Alteration in actin organisation and protein transport after treatment with gliadin peptides

Abstract

Celiac disease is a chronic intestinal inflammatory disease characterized by villus atrophy and malabsorption in genetically predisposed individuals due to gliadin toxicity. Here, we analyze the effects of gliadin toxicity on the actin cytoskeleton and the actin-dependent transport of intestinal proteins in Caco-2 cells or in transfected COS-1 cells. For this cells were treated with peptic-tryptic gluten digest (Frazer’s Fraction, FF) as a source of gliadin peptides. Laser confocal microscopy demonstrated a significant effect of FF on the actin cytoskeleton as assessed by the reduced labeling density below the plasma membrane and around the nucleus. Concomitantly, the actin-dependent vesicular transport of the intestinal proteins sucrase-isomaltase (SI), dipeptidylpeptidase IV (DPPIV) and aminopeptidase N (ApN) to the cell surface was also disturbed. By contrast, the vesicular trafficking of lactase that follows an actin-independent pathway was not affected. Biosynthetic labeling experiments supported these confocal data and further revealed variations in the glycosylation patterns of SI, DPPIV and ApN. Altogether, our data demonstrate that toxic gliadin peptides alter the integrity of actin cytoskeleton leading to impaired trafficking, intracellular block of rafts-associated proteins to the cell surface and modulation of their glycosylation pattern. Grant support SFB 621, Bonn, Germany