Spatial patterning of branching morphogenesis

描述（由申请人提供）：乳腺的树状结构是由分支形态发生产生的，这是一种从预先存在的上皮结构开始的分支位点起始和小管侵入的渐进过程。分支是由正调控因子和负调控因子之间的相互作用控制的，其中任何一个的缺陷都可以引起从增生到恶性生长的异常。我们的长期目标是描绘这些阳性和阴性信号在组织内如何空间整合，以确定哪些细胞分支，从而定义分支模式。我们已经开发出一种基于平版印刷的三维器官型培养模型，该模型概括了乳腺上皮导管的结构，能够对组织几何形状和微环境进行微米级分辨率控制，并在生理相关背景下提供定量数据。工程管道执行一系列完整的形态发生事件，可以通过计算预测。使用这种培养模型，我们已经表明，分支的位置部分地由转化生长因子（TGF）-21，自分泌抑制形态发生的浓度分布决定。此外，我们发现位于分支位置的细胞在形态发生过程中上调间充质标志物的表达。基于这些初步的和已发表的数据，我们提出：1-研究乳腺上皮导管感知和转导TGF 21浓度分布的特征。2-确定形态发生过程中差异表达的间充质标志物，以及这些标志物是否是确定分支位置所必需和/或充分的。我们将进一步测试间充质基因表达的模式是否受TGF 21抑制谱的调控。3-开始剖析分支是如何通过微环境的物理特性调节的，通过确定细胞外基质是否改变分支模式、TGF 21抑制浓度分布或间充质标记物的新表达。这些研究将提供深入了解当地的线索和基因表达的变化，管理分支的位置。 项目相关性：细胞在分支形态发生过程中整合来自刺激和抑制信号的信息，以发育成乳腺的树状结构;这些信号的破坏或失调可导致肿瘤生长并最终发展为坦率的肿瘤。在这里，我们目前的研究旨在了解乳腺上皮细胞如何感知抑制信号，并将其转化为模式化的差异，在分支形态发生的基因表达。

DESCRIPTION (provided by applicant): The tree-like architecture of the mammary gland is generated by branching morphogenesis, a reiterative process of branch site initiation and tubule invasion from a pre-existing epithelial structure. Branching is controlled by the interplay between positive and negative regulators, defects in either of which can give rise to aberrancies ranging from hyperplasia to malignant growth. Our long term goal is to delineate how these positive and negative signals are integrated spatially within the tissue to determine which cells branch, and thereby define the branching pattern. We have developed a lithography-based three-dimensional organotypic culture model that recapitulates the architecture of mammary epithelial ducts, enables micrometer-resolution control of tissue geometry and microenvironment, and provides quantitative data in a physiologically relevant context. The engineered ducts execute a complete series of morphogenetic events that can be predicted computationally. Using this culture model, we have shown that the position of branching is determined in part by the concentration profile of transforming growth factor (TGF)-21, an autocrine inhibitory morphogen. Furthermore, we have found that cells located in positions that branch up- regulate the expression of mesenchymal markers during morphogenesis. Based on these preliminary and published data, we propose: 1- To investigate the features of the TGF21 concentration profile perceived and transduced by mammary epithelial ducts. 2- To determine the mesenchymal markers differentially expressed during morphogenesis, and whether these are necessary and/or sufficient to define position of branching. We will further test whether the pattern of mesenchymal gene expression is regulated by the TGF21 inhibitory profile. 3- To begin to dissect how branching is regulated by the physical properties of the microenvironment, by determining whether the extracellular matrix alters branching pattern, TGF21 inhibitory concentration profile, or neo-expression of mesenchymal markers. These studies will provide insight into the local cues and gene expression changes that govern position of branching. PROJECT RELEVANCE: Cells integrate information from stimulatory and inhibitory signals during branching morphogenesis to develop into the tree-like structure of the mammary gland; disruption or misregulation of these signals can lead to neoplastic growths and eventual development of frank tumors. Here we present studies aimed at understanding how mammary epithelial cells perceive inhibitory signals and translate them into patterned differences in gene expression during branching morphogenesis.