High-level activation by a duodenum-specific enhancer requires functional GATA binding sites

Abstract

The purine metabolic gene adenosine deaminase ( ADA) is expressed at high levels in a well-defined spatiotemporal pattern in the villous epithelium of proximal small intestine. A duodenum-specific enhancer module responsible for this expression pattern has been identified in the second intron of the human ADA gene. It has previously been shown that binding of the factor PDX-1 is essential for function of this enhancer. The studies presented here examine the proposed roles of GATA factors in the enhancer. Site-directed mutagenesis of the enhancer's GATA binding sites crippled enhancer function in 10 lines of transgenic mice, with 9 of the lines demonstrating <1% of normal activity. Detailed studies along the longitudinal axis of mouse small intestine indicate that GATA-4 and GATA-5 mRNA levels display a reciprocal pattern, with low levels of GATA-6 throughout. Interestingly, gel shift studies with duodenal nuclear extracts showed binding only by GATA-4.

Cooperative interactions among intestinal GATA factors in activating the rat liver fatty acid binding protein gene

“…These experiments were repeated twice with similar results. small intestine (14,36), in contrast to our failure to detect GATA-5 protein in the newborn or adult small intestine. This discrepancy may reflect a difference in transcript vs. protein expression as characterized for GATA-6 (5), or a difference in assay sensitivity between mRNA detection and immunohistochemistry, or a difference in cellular gene expression in the intestinal epithelium.…”

“…We previously performed an immunohistochemical survey for GATA factors in the adult intestine and found that GATA-4 and GATA-6 are expressed in adult murine small intestinal enterocytes, with GATA-6 also present in crypt epithelial cells (12). We did not detect GATA-5 in the adult murine intestine (12), although the Gata5 transcript has been detected in the intestine of both late gestation and adult mice (14,36).…”

“…GATA-4 is subject to phosphorylation (8,31,35,46) or acetylation (26), which can increase DNA binding. Intestinal extracts showed only GATA-4 but not GATA-6 binding to sequences containing GATA binding sites despite the presence of both factors in this tissue, suggesting regulation of binding (4,14). Another possible means of interaction between GATA factors present in a single cell is direct binding between factors.…”

GATA-4 upregulates glucose-dependent insulinotropic polypeptide expression in cells of pancreatic and intestinal lineage

“…Members of the latter subfamily are expressed in the gastrointestinal tract in distinct overlapping patterns along the longitudinal axis (Dusing et al, 2003). GATA transcription factors have been found to play critical roles in regulating tissue specific gene expression, and GATA-4 in particular has been shown to play an important role in regulating the transcription of numerous intestinal genes (Boudreau et al, 2002;Divine et al, 2004;Dusing et al, 2003;Fang et al, 2001;Kiela et al, 2003).…”

“…Dusing et al (2003) reported that the purine metabolic gene adenosine deaminase (ADA) gene is expressed at high levels in absorptive enterocytes in the villous epithelium of the proximal small intestine. They reported that a duodenum specific enhancer, which binds both transcription factors PDX-1 and GATA-4, controls this pattern of expression.…”