A Novel Role of SLC26A3 in the Maintenance of Intestinal Epithelial Barrier Integrity.

Abstract

BACKGROUND & AIMS:

The down-regulated in adenoma (DRA) protein, encoded by SLC26A3, a key intestinal chloride anion exchanger, has recently been identified as a novel susceptibility gene for inflammatory bowel disease (IBD). However, the mechanisms underlying the increased susceptibility to inflammation induced by the loss of DRA remain elusive. Compromised barrier is a key event in IBD pathogenesis. The current studies were undertaken to elucidate the impact of DRA deficiency on epithelial barrier integrity and to define underlying mechanisms.

METHODS:

Wild-type and DRA-knockout (KO) mice and crypt-derived colonoids were used as models for intestinal epithelial response. Paracellular permeability was measured by using fluorescein isothiocyanate-dextran flux. Immunoblotting, immunofluorescence, immunohistochemistry, and ribonucleoprotein immunoprecipitation assays were performed. Gut microbiome analysis was conducted to investigate the impact of DRA deficiency on gut microbial communities.

RESULTS:

DRA-KO mice exhibited an increased colonic paracellular permeability with significantly decreased levels of tight junction/adherens junction proteins, including ZO-1, occludin, and E-cadherin. A similar expression pattern of occludin and E-cadherin was observed in colonoids derived from DRA-KO mice and short hairpin RNA-mediated DRA knockdown in Caco-2 cells. Microbial analysis showed gut dysbiosis in DRA-KO mice. However, cohousing studies showed that dysbiosis played only a partial role in maintaining tight junction protein expression. Furthermore, our results showed increased binding of RNA-binding protein CUGBP1 with occludin and E-cadherin genes in DRA-KO mouse colon, suggesting that posttranscriptional mechanisms play a key role in gut barrier dysfunction.

CONCLUSIONS:

To our knowledge, our studies demonstrate a novel role of DRA in maintaining the intestinal epithelial barrier function and potential implications of its dysregulation in IBD pathogenesis.

• Authors: Anoop Kumar, Shubha Priyamvada, Yong Ge, Dulari Jayawardena, Megha Singhal, Arivarasu N Anbazhagan, Ishita Chatterjee, Aneal Dayal, Mitul Patel, Kimia Zadeh, Seema Saksena, Waddah A Alrefai, Ravinder K Gill, Mojgan Zadeh, Ni Zhao, Mansour Mohamadzadeh, Pradeep K Dudeja
• Journal: Gastroenterology (Gastroenterology) Vol. 160 Issue 4 Pg. 1240-1255.e3 (03 2021) ISSN: 1528-0012 [Electronic] United States
• PMID: 33189700 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: Published by Elsevier Inc.

Chemical References

• Antiporters
• CELF1 Protein
• CELF1 protein, mouse
• Cadherins
• Cdh1 protein, mouse
• Chloride-Bicarbonate Antiporters
• Occludin
• Ocln protein, mouse
• SLC26A3 protein, human
• Slc26a3 protein, mouse
• Sulfate Transporters

Topics

• Animals
• Antiporters (deficiency, genetics)
• CELF1 Protein (metabolism)
• Caco-2 Cells
• Cadherins (metabolism)
• Chloride-Bicarbonate Antiporters (deficiency, genetics)
• Disease Models, Animal
• Dysbiosis (immunology, microbiology, pathology)
• Gene Knockdown Techniques
• Humans
• Inflammatory Bowel Diseases (immunology, microbiology, pathology)
• Intestinal Mucosa (immunology, microbiology, pathology)
• Male
• Mice
• Mice, Knockout
• Occludin (metabolism)
• Permeability
• Sulfate Transporters (deficiency, genetics)
• Tight Junctions (pathology)