Molecular cloning and promoter analysis of downregulated in adenoma (DRA).
Downregulated in adenoma (DRA), also referred to as SLC26A3, is an intestinal anion transporter essential for intestinal chloride absorption. Mutations in DRA result in congenital chloride diarrhea. DRA expression has been shown to be induced by differentiation and to be modulated by cytokines. However, mechanisms of DRA gene transcription and its tissue-specific targeting have not yet been investigated. In this study, we cloned a 3,765-bp promoter fragment of human DRA gene and characterized its activity in human colonic LS174T and Caco-2 human colon cell lines. Primer extension identified a single transcriptional initiation site that was identical in both colon cancer cell lines and normal colon. Although hepatic nuclear factor HNF-4 is involved in the basal activity of DRA promoter, sodium butyrate induces its activity in LS174T cells via the binding of Yin Yang 1 (YY1) and GATA transcription factors to their respective cis-elements in promoter region. We also demonstrated a reduction in DRA promoter activity in Caco-2 cells by IFN-gamma, suggesting that regulation of DRA promoter by IFN-gamma may contribute to the pathophysiology of intestinal inflammation. Furthermore, we showed that the DRA promoter fragment is sufficient to drive human growth hormone transgene expression specifically in villus epithelial cells of the small intestine and in differentiated upper crypt and surface epithelial cells of the colon. Our studies provide evidence for the involvement of HNF-4, YY1, and GATA transcription factors in DRA expression in intestinal differentiated epithelial cells.
Alrefai
Waddah A
WA
University of Illinois at Chicago, Jesse Brown VA Medical Center, Medical Research Service, Chicago, IL 60612, USA. walrefai@uic.edu
Wen
Xiaoming
X
Jiang
Wen
W
Katz
Jonathan P
JP
Steinbrecher
Kris A
KA
Cohen
Mitchell B
MB
Williams
Ifor R
IR
Dudeja
Pradeep K
PK
Wu
Gary D
GD
D000236:Adenoma / Q000235:genetics / Q000276:immunology; D000818:Animals; D017920:Antiporters / Q000235:genetics*; D001483:Base Sequence; D045744:Cell Line, Tumor; D027963:Chloride-Bicarbonate Antiporters; D003001:Cloning, Molecular; D015972:Gene Expression Regulation, Neoplastic; D017930:Genes, Reporter; D019382:Human Growth Hormone / Q000235:genetics; D006801:Humans; D007413:Intestinal Mucosa / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000076988:Sulfate Transporters; D014157:Transcription Factors / Q000235:genetics
D017920:Antiporters; D027963:Chloride-Bicarbonate Antiporters; C081011:SLC26A3 protein, human; D000076988:Sulfate Transporters; D014157:Transcription Factors; D019382:Human Growth Hormone