Functional characterization of the promoter of the X-linked ectodermal dysplasia gene.

Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Journal of Biological Chemistry (Impact Factor: 4.65). 10/1999; 274(37):26477-84. DOI:10.1074/jbc.274.37.26477
Source: PubMed

ABSTRACT Anhidrotic ectodermal dysplasia (EDA) is a disorder characterized by poor development of hair, teeth, and sweat glands, and results from lesions in the X-linked EDA gene. We have cloned a 1.6-kilobase 5'-flanking region of the human EDA gene and used it to analyze features of transcriptional regulation. Primer extension analysis located a single transcription initiation site 264 base pairs (bp) upstream of the translation start site. When the intact cloned fragment or truncated derivatives were placed upstream of a reporter luciferase gene and transfected into a series of cultured cells, expression comparable with that conferred by an SV40 promoter-enhancer was observed. The region lacks a TATA box sequence, and basal transcription from the unique start site is dependent on two binding sites for the Sp1 transcription factor. One site lies 38 bp 5' to the transcription start site, in a 71-bp sequence that is sufficient to support up to 35% of maximal transcription. The functional importance of the Sp1 sites was demonstrated when cotransfection of an Sp1 expression vector transactivated the EDA promoter in the SL2 Drosophila cell line that otherwise lacks endogenous Sp1. Also, both Sp1 binding sites were active in footprinting and gel shift assays in the presence of either crude HeLa cell nuclear extract or purified Sp1 and lost activity when the binding sites were mutated. A second region involved in positive control was localized to a 40-bp sequence between -673 and -633 bp. This region activated an SV40 minimal promoter 4- to 5-fold in an orientation-independent manner and is thus inferred to contain an enhancer region.

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    ABSTRACT: Lesions in the anhidrotic ectodermal dysplasia (EDA) gene cause the recessive human genetic disorder X-linked anhidrotic ectodermal dysplasia, which is characterized by the poor development of ectoderm-derived structures. Ectodysplasin-A, the protein encoded by the EDA gene, is a member of the tumor necrosis factor ligand superfamily that forms a collagen triple helix, suggesting functions in signal transduction and cell adhesion. In an effort to elucidate the function of EDA in pathways regulating ectodermal development, we have analyzed promoter elements of the gene. We show here that a binding site for the lymphocyte enhancer factor 1 (Lef-1) transcription factor is active. In electrophoretic mobility shift assays, Lef-1 specifically bound to its site in the EDA promoter. Over-expression of both Lef-1 and beta-catenin significantly increased EDA transcription in co-transfection studies. In addition, indirect stabilization of endogenous beta-catenin stimulated EDA transcription 4- to 13-fold. This is the first direct evidence of a relationship between EDA and the Wnt pathway. We have also investigated whether EDA might function in a feedback loop to modulate Wnt signaling. Over-expression of EDA neither stimulated basal transcription of Wnt-dependent genes, nor inhibited Wnt-dependent activation of transcription. Taken together, our results demonstrate that Wnt signaling does control EDA gene expression, but ectodysplasin-A does not feedback on the Wnt pathway.
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    ABSTRACT: To provide a genetic framework for investigating changes in airway submucosal gland function in human respiratory disease, we have investigated their counterparts in normal and mutant mice. We describe their morphogenesis in relation to the expression of genes encoding conserved intercellular signaling pathways. Submucosal glands are severely reduced in number and size in mice heterozygous for Fgf10. Glands are completely absent in mice lacking Ectodysplasin (Eda) and Edaradd (Eda receptor adaptor protein), members of the tumor necrosis (TNF) superfamily of signaling factors. Furthermore, components of the Eda and closely related pathways are transcribed throughout the respiratory system in the adult mouse. Finally, the temporal and spatial pattern of Bmp4 expression suggests that it may control submucosal gland development and homeostasis. Taken together, our observations have important implications for the better understanding of the submucosal gland remodeling that occurs in human respiratory disease.
    Developmental Dynamics 09/2005; 233(4):1378-85. · 2.59 Impact Factor
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    ABSTRACT: The same morphogenetic signals are often involved in the development of different organs. For developing skin appendages, a model for tissue-specific regulation of signaling is provided by the EDA pathway, which accesses the otherwise ubiquitous NFkappaB transcription factors. EDA signaling is mediated by ectodysplasin, EDAR and EDARADD, which form a new TNF ligand-receptor-adaptor family that is restricted to skin appendages in vertebrates from fish to human. The critical function of the pathway was demonstrated in the hereditary genetic disorder Anhidrotic Ectodermal Dysplasia (EDA), which is characterized by defective formation of hair follicles, sweat glands and teeth. The pathway does not appear to initiate the development of the appendages, but is regulated by and regulates the course of further morphogenesis. In mice, transgenic and knockout strains have increasingly revealed features of the mechanism, and suggest possible non-invasive interventions to alleviate EDA deficiency, especially in sweat glands and eyes.
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