Cortactin and Erk1/2 kinase are involved in Coxiella burnetii entry into host cells

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

San Luis

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

Sociedad Argentina de Investigaciones Bioquímica y Biología Molecular (SAIB)

Cortactin (cttn) is involved in actin cytoskeleton organization regulating cell migration and also host cell-pathogen interaction. Cttn has domains to interact with actin, Arp2/3 and N-WASP. Its activity is regulated by Tyr and Ser phosphorylations catalyzed by Src and Erk kinases, respectively. Coxiella burnetii (Cb) is a pathogen that enters into host cell by a poorly characterized mechanism. We have evidences that cttn is involved in Cb entry. To determine the cttn domains that participate in this process, HeLa cells were transfected with plasmids encoding W22A (NTA domain) and W525K (SH3 domain) cttn mutants that do not interact with Arp2/3 and N-WASP, respectively. Internalization was inhibited in cell overexpressing W525K. We have previously observed that Src activation and cttn Tyr phosphorylation status are important for Cb internalization. To study if Ser-phosphorylation of cttn regulates Cb uptake, HeLa cells overexpressing the cttn mutants S405/418A (non-phosphorylatable) or S405/418D (phospho-mimetic) were infected with Cb. Overexpression of S405/418A caused a reduction in the internalization. We analyzed Erk activation in lysates of HeLa cells infected for different times. The Erk phosphorylation peak was observed at 15 min infection. These results suggest that Cb uptake is regulated by the N-WASP interacting SH3 domain and by Erk-dependent Ser phosphorylation of cttn.