Developmental regulation by miRNAs

描述（由申请人提供）：MicroRNA（miRNAs）最近被描述为一类重要的新型调节分子，其控制无脊椎动物的分化和模式化方面。在脊椎动物中也发现了类似的miRNAs，但它们在高等生物中的功能仍不清楚。该建议旨在了解miRNA在脊椎动物发育过程中的作用。我们已经发现，某些miRNAs在肢体和心脏的形态发生过程中差异表达。我们将使用微阵列和mini-Sage方法来鉴定在这些发育结构中表达的所有miRNA，包括鉴定在发育中的肢芽中表达的miRNA，包括在前肢和后肢原基中差异表达的miRNA以及在心脏原基中左右不对称产生的miRNA。这些miRNA的空间分布将通过北方印迹和通过产生携带“传感器”构建体的瞬时转基因小鼠来确定，所述构建体被设计为在除了存在给定miRNA的地方之外的任何地方表达lacZ。将制作额外的传感器来检查单个miRNA家族（Iet 7）的所有旁系同源物的差异表达模式;以及基因组中簇中编码的几种不同miRNA的差异表达模式。基于这些表达模式，将使用逆转录病毒错误表达在鸡中解决miRNA的功能。最后，我们将研究miR 196家族在调节小鼠Hox基因功能中的作用。将3个miR 196基因座单独敲除，并构建三重突变体。这些miR调节HoxB 8 mRNA的稳定性并调节HoxA 7 mRNA的翻译。将通过敲入方法删除HoxB 8 3 'UTR中的miR 196靶序列，以确定该调控的发育意义，并将HoxA 7 3' UTR中的miR 196靶序列替换为HoxB 8 miR 198靶序列，以测试调控模式（RNA切割与翻译控制）是否在功能上重要。

DESCRIPTION (provided by applicant): MicroRNAs (miRNAs) have recently been described as an important new class of regulatory molecules controlling aspects of differentiation and patterning in invertebrates. Similar miRNAs have been discovered in vertebrates, but their function in higher organisms remains largely unknown. This proposal is directed towards understanding the role of miRNAs during vertebrate development. We have found that certain miRNAs are differentially expressed during morphogenesis of the limb and heart. We will use microarray and mini-Sage approaches to identify all miRNAs expressed in these developing structures, including the identification of miRNAs expressed in the developing limb buds, including those differentially expressed in the fore- and hind-limb primordia as well as those left-right asymetrically produced in the heart primordium. The spatial distribution of these miRNAs will be determined by Northern blot and by production of transient transgenic mice carrying "sensor" constructs which are designed to express lacZ everywhere except where a given miRNA is present. Additional sensors will be made to examine the differential expression patterns of all paralogues of a single miRNA family (Iet7); and also of several distinct miRNAs encoded in a cluster in the genome. Based on these expression patterns, the function of miRNAs will be addressed in the chick using retroviral misexpression. Finally, we will study the roles of 1 family of miRNAs, miR196, in regulating Hox gene function in mice. The 3 miR196 loci will be knocked-out individually and the triple mutant will be constructed. These miRs regulate stability of the HoxB8 mRNA and modulate translation of the HoxA7 mRNA. The miR196 target sequence in the HoxB8 3'UTR will be deleted by a knock-in approach to determine the developmental significance of this regulation and the miR196 target sequence in the HoxA7 3'UTR will be replaced with the HoxB8 miR198 target sequence to test whether the mode of regulation (RNA cleavage versus translational control) functionally matters.