Transforming growth factor-beta increases Escherichia coli K1 adherence,invasion, and transcytosis in human brain microvascular endothelial cells

Escherichia coli K1 traversal of the human brain microvascular endothelial cells (HBMEC) that constitute the blood-brain barrier (BBB) is a complex process involving E. coli adherence to and invasion of HBMEC. In this study, we demonstrated that human transforming growth factor-beta-1 (TGF-beta1) increases E. coli K1 adherence, invasion, and transcytosis in HBMEC. In addition, TGF-beta1 increases RhoA activation and enhances actin condensation in HBMEC. We have previously shown that E. coli K1 invasion of HBMEC requires phosphatidylinositol-3 kinase (PI3K) and RhoA activation. TGF-beta1 increases E. coli K1 invasion in PI3K dominant-negative HBMEC, but not in RhoA dominant-negative HBMEC, indicating that TGF-beta1-mediated increase in E. coli K1 invasion is RhoA-dependent, but not PI3K-dependent. Our findings suggest that TGF-beta1 treatment of HBMEC increases E. coli K1 adherence, invasion, and transcytosis, which are probably dependent on RhoA.     

Phosphatidylinositol 3-kinase activation and interaction with focal adhesion kinase in Escherichia coli K1 invasion of human brain microvascular endothelial cells

Invasion of brain microvascular endothelial cells (BMEC) is a prerequisite for successful crossing of the blood-brain barrier by Escherichia coli K1. We have previously demonstrated the requirement of cytoskeletal rearrangements and activation of focal adhesion kinase (FAK) in E. coli K1 invasion of human BMEC (HBMEC). The current study investigated the role of phosphatidylinositol 3-kinase (PI3K) activation and PI3K interaction with FAK in E. coli invasion of HBMEC. PI3K inhibitor LY294002 blocked E. coli K1 invasion of HBMEC in a dose-dependent manner, whereas an inactive analogue LY303511 had no such effect. In HBMEC, E. coli K1 increased phosphorylation of Akt, a downstream effector of PI3K, which was completely blocked by LY294002. In contrast, non-invasive E. coli failed to activate PI3K. Overexpression of PI3K mutants Deltap85 and catalytically inactive p110 in HBMEC significantly inhibited both PI3K/Akt activation and E. coli K1 invasion of HBMEC. Stimulation of HBMEC with E. coli K1 increased PI3K association with FAK. Furthermore, PI3K/Akt activation was blocked in HBMEC-overexpressing FAK dominant-negative mutants (FRNK and Phe397FAK). These results demonstrated the involvement of PI3K signaling in E. coli K1 invasion of HBMEC and identified a novel role for PI3K interaction with FAK in the pathogenesis of E. coli meningitis.     

Differential fluorescence induction reveals Streptococcus pneumoniae loci regulated by competence stimulatory peptide

Differential fluorescence induction (DFI) in Streptococcus pneumoniae was used as a method for the discovery of genes activated in specific growth environments. Competence stimulatory peptide (CSP) was used as the model inducing system to identify differentially expressed genes. To identify CSP-induced promoters, a plasmid library was constructed by inserting random pieces of S. pneumoniae chromosomal DNA upstream of the promoterless gfpmut2 gene in an Escherichia coli/S. pneumoniae shuttle vector. S. pneumoniae carrying the library were induced with CSP and enriched for green fluorescent protein (GFP)-expressing bacteria using fluorescence-activated cell sorting. A total of 886 fluorescent clones was screened, and 12 differentially activated promoter elements were identified. Sequence analysis of these clones revealed that three were associated with novel competence loci, one of which we show is essential for DNA uptake, and six are known CSP-inducible promoters. We also explored whether competence proteins have a role in virulence and found that mutations in three CSP-inducible genes resulted in attenuated virulence phenotypes in either of two murine infection models. These results demonstrate the utility of DFI as a method for identifying differentially expressed genes in S. pneumoniae and the potential utility of applying DFI to other Gram-positive bacteria.     

Current concepts on Escherichia coli K1 translocation of the blood-brain barrier

The mortality and morbidity associated with neonatal gram-negative meningitis have remained significant despite advances in antimicrobial chemotherapy. Escherichia coli K1 is the most common gram-negative organism causing neonatal meningitis. Our incomplete knowledge of the pathogenesis of this disease is one of the main reasons for this high mortality and morbidity. We have previously established both in vitro and in vivo models of the blood-brain barrier (BBB) using human brain microvascular endothelial cells (HBMEC) and hematogenous meningitis in neonatal rats, respectively. With these in vitro and in vivo models, we have shown that successful crossing of the BBB by circulating E. coli requires a high-degree of bacteremia, E. coli binding to and invasion of HBMEC, and E. coli traversal of the BBB as live bacteria. Our previous studies using TnphoA, signature-tagged mutagenesis and differential fluorescence induction identified several E. coli K1 determinants such as OmpA, Ibe proteins, AslA, TraJ and CNF1 contributing to invasion of HBMEC in vitro and traversal of the blood-brain barrier in vivo. We have shown that some of these determinants interact with specific receptors on HBMEC, suggesting E. coli translocation of the BBB is the result of specific pathogen-host cell interactions. Recent studies using functional genomics techniques have identified additional E. coli K1 factors that contribute to the high degree of bacteremia and HBMEC binding/invasion/transcytosis. In this review, we summarize the current knowledge on the mechanisms underlying the successful E. coli translocation of the BBB.     

67-kDa laminin receptor promotes internalization of cytotoxic necrotizing factor 1-expressing Escherichia coli K1 into human brain microvascular endothelial cells

Escherichia coli K1 is the most common Gram-negative organism causing meningitis, and its invasion of human brain microvascular endothelial cells (HBMEC) is a prerequisite for penetration into the central nervous system. We have reported previously that cytotoxic necrotizing factor 1 (CNF1) contributes to E. coli K1 invasion of HBMEC and interacts with 37-kDa laminin receptor precursor (37LRP) of HBMEC, which is a precursor of 67-kDa laminin receptor (67LR). In the present study, we examined the role of 67LR in the CNF1-expressing E. coli K1 invasion of HBMEC. Immunofluorescence microscopy and ligand overlay assays showed that 67LR is present on the HBMEC membrane and interacts with CNF1 protein as well as the CDPGYIGSR laminin peptide. 67LR was up-regulated and clustered at the sites of E. coli K1 on HBMEC in a CNF1-dependent manner. Pretreatment of CNF1+ E. coli K1 with recombinant 37-kDa laminin receptor precursor reduced the invasion rate to the level of Deltacnf1 mutant, and the invasion rate of CNF1+ E. coli K1 was enhanced in 67LR-overexpressing HBMEC, indicating 67LR is involved in the CNF1+ E. coli K1 invasion of HBMEC. Coimmunoprecipitation analysis showed that, upon incubation with CNF1+ E. coli K1 but not with Deltacnf1 mutant, focal adhesion kinase and paxillin were recruited and associated with 67LR. When immobilized onto polystyrene beads, CNF1 was sufficient to induce internalization of coupled beads into HBMEC through interaction with 67LR. Taken together, this is the first demonstration that E. coli K1 invasion of HBMEC occurs through the ligand-receptor (CNF1-67LR) interaction, and 67LR promotes CNF1-expressing E. coli K1 internalization of HBMEC.     

Escherichia coli K-1 interaction with human brain micro-vascular endothelial cells triggers phospholipase C-gamma1 activation downstream of phosphatidylinositol 3-kinase

Escherichia coli, the most common Gram-negative bacterium that causes meningitis in neonates, invades human brain microvascular endothelial cells (HBMEC) by rearranging host cell actin via the activation of phosphatidylinositol 3-kinase (PI3K) and PKC-alpha. Here, further, we show that phospholipase (PLC)-gamma1 is phosphorylated on tyrosine 783 and condenses at the HBMEC membrane beneath the E. coli entry site. Overexpression of a dominant negative (DN) form of PLC-gamma, the PLC-z fragment, in HBMEC inhibits PLC-gamma1 activation and significantly blocks E. coli invasion. PI3K activation is not affected in PLC-z/HBMEC upon infection, whereas PKC-alpha phosphorylation is completely abolished, indicating that PLC-gamma1 is downstream of PI3K. Concomitantly, the phosphorylation of PLC-gamma1 is blocked in HBMEC overexpressing a dominant negative form of the p85 subunit of PI3K but not in HBMEC overexpressing a dominant negative form of PKC-alpha. In addition, the recruitment of PLC-gamma1 to the cell membrane in both PLC-z/HBMEC and DN-p85/HBMEC is inhibited. Activation of PI3K is associated with the conversion of phosphatidylinositol 4,5-bisphosphate (PIP2) to phosphatidylinositol 1,4,5-trisphosphate (PIP3), which in turn recruits PLC-gamma1 to the cell membrane via its interaction with pleckstrin homology domain of PLC-gamma1. Utilizing the pleckstrin homology domains of PKC-delta and Btk proteins fused to green fluorescent protein (GFP), which specifically interact with PIP2 and PIP3, respectively, we show herein that E. coli invasion induces the breakdown of PIP2 at the plasma membrane near the site of E. coli interaction. PIP3, on the other hand, recruits the GFPBkt to the cell membrane beneath the sites of E. coli attachment. Our studies further show that E. coli invasion induces the release of Ca2+ from intracellular pools as well as the influx of Ca2+ from the extracellular medium. This elevation in Ca2+ levels is completely blocked both in PLC-z/HBMEC and DN-p85/HBMEC, but not in DN-PKC/HBMEC. Taken together, these results suggest that E. coli infection of HBMEC induces PLC-gamma1 activation in a PI3K-dependent manner to increase Ca2+ levels in HBMEC. This is the first report demonstrating the recruitment of activated PLC-gamma1 to the sites of bacterial entry.     

