Hix in Enteric Mesenchymal and Neuronal Development

虽然很明显，在消化系统的间充质或神经元成分的改变发挥了重要作用，在一些先天性运动障碍的人类的病理生理学，很少有人知道这些组件之间的发育相互作用的遗传调控，或所需的肠道间充质分化的遗传程序。 Hlx是一种编码同源异型盒转录因子的基因，是消化系统正常发育和生长所必需的。 我们在初步实验中发现，Hlx是肠神经系统（ENS）和肠间充质正常发育所必需的。 我们的总体假设是，Hlx转录因子调节肠间充质分化和ENS发展所需的间充质-神经元相互作用。 在这个应用中，我们提出了三个具体的目标，以了解Hlx在ENS的发展和肠间充质分化的作用。首先，我们将测试的假设，HLX是所需的正常迁移和肠道定植的神经嵴细胞在小鼠发育。 对于这些实验，我们将使用多巴胺β-羟化酶-LacZ转基因来比较Hlx+/+和Hlx-/-胚胎中神经嵴细胞的位置。 我们的第二个目的是检验Hlx是小鼠发育中神经嵴细胞正常增殖和/或分化所需的假设。 为了检验这一假设，我们将使用特异性肠神经元标志物的免疫组织化学来评估与Hlx+/+胚胎相比，Hlx-/-胚胎中存在的肠神经元谱系。 最后，我们将测试的假设，HLX是需要原始肠间充质细胞发展成平滑肌细胞，卡哈尔间质细胞，和上皮下肌成纤维细胞。 我们将使用两种互补的方法来检验这一假设：Hlx+/+和Hlx-/-胚胎中肠间充质细胞谱系标志物的免疫组织化学，以及平滑肌分化的转基因标志物（由α-平滑肌肌动蛋白和γ-平滑肌肌动蛋白启动子驱动的报告蛋白）。拟议的实验将提供新的见解肠间充质和肠神经元的分化程序和Hlx转录因子的调节。这项研究是补充单独资助的研究集中在HLX基因表达的调控和HLX转录因子的下游目标，特别是那些重要的间充质上皮细胞的相互作用在发展中的识别。

Although it is clear that alterations in mesenchymal or neuronal components of the digestive system play important roles in the pathophysiology of a number of congenital motility disorders of humans, little is known about the genetic regulation of the developmental interplay between these components, or about the genetic programs required for intestinal mesenchymal differentiation. Hlx, a gene encoding a homeobox transcription factor, is required for normal development and growth of the digestive system. We have found in preliminary experiments that Hlx is required for normal development of the enteric nervous system (ENS) and intestinal mesenchyme. Our overarching hypothesis is that the Hlx transcription factor regulates intestinal mesenchymal differentiation and mesenchymal-neuronal interactions required for ENS development. In this application, we propose three specific aims to understand the role of Hlx in ENS development and intestinal mesenchymal differentiation. First, we will test the hypothesis that Hlx is required for normal migration and intestinal colonization of neural crest cells in mouse development. For these experiments we will use the dopamine beta-hydroxylase-LacZ transgene to compare the position of neural crest cells in Hlx+/+ and Hlx-/- embryos. Our second aim is to test the hypothesis that Hlx is required for normal proliferation and/or differentiation of neural crest cells in mouse development. To test this hypothesis, we will use immunohistochemistry for specific enteric neuronal markers to assess the lineages of enteric neurons present in Hlx-/- as compare to Hlx+/+ embryos. Finally, we will test the hypothesis that Hlx is required for development of primitive intestinal mesenchymal cells into smooth muscle cells, interstitial cells of Cajal, and subepithelial myofibroblasts. We will use two complementary approaches to test this hypothesis: immunohistochemistry for markers of intestinal mesenchymal cell lineages in Hlx+/+ and Hlx-/- embryos, and transgene markers of smooth muscle differentiation (reporter proteins driven by alpha- smooth muscle actin and gamma-smooth muscle actin promoters). The proposed experiments will provide novel insights into the differentiation program of intestinal mesenchyme and enteric neurons and their regulation by the Hlx transcription factor. This research is complementary to separately funded research focusing on regulation of Hlx gene expression and the identification of downstream targets of the Hlx transcription factor, particularly those important for mesenchymal-epithelial interactions in development.