Abstract
BackgroundMicroRNA (miRNA) and messenger RNA (mRNA) expression differs in cystic fibrosis (CF) versus non-CF bronchial epithelium. Here, the role of miRNA in basal regulation of the transcription factor ATF6 was investigated in bronchial epithelial cells in vitro and in vivo.MethodsUsing in silico analysis, miRNAs predicted to target the 3′untranslated region (3′UTR) of the human ATF6 mRNA were identified.ResultsThree of these miRNAs, miR-145, miR-221 and miR-494, were upregulated in F508del-CFTR homozygous CFBE41o- versus non-CF 16HBE14o- bronchial epithelial cells and also in F508del-CFTR homozygous or heterozygous CF (n = 8) versus non-CF (n = 9) bronchial brushings. ATF6 was experimentally validated as a molecular target of these miRNAs through the use of a luciferase reporter vector containing the full-length 3′UTR of ATF6. Expression of ATF6 was observed to be decreased in CF both in vivo and in vitro. miR-221 was also predicted to regulate murine ATF6, and its expression was significantly increased in native airway tissues of 6-week-old βENaC-overexpressing transgenic mice with CF-like lung disease versus wild-type littermates.ConclusionsThese results implicate miR-145, miR-221 and miR-494 in the regulation of ATF6 in CF bronchial epithelium, with miR-221 demonstrating structural and functional conservation between humans and mice. The altered miRNA expression evident in CF bronchial epithelial cells can affect expression of transcriptional regulators such as ATF6.
Highlights
MicroRNA and messenger RNA expression differs in cystic fibrosis (CF) versus non-CF bronchial epithelium
Activating transcription factor 6 (ATF6) is predicted to be regulated by miRNAs that are upregulated in CF airway epithelium We previously reported differential expression of 68 miRNAs in CF versus non-CF bronchial brushings by in situ quantitative real-time polymerase chain reaction (qRT-PCR) [10]
A range of other target prediction databases were interrogated, and ATF6 was listed as a putative target of two or more of these miRNAs in six of the eight databases interrogated, Figure 1C, each with only one miRNA recognition element predicted in the ATF6 3′untranslated region (3′UTR)
Summary
MicroRNA (miRNA) and messenger RNA (mRNA) expression differs in cystic fibrosis (CF) versus non-CF bronchial epithelium. The role of miRNA in basal regulation of the transcription factor ATF6 was investigated in bronchial epithelial cells in vitro and in vivo. Affected individuals typically become symptomatic in infancy and childhood and classically present with mucosal infections, exocrine pancreatic insufficiency and elevated sweat chloride levels. It is a multisystem disorder, recurrent lung infections are responsible for the major morbidity and mortality in PWCF. CF occurs due to mutations in the gene encoding the CF transmembrane regulator (CFTR) protein, a cyclic AMP-activated chloride channel that controls the secretion of chloride and bicarbonate ions across the airways and other epithelial surfaces.
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