RAB11-FIP2 AND Rme-1 ARE INVOLVED IN PHAGOCYTOSIS

LEIVA N; PAVAROTTI M; CAPMANY A; COLOMBO MI; DAMIANI MT

Mar del Plata, Buenos Aires, Argentina

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.; 2007

Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular.

Macrophages internalize microorganisms by a process called phagocytosis. We have demonstrated that Rab11, a small GTPase, regulates phagocytosis and recycling from the phagosomal compartment. A Rab11- Family of Interacting Proteins known as FIPs have recently been cloned. All these proteins possess a conservedmotif of 20 amino acids at its C-terminus, the RabBinding Domain.Among the members of Rab11-FIPs, it has been described FIP2. FIP2 has three motifs NPF that interact with EH proteins (Eps15-Homology domains) like Rme-1 (Receptor Mediated Endocytosis). Our objective is to study the involvement of FIP2 and Rme-1 along the phagocytic pathway. We over-express these proteins and several mutant forms fused to fluorescent proteins to analyze their intracellular distribution by confocal microscopy as well as their participation along the phagocytic pathway. In macrophages, FIP2 presents a punctuate pattern throughout the cytosol resembling little endosomes and Rme-1 displays a tubule-vesicular network. Our results demonstrate that both proteins are recruited to early phagosomal membranes in patches like microdomains. The C-terminal domain of FIP2 is necessary for its binding to phagosomes. Both proteins, FIP-2 and Rme-1, might have a role in the internalization step in macrophages.