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

【目的】系统分离与皮肤细胞生长分化相关的基因，为深入研究人类主要皮肤病的发病机制和制定治疗措施奠定基础。[方法]采用RNA差异显示技术，对小鼠皮肤（12.5 ~ 16.5 dpc）进行研究，观察随着发育过程中表皮层的分化程度。【结果】共分离到6个新基因，其表达水平在观察期内呈上升趋势，2个新基因在观察期内呈下降趋势。代表性基因如下。2)Hornerin：Hornerin蛋白在N-末端侧具有Ca结合EF-手结构域，在其余部分具有重复结构。我们发现，角蛋白与前聚丝蛋白共同定位于皮肤、舌、食管和前胃颗粒细胞的角质透明质颗粒中。当正常人角质形成细胞诱导分化高钙，角蛋白的表达增加伴随着原丝聚蛋白。这些结果表明，角蛋白在结构上和功能上与前聚丝蛋白相似，并且与前聚丝蛋白一样参与角化。3)Calmin：Calmin蛋白在N端具有两个肌动蛋白结合的Calponin同源结构域，在C端具有一个跨膜结构域。在皮肤、睾丸、脑（海马、下丘脑和浦肯野细胞）、肝脏和肾脏中表达。表达水平随着这些器官的发育成熟而增加。4)TPIS：TPIS的特征在于具有三肽重复序列，并且推测其参与表皮角质形成细胞的分化。5)其他相关结果：基于这些结果和技术，我们对发育中的小鼠胎盘进行了分析，并成功地分离了一些新的肿瘤相关基因。

[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.