Butyrate increases apical membrane CFTR but reduces chloride secretion in MDCK cells

Abstract

Sodium butyrate and its derivatives are useful therapeutic agents for the treatment of genetic diseases including urea cycle disorders, sickle cell disease, thalassemias, and possibly cystic fibrosis (CF). Butyrate partially restores cAMP-activated Cl− secretion in CF epithelial cells by stimulating ΔF508 cystic fibrosis transmembrane conductance regulator (ΔF508-CFTR) gene expression and increasing the amount of ΔF508-CFTR in the plasma membrane. Because the effect of butyrate on Cl− secretion by renal epithelial cells has not been reported, we examined the effects of chronic butyrate treatment (15–18 h) on the function, expression, and localization of CFTR fused to the green fluorescent protein (GFP-CFTR) in stably transfected MDCK cells. We report that sodium butyrate reduced Cl−secretion across MDCK cells, yet increased apical membrane GFP-CFTR expression 25-fold and increased apical membrane Cl− currents 30-fold. Although butyrate also increased Na-K-ATPase protein expression twofold, the drug reduced the activity of the Na-K-ATPase by 55%. Our findings suggest that butyrate inhibits cAMP-stimulated Cl− secretion across MDCK cells in part by reducing the activity of the Na-K-ATPase.

Impact of Heterogeneity within Cultured Cells on Bacterial Invasion: Analysis of Pseudomonas aeruginosa and Salmonella enterica Serovar Typhi Entry into MDCK cells by Using a Green Fluorescent Protein-Labelled Cystic Fibrosis Transmembrane Conductance Regulator Receptor

“…While butyrate treatment of epithelial cells did not decrease serovar Typhi uptake, it also did not increase uptake, indicating that other cellular processes may have been affected by the butyrate treatment such that the increased levels of the bacterial receptor for ingestion were counterbalanced by changes reducing the epithelial cells' ability to ingest bacteria. Consistent with our finding that increased CFTR expression actually decreased its biologic activity is the recent finding of Moyer et al (12), who showed that butyrate increases apical-membrane expression of CFTR in MDCK-GFP-CFTR cells by 25-fold but decreases Cl Ϫ ion transport. Thus, overexpression of CFTR in cells adversely affects both ion transport properties and bacterial-ingestion activity, indicating that properly regulated levels of CFTR protein are required for its biological activities to be optimal.…”

The Chemopreventive Agent Resveratrol Stimulates Cyclic AMP–Dependent Chloride SecretionIn vitro

“…As shown earlier, short-chain fatty acids inhibit cAMPmediated chloride secretion in rat and rabbit colon (15,40). In Madin-Darby canine kidney cells and Calu-3 cells, butyrate (5 mmol/L) reduced basal as well as cAMP-stimulated I sc (41,42). In contrast, lower concentrations of phenylbutyrate (<2 mmol/L) had no effect on cAMP-stimulated Cl À secretion across Calu-3 cells (42).…”

ThePseudomonas aeruginosaSecreted Protein PA2934 Decreases Apical Membrane Expression of the Cystic Fibrosis Transmembrane Conductance Regulator

“…Madin-Darby canine kidney (MDCK) cells stably expressing a green fluorescent protein-WT CFTR fusion protein (WT-MDCK cells) were established and maintained in culture in a 5% CO 2 -95% air incubator at 37°C as described previously (37,38). The addition of green fluorescent protein to the N terminus of CFTR had no effect on CFTR localization, trafficking, function as a Cl Ϫ channel, or degradation (37).…”