mDia1, an actin nucleating factor, is involved in coxiella burnetii internalization

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

XLVII Reunión Nacional de la Sociedad Argentina de Investigaciones Bioquímica y Biología Molecular

Congreso; XLVII Reunión Nacional de la Sociedad Argentina de Investigaciones Bioquímica y Biología Molecular; 2011

Sociedad Argentina de Investigaciones Bioquímica y Biología Molecular (SAIB)

Phagocytosis is an important host defence mechanism against pathogens. In this process the actin cytoskeleton and their main regulators, the GTPases of Rho family, play an important role. Coxiella burnetii (Cb) is an intracellular pathogen that enters into host cells by a mechanism partially characterized. We have evidences that RhoA is involved in the interaction Cb-host cells. In this work we investigate if Src, ROCK and mDia1, molecules belong to the Rho signalling pathway, participate in the Cb internalization. HeLa cells were treated with PP2 or Y27632, inhibitors of Src and ROCK kinases, respectively, before infection. Both inhibitors diminished Cb uptake. These results suggest that both kinases are involved in Cb entry. To study the role of mDia1, HeLa cells were transfected with pEGFPmDia1-full length (FL), -ÄN3 or -ÄN1 prior infection. mDia1-ÄN3 contains the actin nucleation domain FH1-FH2, while mDia1-ÄN1 contains the RhoA binding domain GBD. Cb internalization was significantly inhibited in cells overexpressing mDia1-ÄN1. When cells overexpressing the different mDia1 constructs were incubated with the kinase inhibitors prior and during infection, Cb internalization was not affected in cell overexpressing mDia1-FL or -ÄN3. These results suggest that mDia1 plays an important role in Cb entry through the Src-RhoA-mDia1/ROCK signalling rout