The actin interacting protein, cortactin, is involved in the Coxiella burnetii phagocytosis

ROSALES, E,; AGUILERA, M; SALINAS, R; CARMINATI, S; COLOMBO, M; BERÓN, W

Mar del Plata, Buenos Aires, Argentina

Congreso; XLIII Reunión Nacional de la Sociedad Argentina de Investigaciones Bioquímica y Biología Molecular (SAIB); 2007

Sociedad Argentina de Investigaciones Bioquímica y Biología Molecular (SAIB)

Coxiella burnetii (CB) is an obligate intracellular pathogen. After has been phagocytosed, the bacteria mature forming large vacuoles where the bacteria multiply. It is known that cortactin plays a role in several phagocytic proccesses and its function is regulated by phosphorylation. To test if cortactin is involved in CB phagocytosis, HeLa cells were transfected with plasmids encoding EGFP-cortactin wild type (WT) and -cortactin phosphorylation defective mutant, and subsecuently infected with CB. In some experiments prior infectioon the cells were treated with vanadate, a general phosphatase inhibitor. Also, the vanadate effect on internalization was tested in tranfected cells. CB was detected by indirect immunofluorescence and the cells were analyzed by confocal microscopy. We have observed that the level of infection in cell overexpressing EGFP alone or EGFP-cortactin mutant was similar, however in cells overexpressing EGFP-cortactin WT the infection level was significantly reduced. This result suggests that cortactin phosphorylation is important for CB uptake. We observed that vanadate inhibited infection what suggets that protein dephosphorylation is involved in that proccess. Interestingly,  the vanadate effect was reverted by overexpression of the phosphorylation defective cortactin. We conclude that cortactin and its phosphorilation state regulate C. burnetii phagocytosis