INTRACELLULAR TRAFFIC OF LRP1 AND GLUT4 IN ALPHA2- MACROGLOBULIN-STIMULATED MIO-M1 CELLS

ACTIS DATO, VIRGINIA; JALDIN-FINCATI, JAVIER; JALDIN-FINCATI, JAVIER; CHIABRANDO, GUSTAVO

Congreso; L Reunion Anual SAIB 2014; 2014

Low density lipoprotein receptor-related protein 1 (LRP1) is an endocytic and signaling receptor, which binds alpha 2-macroglobulin-protease complex (á2M*) and promotes cell migration of Muller glial-derived cell line, MIO-M1. The á2M* induces LRP1 translocation to plasma membrane (PM) by two possible pathways; i) Rab11-dependent recycling route, and ii) exocytosis from LRP1-stored vesicles and Rab11-independent pathway, which can be also stimulated by insulin. Glucose transporter type 4 (GLUT4) is a insulin-regulated glucose transporter found in adipose and muscle tissues. Specialized GLUT4 storage vesicles (GSV) can be translocated to PM by insulin through a Rab10-dependent pathway, increasing the glucose uptake. The failure of GLUT4 translocation is involved in insulin resistance and type 2 diabetes mellitus. LRP1 is the main protein component of GSV, although its function is not completely understood. To examine whether á2M* induces GSV translocation to PM, we have characterized the subcellular localization of LRP1 and GLUT4 in MIO-M1 cells. By confocal microscopy and biotin-labeling protein assay we determine that LRP1 and GLUT4 shown a high colocalization in intracellular vesicles, compatible with GSV, and LRP1 was translocated to PM by á2M*, which was unaffected by the presence of a dominant-negative Rab11. We conclude that á2M* induced LRP1 traffic to PM from GSV.