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作为身体的最外层屏障，保护内部器官免受环境危害，并将必需的液体保持在体内。在胚胎发育期间，单层表皮皮肤干细胞产生表皮、毛囊（HF）和皮脂腺，这是一系列调控途径协调的过程。在成人中，三种皮肤谱系中的每一种的稳态通过不同皮肤干细胞的自我更新和分化而长期维持。通过广泛的研究，已经了解了很多关于在胚胎发育和成体皮肤干/祖细胞的自我更新和分化过程中控制皮肤形态发生的调节网络。然而，最近，一个新的层次的调节介导的miRNA已牵连在动物的发展。miRNAs是一类非编码的小分子RNA（~19- 24 nt），广泛存在于动物和植物中。成熟的miRNA通过在3'非翻译区与其靶mRNA特异性偶联来调节翻译和/或mRNA稳定性。据估计，超过三分之一的蛋白质编码mRNA由miRNA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具有广泛的影响。miRNAs在哺乳动物皮肤形态发生过程中对基因表达和发育转变的全局调节作用以及它们在人类皮肤疾病中的潜在参与引起了人们对这些新型调节因子在皮肤生物学中的作用的极大兴趣。该提案基于我早期的发现，旨在通过关注miR-203来解决miRNA生物学和皮肤生物学的三个突出问题，miR-203是哺乳动物皮肤中最丰富和特异性表达的miRNA。在目标1中，我将通过解决一个重要的问题，即每个miRNA靶标如何在细胞周期调控中对miRNA的功能做出贡献，来剖析miR-203功能的潜在机制。在目标2中，我将通过探索其转录调控来研究miR-203本身的调控如何在皮肤中实现。在目标3中，我将开始研究miR-203的体内功能，通过使用组成型敲除小鼠模型在E14左右的最早基底-基底上转变期间检查其生理功能。总的来说，如果成功的话，这里提出的研究将显着提高我们对单个miRNA在皮肤中的表达，功能和调节的认识。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.