Characterization of protocadherin‐1 expression in primary bronchial epithelial cells: association with epithelial cell differentiation

Abstract

Protocadherin-1 (PCDH1) is a novel susceptibility gene for asthma that is expressed in airway epithelium. We aimed to characterize PCDH1 mRNA transcripts and protein expression in primary bronchial epithelial cells and to determine regulation of PCDH1 during mucociliary differentiation. Total RNA and protein were isolated from human primary bronchial epithelial cells. PCDH1 transcripts were characterized by rapid amplification of cDNA ends in bronchial epithelial cells of 4 subjects. PCDH1 expression was quantified by quantitative RT-PCR and Western blotting in bronchial epithelial cells directly ex vivo and after air liquid interface (ALI) or submerged culture. We identified 5 novel exons on the 5' end and 1 exon on the 3' end of PCDH1. Novel transcripts showed major variation in expression of intracellular conserved motifs. Expression levels of PCDH1 transcripts encoding exon 1-2 were 4-fold higher, and transcripts encoding exon 3-4 were 15-fold higher in freshly isolated bronchial epithelial cells than in submerged cultures. PCDH1 mRNA (3- to 8-fold) and protein levels (2- to 3-fold) were strongly up-regulated during mucociliary differentiation of primary bronchial epithelial cells in ALI cultures. In summary, PCDH1 transcripts display remarkable variability in expression of conserved intracellular signaling domains. Enhanced PCDH1 expression levels strongly correlate with differentiation of bronchial epithelial cells.

The PCDH1 gene and asthma in early childhood

“…PCDH1 belongs to a large group of cell-cell adhesion molecules. It is expressed in several tissues, including airway epithelium and skin keratinocytes [10,11]. It shows intracellular signalling abilities, is thought to play a role in cell repair and is expressed during fetal lung development in mice [12][13][14][15].…”

Fast preparation of a polyclonal antibody against chicken protocadherin 1

“…Abnormalities in delta-pcdhs genes may be responsible for the pathogenesis of several neurological disorders and carcinogenesis. For instance, Koppelman et al (2009) found that pcdh1 was a susceptibility gene for bronchial hyperresponsiveness, and Koning et al (2012) found that pcdh1 was a novel susceptibility gene for asthma that is expressed in airway epithelium. Philibert et al (2012) found that the deficiency of pcdh12 led to modifications in the structure and function of arteries.…”

Protocadherin-1: epithelial barrier dysfunction in asthma and eczema

“…The three-exon isoform does not encode the cytoplasmic domains CM1-3 that are present in the five-exon isoform. Recently, a sixth exon and alternative expression of exon 1 were identified in bronchial epithelial cells [11], whereas skin epithelial expression of PCDH1 has not been extensively characterised to date.…”

“…So far, no data are available on the functional effects of any of the asthma-and eczema-associated SNPs. Finally, adding to the complexity of PCDH1, its expression is also probably regulated by epigenetic mechanisms that include gene methylation, given the identification of exon 1A as a CpG island that is potentially methylated [11].…”

“…We hypothesise that PCDH1 dysfunction contributes to the defect in epithelial barrier function observed in both asthma and eczema by regulating the process of epithelial cell differentiation and/or repair. PCDH1 mRNA and protein expression is strikingly upregulated during primary bronchial epithelial cell differentiation, suggesting a role for PCDH1 in achieving or maintaining terminal differentiation of the airway epithelium [11]. The regulation of PCDH1 expression in the skin during epidermal differentiation has not been characterised to date, although PCDH1 expression is markedly induced in primary keratinocytes late during the repair process after scratch wounding [12].…”