Direct repression of anoctamin 1 ( ANO1 ) gene transcription by Gli proteins

Abstract

The Ca2+‐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 ANO1 promoter contains binding sites for the glioma‐associated oncogene (Gli) proteins. We investigated regulation of ANO1 transcription by Gli. ANO1 promoter activity was determined using a luciferase reporter system. Binding and functional effects of Glis on ANO1 transcription and expression were demonstrated by chromatin immunoprecipitation, small interfering RNA knockdown, PCR, immunolabeling, and recordings of Ca2+‐activated Cl− currents in human embryonic kidney 293 (HEK293) cells. Results from previous genome‐wide association studies were used to test ANO1 promoter polymorphisms for association with disease. Gli1 and Gli2 bound to the promoter and repressed ANO1 transcription. Repression depended on Gli binding to a site close to the ANO1 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 ANO1 RNA and Ca2+‐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 ANO1 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 (ANO1) gene transcription by Gli proteins. FASEB J. 33, 6632–6642 (2019). http://www.fasebj.org

Differential phosphorylation determines the repressor and activator potencies of GLI1 proteins and their efficiency in modulating the HPV life cycle

“…Here, we show that GLI1FL, but not GLI1ΔN, is capable of acting as a transcriptional repressor of HPV18 early promoters. While GLI1 is generally thought to act only as a transcriptional activator, several groups have also suggested that it might repress certain genes in a context dependent manner [30][31]. Although such overexpression experiments are often difficult to interpret, we believe that the significant difference between the repressor activities of GLI1FL and GLI1ΔN indicates that the effect is direct and not an experimental artefact.…”

Calcium-Activated Chloride Channel ANO1/TMEM16A: Regulation of Expression and Signaling

“…In gastric cancer cells, the specificity protein 1 (SP1) was shown to bind ANO1 promoter and recruit the mixed lineage leukemia MLL1 protein to promoter region, facilitating histone H3K4 trimethylation, and subsequently promoting ANO1transcription (Zeng et al, 2019). On the other hand, glioma-associated oncogene proteins Gli1/2 were shown to bind and repress ANO1 promoter activation and ANO1 expression in HEK293 model (Mazzone et al, 2019). DNA methylation was also shown to regulate ANO1 expression.…”

Prototypical pacemaker neurons interact with the resident microbiota

“…Dysfunction of the pacemaker system contributes to functional gastrointestinal disorders, such as irritable bowel syndrome (IBS), chronic constipation, and intestinal pseudo-obstruction ( 9 – 12 ). The Ca 2+ -activated Cl − -channel Anoctamin-1 (encoded by the ANO1 gene) and the voltage-gated Na + -channel Nav1.5 ( SCN5A gene) represent molecular markers of the interstitial pacemaker cells in human and mice ( 13 – 15 ), and DNA variants in the corresponding genes have been shown to associate with increased risk of IBS ( 16 – 18 ). Ion channel dysfunction (channelopathy) appears to be a plausible pathogenetic mechanism in functional gastrointestinal disorders ( 19 ), as the transient receptor potential cation channel TRPM8 (known as the cold and menthol receptor) and other ion channels have also been implicated in IBS susceptibility and gut dysmotility ( 20 – 23 ).…”