Lamellipodin Is Important for Cell-to-Cell Spread and Actin-Based Motility in Listeria monocytogenes

Abstract

Listeria monocytogenes is a foodborne pathogen capable of invading a broad range of cell types and replicating within the host cell cytoplasm. This paper describes the colocalization of host cell lamellipodin (Lpd) with intracellular L. monocytogenes detectable 6 h postinfection of epithelial cells. The association was mediated via interactions between both the peckstrin homology (PH) domain in Lpd and phosphatidylinositol (3,4)-bisphosphate [PI(3,4)P2] on the bacterial surface and by interactions between the C-terminal EVH1 (Ena/VASP [vasodilator-stimulated phosphoprotein] homology domain 1) binding domains of Lpd and the host VASP (vasodilator-stimulated phosphoprotein) recruited to the bacterial cell surface by the listerial ActA protein. Depletion of Lpd by short interfering RNA (siRNA) resulted in reduced plaque size and number, indicating a role for Lpd in cell-to-cell spread. In contrast, overexpression of Lpd resulted in an increase in the number of L. monocytogenes-containing protrusions (listeriopods). Manipulation of the levels of Lpd within the cell also affected the intracellular velocity of L. monocytogenes, with a reduction in Lpd corresponding to an increase in intracellular velocity. These data, together with the observation that Lpd accumulated at the interface between the bacteria and the developing actin tail at the initiation of actin-based movement, indicate a possible role for Lpd in the actin-based movement and the cell-to-cell spread of L. monocytogenes.

Actin-based motility and cell-to-cell spread of bacterial pathogens

“…siRNA-mediated depletion of nexillin results in irregularly shaped actin tails, possibly due to defects in nexillin-mediated actin filament crosslinking and stabilization of the actin network [31]. Lpd depletion or overexpression differentially influences the percentage of motile L. monocytogenes and their velocity, with subsequent effects on cell-to-cell spread [32]. These effects may be mediated through Lpd’s interaction with VASP on the bacterial surface [32], in agreement with VASP’s previously-discovered role in regulating ActA-mediated polymerization [33-35].…”

“…Lpd depletion or overexpression differentially influences the percentage of motile L. monocytogenes and their velocity, with subsequent effects on cell-to-cell spread [32]. These effects may be mediated through Lpd’s interaction with VASP on the bacterial surface [32], in agreement with VASP’s previously-discovered role in regulating ActA-mediated polymerization [33-35]. As with L. monocytogenes and S. flexneri , R. parkeri Sca2-mediated actin-based motility also requires a core set of host actin-binding proteins, which includes profilin, fimbrin/T-plastin, capping protein and cofilin [36].…”

Recent advances in understanding Listeria monocytogenes infection: the importance of subcellular and physiological context

“…Interestingly, lamellipodin is recruited to Lm actin comet tails independently of Ena/VASP, highlighting that lamellipodin can bind to F-actin. Although lamellipodin promotes cell-to-cell spread, curiously, lamellipodin knockdown increased the speed of actin-propelled Lm 56 . How lamellipodin both promotes Lm intercellular spread and appears to reduce Lm comet tail speed remains to be clarified.…”

Lamellipodin tunes cell migration by stabilizing protrusions and promoting adhesion formation

“…Apart from aforementioned functions in lamellipodium protrusion and migration, Lpd has also been implicated in various additional processes either involving or at least impacting on actin dynamics. These processes include additional types of protrusion, such as those mediating cell-to-cell spreading of pathogenic Listeria monocytogenes (Wang et al, 2015), but also integrin activation through its binding to talin (Lagarrigue et al, 2015;Lee et al, 2009;Watanabe et al, 2008) or the fast endophilin-mediated endocytosis (FEME) pathway (Boucrot et al, 2015;Chan Wah Hak et al, 2018). How Lpd sorts to or is regulated within these distinct subcellular structures, remains to be investigated.…”