Lactase Gene Transcription Is Activated in Response to Hypoxia in Intestinal Epithelial Cells

DRA (downregulated in adenoma) or SLC26A3 is the major apical anion exchanger mediating Cl− absorption in intestinal epithelial cells. Disturbances in DRA function and expression have been implicated in diarrheal conditions such as congenital chloride diarrhea and inflammatory bowel diseases. Previous studies have shown that DRA is subject to regulation by short-term and transcriptional mechanisms. In this regard, we have recently shown that short-term treatment by lysophosphatidic acid (LPA), an important bioactive phospholipid, stimulates Cl−/HCO3−(OH−) exchange activity via an increase in DRA surface levels in human intestinal epithelial cells. However, the long-term effects of LPA on DRA at the level of gene transcription have not been examined. The present studies were aimed at investigating the effects of LPA on DRA function and expression as well as elucidating the mechanisms underlying its transcriptional regulation. Long-term LPA treatment increased the Cl−/HCO3− exchange activity in Caco-2 cells. LPA treatment (50–100 μM) of Caco-2 cells significantly stimulated DRA mRNA levels and DRA promoter activity (−1183/+114). This increase in DRA promoter activity involved the LPA2 receptor and phosphatidylinositol 3-kinase (PI3K)/AKT pathways. Progressive deletions from −1183/+114 to −790/+114 abrogated the stimulatory effects of LPA, indicating that the −1183/−790 promoter region harbors LPA response elements. Utilizing EMSA and mutational studies, our results showed that LPA induced the DRA promoter activity in a c-Fos-dependent manner. LPA also increased the protein expression of c-Fos and c-Jun in Caco-2 cells. Furthermore, overexpression of c-Fos but not c-Jun enhanced the DRA promoter activity. This increase in DRA transcription in response to LPA indicates that LPA may act as an antidiarrheal agent and could be exploited for the treatment of diarrhea associated with inflammatory or infectious diseases of the gut.

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Oxidized fat induces oxidative stress but has no effect on NF-κB-mediated proinflammatory gene transcription in porcine intestinal epithelial cells

Inflammation Research ◽

10.1007/s00011-006-6122-y ◽

2007 ◽

Vol 56 (3) ◽

pp. 118-125 ◽

Cited By ~ 34

Author(s):

R. Ringseis ◽

N. Piwek ◽

K. Eder

Keyword(s):

Oxidative Stress ◽

Epithelial Cells ◽

Gene Transcription ◽

Intestinal Epithelial Cells ◽

Intestinal Epithelial ◽

Proinflammatory Gene ◽

Oxidized Fat

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A host cell long noncoding RNA NR_033736 regulates type I interferon-mediated gene transcription and modulates intestinal epithelial anti-Cryptosporidium defense

PLoS Pathogens ◽

10.1371/journal.ppat.1009241 ◽

2021 ◽

Vol 17 (1) ◽

pp. e1009241

Author(s):

Juan Li ◽

Kehua Jin ◽

Min Li ◽

Nicholas W. Mathy ◽

Ai-Yu Gong ◽

...

Keyword(s):

Epithelial Cells ◽

Host Cell ◽

Gene Transcription ◽

Intestinal Epithelial Cells ◽

Immune Defense ◽

Fine Tuning ◽

Type I ◽

Intestinal Epithelial ◽

Type I Ifn ◽

Innate Defense

The gastrointestinal epithelium guides the immune system to differentiate between commensal and pathogenic microbiota, which relies on intimate links with the type I IFN signal pathway. Epithelial cells along the epithelium provide the front line of host defense against pathogen infection in the gastrointestinal tract. Increasing evidence supports the regulatory potential of long noncoding RNAs (lncRNAs) in immune defense but their role in regulating intestinal epithelial antimicrobial responses is still unclear. Cryptosporidium, a protozoan parasite that infects intestinal epithelial cells, is an important opportunistic pathogen in AIDS patients and a common cause of diarrhea in young children in developing countries. Recent advances in Cryptosporidium research have revealed a strong type I IFN response in infected intestinal epithelial cells. We previously identified a panel of host cell lncRNAs that are upregulated in murine intestinal epithelial cells following microbial challenge. One of these lncRNAs, NR_033736, is upregulated in intestinal epithelial cells following Cryptosporidium infection and displays a significant suppressive effect on type I IFN-controlled gene transcription in infected host cells. NR_033736 can be assembled into the ISGF3 complex and suppresses type I IFN-mediated gene transcription. Interestingly, upregulation of NR_033736 itself is triggered by the type I IFN signaling. Moreover, NR_033736 modulates epithelial anti-Cryptosporidium defense. Our data suggest that upregulation of NR_033736 provides negative feedback regulation of type I IFN signaling through suppression of type I IFN-controlled gene transcription, and consequently, contributing to fine-tuning of epithelial innate defense against microbial infection.

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Sp1 and Sp3 mediate NHE2 gene transcription in the intestinal epithelial cells

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00443.2006 ◽

2007 ◽

Vol 293 (1) ◽

pp. G146-G153 ◽

Cited By ~ 8

Author(s):

Ping Hua ◽

Hua Xu ◽

Jennifer K. Uno ◽

Maciej A. Lipko ◽

Jiali Dong ◽

...

Keyword(s):

Transcription Factors ◽

Epithelial Cells ◽

Gene Transcription ◽

Promoter Region ◽

Promoter Activity ◽

Intestinal Epithelial Cells ◽

Gene Promoter ◽

Minimal Promoter ◽

Intestinal Epithelial ◽

Minimal Promoter Region

Our previous studies have identified a minimal Sp1-driven promoter region (nt −36/+116) directing NHE2 expression in mouse renal epithelial cells. However, this minimal promoter region was not sufficient to support active transcription of NHE2 gene in the intestinal epithelial cells, suggesting the need for additional upstream regulatory elements. In the present study, we used nontransformed rat intestinal epithelial (RIE) cells as a model to identify the minimal promoter region and transcription factors necessary for the basal transcription of rat NHE2 gene in the intestinal epithelial cells. We identified a region within the rat NHE2 gene promoter located within nt −67/−43 upstream of transcription initiation site as indispensable for the promoter function in intestinal epithelial cells. Mutations at nt −56/−51 not only abolished the DNA-protein interaction in this region, but also completely abolished NHE2 gene promoter activity in RIE cells. Supershift assays revealed that Sp1 and Sp3 interact with this promoter region, but, contrary to the minimal promoter indispensable for renal expression of NHE2, both transcription factors expressed individually in Drosophila SL2 cells activated rat NHE2 gene promoter. Moreover, Sp1 was a weaker transactivator and when coexpressed in SL2 cells it reduced Sp3-mediated NHE2 basal promoter activity. Furthermore, DNase I footprinting confirmed that nt −58/−51 is protected by nuclear protein from RIE cells. We conclude that the mechanism of basal control of rat NHE2 gene promoter activity is different in the renal and intestinal epithelium, with Sp3 being the major transcriptional activator of NHE2 gene transcription in the intestinal epithelial cells.

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