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 calledphagocytosis. We have demonstrated that Rab11, a small GTPase,regulates phagocytosis and recycling from the phagosomalcompartment. A Rab11- Family of Interacting Proteins known asFIPs have recently been cloned. All these proteins possess aconservedmotif of 20 amino acids at its C-terminus, the RabBindingDomain.Among the members of Rab11-FIPs, it has been describedFIP2. FIP2 has three motifs NPF that interact with EH proteins(Eps15-Homology domains) like Rme-1 (Receptor MediatedEndocytosis). Our objective is to study the involvement of FIP2 andRme-1 along the phagocytic pathway. We over-express theseproteins and several mutant forms fused to fluorescent proteins toanalyze their intracellular distribution by confocalmicroscopy as well as their participation along the phagocyticpathway. In macrophages, FIP2 presents a punctuate patternthroughout the cytosol resembling little endosomes and Rme-1displays a tubule-vesicular network. Our results demonstrate thatboth proteins are recruited to early phagosomal membranes inpatches like microdomains. The C-terminal domain of FIP2 isnecessary for its binding to phagosomes. Both proteins, FIP-2 andRme-1, might have a role in the internalization step in macrophages.