Identification of MEK- and phosphoinositide 3-kinase-dependent signalling as essential events during Chlamydia pneumoniae invasion of HEp2 cells

Abstract

SummaryThe ability of Chlamydia pneumoniae to survive and cause disease is predicated on efficient invasion of cellular hosts. While it is recognized that chlamydial determinants are important for mediating attachment and uptake into non-phagocytic cells, little is known about the bacterial ligands and cellular receptors that facilitate invasion or host cell signal transduction pathways implicated in this process. We used transmission and scanning electron microscopy to demonstrate that attachment of bacteria to host cells induced the appearance of microvilli on host cell membranes. Invasion occurred 30-120 min after cell contact with the subsequent loss of membrane microvilli. Using an epithelial cell infection model, C. pneumoniae invasion caused a rapid and sustained increase in MEK-dependent phosphorylation and activation of ERK1/2, followed by PI 3-kinase-dependent phosphorylation and activation of Akt. Tyrosine phosphorylation of focal adhesion kinase (FAK) preceded its appearance in a complex with the p85 subunit of PI 3-kinase during chlamydial invasion and isoformspecific tyrosine phosphorylation of the docking protein Shc also occurred at the time of attachment and entry of bacteria. Chlamydia entry but not attachment could be abrogated with specific inhibitors of MEK, PI 3-kinase and actin polymerization, demonstrating the importance of these signalling pathways and an intact actin cytoskeleton for C. pneumoniae invasion. These results suggest that activation of specific cell signalling pathways is an essential strategy used by C. pneumoniae to invade epithelial cells.

High Mobility Group Nucleosomal Binding Domain 2 Protein Protects Bladder Epithelial Cells from Klebsiella pneumoniae Invasion

“…30) Mitogen-activated protein kinase (MAPK) family members are involved in host cell invasion by several pathogenic bacteria. [17][18][19][20][21] Invasion of epithelial cells represents a potential pathogenic mechanism for K. pneumoniae. We explored the role of mitogen-activated protein kinase kinases (MEK 1/2) and the extracellular signalregulated kinases (ERK 1/2) in K. pneumoniae invasion.…”

“…[17][18][19][20][21] Pretreatment with the MEK1/2 inhibitor PD98059 significantly reduced K. pneumoniae 03183 uptake by T 24 cells (Fig. 1).…”

Polymeric Immunoglobulin Receptor-mediated Invasion of Streptococcus pneumoniae into Host Cells Requires a Coordinate Signaling of SRC Family of Protein-tyrosine Kinases, ERK, and c-Jun N-terminal Kinase

“…MAP and SAP kinases have been demonstrated to be involved in host cell invasion and cytokine release induced by different pathogenic bacteria. For example, activation of several MAPKs were found in response to epithelial cell infection with S. aureus, C. pneumoniae, L. monocytogenes, enteropathogenic E. coli, and S. enterica serovar Typhimurium (41)(42)(43)(44)(45). In particular JNK activation was described to be associated with the invasion of Porphyromonas gingivalis in gingival cells, N. gonorrhoeae in epithelial cells, and N. meningitidis infection of human brain-derived microvascular endothelial cells (46 -48).…”

Invasion of HeLa cells by group B streptococcus requires the phosphoinositide-3-kinase signalling pathway and modulates phosphorylation of host-cell Akt and glycogen synthase kinase-3

“…The role of PI3K and phosphoinositide metabolism in bacterial pathogenesis is becoming increasingly appreciated. A requirement for PI3K in host-cell invasion has been identified for the pathogens group A streptococcus (GAS) (Purushothaman et al, 2003), Helicobacter pylori (Kwok et al, 2002), Chlamydia pneumoniae (Coombes & Mahony, 2002) and Listeria monocytogenes (Ireton et al, 1999), to name just a few. The result of manipulation of this pathway by a pathogen is coordination of actin rearrangement, leading to internalization of the organism.…”