DIFFERENTIAL INTRACELLULAR TRAFFIC OF LRP1 INDUCED BY ALPHA 2- MACROGLOBULIN AND INSULIN

ACTIS DATO V; JALDIN-FINCATI JR; VAZQUEZ MM ; BONACCI GR; SÁNCHEZ MC; CHIABRANDO GA

Mar del Plata, Provincia de Buenos Aires

Congreso; LI Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2015

SAIB

CB-P18DIFFERENTIAL INTRACELLULAR TRAFFIC OF LRP1 INDUCED BY ALPHA 2- MACROGLOBULIN AND INSULINActis Dato V1, Jaldin Fincati J2, Vázquez MM1, Bonacci GR1, Sanchez MC1, Chiabrando GA1. 1CIBICI-CONICET and Dpto Bioq Clin Fac Cs Quimicas UNC. 2The Hosp for Sick Children Toronto Canada. E-mail: vactisdato@fcq.unc.edu.arLow density lipoprotein receptor-related 1 (LRP1) is an endocytic and signaling receptor. Alpha 2-Macroglobulin- protease complex (α2M*) is a LRP1 ligand, which internalizes by endocytosis and degrades in lysosomes. α2M* also induces the LRP1 trafficking to plasma membrane (PM) through non-characterized exocytic route. Glucose transporter type 4 (GLUT4) is an insulin-regulated glucose transporter expressed in adipose and muscle cells, which is stored in specialized GLUT4 storage vesicles (GSVs). Insulin stimulation induces GSVs traffic to PM by exocytosis, with increased GLUT4 expression and glucose uptake at cell surface level. The failure of GLUT4 traffic is involved in Type 2 Diabetes Mellitus. LRP1 is the main protein component of GSVs, although its function in these vesicles is not completely understood. Herein we study if LRP1 and GLUT4 share the same exocytic route in HeLa and MIO-M1 cells cultured in the presence of α2M* (60 nM) or insulin (100 nM) at different times at 37 °C. By confocal microscopy we found LRP1 and GLUT4 colocalization in intracellular vesicles suggesting GSVs in both types of cells. By biotin-labeling protein assay, we showed that LRP1 translocates to PM with α2M*or insulin. The α2M*-induced LRP1 traffic was abolished by PD98059 but not by LY294002. These results suggest that α2M* and insulin induce the LRP1 sorting to PM by different exocytic routes.