Transcriptional complexity at the Hoxa5 locus: Characterization of the role of the Hoxa5-associated long noncoding RNAs

从受精卵到多细胞生物体的发育是一个复杂的过程，涉及许多基因在空间和时间上精确表达。Hox基因编码控制其他基因表达的蛋白质。它们在决定胚胎形成的遗传等级中占据关键地位。Hox基因的突变会导致一系列影响胚胎的异常，并在成年人中引起疾病，这表明Hox基因在整个生命过程中的作用范围很大。一系列复杂的不同调控模式控制Hox基因的特异性表达，表明正确的Hox表达对生物体正常发育的重要性。这些模式之一涉及在整个基因组中发现的长非编码（lnc）RNA，并沿着Hox基因簇存在。我们的实验室有兴趣在阐明的分子机制负责的时空模式的Hox基因表达在哺乳动物的发展。我们使用Hoxa5基因作为模型。我们已经证明，Hoxa 5对于包括骨骼，肺，肠道，卵巢，甲状腺和乳腺在内的几种结构的形成至关重要，揭示了Hoxa 5对正常发育的关键作用。此外，我们还发现Hoxa 5在胚胎中的特异性区域表达受多种DNA序列和转录因子的控制。产生含有Hoxa5序列的多个RNA，但只有一个编码HOXA 5蛋白。其他Hoxa5相关的lncRNA具有发育调节的表达，表明它们也参与胚胎形成。然而，它们的确切功能以及它们如何整合到发育程序中仍然未知。我们的工作假设是，Hoxa5相关的lncRNA是重要的协调时空表达的Hox基因在胚胎发育过程中，他们也有助于控制大规模的基因表达程序参与发展。我们将通过分析Hoxa5相关lncRNA在小鼠胚胎发育过程中所起的作用来研究Hoxa5表达的控制机制。这将通过使用分子和遗传方法来解决。我们的研究计划将导致更好地了解Hox表达的精确调控，这对Hox基因功能至关重要，因此对正确的胚胎发育至关重要。

The development of a multicellular organism from the fertilized egg is a complex process involving numerous genes expressed precisely in space and time. Hox genes encode proteins that control the expression of other genes. They occupy a key position in the genetic hierarchy dictating the formation of the embryo. Mutations in Hox genes result in a panoply of anomalies affecting the embryo and causing diseases in the adult, pinpointing the large range of action of Hox genes throughout life. A complex array of different modes of regulation governs the specific expression of Hox genes indicative of the importance of correct Hox expression for the normal development of the organism. One of these modes involves the long noncoding (lnc) RNAs found throughout the genome and present along the Hox gene clusters. Our laboratory is interested in elucidating the molecular mechanisms responsible for the spatio-temporal pattern of Hox gene expression during mammalian development. We use the Hoxa5 gene as a model. We have shown that Hoxa5 is essential for the formation of several structures including the skeleton, the lung, the gut, the ovary, and the thyroid and mammary glands, revealing the crucial role of Hoxa5 for normal development. Moreover, we have discovered that the Hoxa5 specific regional expression in the embryo is under the control of several DNA sequences and transcriptional factors. Multiple RNAs containing Hoxa5 sequences are produced but only one encodes for the HOXA5 protein. The other Hoxa5-associated lncRNAs possess a developmentally-regulated expression suggesting that they are also involved in embryo formation. However, their exact function and how they are integrated in the developmental program remain unknown. Our working hypothesis is that the Hoxa5-associated lncRNAs are important for the coordinated spatio-temporal expression of the Hox genes during embryogenesis and they also contribute to the control of large-scale gene expression programs involved in development. We will pursue our study of the control mechanisms of Hoxa5 expression by analyzing the role played by Hoxa5-associated lncRNAs during mouse embryogenesis. This will be addressed by using molecular and genetic approaches. Our research program will lead to a better understanding of the precise regulation of Hox expression, which is essential for Hox gene function and hence for the correct embryo development.**