MicroRNA-mediated Regulation in Mammalian Skin

描述(由申请人提供)： 哺乳动物的皮肤及其附属物起着身体最外层的屏障作用，以保护内部器官免受环境危害，并将必要的液体保留在体内。在胚胎发育期间，单层表皮皮肤干细胞形成表皮、毛囊(HF)和皮脂腺，这一过程由一系列调节途径协调。在成人中，三种皮肤谱系的动态平衡是通过不同皮肤干细胞的自我更新和分化来长期维持的。通过广泛的研究，人们已经了解到在胚胎发育过程中控制皮肤形态发生的调控网络，以及成人皮肤干细胞/祖细胞的自我更新和分化。然而，最近，由miRNAs介导的一层新的调节层被认为与动物发育有关。MiRNAs是一个非编码的小RNA家族(~19-24nt)，在广泛的动植物中表达。成熟的miRNAs通过与其位于3‘非翻译区的靶mRNA特异性地结合来调节翻译和/或mRNA的稳定性。据估计，超过三分之一的蛋白质编码的mRNAs受miRNAs调控。反过来，miRNA介导的调控被认为对转录组的蛋白质输出和基因调控网络的进化都有广泛的影响。MiRNAs在哺乳动物皮肤形态发生过程中全局调控基因表达和发育转变的潜力，以及它们在人类皮肤病中的潜在参与，引起了人们对这些新的调节因子在皮肤生物学中的作用的极大兴趣。这项建议是基于我早期的发现，旨在通过关注miR-203来解决miRNA生物学和皮肤生物学的三个悬而未决的问题，miR-203是哺乳动物皮肤中表达最丰富和特异的miRNA。在目标1中，我将通过解决一个重要的问题来剖析miR-203‘S功能的潜在机制，即每个miRNA靶点如何参与miRNA在细胞周期调控中的功能。在目标2中，我将通过探索miR-203的转录调控来研究miR-203本身是如何在皮肤中实现调控的。在目标3中，我将开始研究miR-203‘S在体内的功能，通过结构性基因敲除小鼠模型检测其在E14前后最早的基底部-基上基转换中的生理功能。综上所述，这里提出的研究，如果成功，将极大地增强我们对单个miRNA在皮肤中的表达、功能和调节的了解。在正常发育条件下从这些研究中获得的知识也将为研究miRNA在人类疾病中的作用铺平道路，例如调节网络出错的皮肤癌。

DESCRIPTION (provided by applicant): Mammalian skin and its appendages function as the outermost barrier of the body to protect inner organs from environmental hazards and keep essential fluids within the body. During embryonic development, a single layer of epidermal skin stem cells gives rise to the epidermis, hair follicles (HF) and the sebaceous gland, a process orchestrated by an array of regulatory pathways. In adult, homeostasis of each of three skin lineages is maintained long-term through self-renewal and differentiation of distinct skin stem cells. Through extensive investigation, much has been learned about the regulatory networks that control skin morphogenesis during embryonic development and self-renewal and differentiation of adult skin stem/progenitor cells. Recently, however, a novel layer of regulation mediated by miRNAs has been implicated in animal development. MiRNAs are a family of non-coding, small RNAs (~19-24nt) expressed in a wide range of animals and plants. Mature miRNAs act by specifically coupling with their target mRNAs at the 3' untranslated region to regulate the translation and/or mRNA stability. It is estimated that more than one third of protein-encoding mRNAs are regulated by miRNAs. In turn, miRNA-mediated regulation is believed to have a widespread impact on both protein output of transcriptome and evolution of gene regulatory networks. MiRNAs' potentials in globally regulating gene expression and developmental transitions during mammalian skin morphogenesis as well as their potential involvement in human skin diseases have attracted significant interests in the role of these novel regulators in skin biology. This proposal is based on my earlier findings and built to address three outstanding questions of miRNA biology and skin biology by focusing on miR-203, the most abundantly and specifically expressed miRNA in mammalian skin. In aim 1, I will dissect the underlying mechanisms of miR-203's functions by addressing an important question, that is, how each miRNA target contributes to the miRNA's functions in cell cycle regulation. In aim 2, I will investigate how the regulation of miR-203 itself is achieved in the skin by exploring its transcriptional regulation. In aim 3, I will begin to investigate miR-203's in vivo functions by examining its physiological functions during the earliest basal-suprabasal transition around E14 with a constitutive knockout mouse model. Taken together, studies proposed here, if successful, will significantly enhance our knowledge about individual miRNA's expression, function and regulation in the skin. The knowledge gained from these studies under normal development condition will also pave the way to investigate miRNA's roles in human diseases e.g. skin cancers where regulatory networks go awry.