The Relationship between Coxiella burnetii and Rho GTPases of Host Cell during Infection

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

Mendoza

Congreso; XLVIII Reunión Nacional de la Sociedad Argentina de Investigaciones Bioquímica y Biología Molecular (SAIB).; 2012

Sociedad Argentina de Investigaciones Bioquímica y Biología Molecular (SAIB).

Phagocytosis is an important host defense mechanism against pathogens. In this process the actin cytoskeleton and GTPases of Rho family play important roles. Coxiella burnetii (Cb) is an intracellular pathogen that enters into host cells by a mechanism poorly characterized. We have evidences that GTPases of Rho family are involved in the interaction Cb-host cells. In this work we investigate the roles of RhoA, Rac1 and Cdc42 in the Cb internalization. In order to do so, HeLa cells were treated with Toxin B, an inhibitor of Rho GTPases, and infected with Cb. We observed that Toxin B diminished Cb uptake. Similar results were observed in HeLa cells overexpressing the dominant negative mutants of the Rho GTPases. These results suggest that these GTPases are important for Cb internalization. Since RhoA showed the strongest effect, we decide to examine the involvement of RhoA effectors ROCK and mDia1 on Cb entry. By using Y27632, an inhibitor of ROCK, we observed in treated cells a decrease in Cb uptake. On the other hand, cells transfected with pEGFP encoding the negative mutant mDia1-ΔN1 (RhoA binding domain) showed lower level of internalization regarding those transfected with pEGFPmDia1-full length (FL) or -ΔN3 (actin polymerization domain). These results suggest that the effectors of RhoA, ROCK and mDia1, participate in the phagocytosis of Cb.