Calcium signaling events in Streptococcus pneumoniae invasion of human type Ⅱ pneumocytes

Abstract

Abstract: Objective To study whether Streptococcus pneumoniae (S.pn) can provoke filamentous actin (F-actin) rearran-gements in vitro through calcium signaling pathways in type Ⅱ pneumocytes(A549 cells), resulting in S.pn invasion of the cells. Method After FITC-phalloidin labeling of F-actin, F-actin rearrangements were observed by S.pn adhesion to type pneumocyte A549 cells. S.pn invasion of A549 cells was determined by pretreating A549 cells with cytochalasin D. To investigate whether F-actin rearrangements could be blocked by Ca²⁺ inhibitors, A549 cells were pretreated with Ca²⁺ inhibitors dantrolene, and loaded in Fura-2/AM probe to determine the concentration of cytosolic free calcium by S.pn adhesion to A549 cells after 30, 60, and 90 min respectively. Results Intact S.pn can promote F-actin rearrangements. Cytochalasin D was able to prevent S.pn invasion of A549 cells. No invasion of A549 cell can be determined at 0.25 μg/ml of cytochalasin D. One subset of the inhibitors of Ca²⁺ signal transduction molecules blocked F-actin rearrangements dose-dependently, and S.pn adhesion of A549 cells for 30, 60, and 90 min increased cytosolic free calcium, reaching (487.5±38.1),(548.2±35.6) and (557.2±47.5) nmol/L, respectively. They were higher than of the control group. Conclusion S.pn can provoke F-actin rearrangements through Ca²⁺ signaling pathways, which further leads to S.pn invasion of A549 cells.

CLC Number:

R378.14

XU Bang-lao¹, YIN Yi-bing². Calcium signaling events in Streptococcus pneumoniae invasion of human type Ⅱ pneumocytes[J]. Journal of Southern Medical University, 2004, 24(02): 168-171,176.

References

[1] Gillespie SH. Aspects ofpneumococcal infection including bacterial virulence, host response and vaccination[J]. J Med Microbiol,1989, 28(9): 237-48.
[2] Dytoc M, Fedorko L, Sherman PM. Signal transduction in human epithelial cells infected with attaching and effacing Escherichia coli in vitro[J]. Gastroenterology, 1999, 106(21): 1150-61.
[3] Philpott DJ, Ismaili A, Dytoc MT. Increased adherence of Escherichia coli RDEC-1 to human tissue culture cells results in the activation of host signaling pathways[J]. J Infect Dis, 1995, 172(13): 136-43.
[4] Lacks SA. Study of genetic material determining an enzyme activity in pneumococcus[J]. Biochem Biophys Acta, 1960, 39(7): 508-17.
[5] Peiffer I, Servin AL, Bemet-Camard MF. Piracy of decay-accelerating factor (CD55) by the diffusely adhering strain Escherichia coli C1845 promotes cytoskeletal F-actin rearrangements in cultured human intestinal INT407 cells[J]. Infect Immun, 1998, 66(9): 4036-42.
[6] Paton JC. Molecular analysis of the pathogenicity of streptococcus pneumoniae: therole of pneumococcal proteins[J]. Annu Rev Microbiol, 1993, 47(22): 89-115.
[7] 刘振伟.用Fura-2测定缺氧时海马细胞内游离钙离子浓度的变化[J].细胞生物学杂志(J Cytobiol),1994,16(3):141-3.
[8] Dana JP, Ismaili A, Dytoc MT, et al. Increased adherence of Escherichia coli RDEC-1 to human tissue culture cells results in the activation of host signaling pathways[J]. J Infect Dis, 1998, 172 (1):136-43.
[9] Mitchell TJ. Celluar microbiology: an integrated approach to understanding pathogenesis of infection[J]. J Cell Sci, 2000, 113 (pt 19):3355-6.
[10] 杨建一.医学细胞生物学[M].北京:人民卫生出版社,2000.127-48.
[11] Finlay BB, Cossart P. Exploitation of mammalian host cell function by bacterial pathogens[J]. Science, 1997, 276(5313): 718-25.