Phagocytosis of Coxiella burnetii requieres PIP5k and Arf6

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

Villa Carlos Paz, Córdoba, Argentina

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigaciones Bioquímica y Biología Molecular (SAIB); 2008

Sociedad Argentina de Investigaciones Bioquímica y Biología Molecular (SAIB)

Coxiella burnetii (Cb) is an intracellular pathogen that causes Q Fever desease. This pathogen entries into the host cell by phagocytosis. Phagocytosis is a process that involves actin dynamic regulated by Rho and Arf GTPases. During phagocytosis Arf6 (class III Arf) actives PIP5K which generates PI(4,5)P2 that interacts with actin cytoskeleton effectors. We analyzed if Arfs, in paticular Arf6, and PIP5K are involved in the Cb internalization by the host cell.We tested the effect of brefeldin A (BFA), a class I and II Arfs inhibitor, upon the internalization process. HeLa cells were treated with BFA, then infected and processed for indirect immunofluorescence and analyzed by confocal microscopy. We observed that BFA did not affect Cb internalization. We decided to check if Arf6, a BFA-insensitive Arf, could be involved in that process. Before infection, Hela cells were transfected with pEGFP-Arf6 wild type (WT) or -Arf6T27N (inactive mutant). We observed that Arf6T27N diminished the number of internalized Cb compared with WT. To study if PIP5K is recruited to the plasma membrane during Cb uptake, HeLa cells were tranfected with pcDNA3Myc-PIP5K and processed as above. We observed that PIP5K was recruited at the bacterial entry sites. These results suggest that Arf6 and PIP5K are involved in the host cell interaction of Cb.