Effect of alcohol on miR-212 expression in intestinal epithelial cells and its potential role in alcoholic liver disease.
OBJECTIVE
Alcohol-induced gut leakiness is a key factor in alcoholic liver disease (ALD); it allows endotoxin to enter the circulation and initiate liver damage. Zonula occludens 1 (ZO-1) protein is a major component of tight junctions that regulates intestinal permeability. microRNAs (miRNAs) are recently discovered regulatory molecules that inhibit expression of their target genes.


OBJECTIVE
(i) to investigate the effect of alcohol on miRNA-212 (miR-212) and on expression of its predicted target gene, ZO-1, (ii) to study the potential role of miR-212 in the pathophysiology of ALD in man.


METHODS
Using a TaqMan miRNA assay system, we measured miR-212 expression levels in colon biopsy samples from patients with ALD and in Caco-2 cells (a human intestinal epithelial cell line) treated with or without EtOH. We measured ZO-1 protein levels using western blots. ZO-1 mRNA was assayed using real-time PCR. Intestinal barrier integrity was measured using fluorescein sulfonic acid clearance and immunofluorescent staining for ZO-1.


RESULTS
Ethanol increased miR-212 expression, decreased ZO-1 protein levels, disrupted tight junctions, and increased the permeability of monolayers of Caco-2 cells. An miR-212 over-expression is correlated with hyperpermeability of the monolayer barrier. miR-212 levels were higher in colon biopsy samples in patients with ALD than in healthy controls; ZO-1 protein levels were lower.


CONCLUSIONS
These data suggest a novel mechanism for alcohol-induced gut leakiness, one in which EtOH induces miR-212 over-expression which causes gut leakiness by down-regulating ZO-1 translation. This mechanism is a potential therapeutic target for leaky gut in patients with or at risk for ALD.
Tang
Yueming
Y
Division of Digestive Disease and Nutrition, Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois 60612, USA. yueming_tang@rush.edu
Banan
Ali
A
Forsyth
Christopher B
CB
Fields
Jeremy Z
JZ
Lau
Cynthia K
CK
Zhang
Li Juan
LJ
Keshavarzian
Ali
A
D001706:Biopsy; D018938:Caco-2 Cells; D002463:Cell Membrane Permeability / Q000235:genetics; D003106:Colon / Q000473:pathology; D015536:Down-Regulation / Q000235:genetics; D004847:Epithelial Cells / Q000473:pathology*; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D007413:Intestinal Mucosa / Q000473:pathology*; D008108:Liver Diseases, Alcoholic / Q000235:genetics* / Q000473:pathology; D008565:Membrane Proteins / Q000235:genetics; D035683:MicroRNAs / Q000235:genetics*; D010750:Phosphoproteins / Q000235:genetics; D062826:Zonula Occludens-1 Protein
D008565:Membrane Proteins; D035683:MicroRNAs; D010750:Phosphoproteins; D062826:Zonula Occludens-1 Protein; C525709:MIR221, human; C569042:TJP1 protein, human