Effect of rpoS mutations on stress-resistance and invasion of brain microvascular endothelial cells in Escherichia coli K1

Escherichia coli K1 strains are predominant in causing neonatal meningitis. We have shown that invasion of brain microvascular endothelial cells (BMEC) is a prerequisite for E. coli K1 crossing of the blood-brain barrier. BMEC invasion by E. coli K1 strain RS218, however, has been shown to be significantly greater with stationary-phase cultures than with exponential-phase cultures. Since RpoS participates in regulating stationary-phase gene expression, the present study examined a possible involvement of RpoS in E. coli K1 invasion of BMEC. We found that the cerebrospinal fluid isolates of E. coli K1 strains RS218 and IHE3034 have a nonsense mutation in their rpoS gene. Complementation with the E. coli K12 rpoS gene significantly increased the BMEC invasion of E. coli K1 strain IHE3034, but failed to significantly increase the invasion of another E. coli K1 strain RS218. Of interest, the recovery of E. coli K1 strains following environmental insults was 10-100-fold greater on Columbia blood agar than on LB agar, indicating that growing medium is important for viability of rpoS mutants after environmental insults. Taken together, our data suggest that the growth-phase-dependent E. coli K1 invasion of BMEC is affected by RpoS and other growth-phase-dependent regulatory mechanisms.     

大肠杆菌侵袭基因缺失突变株与人脑微血管内皮细胞的相互作用

ibeA,ibeB,ibeC是与大肠杆菌侵袭人脑微血管内皮细胞(HBMEC)密切相关的基因,但迄今各基因的功能并不清楚。应用侵袭分析和免疫荧光技术分析了各基因的缺失突变型及野生型大肠杆菌对HBMEC的侵袭、细胞骨架与细胞间紧密连接的影响。结果显示：野生型菌大肠杆菌侵袭率为3.46％,而ibeA,ibeB,ibeC缺失突变株分别为0.54％、0．82％和0.73％：ibeA缺失突变型与野生型大肠杆菌作用相似,可引起HBMEC的细胞骨架蛋白分布改变,在细胞膜处呈明显的聚集,而ibeB和ibeC缺失突变株并未引起细胞骨架的明显改变;野生型和ibeA缺失突变型大肠杆菌可引起紧密连接结构的明显改变,而ibeB和ibeC缺失突变株对紧密连接结构的影响不明显。这些观察到的结果提示：ibeB和ibeC基因产物可能在调节细胞骨架和影响细胞紧密连接中起重要作用,而ibeA基因产物在其中的作用较小。     

Role of Rac1 in Escherichia coli K1 invasion of human brain microvascular endothelial cells

