CB-P17.
ENDOCYTIC RECYCLING OF LRP1 IN ALPHA 2-
MACROGLOBULIN-STIMULATEDCELLS
Jaldin-Fincati JR, BarcelonaPF, Sánchez MC, Chiabrando GA.
CIBICI (CONICET) Departamento de Bioquímica Clínica
Facultad de Ciencias Químicas Univ Nac Córdoba. E-mail:
jfincati@mail.fcq.unc.edu.ar
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 alpha 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
MIO-M1 and HeLa 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 increase of LRP1 localization in Rab5 and Rab11-
recycling compartments respect to cells without stimulation. Then,
LRP1 immunoprecipitation techniques of biotin-labeled cell
surface proteins were used to show that 2M* promoted 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.
