IHEM   20887
INSTITUTO DE HISTOLOGIA Y EMBRIOLOGIA DE MENDOZA DR. MARIO H. BURGOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
CD44 participates in the internalization of Coxiella burnetii.
Autor/es:
ORTIZ FLORES, RM; CAYADO-GUTIÉRREZ, N; DISTEL, JS; BERÓN, W
Lugar:
Mendoza
Reunión:
Congreso; Congreso; XXXIV Reunión Científica Anual organizada por la Sociedad de Biología de Cuyo; 2016
Institución organizadora:
Sociedad de Biología de Cuyo
Resumen:
Coxiella burnetii (Cb) is an intracellular pathogen that enters into non-professional phagocytes using integrin αvβ3 as receptors, but the internalization mechanism is poorly characterized. Conventional phagocytosis is an essential host defense process against pathogens. It requires receptors that recognize patterns on pathogens, and actin cytoskeletal remodeling to guide the plasma membrane around the pathogens. CD44 receptor can be sufficient to stimulates phagocytosis. CD44 has an N-terminal extracellular domain which contains dockings sites for hyaluronan and other ligands, a short transmembrane region, and a C-terminal cytoplasmic tail that interact with actin associated proteins such as ankirin and ERM (ezrin, radixin and moesin). We previously described the importance of ezrin in the internalization of Cb. The goal of the present work was to analyze the role of CD44 and its relationship with ezrin in the phagocytosis of Cb. In this study, HeLa cells were transfected with pEGFP-vector, pSuper-vector, -CD44-shRNA, -scramble-shRNA, pEGFP-CD44-rescue (shRNA-resistant form), pFLAG-myc-vector, -CD44-WT (Wild Type), -CD44-KR (mutation in ERM binding site), -CD44-ΔICD (deletion of the intracellular domain), -CD44-ΔE (deletion of extracellular domain). After 36h, the cells were infected with Cb for 6h, processed for indirect immunofluorescence and analyzed by confocal microscopy to quantify internalized Cb. A significant decrease in the uptake of Cb was observed in CD44 knocked down cells with CD44-shRNA, however the bacterial internalization was fully restored in cells co-transfected with the rescue vector. The overexpression of CD44 WT did not affect the Cb uptake but the overexpression of the CD44 mutants KR, ΔICD and ΔE did. Interestingly, the overexpressed CD44 WT localized in small vacuoles containing Cb. These results suggest that CD44 participates in the infection of HeLa cells with Cb which reside into early and small phagosomes.