Invasion of endothelial cells by Neisseria meningitidis requires cortactin recruitment by a phosphoinositide-3-kinase/Rac1 signalling pathway triggered by the lipo-oligosaccharide

Abstract

Type-IV-pilus-mediated adhesion of Neisseria meningitidis (also known as meningococcus) to human endothelial cells induces the formation of membrane protrusions leading to bacterial uptake. We have previously shown that these protrusions result from a Rho- and Cdc42-dependent cortical actin polymerization, and from the activation of the ErbB2 tyrosine-kinase receptor and the Src kinase, leading to tyrosine phosphorylation of cortactin. We report here that N. meningitidis mutants expressing a deglycosylated lipo-oligosaccharide are poorly invasive. These mutants show structurally altered actin polymerization. Moreover, although they efficiently recruit and activate ErbB2 and Src, these mutants are defective in the recruitment and phosphorylation of cortactin. We demonstrate that phosphorylated cortactin controls the cortical actin polymerization, which leads to membrane protrusion formation. In addition, we show that cortactin recruitment is dependent on the activation of a phosphoinositide-3-kinase/Rac1-GTPase signalling pathway, which is required for actin polymerization and internalization of N. meningitidis, and is not activated by the mutant strains. Altogether, these results define a new role for the lipo-oligosaccharide in triggering a phosphoinositide-3-kinase/Rac1 signalling required to elicit an efficient uptake of N. meningitidis in non-phagocytic cells.

Disease and Carrier Isolates of Neisseria meningitidis Cause G 1 Cell Cycle Arrest in Human Epithelial Cells

“…For our study, we chose N. meningitidis MC58 as a prototype ST-32 cc strain and strain ␣711 as a genetically related carrier isolate from the ST-32 cc. We also included N. meningitidis isolate 8013/clone 12 from the ST-18 cc (also known as clone 12 or 2C43), which has been used to study the interaction between N. meningitidis and brain endothelial cells (57)(58)(59)(60). Isolate ␣4 was chosen as a genetically related carrier isolate to 8013/clone 12.…”

Cortactin Has an Essential and Specific Role in Osteoclast Actin Assembly

“…The only study of loss of cortactin function in an intact organism is in Drosophila, where complete loss-of-function mutations of the sole cortactin gene had only minor effects, producing smaller F-actin ring canals of germline cells and impaired migration of border cells in oogenesis (Somogyi and Rorth, 2004). In cultured cells, a variety of studies point to a role for cortactin in actin-based processes such as pathogen invasion (Lambotin et al, 2005;Selbach and Backert, 2005), endocytosis (Merrifield et al, 2005;Sauvonnet et al, 2005), post-Golgi transport (Cao et al, 2005), cell adhesion (El Sayegh et al, 2004;Helwani et al, 2004), and lamellipodial persistence (Bryce et al, 2005). In these studies, cortactin was generally found to associate with sites of actin assembly, and, in some cases, expression of cortactin mutants or knockdown of cortactin produced partial loss of actin-based motility or actin cytoskeleton assembly.…”

Pathogens Penetrating the Central Nervous System: Infection Pathways and the Cellular and Molecular Mechanisms of Invasion

“…Cortical actin is then polymerized in a Rho GTPase-and Cdc42-dependent manner, which leads to the formation of cell membrane protrusions (186). In human bone marrow endothelial cells, the recruitment of cortactin and formation of membrane protrusions were also shown to be dependent on the activation of a phosphoinositide-3-kinase/Rac1 signaling pathway by lipooligosaccharide (190).…”