Escherichia coli K1 invasion of human brain microvascular endothelial cells (HBMEC) requires the reorganization of host cytoskeleton at the sites of bacterial entry. Both actin and myosin constitute the cytoskeletal architecture. We have previously shown that myosin light chain (MLC) phosphorylation by MLC kinase is regulated during E. coli invasion by an upstream kinase, p21-activated kinase 1 (PAK1), which is an effector protein of Rac and Cdc42 GTPases, but not of RhoA. Here, we report that the binding of only Rac1 to PAK1 decreases in HBMEC upon infection with E. coli K1, which resulted in increased phosphorylation of MLC. Overexpression of a constitutively active (cAc) form of Rac1 in HBMEC blocked the E. coli invasion significantly, whereas overexpression of a dominant negative form had no effect. Increased PAK1 phosphorylation was observed in HBMEC expressing cAc-Rac1 with a concomitant reduction in the phosphorylation of MLC. Immunocytochemistry studies demonstrated that the inhibition of E. coli invasion into cAc-Rac1/HBMEC is due to lack of phospho-MLC recruitment to the sites of E. coli entry. Taken together the data suggest that E. coli modulates the binding of Rac1, but not Cdc42, to PAK1 during the invasion of HBMEC.     

FimH-mediated Escherichia coli K1 invasion of human brain microvascular endothelial cells

Adhesion to brain microvascular endothelial cells, which constitute the blood-brain barrier is considered important in Escherichia coli K1 bacterial penetration into the central nervous system. Type 1 fimbriae are known to mediate bacterial interactions with human brain microvascular endothelial cells (HBMEC). Here, we demonstrate that type 1 fimbriae, specifically FimH adhesin is not only an adhesive organelle that provides bacteria with a foothold on brain endothelial cells but also triggers signalling events that promote E. coli K1 invasion in HBMEC. This is shown by our demonstrations that exogenous FimH increases cytosolic-free-calcium levels as well as activates RhoA. Using purified recombinant mannose-recognition domain of FimH, we identified a glycosylphosphatidylinositol-anchored receptor, CD48, as a putative HBMEC receptor for FimH. Furthermore, E. coli K1 binding to and invasion of HBMEC were blocked by CD48 antibody. Taken together, these findings indicate that FimH induces host cell signalling cascades that are involved in E. coli K1 invasion of HBMEC and CD48 is a putative HBMEC receptor for FimH.     

Nitric oxide/cGMP signalling induces Escherichia coli K1 receptor expression and modulates the permeability in human brain endothelial cell monolayers during invasion

Escherichia coli K1 invasion of human brain microvascular endothelial cells (HBMEC) mediated by outer membrane protein A (OmpA) results in the leakage of HBMEC monolayers. Despite the influence of nitric oxide (NO) in endothelial cell tight junction integrity, its role in E. coli -induced HBMEC monolayer permeability is poorly defined. Here, we demonstrate that E. coli invasion of HBMEC stimulates NO production by increasing the inducible nitric oxide synthase (iNOS) expression. Exposure to NO-producing agents enhanced the invasion of OmpA⁺ E. coli and thereby increased the permeability of HBMEC. OmpA⁺ E. coli- induced NO production lead to increased generation of cGMP and triggered the expression of OmpA receptor, Ec-gp96 in HBMEC. Pre-treatment of HBMEC with iNOS inhibitors or by introducing siRNA to iNOS, but not to eNOS or cGMP inhibitors abrogated the E. coli- induced expression of Ec-gp96. Overexpression of the C-terminal truncated Ec-gp96 in HBMEC prevented NO production and its downstream effector, cGMP generation and consequently, the invasion of OmpA⁺ E. coli. NO/cGMP production also activates PKC-α, which is previously shown to be involved in HBMEC monolayer leakage. These results indicate that NO/cGMP signalling pathway plays a novel role in OmpA⁺ E. coli invasion of HBMEC by enhancing the surface expression of Ec-gp96.     

Outer membrane protein A of Escherichia coli K1 selectively enhances the expression of intercellular adhesion molecule-1 in brain microvascular endothelial cells

Escherichia coli K1 meningitis is a serious central nervous system disease with unchanged mortality and morbidity rates for last few decades. Intercellular adhesion molecule 1 (ICAM-1) is a cell adhesion molecule involved in leukocyte trafficking toward inflammatory stimuli at the vascular endothelium; however, the effect of E. coli invasion of endothelial cells on the expression of ICAM-1 is not known. We demonstrate here that E. coli K1 invasion of human brain microvascular endothelial cells (HBMEC) selectively up-regulates the expression of ICAM-1, which occurs only in HBMEC invaded by the bacteria. The interaction of outer membrane protein A (OmpA) of E. coli with its receptor, Ecgp, on HBMEC was critical for the up-regulation of ICAM-1 and was depend on PKC-alpha and PI3-kinase signaling. Of note, the E. coli-induced up-regulation of ICAM-1 was not due to the cytokines secreted by HBMEC upon bacterial infection. Activation of NF-kappaB was required for E. coli mediated expression of ICAM-1, which was significantly inhibited by over-expressing the dominant negative forms of PKC-alpha and p85 subunit of PI3-kinase. The increased expression of ICAM-1 also enhanced the binding of THP-1 cells to HBMEC. Taken together, these data suggest that localized increase in ICAM-1 expression in HBMEC invaded by E. coli requires a novel interaction between OmpA and its receptor, Ecgp.     

