Gliadin peptide P31-43 localises to endocytic vesicles and interferes with their maturation.
BACKGROUND
Celiac Disease (CD) is both a frequent disease (1:100) and an interesting model of a disease induced by food. It consists in an immunogenic reaction to wheat gluten and glutenins that has been found to arise in a specific genetic background; however, this reaction is still only partially understood. Activation of innate immunity by gliadin peptides is an important component of the early events of the disease. In particular the so-called "toxic" A-gliadin peptide P31-43 induces several pleiotropic effects including Epidermal Growth Factor Receptor (EGFR)-dependent actin remodelling and proliferation in cultured cell lines and in enterocytes from CD patients. These effects are mediated by delayed EGFR degradation and prolonged EGFR activation in endocytic vesicles. In the present study we investigated the effects of gliadin peptides on the trafficking and maturation of endocytic vesicles.


RESULTS
Both P31-43 and the control P57-68 peptide labelled with fluorochromes were found to enter CaCo-2 cells and interact with the endocytic compartment in pulse and chase, time-lapse, experiments. P31-43 was localised to vesicles carrying early endocytic markers at time points when P57-68-carrying vesicles mature into late endosomes. In time-lapse experiments the trafficking of P31-43-labelled vesicles was delayed, regardless of the cargo they were carrying. Furthermore in celiac enterocytes, from cultured duodenal biopsies, P31-43 trafficking is delayed in early endocytic vesicles. A sequence similarity search revealed that P31-43 is strikingly similar to Hrs, a key molecule regulating endocytic maturation. A-gliadin peptide P31-43 interfered with Hrs correct localisation to early endosomes as revealed by western blot and immunofluorescence microscopy.


CONCLUSIONS
P31-43 and P57-68 enter cells by endocytosis. Only P31-43 localises at the endocytic membranes and delays vesicle trafficking by interfering with Hrs-mediated maturation to late endosomes in cells and intestinal biopsies. Consequently, in P31-43-treated cells, Receptor Tyrosine Kinase (RTK) activation is extended. This finding may explain the role played by gliadin peptides in inducing proliferation and other effects in enterocytes from CD biopsies.
Barone
Maria Vittoria
MV
Pediatric Department and European Laboratory for the Investigation of Food-Induced Disease, University of Naples Federico II, Naples, Italy.
Nanayakkara
Merlin
M
Paolella
Giovanni
G
Maglio
Mariantonia
M
Vitale
Virginia
V
Troiano
Raffaele
R
Ribecco
Maria Teresa Silvia
MT
Lania
Giuliana
G
Zanzi
Delia
D
Santagata
Sara
S
Auricchio
Renata
R
Troncone
Riccardo
R
Auricchio
Salvatore
S
D000595:Amino Acid Sequence; D000818:Animals; D001706:Biopsy; D018938:Caco-2 Cells; D002453:Cell Cycle; D056827:Endosomal Sorting Complexes Required for Transport / Q000737:chemistry / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism; D020895:Enterocytes / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism; D005903:Gliadin / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007421:Intestine, Small / Q000473:pathology; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism; D021381:Protein Transport; D051381:Rats; D022161:Transport Vesicles / Q000378:metabolism*
D056827:Endosomal Sorting Complexes Required for Transport; D010446:Peptide Fragments; D010750:Phosphoproteins; C096164:hepatocyte growth factor-regulated tyrosine kinase substrate; D005903:Gliadin; D066246:ErbB Receptors
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