Escherichia coli Invasion Protein yijP Induces Apoptosis of Human Brain Microvascular Endothelial Cells

Abstract: In order to further characterize the role of invasion locus yijP in the pathogenesis of E. coli meningitis， the yijP gene (about 1.04 kb) was subcloned into pQE30， and expressed in E.coli M15(pREP4) as His-tagged confluence protein induced by IPTG. The successfully harvested confluence protein by Ni-NTA agarose affinity chromatography was refolded by dialysis. Phase contrast microscopy was used to observed the morphological changes of human brain microvascular endothelial cells (HBMEC)， and Hoechst 33258 staining， DNA agarose gel electrophoresis， FACScan flow cytometer and Western blotting were employed to investigate the type of the cell death. The results showed that the confluence protein yijP was toxic to HBMEC. Besides the cell shrinkage and nuclear condensation， DNA fragmentation， a sub-diploid peak and activity cleavage of caspase-3 were detected， which were the characteristics of the cell apoptosis. All these phenomena occurred after 16-hour incubation with the yijP. Our results indicated that yijP protein may act as a kind of toxin to induce delayed apoptosis of HBMEC.

CSTR: 32200.14.cjcb.2005.06.0015