Vesicular trasport along the phagocytic pathway in streptolysin O permeabilized macrophages: Role of small GTPasa Rab11

LEIVA N; PAVAROTTI M; COLOMBO MI; DAMIANI MT

Bariloche. Río Negro. Argentina.

Congreso; XXXIX Reunión Científica Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2003

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular. SAIB

 Macrophages engulf large particles in vesicles called phagosomes. Phagosome maturation involves a series of membrane fusion and budding events resulting in phagolysosome formation and in the recycling to the cell surface of membrane and many phagosomal proteins. Our objective was to reconstitute phagosome maturation in macrophages permeabilized with streptolysin O (SLO) and to evaluate the participation of Rab11 in trafficking along the phagocytic via. In permeabilized cells, addition of GTPgs significantly enhances recycling from phagosomes, while GDPbs inhibits it, implying GTPases in this transport event. In agreement with the results obtained with macrophages overexpressing Rab11wt, addition of recombinant GST-Rab11wt to permeabilized cells stimulates recycling from the phagosomal compartment In contrast, overexpression of Rab11:S25N, a mutant preferentially locked in the GDP-bound state, decreases the recycling of proteins from phagosomes in a similar extent as does the addition of the recombinant GST-Rab11:S25N to SLO permeabilized cells. The results obtained demonstrate that SLO permeabilized macrophages could be an useful tool to study the molecular machinery involved in transport along the phagocytic pathway. In this system, trafficking could be manipulated  by the addition of proteins or reagents that usually do not cross the plasma membrane. Our results show that recycling from the phagosomal compartment is regulated by the small GTPase rab11.