Dual acylation is required for trafficking of growth-associated protein-43 (GAP-43) to endosomal recycling compartment via an Arf6-associated endocytic vesicular pathway.
GAP-43 (growth-associated protein-43) is a dually palmitoylated protein, at cysteine residues at positions 3 and 4, that mostly localizes in plasma membrane both in neural and non-neural cells. In the present study, we have examined membrane association, subcellular distribution and intracellular trafficking of GAP-43 in CHO (Chinese hamster ovary)-K1 cells. Using biochemical assays and confocal and video microscopy in living cells we demonstrated that GAP-43, at steady state, localizes at the recycling endosome in addition to the cytoplasmic leaflet of the plasma membrane and TGN (trans-Golgi network). Pharmacological inhibition of newly synthesized GAP-43 acylation or double mutation of Cys3 and Cys4 of GAP-43 completely disrupts TGN, plasma membrane and recycling endosome association. A combination of selective photobleaching techniques and time-lapse fluorescence microscopy reveals a dynamic association of GAP-43 with recycling endosomes in equilibrium with the plasma membrane pool. Newly synthesized GAP-43 is found mainly associated with the TGN, but not with the pericentriolar recycling endosome, and traffics to the plasma membrane by a brefeldin A-insensitive pathway. Impairment of plasma membrane fusion and internalization by treatment with tannic acid does affect the trafficking of GAP-43 from plasma membrane to recycling endosomes which reveals a vesicle-mediated retrograde trafficking of GAP-43. Here, we also show that internalization of GAP-43 is regulated by Arf (ADP-ribosylation factor) 6. Taken together, these results demonstrate that dual acylation is required for sorting of peripheral membrane-associated GAP-43 to recycling endosome via an Arf6-associated endocytic vesicular pathway.
Centro de Investigaciones en Química Biológica de Córdoba (UNC-CONICET), Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba X5000HUA, Argentina.
Alejandra
A
Trenchi
Guillermo A
GA
Gomez
Jose L
JL
Daniotti
D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D016466:CHO Cells; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D011992:Endosomes / Q000378:metabolism*; D019922:GAP-43 Protein / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D022161:Transport Vesicles / Q000235:genetics / Q000378:metabolism*; D021601:trans-Golgi Network / Q000235:genetics / Q000378:metabolism
D000089982:ADP-Ribosylation Factor 6; D019922:GAP-43 Protein; D020727:ADP-Ribosylation Factors; C000715727:Arf6 protein, mouse