Increased phosphorylation of two 48 kDa nuclear proteins in fibroblasts derived from psoriatic patients.

Psoriasis is a hereditary disease primarily affecting the skin and characterized by an abnormally high proliferation rate of the epidermal cells. Based on some recent reports indicating that the dermal compartment of the skin is involved in the hyperproliferative process, too, we investigated the nuclear protein pattern of human skin fibroblasts in cell cultures obtained from skin biopsy specimens of normal volunteers and from involved and healthy skin of untreated psoriatic patients. To eludicate the extent of phosphorylation of these proteins which occurs as a cell cycle-specific event, we performed in vitro phosphorylation of the 5 M ureasoluble nuclear proteins after serum stimulation of starved fibroblasts. Without exogeneous kinase in the assay the phosphorylation of several acidic proteins was detected. Two of them with a pI of 3.5 and a molecular mass near 48 kDa seem to be enhanced in synthesis and modification in the psoriatic fibroblasts indicating a specific function particularly in these cells.