C/EDB BETA AND CHOP IN EPIDERMAL DIFFERENTIATION

哺乳动物的皮肤是一个重要的器官，用来维持水分和 平衡电解质，排除毒素和病原体，参与 免疫监视。这些功能在很大程度上归因于 皮肤的上皮层(表皮)。表皮中的排列紊乱 在牛皮癣等疾病中的作用，或在环境损伤中的作用 例如暴露在紫外线下，是由于大脑中的 角质形成细胞增殖和分化的精确平衡 制定正常的表皮分化程序。这一差额 在细胞内的基因转录水平上受一种 转录因子的种类，其特性和作用机制 行动现在才被赏识。这项提案将考验 假设一个相对较新的核转录家族 因子，CCAAT增强子结合蛋白(C/EBPs)，发挥着 在表皮分化中起着重要的调节作用。基于 证明存在C/EBPS的初步数据 体内和体外的皮肤角质形成细胞，建议的 实验将以一种因果的方式确定，两个成员如何 C/EBP家族(C/EBPbeta和CHOP)可能对正常和 表皮分化程序的有序进行。稳定 角质形成细胞系，表达多西环素诱导的转基因 编码C/EBPbeta和CHOP的激活物和抑制物(包括 反义RNA和C/EBPs的抑制蛋白亚型)将被 在体外钙依赖分化模型中进行了研究。 将检测生长和分化参数的变化。 在用多西环素诱导转基因后。作为体内的 与这些研究相关的是，稳定的角质形成细胞株将被移植 在裸鼠的背部，测试多西环素诱导的变化 在移植部位形成的表皮中。这些研究的结果可能 增强我们对控制从 增殖到分化，在后来的事件中，如细胞凋亡， 在表皮中。这些研究将为以后的研究奠定基础 观察C/EBPβ和CHOP变化的意义 在牛皮癣和暴露于紫外线的皮肤中的表达。因此，变化 C/EBPbeta和CHOP调控的基因表达可能参与其中 不仅在正常平衡的增殖和分化中 表皮，而且在表皮疾病和皮肤反应中也是如此 对环境的伤害。

Mammalian skin is a vital organ that serves to maintain fluid and electrolyte balance, exclude toxins and pathogens, and participate in immune surveillance. These functions are largely attributable to the epithelial layer of the skin (the epidermis). Derangements in epidermal function in diseases such as psoriasis, or in environmental injuries such as exposure to ultraviolet light, result from abnormalities in the precise balance of keratinocyte proliferation and differentiation that constitute the normal epidermal differentiation program. This balance is regulated within cells at the level of gene transcription by a variety of transcription factors whose identities and mechanisms of action are only now being appreciated. This proposal will test the hypothesis that a relatively new family of nuclear transcription factors, the CCAAT-enhancer binding proteins (C/EBPs), plays an important regulatory role in epidermal differentiation. Based upon preliminary data that demonstrate the presence of C/EBPS in keratinocytes of the skin, both in vivo and in vitro, the proposed experiments will establish, in a causal manner, how two members of the C/EBP family (C/EBPbeta and CHOP) may be critical for the proper and orderly progression of the epidermal differentiation program. Stable keratinocyte cell lines, expressing doxycyline-inducible transgenes that encode both activators and inhibitors of C/EBPbeta and CHOP (including antisense RNA, and inhibitory protein isoforms of C/EBPs) will be studied in a calcium-dependent differentiation model in vitro. Alterations in parameters of growth and differentiation will be assayed after induction of the transgenes with doxycycline. As an in vivo correlate to these studies, stable keratinocyte lines will be grafted onto the backs of nude mice, to test for doxycycline-inducible changes in the epidermis formed at the graft site. Results of these studies may enhance our understanding of mechanisms that govern the switch from proliferation to differentiation, and in later events such as apoptosis, in the epidermis. These studies will build a foundation for later studies on the significance of observed changes in C/EBPbeta and CHOP expression in psoriasis and in skin exposed to UV light. Thus, changes in C/EBPbeta and CHOP-regulated gene expression are probably involved not only in the normal balance proliferation and differentiation in the epidermis, but also in epidermal disease and in responses of the skin to environmental injury.