PSORS1C2 gene

PSORS1C2 (Psoriasis Susceptibility 1 Candidate 2) is a protein coding gene located on chromosome 6p21.33. PSORS1C2 is a gene located between coiled-coil alpha-helical rod protein 1 (CCHCR1) and corneodesmosin (CDSN) within psoriasis susceptibility 1 locus (PSORS1).

In contrast to the CCHCR1 gene, which is present in all vertebrates studied, PSORS1C2 and CDSN are exclusive to mammals. This suggests that these genes arose after the evolutionary divergence of mammals and reptiles.

CDSN is conserved in aquatic mammals, whereas PSORS1C2 orthologs have gene-inactivating frame-shift mutations in cetaceans, in which the epidermal differentiation program has degenerated. PSORS1C2 is expressed in human tissues mainly in the epidermis and much more weakly in the thymus (Abbas Zadeh S et al. 2017) .

PSORS1C2 mRNA is strongly upregulated during terminal differentiation of human keratinocytes in vitro (Abbas Zadeh S et al. (2017). Immunohistochemical studies revealed that PSORS1C2 is exclusively expressed in the granular layer of the epidermis and in keratinizing epithelial cells of the Hassall bodies of the thymus. Thus, it can be hypothesized that the encoded PSORS1C2 protein functions as a keratinocyte keratinization-associated protein that originated in evolutionarily basal mammals and underwent gene inactivation in association with the loss of skin barrier function in aquatic mammals.

Diseases associated with PSORS1C2 include psoriasis.

1. Abbas Zadeh S et al. (2017) Phylogenetic profiling and gene expression studies implicate a primary role of PSORS1C2 in terminal differentiation of keratinocytes. Exp Dermatol 26:352-358.