Relevance of genes involved in skin tissue formation to human diseases and its application for regenerative medicine.

该研究项目旨在识别参与皮肤形成的基因，并根据基因产物的分子机制制定治疗措施。主要研究结果如下：我们发现一个钙结合蛋白S100C/A11介导高钙和TGFβ的生长抑制信号，这是正常人角质形成细胞的代表性生长抑制因子。暴露于高Ca或TGFβ时，S100C/A11被PKCα磷酸化并转移到细胞核中，通过激活Sp1诱导p21/WAF1。除了这一共同途径外，我们还发现了众所周知的独特途径，即nfat1介导的高Ca和TGFβ介导的smad介导的高Ca和TGFβ途径，对于生长抑制是必不可少的。表皮角质形成细胞的角化：新分离基因hornerin的特征hornerin是一个新分离的基因，它与角化的关键蛋白profilaggrin具有共同的结构特征。成年小鼠的皮肤、舌头、食道和前胃的分层上皮细胞中表达角蛋白。我们还分离并鉴定了人类同源基因。出乎意料的是，在正常成人躯干皮肤中没有检测到角蛋白，而在再生表皮和银屑病表皮中却有诱导。成人骨髓细胞向皮肤细胞的分化我们将小鼠胚胎皮肤细胞悬液接种到裸鼠背部的硅腔中，建立了皮肤重建系统。我们发现成年小鼠骨髓细胞与胚胎皮肤细胞移植后分化为皮肤细胞，包括形成表皮、毛囊和皮脂腺的细胞。从小鼠胚胎皮肤中分离干细胞我们通过将小鼠胚胎皮肤细胞接种到热敏合成凝胶中分离干细胞。

This research project is aiming to identify genes involved in the formation of skin and to develop therapeutic measures based on the molecular mechanisms of the gene products. Major results obtained are as follows.1.Growth regulation of human keratinocytes : A novel pathway involving S100C/A11We found that a Ca-binding protein S100C/A11 mediates the growth inhibitory signal of both high Ca and TGFβ which are representative growth suppressors for normal human keratinocytes. On exposure to high Ca or TGFβ, S100C/A11 was phosphorylated by PKCα and transferred to nuclei, where it induced p21/WAF1 through activation of Sp1. In addition to this common pathway, we showed that the well-known unique pathways, the NFAT1-mediated and Smad-mediated pathways for high Ca and TGFβ, respectively, were indispensable for the growth inhibition.2.Keratinization of epidermal keratinocytes : Characterization of newly-isolated gene, hornerinHornerin is a newly isolated gene, which has common structural features with profilaggrin, a key protein for keratinization. In adult mouse, hornerin was expressed in stratified epithelial cells of the skin, tongue, esophagus, and forestomach. We also isolated and characterized the human ortholog. Unexpectedly, hornerin protein was not detected in normal adult trunk skin but induced in the regenerating epidermis and psoriatic epidermis.3.Differentiation of adult bone marrow cells into skin cellsWe established a skin reconstitution system by inoculating a suspension of mouse embryonic skin cells into a silicon chamber on the back of nude mice. We showed that adult mouse bone marrow cells were differentiated into skin cells including cells forming epidermis, hair follicles, and sebaceous glands when transplanted with the embryonic skin cells.4.Isolation of stem cells from mouse embryonic skinWe isolated stem cells by inoculating mouse embryonic skin cells into a thermo-sensitive synthetic gel.