Progesterone Withdrawal/Tight Junction Closure--Pregnant

从孕晚期静止的腔上皮细胞转变为活跃的泌乳细胞，是一系列事件的结果。这种转变是由持续存在高血浆催乳素和正常糖皮质激素的孕酮下降引发的。过渡到泌乳的一个关键事件是紧密连接的关闭，建立一个物理屏障，提供乳腺管腔与间质空间的功能分离。我们的目标是确定黄体酮戒断和紧密连接关闭之间的机制联系。我们将使用微阵列分析来确定伴随这种转变的调控基因的变化。(2)我们将使用蛋白质组学（2D凝胶电泳/质谱）来检测闭合过程中紧密连接蛋白的变化，以确定相关蛋白。(3)候选调控基因和蛋白的时空分布将被检测，以确定它们的表达方式是否与紧密连接关闭的调控作用一致。(4)适当表达的蛋白质的功能假设将在体内进行测试，利用导管内注射腺病毒载体和适当的转基因和敲除动物。这些实验将提供深入了解紧密连接调节的机制，应该找到广泛的生物学适用性。此外，更好地了解产后早期紧密结闭合的机制和调节将对预防和治疗母乳喂养问题具有重要的临床意义，这些问题对儿童健康的影响日益得到认识。

The stage II transition of the mammary epithelium to copious milk secretion results from a precise cascade of events that transform the quiescent luminal epithelial cells of late pregnancy into active milk secreting cells. This transition is triggered by a fall in progesterone in the continued presence of high plasma prolactin and normal glucocorticoid. A critical event in the transition to lactation is the closure of tight junctions, erecting a physical barrier that provides functional separation of the lumen of the mammary gland from the interstitial space. Our goal is to determine the mechanistic linkage between progesterone withdrawal and tight junction closure. (1) We will determine changes in regulatory genes that accompany this transition using microarray analysis. (2) We will examine changes in tight junction proteins that occur during closure using proteomics (2D gel electrophoresis/mass spectrometry) to identify the relevant proteins.(3) The spatial and temporal distribution of candidate regulatory genes and proteins will be examined to determine whether they are expressed in a manner consistent with a role in regulation of tight junction closure. (4) Functional hypotheses about proteins that are expressed appropriately will be tested in vivo, utilizing intraductal injection of adenoviral vectors and transgenic and knock-out animals as appropriate. These experiments will provide insight into the mechanisms of tight junction regulation that should find broad biological applicability. In addition a better understanding of the mechanisms and regulation of tight junction closure during the early post-partum period will have significant clinical implications for the prevention and treatment of breast-feeding problems whose impact on child health is increasingly recognized.