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Regulation of Human Intestinal SLC26A3 Expression by Hepatocyte Nuclear Factors
Author(s) -
Kumar Anoop,
Alakkam Anas,
Borthakur Alip,
Anbazhagan Arivarasu N,
Saksena Seema,
Gill Ravinder K,
Malakooti Jaleh,
Alrefai Waddah A,
Dudeja Pradeep K
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.1162.11
Subject(s) - hepatocyte nuclear factors , gene silencing , hepatocyte nuclear factor 4 , transcription factor , chemistry , microbiology and biotechnology , hepatocyte , biology , gene , biochemistry , in vitro , nuclear receptor
DRA (Down Regulated in Adenoma, SLC26A3) plays a key role in Cl − absorption in the intestine. DRA expression is decreased in congenital chloride diarrhea and IBD. Hepatocyte nuclear factor 4 α (HNF4 α) has been shown to modulate basal DRA expression in Caco2 cells whereas intestine‐specific HNF1α/HNF1β deficient mice showed diarrheal phenotype and decreased DRA expression. However, the role of individual HNFs or their combined effects on DRA expression is not known. Therefore, detailed analysis of DRA transcription was performed in response to over‐expression or silencing of HNFs. Results showed that overexpression of HNF1α, HNF1β or HNF4α in Caco‐2 cells increased DRA promoter activity by ~20, 10, and 2.5 fold, respectively (p<0.05). Similarly, their overexpression increased DRA mRNA levels (~ 4–5 fold with HNF1α, ~2–3 with HNF1β and ~1.5 with HNF4α (p<0.05). DRA mRNA expression decreased by ~50%, 35% and 30% by silencing of HNF1α, HNF1β and HNF4α, respectively. Silencing both HNF1α and HNF1β further decreased DRA expression (~70%). The attenuation of HNF1α decreased the level of HNF4α (but not HNF1β) and vice versa indicating that HNFs can modulate the expression of each other as well. ChIP assays revealed that DRA promoter harbors binding sites for HNFs at − 814/−219 bp region. These studies demonstrate that HNFs directly stimulate DRA expression and could serve as novel anti‐diarrheal targets. (Grant Support: VA/NIDDK/Gates Foundation)