37-kDa Laminin Receptor Precursor Modulates Cytotoxic Necrotizing Factor 1–mediated RhoA Activation and Bacterial Uptake

Abstract

Cytotoxic necrotizing factor 1 (CNF1) is a bacterial toxin known to activate Rho GTPases and induce host cell cytoskeleton rearrangements. The constitutive activation of Rho GTPases by CNF1 is shown to enhance bacterial uptake in epithelial cells and human brain microvascular endothelial cells. However, it is unknown how exogenous CNF1 exhibits such phenotypes in eukaryotic cells. Here, we identified 37-kDa laminin receptor precursor (LRP) as the receptor for CNF1 from screening the cDNA library of human brain microvascular endothelial cells by the yeast two-hybrid system using the N-terminal domain of CNF1 as bait. CNF1-mediated RhoA activation and bacterial uptake were inhibited by exogenous LRP or LRP antisense oligodeoxynucleotides, whereas they were increased in LRPoverexpressing cells. These findings indicate that the CNF1 interaction with LRP is the initial step required for CNF1-mediated RhoA activation and bacterial uptake in eukaryotic cells.

Rho GTPases as pathogen targets: Focus on curable sexually transmitted infections

“…118 Interestingly, some microorganisms, through the release of adhesion molecules, bind to fibronectin and activate Rho GTPases to promote host cell invasion. 119 For instance, the bacterial fibronectin-binding protein of Campylobacter jejuni, CadF, and the intact flagellum are involved in eukaryotic Rac1 GTPase activation and host cell invasion. 116,120 It has been postulated that CadF binding to fibronectin results in integrin clustering and activation.…”

Ca2+/calmodulin-dependent invasion of microvascular endothelial cells of human brain by Escherichia coli K1

“…We have previously shown that the E. coli K1 invasion of HBMEC is the result of interactions of bacterial structures with their respective HBMEC receptors (Kim 2003). For example, E. coli K1 proteins, such as IbeA and cytotoxic necrotizing factor (CNF) 1, contribute to the invasion of HBMEC and interact with specific receptors present on HBMEC, a 45-kDa protein and 69LR, respectively (Nemani et al 1999a;Chung et al 2003). We have also shown that FimH, one of the E. coli structures contributing to the binding to and invasion of HBMEC is able to induce Ca 2+ changes in HBMEC through its interaction with the putative CD48 receptor: preincubation of HBMEC with FimH or CD48 antibody prevents subsequent CD48-induced or FimH-induced [Ca 2+ ] i changes, respectively (Khan et al 2007).…”

Bacterial induction of Snail1 contributes to blood-brain barrier disruption

“…Recently, we have demonstrated that the GBS pilus protein PilA and Srr-1 interact with components of the host extracellular matrix (ECM) to promote BBB interactions and the development of meningitis (8,9). Other meningeal pathogens, such as Streptococcus pneumoniae (SPN), E. coli K1, Neisseria meningitidis, and Haemophilus influenza type B (HiB, also bind ECM components and ECM receptors (e.g., integrins and laminin receptor) to mediate bacterial-BBB interactions (12)(13)(14)(15). Given that host ECM components and receptors preferentially localize to the basolateral surface of polarized BBB endothelium (16), we hypothesized that disruption of junctional protein complexes in brain endothelium is the first step leading to bacterial access to basally expressed receptors.…”