Direct repression of anoctamin 1 () gene transcription by Gli proteins.

The Ca-activated Cl channel, anoctamin 1 (Ano1, also known as transmembrane protein 16A) contributes to intestinal pacemaking, fluid secretion, cellular excitability, and tissue development. The human promoter contains binding sites for the glioma-associated oncogene (Gli) proteins. We investigated regulation of transcription by Gli. promoter activity was determined using a luciferase reporter system. Binding and functional effects of Glis on transcription and expression were demonstrated by chromatin immunoprecipitation, small interfering RNA knockdown, PCR, immunolabeling, and recordings of Ca-activated Cl currents in human embryonic kidney 293 (HEK293) cells. Results from previous genome-wide association studies were used to test promoter polymorphisms for association with disease. Gli1 and Gli2 bound to the promoter and repressed transcription. Repression depended on Gli binding to a site close to the transcriptional start site. Mutation of this site prevented Gli binding and transcriptional repression. Knockdown of Gli expression and inhibition of Gli activity increased expression of RNA and Ca-activated Cl currents in HEK293 cells. A single-nucleotide polymorphism prevented Gli binding and showed association with irritable bowel syndrome. We conclude that Gli1 and Gli2 repress by a novel mechanism that is independent of Gli cleavage and that has a role in gastrointestinal function.-Mazzone, A., Gibbons, S. J., Eisenman, S. T., Strege, P. R., Zheng, T., D'Amato, M., Ordog, T., Fernandez-Zapico, M. E., Farrugia, G. Direct repression of anoctamin 1 () gene transcription by Gli proteins.