Systematic Isolation of Novel Genes Involved in Regulation of Growth and Differentiation of Slain Cells and Their Relevance to Human Diseases.

[目的]为了更好地了解人类主要皮肤病的发病机制，并建立基本的治疗措施，我们计划系统地分离参与皮肤细胞生长和分化调控的基因。[方法]利用RNA差异显示技术，在小鼠皮肤(12.5DPC~16.5DPC)的发育过程中，随着发育的进展，在现有的皮肤层(S)上增加了更多分化的表皮层。[结果]我们分离到6个新基因，其表达水平在观察期间上升，2个新基因，在此期间表达谱呈下降趋势。具有代表性的基因如下。2)Hornerin：Hornerin蛋白在N-末端有一个钙结合的EF-Hand结构域，其余部分具有重复结构。我们发现，在皮肤、舌头、食道和前胃的颗粒细胞角质透明质颗粒中，Hornerin蛋白和profilaggrin是共存的。当高钙诱导正常人角质形成细胞分化时，随着Profilaggrin的增加，Hornerin的表达增加。这些结果表明，Hornerin在结构和功能上与Frofilaggrin相似，并与profilaggrin一样参与角化。3)Calmin：Calmin蛋白在N端有两个肌动蛋白结合的钙蛋白同源结构域，在C端有一个跨膜结构域。它在皮肤、睾丸、脑(海马体、下丘脑和浦肯野细胞)、肝脏和肾脏中表达。随着这些器官的发育成熟，其表达水平也随之增加。4)TPIS：TPIS以含有四肽重复序列为特征，可能参与了表皮角质形成细胞的分化。5)其他相关结果：在这些结果和技术的基础上，我们对发育中的小鼠胎盘进行了分析，并成功地分离出了一些新的癌症相关基因。

[Objective] In aiming of better understanding of the mechanisms underlying in major human skin diseases and establishing fundamental therapeutic measures, we planned to systematically isolate genes involved in the regulation of growth and differentiation of skin cells.[Methods] RNA differential display was applied to developing mouse skin (12.5 dpc to 16.5 dpc) in which more differentiated epidermal layers are added to existing layer(s) with the progress of development.[Results] We have isolated 6 novel genes, expression levels of which increased during the observation period, and 2 novel genes, which showed a decreasing expression profile during the period. Representative genes are as follows. 2) Hornerin : Hornerin protein has a Ca-binding EF-hand domain in the N-terminal side and repetitive structures in the remaining part. We showed that hornerin protein was co-localized with profilaggrin in keratohyalin granules of granular cells in the skin, tongue, esophagus, and forestomach. When normal human keratinocytes were induced to differentiate by high Ca, expression of hornerin was increased concomitantly with profilaggrin. These results indicate that hornerin is structurally and functionally similar to frofilaggrin and involved in keratinization like profilaggrin. 3) Calmin : Calmin protein has two actin-binding calponin-homology domains at the N-terminus and a transmembrane domain at the C-terminus. It is expressed in the skin, testis, brain (hippocampus, hypothalamus, and Purkinje cells), liver and kidney. The expression levels increase in association with developmental maturation of those organs. 4) tpis : tpis is characterized by possessing tetratriopeptide repeats and presumably involved in differentiation of epidermal keratinocytes. 5) Other related results : Based on these results and techniques, we analyzed developing mouse placenta and succeeded in isolating a number of novel cancer-related gene.