Escherichia coli outer membrane protein A adheres to human brain microvascular endothelial cells

Escherichia coli K1 is the most common gram-negative bacterium causing neonatal meningitis. The outer membrane protein A (OmpA) assembles a beta-barrel structure having four surface-exposed loops in E. coli outer membrane. OmpA of meningitis-causing E. coli K1 is shown to contribute to invasion of the human brain microvascular endothelial cells (HBMEC), the main cellular component of the blood-brain barrier (BBB). However, the direct evidence of OmpA protein interacting with HBMEC is not clear. In this study, we showed that OmpA protein, solubilized from the outer membrane of E. coli, adhered to HBMEC surface. To verify OmpA interaction with the HBMEC, we purified N-terminal membrane-anchoring beta-barrel domain of OmpA and all surface-exposed loops deleted OmpA proteins, and showed that the surface-exposed loops of OmpA were responsible for adherence to HBMEC. These findings indicate that the OmpA is the adhesion molecule with HBMEC and the surface-exposed loops of OmpA are the determinant of this interaction.     

Identification of a surface protein on human brain microvascular endothelial cells as vimentin interacting with Escherichia coli invasion protein IbeA

Escherichia coli K1 is the most common gram-negative bacteria that cause meningitis during the neonatal period. The ibeA gene product in E. coli K1 has been characterized as a virulence factor that contributes to the binding to and invasion of brain microvascular endothelial cells (BMEC). Here, we identified a surface protein on human BMEC, vimentin, that interacts with the E. coli invasion protein IbeA. The binding sites of the IbeA-vimentin interaction are located in the 271-370 residue region of IbeA and the vimentin head domain. The regulatory protease factor Xa is able to cleave IbeA between R297 and K298 residues, and this cleavage abolishes the IbeA-vimentin interaction.     

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

Escherichia coli K1 invasion of microvascular endothelial cells of human brain (HBMEC) is required for E. coli penetration into the central nervous system, but the microbial-host interactions that are involved in this invasion of HBMEC remain incompletely understood. We have previously shown that FimH, one of the E. coli determinants contributing to the binding to and invasion of HBMEC, induces Ca²⁺ changes in HBMEC. In the present study, we have investigated in detail the role of cellular calcium signaling in the E. coli K1 invasion of HBMEC, the main constituents of the blood-brain barrier. Addition of the meningitis-causing E. coli K1 strain RS218 (O18:K1) to HBMEC results in transient increases of intracellular free Ca²⁺. Inhibition of phospholipase C with U-73122 and the chelating of intracellular Ca²⁺ by BAPTA/AM reduces bacterial invasion of HBMEC by approximately 50%. Blocking of transmembrane Ca²⁺ fluxes by extracellular lanthanum ions also inhibits the E. coli invasion of HBMEC by approximately 50%. In addition, E. coli K1 invasion is significantly inhibited when HBMEC are pretreated by the calmodulin antagonists, trifluoperazine or calmidazolium, or by ML-7, a specific inhibitor of Ca²⁺/calmodulin-dependent myosin light-chain kinase. These findings indicate that host intracellular Ca²⁺ signaling contributes in part to E. coli K1 invasion of HBMEC. This work was supported by the American Heart Association (grant SDG 0435177N to Y.K.) and by NIH grants (to K.S.K.).     

Regulation of protein kinase C in Escherichia coli K1 invasion of human brain microvascular endothelial cells.

