Role of LP1 endocytosis respect to the intracelular signalling induced by its ligand á2M.

JALDIN-FINCATI JR; SÁNCHEZ MC; CACERES LC; CHIABRANDO GA

San Miguel de Tucumán

Congreso; .- XLV Reunion Anual de la Sociedad Argentina de Investigacion en Bioquimica y Biología Molecular (SAIB) 2009. 10-13 de Noviembre de 2009. San Miguel de Tucumán, Tucumán, Argentina; 2009

SAIB

The LDL receptor-related protein 1 (LRP1) is an endocytic receptor involved in the activated á2Macroglubulin (á2M*) internalization by clathrin-coated pits. We demonstrated that LRP1 mediates the á2M*-induced MAPK activation, promoting MMPs expression, cellular proliferation and migration. However, the molecular mechanisms that regulate the intracellular signaling activity of LRP1 are unknown. Considering that in other ligand-receptor systems the endocytosis play a key role in the regulation of the intracellular signaling, the aim of this work was to evaluate whether the LRP1 endocytosis is implicated in the intracellular signaling activity of this receptor interacting with á2M*. For this propose we used different cell lines incubated in the presence of á2M*. The á2M*-induced MAPK-ERK1/2 phosphorylation was evaluated by Western blot, whereas endocytosis was analyzed by immunoflurescence microscopy and flow cytometry. To evaluate the endocytosis effect on the á2M*-induced MAPK activation the cells were cultured in the presence of hiperosmolar sucrose medium, K+-depleted medium and cytoplasm acidification to block at different levels the clathrin-mediated endocytosis. Our data demonstrate that endocytic function of LRP1 is needed to promote intracellular signaling of á2M*-induced MAPK activation, suggesting similar adaptor proteins are involved in both cellular processes.