Ganglioside GD3 traffics from Trans-Golgi network to plasma membrane by a Brefeldin A insensitive exocitic pathway

CRESPO PILAR M.; IGLESIAS-BARTOLOMÉ, RAMIRO; DANIOTTI, JOSÉ L

Iguazú, Misiones, Argentina

Congreso; XL Reunión Nacional de la Sociedad Argentina de Investigación en Bioquímica y Biología Celular (SAIB); 2004

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

GANGLIOSIDE GD3 TRAFFICS FROM TRANS-GOLGI NETWORK TO PLASMA MEMBRANE BY A BREFELDIN A- INSENSITIVE EXOCYTIC PATHWAY Crespo, Pilar M., Iglesias-Bartolomé, Ramiro and Daniotti, José L CIQUIBIC-Departamento de Química Biológica, Facultad de Ciencias Químicas, U.N.C. E-mail: pcrespo@dqb.fcq.unc.edu.ar Gangliosides, complex glycosphingolipids containing sialic acids, are synthesized in the lumen of the Golgi complex and appear unable to translocate from the lumenal toward the cytosolic surface of Golgi membrane to access the monomeric lipid transport. As a consequence, they can only leave the Golgi complex via the lumenal surface of transport vesicles. In this work, we analyzed the exocytic transport of the disialo ganglioside GD3 from trans-Golgi network (TGN) to plasma membrane in CHO-K1 cells, by immunodetection of endogenously synthesized GD3. We found that ganglioside GD3, unlike another luminal membrane-bounded lipid (glycosylphosphatidylinositol-anchored protein), did not partition into GEM domains in the Golgi complex and trafficked from TGN to plasma membrane by a BFA-insensitive exocytic pathway. Moreover, dominant negative form of Rab11, which prevent exit of vesicular stomatitis virus glycoprotein (VSVG) from the Golgi complex, did not influence the capacity of GD3 to reach the cell surface. Our results strongly support the notion that most ganglioside GD3 traffics from TGN to plasma membrane by a non-conventional vesicular pathway where lateral membrane segregation of VSVG (non-GEM resident) and GPI-anchored proteins (GEM resident) from GD3 is required before exiting TGN. Financiado por: Fundación Antorchas, CONICET, SECyT-UNC.