OBJECTIVETo investigate the role of phospholipase C(PLC) in cytoskeleton rearrangement of mouse dendritic cells invaded by Mycobacterium tuberculosis.

METHODSMouse dendritic DC2.4 cells were co-cultured with Mycobacterium tuberculosis H37Rv. F-actin of DC2.4 cells were strained with phalloidin-TRITC, the microtubule was stained with anti-β-tubulin monoclonal antibody and FITC-conjugated AffiniPure anti-mouse IgG. The changes of cytoskeleton in DC2.4 cells induced by Mycobacterium tuberculosis H37Rv were determined by fluorescence microscopy and the rates of F-actin rearrangements were calculated. The expressions of PLC in cytoplasm and cytomembrane of DC2.4 cells were measured by ELISA. DC2.4 cells were pretreated with PLC inhibitor U73122, then F-actin rearrangements induced by invasion of Mycobacterium tuberculosis were observed.

RESULTSBacterial invasion was observed while DC2.4 cells were co-incubated with Mycobacterium tuberculosis H37Rv for 2 h. The rates of invasion were (26.1 ± 4.5)%, (39.9 ± 5.6)%, (51.2 ±5.9)%, (57.9 ± 6.1)% and (63.9 ± 6.8)% at 4, 6, 8, 10 and 12 h of co-culture, respectively; while those were (13.6 ± 3.1)%, (14.2 ± 3.9)%, (15.1 ± 4.3)%, (16.8 ± 4.0)% and (18.3 ± 5.2)% after blocked by PLC, respectively. The rates of the F-actin rearrangements at 2, 4, 6, 8, 10 and 12 h after DC2.4 cells were invaded by H37Rv were (26.9 ± 1.5)%, (59.3 ± 2.8)%, (72.7 ± 4.8)%, (78.2 ± 5.9)%, (63.3 ± 2.9)% and (43.2 ± 2.6)%, respectively; while those were (18.5 ± 1.2)%, (22.3 ± 1.7)%, (3.6 ± 2.5)%, (24.8 ± 2.3)%, (22.3 ± 1.3)% and (23.8 ± 1.8)% after blocked by PLC, respectively. There were no changes of the microtubule observed in DC2.4 cells at the same time points. The rates of the F-actin rearrangements before blocked by PLC were higher than those after PLC blockade at 4, 6, 8 and 10 h (P <0.05). The expressions of PLC in cytomembrane in DC2.4 cells increased after 2 h and reached its highest level at 8 h. The PLC inhibitor U73122 inhibited the expressions of PCL in cytomembrane of DC2.4 cells, but not in cytoplasm.

CONCLUSIONMycobacterium tuberculosis can provoke to F-actin rearrangements through PLC molecule, which would further lead to Mycobacterium tuberculosis invasion of DC2.4 cells.

Actins ; metabolism ; Animals ; Cell Line ; Coculture Techniques ; Cytoskeleton ; metabolism ; Dendritic Cells ; cytology ; microbiology ; Mice ; Microtubules ; metabolism ; Mycobacterium tuberculosis ; pathogenicity ; Type C Phospholipases ; metabolism