Escherichia coliinteraction with human brain microvascular endothelial cells induces signal transducer and activator of transcription 3 association with the C-terminal domain of Ec-gp96, the outer membrane protein A receptor for invasion

Abstract

SummaryOur inability to develop new therapeutic strategies to prevent meningitis due to Escherichia coli K1 is attributed to our incomplete understanding of the pathophysiology of the disease. Previously, we demonstrated that outer membrane protein A of E. coli interacts with a gp96 homologue, Ec-gp96, on human brain microvascular endothelial cells (HBMEC) for invasion. However, signalling events mediated by Ec-gp96 that allow internalization of E. coli are incompletely understood. Here, we demonstrate that signal transducer and activator of transcription 3 (Stat3) activation and its interaction with Ec-gp96 were critical for E. coli invasion. The activated Stat3 was colocalized with Ec-gp96 at the actin condensation sites, and overexpressing a dominant negative (DN) form of Stat3 in HBMEC significantly abrogated the invasion. Furthermore, overexpression of Ec-gp96D200, the C-terminal 214-amino-acid truncated Ec-gp96, prevented the invasion of E. coli in HBMEC. In contrast, lack of ATP binding by gp96 did not affect the invasion. Overexpression of DN forms of either phosphatidyl inositol-3 kinase (PI3-kinase) subunit p85 or protein kinase C-a (PKC-a) had no effect on the activation of Stat3 and its association with Ec-gp96, whereas overexpression of DN-Stat3 abolished the activation of both PI3-kinase and PKC-a. Together, our findings identified a novel interaction of Stat3 with Ec-gp96, upstream of PI3-kinase and PKC-a activation that is required for the invasion of E. coli into HBMEC.

Listeria monocytogenes Triggers the Cell Surface Expression of Gp96 Protein and Interacts with Its N Terminus to Support Cellular Infection

“…OmpA interacts with the N terminus of Gp96 at the surface of human brain microvascular endothelial cells to promote infection (38). Here we show that despite the lack of homology shared between OmpA and Vip the listerial protein also interacts with the N terminus of Gp96.…”

Bacterial Virulence in the Moonlight: Multitasking Bacterial Moonlighting Proteins Are Virulence Determinants in Infectious Disease

“…The two 90-kDa heat shock proteins of human cells, Hsp90 and gp96, are increasingly seen to play important roles in bacterial virulence and may open up new therapeutic avenues. The role of these proteins was first discovered when it was found that gp96 on the outer surface of (122), and the levels of Ec-gp96 are controlled by nitric oxide/cGMP signaling (125). gp96 is an endoplasmic reticulum (ER) Hsp90 family member, and evidence has recently been found for its role in the uptake of bacterial toxins.…”

Elevated Inflammatory Response in Caveolin-1-deficient Mice with Pseudomonas aeruginosa Infection Is Mediated by STAT3 Protein and Nuclear Factor κB (NF-κB)

“…Recently, STAT3 was found to interact with Cav-1 and heat shock protein 90 in plasma membrane rafts during Escherichia coli infection (26). Cav-1 is also related to a JAK2/STAT5 pathway because Cav-1 is homologous to the pseudosubstrate for SOCS.…”