P63 expression pattern during rat epidermis morphogenesis and the role of p63 as a marker for epidermal stem cells

Recent evidence has suggested that p63 plays a particular role in maintaining the population of epidermal stem cells (ESCs), but the expression pattern of p63 during normal rat epidermis development is still unknown. We investigated the expression of p63 during development and differentiation of rat epidermis and identified whether p63 is a specific marker of rat ESCs cultured in vitro.

Skin biopsies were obtained from embryonic day (E) 12 rat embryo, newborn, and 4-week-old rats. Immunohistochemistry was used to monitor the expression profile of p63. ESCs were isolated from newborn rat epidermis by rapid adhesion to IV collagen and examined by immunofluorescence staining to detect p63 and k14 expression.

P63 expression was first observed at E12 when the epidermis was only a simple-layer surface ectoderm. P63 continued to be expressed as the epidermis matured but restricted to the basal layer. In adult trunk epidermis, p63 was expressed in both the hair follicle and the sebaceous glands. Immunofluorescence staining for ESCs was double positive for p63 and k14.

These expression data suggest a role of p63 in the development of rat epidermis. P63 transcription factor may be a specific marker of keratinocyte progenitor cells.