Staphylococcus aureus recruits Cdc42GAP through recycling endosomes and the exocyst to invade human endothelial cells

Abstract

Activation and invasion of the vascular endothelium by Staphylococcus aureus is a major cause of sepsis and endocarditis. For endothelial cell invasion, S. aureus triggers actin polymerization through Cdc42, N-WASp (also known as WASL) and the Arp2/3 complex to assemble a phagocytic cup-like structure. Here, we show that after stimulating actin polymerization staphylococci recruit Cdc42GAP (also known as ARHGAP1) which deactivates Cdc42 and terminates actin polymerization in the phagocytic cups. Cdc42GAP is delivered to the invading bacteria on recycling endocytic vesicles in concert with the exocyst complex. When Cdc42GAP recruitment by staphylococci was prevented by blocking recycling endocytic vesicles or the exocyst complex, or when Cdc42 was constitutively activated, phagocytic cup closure was impaired and endothelial cell invasion was inhibited. Thus, to complete invasion of the endothelium, staphylococci reorient recycling endocytic vesicles to recruit Cdc42GAP, which terminates Cdc42-induced actin polymerization in phagocytic cups. Analogous mechanisms might govern other Cdc42-dependent cell functions.

A role for host cell exocytosis in InlB-mediated internalisation ofListeria monocytogenes

“…Interestingly, previous reports indicate that the mammalian exocyst complex promotes internalisation of Salmonella enterica serovar Typhimurium or Staphylococcus aureus (Nichols & Casanova, 2010;Rauch et al, 2016). To the best of our knowledge, our work with Listeria is the only study that demonstrates a role for the core exocytosis machinery (i.e., SNARE and SM proteins) in bacterial uptake.…”

Interaction of microbial pathogens with host exocytic pathways

“…Recent results indicate that the bacterial pathogens Listeria monocytogenes and Staphylococcus aureus each co‐opt RE‐mediated exocytosis in order to induce their internalisation into human cells (Rauch et al, ; Van Ngo et al, ). Key findings from these studies are discussed below.…”

“…Importantly, recent work by Rauch et al demonstrates that completion of entry of S. aureus into endothelial cells requires downregulation of Cdc42 in phagocytic cups. Interestingly, inhibition of Cdc42 is achieved through the exocytic recruitment of the GTPase‐activating protein (GAP), Cdc42GAP (Figure a; Rauch et al, ).…”

“…Cdc42GAP was found to be recruited around S. aureus or latex beads coated with FnBPA during of internalisation of these particles into endothelial cells (Rauch et al, ). Moreover, RNAi‐mediated depletion of Cdc42GAP or expression of a constitutively activated form of Cdc42 (Cdc42.Q61L) prevents the closure of phagocytic cups around FnBPA‐coated beads.…”

“…However, the successful completion of bacterial engulfment may require localised downregulation of actin polymerisation at the base of phagocytic cups, in order to allow phagosomes to sink into the cytosol and seal (Levin, Grinstein, & Canton, 2016). Cdc42GAP was found to be recruited around S. aureus or latex beads coated with FnBPA during of internalisation of these particles into endothelial cells (Rauch et al, 2016). Moreover, RNAi-mediated depletion of Cdc42GAP or expression of a constitutively activated form of Cdc42 (Cdc42.Q61L) prevents the closure of phagocytic cups around FnBPA-coated beads.…”