Escherichia coli is one of the most important pathogens involved in the development of neonatal meningitis in many parts of the world. Traversal of E. coli across the blood-brain barrier is a crucial event in the pathogenesis of E. coli meningitis. Our previous studies have shown that outer membrane protein A (OmpA) expression is necessary in E. coli for a mechanism involving actin filaments in its passage through the endothelial cells. Focal adhesion kinase (FAK) and phosphatidylinositol 3-kinase (PI3K) have also been activated in host cells during the process of invasion. In an attempt to elucidate the mechanisms leading to actin filament condensation, we have focused our attention on protein kinase C (PKC), an enzyme central to many signaling events, including actin rearrangement. In the current study, specific PKC inhibitors, bisindolmaleimide and a PKC-inhibitory peptide, inhibited E. coli invasion of human brain microvascular endothelial cells (HBMEC) by more than 75% in a dose-dependent manner, indicating a significant role played by this enzyme in the invasion process. Our results further showed that OmpA+ E. coli induces significant activation of PKC in HBMEC as measured by the PepTag nonradioactive assay. In addition, we identified that the PKC isoform activated in E. coli invasion is a member of the conventional family of PKC, PKC-alpha, which requires calcium for activation. Immunocytochemical studies have indicated that the activated PKC-alpha is associated with actin condensation beneath the bacterial entry site. Overexpression of a dominant negative mutant of PKC-alpha in HBMEC abolished the E. coli invasion without significant changes in FAK phosphorylation or PI3K activity patterns. In contrast, in HBMEC overexpressing the mutant forms of either FAK or PI3K, E. coli-induced PKC activation was significantly blocked. Furthermore, our studies showed that activation of PKC-alpha induces the translocation of myristoylated alanine-rich protein kinase C substrate, an actin cross-linking protein and a substrate for PKC-alpha, from the membrane to cytosol. This is the first report of FAK- and PI3K-dependent PKC-alpha activation in bacterial invasion related to cytoskeletal reorganization.     

Enhanced Escherichia coli invasion of human brain microvascular endothelial cells is associated with alternations in cytoskeleton induced by nicotine

Although epidemiological studies have shown that exposure to tobacco smoking significantly increases the risk of bacterial meningitis, heretofore the pathogenic effects of smoking on this disease have been poorly understood. In order to dissect this issue, we have investigated the effects of nicotine, the major component of tobacco, on E. coli invasion of human brain microvascular endothelial cells (HBMEC). Our studies showed that E. coli invasion of HBMEC was significantly enhanced by nicotine in a dose-dependent manner. The nicotine-mediated enhancement was associated with actin cytoskeleton rearrangement and morphological changes in the eukaryotic host cell that are essential for bacterial entry. The recombinant IbeA protein and alpha-bungarotoxin (a nicotinic acetylcholine receptor antagonist) were able to efficiently block the nicotine-mediated cellular effects, suggesting the involvement of the IbeA and nicotinic receptors. Blocking of phosphatidylinositol 3-kinase (PI3K) by LY294002 abolished the entry of E. coli in HBMECs treated with nicotine in a dose-dependent manner. Inhibition of PI3K was associated with decreased phosphorylation of Akt and actin cytoskeletal rearrangement. In contrast to PI3K, blockage of Rho kinase (ROCK) by Y27632 upregulated both nicotine- and E. coli-mediated cellular responses. Thus, this study provides experimental evidence for the first time that the major component of tobacco, nicotine, enhances meningitic E. coli invasion of HBMEC through modulation of cytoskeleton.     

Involvement of Src tyrosine kinase in Escherichia coli invasion of human brain microvascular endothelial cells

Invasion of brain microvascular endothelial cells is a prerequisite for successful crossing of the blood-brain barrier by Escherichia coli (E. coli), but the underlying mechanism remains unclear. Here we showed activation of Src tyrosine kinase in E. coli K1 invasion of human brain microvascular endothelial cells (HBMEC). E. coli invasion of HBMEC and the E. coli-induced rearrangement of actin filaments were blocked by Src inhibitors. Overexpression of dominant-negative Src in HBMEC significantly attenuated E. coli invasion and the concomitant actin filaments rearrangement. Furthermore, E. coli K1-triggered phosphatidylinositol 3-kinase (PI3K) activation in HBMEC was effectively blocked by Src inhibitors and dominant-negative Src. These results demonstrated the involvement of Src and its interaction with PI3K in E. coli K1 invasion of HBMEC.

Structured summary

MINT-7296127, MINT-7296136: Src (uniprotkb:P12931) physically interacts (MI:0915) with p85 (uniprotkb:P27986) by anti bait coimmunoprecipitation (MI:0006)MINT-7296149: F-actin (uniprotkb:P60709) and Src-DN (uniprotkb:P12931) colocalize (MI:0403) by fluorescence microscopy (MI:0416)