Transport and function of syntaxin 3 in human epithelial intestinal cells.
To follow the transport of human syntaxin (Syn) 3 to the apical surface of intestinal cells, we produced and expressed in Caco-2 cells a chimera made of the entire Syn3 coding sequence and the extracellular domain of the human transferrin receptor (TfR). This chimera (Syn3TfR) was localized to the apical membrane and was transported along the direct apical pathway, suggesting that this is also the case for endogenous Syn3. To test the potential role of Syn3 in apical transport, we overexpressed it in Caco-2 cells and measured the efficiency of apical and basolateral delivery of several endogenous markers. We observed a strong inhibition of apical delivery of sucrase-isomaltase (SI), an apical transmembrane protein, and of alpha-glucosidase, an apically secreted protein. No effect was observed on the basolateral delivery of Ag525, a basolateral antigen, strongly suggesting that Syn3 is necessary for efficient delivery of proteins to the apical surface of intestinal cells.
Breuza
L
L
Laboratoire de Génétique et Physiologie du Développement, Institut de Biologie du Développement de Marseille, Centre National de la Recherche Scientifique, Université de la Méditerranée, Marseille, France.
Fransen
J
J
Le Bivic
A
A
D000943:Antigens, Differentiation / Q000378:metabolism; D001692:Biological Transport / Q000502:physiology; D018938:Caco-2 Cells; D002455:Cell Division / Q000187:drug effects / Q000235:genetics; D002999:Clone Cells / Q000166:cytology / Q000378:metabolism; D018819:Dipeptidyl Peptidase 4 / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D011499:Protein Processing, Post-Translational / Q000235:genetics; D050765:Qa-SNARE Proteins; D011990:Receptors, Transferrin / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D013394:Sucrase-Isomaltase Complex / Q000378:metabolism; D014162:Transfection; D000520:alpha-Glucosidases / Q000378:metabolism
D000943:Antigens, Differentiation; D008565:Membrane Proteins; D050765:Qa-SNARE Proteins; D011990:Receptors, Transferrin; D011993:Recombinant Fusion Proteins; D013394:Sucrase-Isomaltase Complex; D000520:alpha-Glucosidases; D018819:Dipeptidyl Peptidase 4