Identification of transcripts overexpressed during airway epithelium differentiation

Human airway epithelium, the defence at the forefront of protecting the respiratory tract, evacuates inhaled particles by a permanent beating of epithelial cell cilia. When deficient, this organelle causes primary ciliary dyskinesia, and, despite numerous studies, data regarding ciliated cell gene expression remain incomplete. The aim of the present study was to identify genes specifically expressed in human ciliated respiratory cells via transcriptional analysis. The transcriptome of dedifferentiated epithelial cells was subtracted from that of fully redifferentiated cells using complementary DNA representational difference analysis. In order to validate the results, gene overexpression in ciliated cells was confirmed by real-time PCR, and by comparing the present list of genes overexpressed in ciliated cells to lists obtained in previous studies. A total of 53 known and 12 unknown genes overexpressed in ciliated cells were identified. The majority (66%) of known genes had never previously been reported as being involved in ciliogenesis, and the unknown genes represent hypothetical novel transcript isoforms or new genes not yet reported in databases. Finally, several genes identified here were located in genomic regions involved in primary ciliary dyskinesia by linkage analysis. In conclusion, the present study revealed sequences of new cilia-related genes, new transcript isoforms and novel genes which should be further characterised to aid understanding of their function(s) and their probable disorder-related involvement.