Roles of Hox genes in skin and hair follicle development

描述（申请人提供）：Hox转录调节因子在哺乳动物发育中起重要作用。虽然它们在皮肤及其附属物的发育和再生中的作用目前尚未得到充分研究，但这一点正受到越来越多的关注。一个值得注意的例子是Hoxc 13，它对正常毛囊发育至关重要。由我们创建的hoxc/3过表达转基因小鼠和Hoxc 13缺失小鼠都表现出严重的毛发生长缺陷，导致脱发。转基因小鼠的DMA微阵列分析和随后通过各种方法的验证鉴定了Foxql和Foxnl（在裸和缎子中突变）、原癌基因Junb、桥粒钙粘蛋白基因Dsc 2和几种毛发角蛋白基因作为Hoxc 13调节的推定靶标。我们的研究结果支持了Hoxc 13在控制毛囊分化的复杂调控网络中发挥核心作用的假设。定义这个网络对于理解许多皮肤和毛发疾病的机制至关重要，包括导致脱发和一些皮肤癌的疾病。我们的总体目标是：1）确定Hoxc 13是否直接与特定的靶基因相互作用。对照元件将通过DNA结合、共转染和染色质免疫沉淀试验以及在转基因和无效小鼠中使用报告基因分析的体内Hoxc 13依赖性调节来定义。2)我们将确定是否Hoxc 13和Foxgl蛋白调节公认的共同靶基因合作或独立。我们将测试推定的Foxql和Hoxc 13结合位点在Dsc 2的启动子区域中的功能作为体外范例，并确定这些是否在共转染测定中介导潜在的合作/协同反应。3)最后，我们将定义毛囊分化所必需的Hoxc 13依赖的调控基因网络。在5个时间点，将使用来自转基因小鼠和裸小鼠的皮肤样品与适当的对照进行比较性纵向DNA微阵列分析。这些数据将确定在毛囊发育的不同形态发生阶段Hoxc 13过度表达或不表达的影响。使用Incidity Network Analysis（c）和其他生物信息学工具将使我们能够开发一个由Hoxc 13控制的调控毛囊分化的遗传网络的概念框架。与公共卫生的相关性：我们正在定义一个控制哺乳动物毛囊和毛干发育的基因网络。任何或所有这些基因的突变导致各种类型的脱发，其中许多与特定的人类皮肤病相同。我们的目标是确定这些基因如何相互作用，这将最终确定如何治疗这些疾病。

DESCRIPTION (provided by applicant): Hox transcriptional regulators play important roles in mammalian development. While their role in the development and regeneration of skin and its appendages is currently understudied, this is receiving increasing attention. A notable case is Hoxc13, which is essential for normal hair follicle development. Both hoxc/3-overexpressing transgenic mice created by us and Hoxc13 null mice exhibit severe hair growth defects resulting in alopecia. DMA microarray analysis of the transgenic mice and subsequent validation by various methods identified Foxql and Foxnl (mutated in nude and satin), proto-oncogene Junb, desmosomal cadherin gene Dsc2, and a several hair keratin genes as putative targets of Hoxc13 regulation. Our results support the hypothesis that Hoxc13 plays a central role in a complex regulatory network controlling hair follicle differentiation. Defining this network is critical for understanding mechanisms involved in numerous skin and hair diseases, including diseases that result in alopecia and some skin cancers. Our overall aims are to 1) determine whether Hoxc13 directly interacts with specific target genes. Control elements will be defined by DNA binding, co-transfection and chromatin immunoprecipitation assays, and Hoxc13-dependent regulation in vivo using reporter gene analysis in both transgenic and null mice. 2) We will determine whether Hoxc13 and Foxgl proteins regulate putative common target genes either cooperatively or independently. We will test functionality of putative Foxql and Hoxc13 binding sites in the promoter region of Dsc2 as a paradigm in vitro, and determine whether these mediate potential cooperative/synergistic responses in co-transfection assays. 3) Lastly, we will define Hoxc13-dependent regulatory gene networks essential for hair follicle differentiation. Comparative longitudinal DNA microarray analysis will be done using skin samples from both transgenic and null mice with appropriate controls at 5 time points. These data will define the effect of over- or nonexpression of Hoxc13 at distinct morphogenetic stages of hair follicle development. Use of Ingenuity Network Analysis(c) and other bioinformatics tools will allow us to develop a conceptual framework of a Hoxc13-controlled genetic network regulating hair follicle differentiation. Relevance to Public Health: We are defining a gene network that controls development of hair follicles and hair shafts in mammals. Mutations in any or all of these genes result in a various types of alopecia, many of which are identical to specific human skin diseases. Our goal is to determine how these genes interact with each other, which will ultimately define how these diseases can be approached therapeutically.