DIFFERENTIAL EXPRESSION OF THE REGULARLY SPLICED WILD-TYPE P53 AND ITS COOH-TERMINAL ALTERNATIVELY SPLICED FORM DURING EPIDERMAL DIFFERENTIATION

In the present study, we investigated the role of p53 in the different iation of epidermal keratinocyte cells. The interrelationship between p53 expression and the various stages of epidermal differentiation and the role of the COOH terminus of the p53 molecule in this process wer e determined by comparing the expression of the regularly spliced p53 (RSp53) molecule and that of the COOH-terminal alternatively spliced ( ASp53) form, p53 mRNA distribution was studied by in situ analysis of frozen skin sections and by reverse transcription-PCR analysis of the various wild-type p53 forms expressed in neonatal skin cell fractions separated by Percoll gradient, p53 protein levels were measured by flu orescence-activated cell sorting analysis and immunohistochemistry, us ing antibodies that recognize either the COOH terminus of RSp53 or ASp 53. The results show that although less mature keratinocyte cells pred ominantly express the RSp53 form, the more mature cells preferentially express the ASp53 form. Therefore, it is possible that the two p53 fo rms are associated with different functions required at the various st ages of keratinocyte differentiation, The results suggest that the COO H-terminal domain of the p53 molecule is important for its activity in the process of keratinocyte differentiation.