Transcriptional downregulation of tight junction protein ZO-1 in active coeliac disease is reversed after a gluten-free diet.
Coeliac disease is an autoimmune enteropathy characterized by an enhanced permeability of the intestinal epithelial barrier. In epithelial cells paracellular permeability is regulated by intercellular tight junction. The cytoplasmic protein ZO-1 interacts directly with F-actin and plays a pivotal role in the structural and functional organization of tight junction.


OBJECTIVE
The aim of this study was to investigate the expression and localization of ZO-1 in the intestinal mucosa of coeliac patients.


METHODS
Twenty patients with active coeliac disease, seven of whom underwent a repeat biopsy following a gluten-free diet and 27 control subjects, were studied. In all subjects, three biopsies were obtained from distal duodenum during upper gastrointestinal endoscopy. ZO-1 protein localization and levels were detected by immunofluorescence followed by confocal microscopy analysis and immunoblotting. ZO-1 mRNA expression was assessed by RT-PCR. F-actin distribution was also investigated.


RESULTS
In patients with active coeliac disease, both ZO-1 protein levels and mRNA were clearly reduced. Cytoskeletal organization was disrupted with F-actin staining concentrated at the subcortical and basal surface regions. Abnormalities in ZO-1 expression and actin organization were reversed after a gluten-free diet.


CONCLUSIONS
In active coeliac disease, ZO-1 protein expression is downregulated at the transcriptional level in association with F-actin redistribution. These changes are completely reversed after a gluten-free diet and could contribute to the increased intestinal paracellular permeability observed in this disorder.
Pizzuti
D
D
Department of Surgical and Gastroenterological Sciences, Section of Gastroenterology, University of Padua, Via Giustiniani 2, 35128 Padua, Italy.
Bortolami
M
M
Mazzon
E
E
Buda
A
A
Guariso
G
G
D'Odorico
A
A
Chiarelli
S
S
D'Incà
R
R
De Lazzari
F
F
Martines
D
D
D000199:Actins / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D015153:Blotting, Western; D016022:Case-Control Studies; D002446:Celiac Disease / Q000178:diet therapy* / Q000235:genetics / Q000378:metabolism*; D002648:Child; D018753:Diet, Protein-Restricted; D015536:Down-Regulation; D004386:Duodenum / Q000378:metabolism / Q000473:pathology; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism / Q000473:pathology; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D018613:Microscopy, Confocal; D008875:Middle Aged; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D062826:Zonula Occludens-1 Protein
D000199:Actins; D008565:Membrane Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein