Article

Genomic, tissue expression, and protein characterization of pCLCA1, a putative modulator of cystic fibrosis in the pig

Department of Veterinary Pathology, Freie Universität Berlin, Berlin, Germany.
Journal of Histochemistry and Cytochemistry (Impact Factor: 2.4). 09/2009; 57(12):1169-81. DOI: 10.1369/jhc.2009.954594
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ABSTRACT Recent studies have identified members of the CLCA (chloride channels, calcium-activated) gene family as potential modulators of the cystic fibrosis (CF) phenotype, but differences between the human and murine CLCA genes and proteins may limit the use of murine CF models. Recently established pig models of CF are expected to mimic the human disease more closely than the available mouse models do. Here, we characterized the porcine CLCA gene locus, analyzed the expression pattern and protein processing of pCLCA1, and compared it to its human ortholog, hCLCA1. The porcine CLCA gene family is located on chromosome 4q25, with a broad synteny with the human and murine clca gene loci, except for a pig-specific gene duplication of pCLCA4. Using pCLCA1-specific antibodies, the protein was immunohistochemically localized in mucin-producing cells, including goblet cells and mucinous glands in the respiratory and alimentary tracts. Similar to hCLCA1, biochemical characterization of pCLCA1 identified a secreted soluble protein that could serve as an extracellular signaling molecule or functional constituent of the protective mucous layers. The results suggest that pCLCA1 shares essential characteristics of hCLCA1, supporting the pig model as a promising tool for studying the modulating role of pCLCA1 in the complex pathology of CF.

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    • "Species-specific variations in genomic structure may give rise to limited comparability of expression data observed for a specific molecule in different species. For example , entire gene duplications or silencing of genes have been observed in the pig but not in humans for the chloride channels, calcium-activated (CLCA) family of genes, which have been proposed as potential modulators of the CF phenotype (Plog et al. 2009). Our computational genomic analyses revealed no such differences in the pCFTR gene locus, including duplications, premature stop codons within the coding region, or other structural differences that could account for principally different expressions when compared with hCFTR (not shown). "
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