CORTACTIN PHOSPHORYLATION AND SRC KINASE ACTIVITY ARE INVOLVED IN COXIELLA BURNETII PHAGOCYTOSIS.

ROSALES, E; AGUILERA, M; SALINAS, R; CARMINATI, S; KIERBEL, A; BERON, W

Puerto Madryn

Congreso; la XLVI Reunión Nacional de la Sociedad Argentina de Investigaciones Bioquímica y Biología molecular (SAIB).; 2010

Cortactin is an actin interacting protein that regulates ruffles and lamellipodia formation during cell migration. It has been also involved in phagocytosis of E.coli, Chlamydia, Shigella and Listeria. Cortactin has domains to interact with the actin dynamic machinery and its function is regulated by Tyr and Ser phosphorylation catalyzed by Src and Erk kinases, respectively. Coxiella burnetii (Cb) is an intracellular pathogen that enters to host cell by a poorly characterized mechanism. We study early steps of Cb phagocytosis related to actin cytoskeleton. We have observed that Tyr dephosphorylation of cortactin is required for Cb phagocytosis. To study if Src is involved in this process, HeLa cells overexpressing cortactin mutants were treated with SU6656, a Src inhibitor, before infection. We estimate phagocytic activity measuring internalized bacteria by indirect immunofluorescence and confocal microscopy. We observed that SU6656 affected Cb phagocytosis. On the other hand, we quantified the Src and cortactin phosphorylation stage by SDS-PAGE and Western Blot in lysates obtained from HeLa cells infected for different times. We detected highest phosphorylation levels at 15 min of infection for Src and 60 min for cortactin. These results suggest that Src activation and cortactin phosphorylation could be important at the early and late steps of Cb internalization, respectively.