Dab1 expression and activity in mammary epithelial cells.

描述（由申请人提供）：作为发育中的中枢神经系统中细胞定位和迁移的关键调节因子，已对reelin信号通路进行了超过50年的研究。我的实验室最近发现了一个新的作用，reelin信号调节乳腺形态发生。使用免疫组织化学方法和报告基因表达，我们已经表明，reelin信号通路的组分在发育和成熟的乳腺中表达，并且reelin信号通路的改变会导致体内导管分支不当并破坏上皮组织，导致乳腺导管发育异常网络。我们还表明，孤立的乳腺上皮细胞，内衬导管腔，减缓其迁移的存在下reelin蛋白。这些观察结果导致的假设，reelin信号可能是一个重要的调节细胞迁移的乳腺。这项提案将解决如何Dab1，一个细胞内的衔接蛋白，被激活的reelin信号，功能调节乳腺上皮细胞的行为。Dab 1的几种亚型已被确定在胚胎脑和视网膜，这些亚型可能允许一个差异的反应存在的reelin和一个微妙的反应reelin信号。我的实验室已经证明了几种不同的Dab1亚型在乳腺中的表达，这一建议将确定这些亚型的生物学功能。首先，我们将确定何时何地表达不同的亚型，期望在增殖和迁移的乳腺上皮细胞中表达的亚型将不同于在静止细胞中表达的亚型。其次，我们将确定是否改变亚型表达改变乳腺上皮细胞在体外和体内的行为。第三，我们将确定哪些元素的reelin信号通路激活的不同Dab1亚型在乳腺上皮细胞。在神经元细胞中，有几种可供选择的结果，我们预计亚型表达可能决定哪些通路的元素在乳腺上皮细胞中被激活。总之，这些实验将证明Dab1亚型的差异表达对于乳腺细胞行为的调节是重要的。了解调节乳腺上皮细胞迁移的机制可能最终导致抑制乳腺癌细胞转移性迁移的治疗方法。

DESCRIPTION (provided by applicant): The reelin signaling pathway has been studied for over 50 years as a critical regulator of cell positioning and migration in the developing central nervous system. My laboratory has recently identified a novel role for reelin signaling in regulating mammary gland morphogenesis. Using immunohistochemical approaches and reporter gene expression, we have shown that components of the reelin signaling pathway are expressed in the developing and mature mammary gland and that alterations in reelin signaling cause improper ductal branching and disrupt epithelial organization in vivo, resulting in abnormal development of the mammary ductal network. We have also shown that isolated mammary epithelial cells, which line the ductal lumen, slow their migration in the presence of reelin protein. These observations lead to the hypothesis that reelin signaling may be a critical regulator of cell migration in the mammary gland. This proposal will address how Dab1, an intracellular adaptor protein that is activated in response to reelin signaling, functions in regulating the behavior of mammary epithelial cells. Several isoforms of Dab1 have been identified in embryonic brain and retina; these isoforms may allow a differential response to the presence of reelin and a nuanced response to reelin signaling. My laboratory has demonstrated the expression of several distinct Dab1 isoforms in the mammary gland and this proposal will determine the biological functions of these isoforms. First, we will determine when and where the different isoforms are expressed, with the expectation that isoforms expressed in proliferating and migrating mammary epithelial cells will be different from isoforms expressed in quiescent cells. Second, we will determine if changing isoform expression alters the behavior of mammary epithelial cells both in vitro and in vivo. Third, we will determine which elements of the reelin signaling pathway are activated by the different Dab1 isoforms in mammary epithelial cells. There are several alternative outcomes to reelin signaling in neuronal cells and we expect that isoform expression may dictate which elements of the pathways are activated in mammary epithelial cells. Together, these experiments will demonstrate that differential expression of Dab1 isoforms is important for the regulation of cellular behaviors in the mammary gland. Understanding the mechanisms that regulate mammary epithelial cell migration may ultimately lead to therapeutic approaches to inhibit the metastatic migration of breast cancer cells.