A microRNA network regulates expression and biosynthesis of wild-type and ΔF508 mutant cystic fibrosis transmembrane conductance regulator

Abstract

Production of functional proteins requires multiple steps, including gene transcription and posttranslational processing. MicroRNAs (miRNAs) can regulate individual stages of these processes. Despite the importance of the cystic fibrosis transmembrane conductance regulator (CFTR) channel for epithelial anion transport, how its expression is regulated remains uncertain. We discovered that miRNA-138 regulates CFTR expression through its interactions with the transcriptional regulatory protein SIN3A. Treating airway epithelia with an miR-138 mimic increased CFTR mRNA and also enhanced CFTR abundance and transepithelial Cl − permeability independent of elevated mRNA levels. An miR-138 anti-miR had the opposite effects. Importantly, miR-138 altered the expression of many genes encoding proteins that associate with CFTR and may influence its biosynthesis. The most common CFTR mutation, ΔF508, causes protein misfolding, protein degradation, and cystic fibrosis. Remarkably, manipulating the miR-138 regulatory network also improved biosynthesis of CFTR-ΔF508 and restored Cl − transport to cystic fibrosis airway epithelia. This miRNA-regulated network directs gene expression from the chromosome to the cell membrane, indicating that an individual miRNA can control a cellular process more broadly than recognized previously. This discovery also provides therapeutic avenues for restoring CFTR function to cells affected by the most common cystic fibrosis mutation.

Regulation of Cystic Fibrosis Transmembrane Conductance Regulator by MicroRNA-145, -223, and -494 Is Altered in ΔF508 Cystic Fibrosis Airway Epithelium

“…Many of the in vivo observations could be replicated in cell culture in the absence of patient-specific stimuli, indicating an intrinsic effect. This study validates CFTR as a target of miR-223, and complements and extends the findings of recent reports documenting miRNA influences over CFTR expression (10,24,25). Gillen et al (10) reported varying degrees of miRNA/CFTR interaction in pancreatic and colonic cell lines, and of 13 miRNAs examined found 4 that are predicted to target CFTR and are expressed in primary bronchial and tracheal cells (miR-101, -145, -331-3p, and -494).…”

“…However, this does not account for those not tested in our arrays, which may also be of significance in the CF lung or miRNAs targeting CFTR by indirect means. For example, Ramachandran et al (25) reported indirect regulation of CFTR by miR-138, an miRNA also increased in CF in our profiling study but not predicted to target CFTR, and therefore not pursued in this study.…”

SYVN1, NEDD8, and FBXO2 Proteins Regulate ΔF508 Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Ubiquitin-mediated Proteasomal Degradation

“…MiR-138 and SIN3A Regulate Genes Influencing CFTR Biosynthesis-We previously reported that miR-138 overexpression or SIN3A knockdown improved ⌬F508-CFTR trafficking and function in airway epithelia and altered transcript levels of target genes (9). Global mRNA transcript profiling after miR-138 overexpression and SIN3A inhibition were performed in the human airway Calu-3 cell line, a respiratory epithelial model (9 -11).…”

“…Our previous study revealed a gene expression network associated with improved ⌬F508-CFTR biosynthesis and functional rescue (9). In the present study, we mined these data to identify individual gene targets with putative roles along the ERQC-ERAD pathways.…”

MicroRNA 224 Regulates Ion Transporter Expression in Ameloblasts To Coordinate Enamel Mineralization

“…miRNAs play a role in almost all aspects of metazoan biology by buffering cell states, as well as driving cell fate transitions (8). CFTR has been reported to be regulated by microRNA 138 (miR-138) in airway epithelia through interaction with the transcriptional regulatory protein SIN3A (9). AE2 activity is diminished by miR-506 upregulation in cholangiocytes from primary biliary cirrhosis patients, which binds directly to the 3= UTR region of Slc4a2 mRNA, ultimately impairing biliary secretory functions (10).…”