P63 identifies keratinocyte stem cells. Proc Natl Acad Sci USA

Laboratory of Tissue Engineering IDI, Istituto Dermopatico dell'Immacolata, 00040 Rome, Italy.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 04/2001; 98(6):3156-61. DOI: 10.1073/pnas.061032098
Source: PubMed


The proliferative compartment of stratified squamous epithelia consists of stem and transient amplifying (TA) keratinocytes. Some polypeptides are more abundant in putative epidermal stem cells than in TA cells, but no polypeptide confined to the stem cells has yet been identified. Here we show that the p63 transcription factor, a p53 homologue essential for regenerative proliferation in epithelial development, distinguishes human keratinocyte stem cells from their TA progeny. Within the cornea, nuclear p63 is expressed by the basal cells of the limbal epithelium, but not by TA cells covering the corneal surface. Human keratinocyte stem and TA cells when isolated in culture give rise to holoclones and paraclones, respectively. We show by clonal analysis that p63 is abundantly expressed by epidermal and limbal holoclones, but is undetectable in paraclones. TA keratinocytes, immediately after their withdrawal from the stem cell compartment (meroclones), have greatly reduced p63, even though they possess very appreciable proliferative capacity. Clonal evolution (i.e., generation of TA cells from precursor stem cells) is promoted by the sigma isoform of the 14-3-3 family of proteins. Keratinocytes whose 14-3-3final sigma has been down-regulated remain in the stem cell compartment and maintain p63 during serial cultivation. The identification of p63 as a keratinocyte stem cell marker will be of practical importance for the clinical application of epithelial cultures in cell therapy as well as for studies on epithelial tumorigenesis.

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Available from: Graziella Pellegrini,
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    • "The present study was aimed to compare the effects human versus mouse EGF activity on cell confluency and culture duration, since it has previously shown that the affinities of mEGF for human low affinity receptors and high affinity receptors are much lower than those of hEGF (Connolly and Rose, 1987). Also we have quantified the effect of human EGF on the expression of corneal stem cell marker (P63) (Pellegrini et al., 2001) versus corneal epithelial differentiation marker (K3) (Rodriguez et al., 1987) in order to define optimal culture conditions to obtain high quantities of undifferentiated cells for autologous transplantation. "
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