III effector TarP on epithelium was able to grow C . trachomatis in various cell types including HaCaT cells [ 24 ]. HaCaT cells are one of the cell lines than can be used to interrogate cell differentiation, growth kinetics, and gene expression of C .…”