Expression of the cystic fibrosis transmembrane conductance regulator gene in the respiratory tract of normal individuals and individuals with cystic fibrosis.

Abstract

The most common mutation of the cystic fibrosis transmembrane conductance regulator gene, CFTR, associated with the clinical disorder cystic fibrosis (CF) is called "APhe5N," a triple-base deletion resulting in loss of phenylalanine at residue 508 of the predicted 1480-amino acid CFTR CFTR gene expression quantified by limited polymerase chain reaction amplification showed that in normal individuals, CFTR mRNA transcripts are expressed in nasal, tracheal, and bronchial epithelial cells at -1-2 copies per cell, more than 100-fold greater than in pharyngeal epithelium. Importantly, allele-specific hybridization studies demonstrated that the normal and APhe5" CFTR alleles are expressed in the respiratory epithelium in similar amounts.Cystic fibrosis (CF) is a fatal recessive disorder caused by mutations of the CF transmembrane conductance regulator gene, CFTR, whose postulated protein product is a 1480-amino acid membrane protein thought to modulate Clsecretion across the apical membrane of epithelial cells (1-4). The most common mutation of the CFTR gene is called "Afe 508 ," a triple-base deletion resulting in loss of the codon for phenylalanine at residue 508 of the predicted protein sequence found on ;'"70% ofchromosomes containing an abnormal CFTR gene (3, 4). All organs with exocrine glands are affected by abnormalities of the CFTR gene, but the major clinical manifestations are in the respiratory tract, with impacted mucus, chronic infection, and inflammation with subsequent derangements of airways and lung parenchyma (1). It is not known how mutations in the CFTR gene cause the respiratory abnormalities, but it is assumed to be directly related to abnormalities in expression of the CFTR gene in the respiratory epithelium. As an approach to this question, the present study is directed toward quantifying in vivo CFTR gene expression at the mRNA level in respiratory epithelium of normals and individuals with CF. METHODS

Characterization of Wild-Type and ΔF508 Cystic Fibrosis Transmembrane Regulator in Human Respiratory Epithelia

“…The level of the mRNA expression appeared to decrease distally through the airways, consistent with previous PCR data (Trapnell et al, 1991) and functional studies (Knowles et al, 1981).…”

Pulmonary inflammation associated with repeated, prenatal exposure to an E1, E3-deleted adenoviral vector in sheep

“…4,5 Preparations of Av1nBg were carefully screened and certified free of pathogenic organisms and evaluated for the presence of E1a-containing 'wild-type' virus using quantitative PCR. 41 The level of sensitivity of this detection system is 1 p.f.u. of wild-type virus in 10 8 p.f.u.…”

A shortened adeno-associated virus expression cassette for CFTR gene transfer to cystic fibrosis airway epithelia

“…Previous studies showed that the endogenous CFTR promoter is very weak, producing perhaps one to two transcripts per cell (45). Even as little as 8% of normal transcripts seem to preserve normal lung function (46).…”