Endocytic recycling of LRP1 in alpha 2-macroglobulin-stimulated cells.

JALDIN-FINCATI JR; BARCELONA PF; SÁNCHEZ MC; CHIABRANDO GA

Potrero de los Funes, San Luis

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2011

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

The LDL receptor-related protein 1 (LRP1) is an endocytic and signaling receptor, which play an key role in the cellular migration and proliferation. Previously we demonstrated that 2- Macroglubulin (2M*) induced intracellular signaling activation via LRP1, which is characterized by PKC and MAPK activation. Our hypothesis is that the cellular function of LRP1 involves the endocytic recycling and cell surface sorting of this receptor in 2M*-stimulated cells. Hence, in this work we tried to characterize the endocytic recycling and cell membrane sorting of LRP1 in MIOM1 cells stimulated with 2M*. Using confocal microscopy, flow cytometry and a recombinant mini-receptor version of LRP1 (mLRP4/GFP) we demonstrated that 2M* induced the LRP1 localization in Rab11-recycling compartments between 15-30 min after 2M* stimulation. Then, by TIRF microscopy and LRP1 immunoprecipitation techniques of biotin-labeled cell surface proteins we showed that 2M* promoted (after 15 min) the intracellular sorting of the constitutive LRP1 and mLRP4 to the cell membrane. This sorting was partially blocked by the negative dominant mutant form of Rab11. However, other Rab forms, probably Rab8 and Rab6, could be involved in this sorting process. Our data suggest that the LRP1 function in2M*-stimulated cells is dependent on the endocytic recycling of this receptor