PISCOPO, CARMELO (2017) EFFECT OF SODIUM BUTYRATE ON TRANSCRIPTIONAL REGULATION OF CFTR GENE. [Tesi di dottorato]

Preview

Text PISCOPO_Thesis.pdf Download (1MB) | Preview

Collection description

Cystic Fibrosis (CF) is an autosomal recessive disease caused by mutations in the cystic fibrosis transmembrane regulator (CFTR) gene, a member of the ATP-binding cassette (ABC) transporter superfamily. It acts in the apical part of epithelial cells as a plasma-membrane, cyclic AMP-activated chloride anion, bicarbonate anion and glutathione channel. CFTR is required for cell surface water-salt homeostasis and normal function of epithelia lining in the airways, intestinal tract, pancreatic ducts, salivary and sweat glands, liver and others. To date there are about 2000 mutations reported in CFTR gene that are generally classified in 6 different classes. The therapy of cystic fibrosis is still mainly simpthomatic but recently two novel classes of drugs were accepted for use in clinical practice even if in few patient with specific mutation called Ivafactor (potentiator of CFTR activity) and Lumafactor (corrector of CFTR activity). Although such therapies have improved the life expectancy of CFTR patients, they are still non resolutive in many cases and, moreover, are unable to work for all mutation’s classes. In order to identify novel molecules involved in CFTR transcriptional regulation, in addition to the correctors and potentiators that act at protein levels, we investigated the role of butyrate. Butyrate is a short-chain fatty acid and it is already in use in medical care. It’s involved in a variety of cellular events but is still unknown if it could have a putative role, direct or indirect, in the expression and modulation of CFTR. Preliminary data from our group indicate that butyrate enhance the CFTR expression in some cellular lines. To define if this effect is due to a direct mechanism on the CFTR promoter activity, we have focused our attention to the promoter region of CFTR gene to identify potential butyrate responsive elements (BRE) and their putative binding protein factors. To this purpose, we have performed a luciferase assay to compare the transcriptional activity of 6 deletion mutants of CFTR promoter. All constructs displayed increased luciferase activity under butyrate treatment in 3 different cell types: A549, Caco2 and Panc1. These data suggest that the butyrate effect on CFTR promoter activity is not mediated by a specific BRE element but most probably it is related to the Histone Deacetylase (HDAC) inhibitor activity of butyrate, and we confirmed this mechanism by treatment with Tricostatin (TSA), a specific histone deacetylase inhibitor, that demonstrated the same effect of butyrate on CFTR expression. Our study confirms that butyrate enhance CFTR expression. Such effect is not due to the interaction of butyrate with promoter responsive elements, but it depends on its effect on histone deacetylase inhibitor activity. Butyrate might be useful in patient with CF bearing mutations that permit a residual activity of the protein enhancing CFTR expression.

Downloads

Actions (login required)

View Item