Role of Beclin1 and Bcl-2 in the development of the Coxiella burnetii replicative vacuole.

VAZQUEZ C. L.,; COLOMBO, M. I.

Mar del Plata

Congreso; XLIII Reunión Anual de la SAIB. 17; 2007

Several pathogens have developed different strategies to invade and survive into the host cell, avoiding degradation. Coxiella burnetii is an obligate intracellular pathogen that invades and multiplies in acidic vacuoles with lysosomal characteristics. We have previously shown that Coxiella interacts with the autophagic pathway as a strategy for its survival and replication. In the present work we have explored the role of Beclin1 and Bcl-2 in C. burnetii infected cells. Beclin1, a Bcl-2 interacting protein, is a component of the class III PI-3 kinase complex, required for autophagy. Bcl-2 functions as an anti-apoptotic protein which inhibits autophagy. HeLa cells were transfected with pFLAG-Beclin1 and then infected with C. burnetii . Interestingly, Beclin1 was markedly recruited to the membrane of Coxiella-replicative vacuoles (CRVs). Moreover, overexpression of this protein increased the size and number of CRVs, whereas Beclin1 depletion, by a short interfering RNA, caused a decrease in vacuole size. To evaluate whether Bcl-2 has an effect in Coxiella infection, HeLa cells were transfected with GFP-Bcl-2. Surprisingly we found that Bcl-2 was also recruited to the CRV, however, although overexpressed Bcl-2 increased vacuole number, the CRVs size was markedly reduced. These results indicate that whereas Beclin1 favors the development of CRV, Bcl-2 alters Coxiella replicative niche.