Differential expression of p63 isoforms in normal skin and hyperproliferative conditions

The p63 is regarded as a potential stem cell marker.

Expression of p63 isoforms was examined in normal skin and hyperproliferative conditions including psoriasis and artificial skin equivalents (SEs). Rapidly adhering (RA) and slowly adhering (SA) cells were isolated, and Western blotting was performed.

Expression of p63 (4A4) and p63 (H-137) is similar in all conditions, although there is some variation in psoriasis. However, expression of p63alpha (C-12) is markedly different. In normal skin, p63alpha (C-12)-positive cells were scattered in whole epidermis. But in psoriasis, p63alpha (C-12)-positive cells were observed at the tips of rete ridges. In SEs, p63alpha (C-12)-positive cells were not well observed. Western blot results showed that the RA cells express p63 (4A4) and p63 (H-137) strongly compared with SA or nonadhering (NA) cells. In contrast, SA or NA cells strongly express p63alpha (C-12).

Results suggest that both p63 (4A4) and p63 (H-137) can detect epidermal stem cells. But, p63 (H-137) seemed to be a better marker because p63 (H-137)-positive cells were more localized at basal layer. In addition, it can be said that p63alpha (C-12) can detect TAp63, which is important in differentiation of epidermis. Furthermore, it is concluded that molecular control of TAp63 is especially disorganized in hyperproliferative condition including psoriasis and SEs.