A study of protein synthesis in cells cultured from involved psoriatic skin

Using histochemical techniques an abnormal programme of epidermal differentiation has been well documented in psoriasis. In order to characterise further the biochemistry of this process we have cultured dermal fibroblasts and epidermal keratinocytes from involved psoriatic skin. This has facilitated metabolic radiolabelling of skin cells and analysis of protein synthesis by two-dimensional polyacrylamide gel electrophoresis. The expression of keratin and differentiation markers was identical to that of normal keratinocytes, suggesting that psoriatic epidermal differentiation is not truncated in vitro as has been postulated to be the case in vivo. Low molecular mass components (5-8.5 kDa), previously shown to be upregulated in suprabasal keratinocytes, were detected in epidermal fractions from psoriatic skin enriched for basal cells. Of special interest was a component of 26 kDa, pI 5.9, which was highly upregulated in psoriatic as compared to normal cultured keratinocytes and was not detected in fibroblasts. These findings are in accord with a qualitatively abnormal pattern of differentiation for keratinocytes in the involved psoriatic epidermis.

A comparative study of protein synthesis by keratinocytes and fibroblasts in vitro using two-dimensional gel electrophoresis and dual isotope autoradiography

A procedure is described for the detection of keratinocyte specific proteins. Fibroblasts and keratinocytes were isolated from human skin and radiolabelled in vitro. Samples were separated by two-dimensional polyacrylamide gel electrophoresis to compare the proteins synthesised by the different types of cultured skin cells. Dual label autoradiography of samples radiolabelled with [35S]methionine and [75Se]selenomethionine was used to identify keratinocyte specific proteins. We report 45 keratinocyte-specific components and identify some of these proteins. The differential expression of these proteins and their relevance to epidermal differentiation are discussed.