Pellegrini G, Dellambra E, Golisano O, Martinelli E, Fantozzi I, Bondanza S, Ponzin D, McKeon F, De Luca M
Laboratory of Tissue Engineering IDI, Istituto Dermopatico dell'Immacolata, 00040 Rome, Italy.
Proc Natl Acad Sci U S A. 2001 Mar 13;98(6):3156-61. doi: 10.1073/pnas.061032098.
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.
复层鳞状上皮的增殖区室由干细胞和瞬时扩增（TA）角质形成细胞组成。一些多肽在假定的表皮干细胞中比在TA细胞中更丰富，但尚未鉴定出仅限于干细胞的多肽。在这里，我们表明p63转录因子是上皮发育中再生增殖所必需的p53同源物，它能将人角质形成干细胞与其TA后代区分开来。在角膜内，核p63由角膜缘上皮的基底细胞表达，但不由覆盖角膜表面的TA细胞表达。人角质形成干细胞和TA细胞在培养中分离时分别产生全克隆和副克隆。我们通过克隆分析表明，p63在表皮和角膜缘全克隆中大量表达，但在副克隆中无法检测到。TA角质形成细胞在从干细胞区室退出后（部分克隆），即使它们具有非常可观的增殖能力，其p63也会大大降低。14-3-3蛋白家族的sigma异构体促进克隆进化（即从前体干细胞产生TA细胞）。14-3-3最终sigma被下调的角质形成细胞留在干细胞区室并在连续培养期间维持p63。将p63鉴定为角质形成干细胞标志物对于上皮培养物在细胞治疗中的临床应用以及上皮肿瘤发生研究具有实际重要性。
