Functional Development of the Mammary Gland

说明(由申请人提供)：这是美国儿科学会的建议，所有儿童至少在生命的前六个月内接受母乳喂养[2]，尽管有这一建议，但在过去20年里，乳腺的功能发育及其结果--乳汁分泌--相对较少受到关注。在这个计划项目中，我们试图通过召集六名具有不同专业知识的合格调查人员来检查乳汁分泌调节和机制的四个关键方面，以弥补这一不足。在项目I中，我们将检验一个新的假说，该假说将乳腺中平衡的糖酵解与脂质合成和细胞存活联系起来。我们推测，由丝氨酸/苏氨酸激酶Akt/PKB调节的己糖激酶活性/构象的变化在这两个功能之间提供了关键的联系。我们将在转基因小鼠身上测试这一假设。在项目II中，我们将研究在乳腺肺泡细胞中形成细胞质脂滴(CLD)的分子和细胞生物学基础，测试这些实体起源于内质网中的特定区域的假设，内质网中包含合成它们所需的所有合成机器。在项目III中，我们将仔细研究孕酮抑制妊娠晚期乳汁分泌的机制，研究直接和间接机制以及它们在乳腺中对含有孕激素受体的细胞和其他细胞的定位。LacZ被定位于孕激素受体编码区，绿色荧光蛋白被定位于b-酪蛋白编码区的转基因小鼠将被用来实现这一目标。在项目IV中，我们将开始研究PKC*在怀孕、哺乳和退化过程中对细胞增殖和凋亡的作用。这种丝氨酸/苏氨酸激酶是上皮细胞凋亡的上游调节因子，我们将用它来阐明乳汁停滞或激素停用可能影响乳腺上皮细胞存活的途径。这些研究将为理解为什么哺乳并不总是以最佳方式进行奠定了基础，从长远来看，应该有助于我们增加婴儿，特别是早产儿的母乳供应，对他们来说，母乳是优先事项。

DESCRIPTION (provided by applicant): It is the recommendation of the American Academy of Pediatrics that all children be breast-fed for at least the first six months of life [2], Despite this recommendation, the functional development of the mammary gland and the result of that development, milk secretion, have received relatively little attention over the past two decades. In this program project we seek to remedy this deficit by bringing together six well-qualified investigators with varying expertise to examine four critical aspects of the regulation and mechanism of milk secretion. In Project I we will examine a new hypothesis that links balanced glycolysis in the mammary gland both to lipid synthesis and cell survival. We hypothesize that changes in the activity/ conformation of hexokinase regulated by the serine/threonine kinase Akt/PKB provide the crucial link between these two functions. We will test the hypothesis in genetically altered mice. In Project II, we will examine the molecular and cell biological basis of the formation of cytoplasmic lipid droplets (CLD) in the mammary alveolar cell, testing the hypothesis that these entities originate within specialized domains in the endoplasmic reticulum containing all the necessary synthetic machinery machine for their synthesis. In project III, we will scrutinize the mechanisms by which progesterone inhibits the initiation of milk secretion in late pregnancy examining both direct and indirect mechanisms and their localization in the mammary gland to progesterone receptor containing cells and other cells. Strains of genetically altered mice in which the LacZ has been targeted to the progesterone receptor coding region and green fluorescent protein to the b-casein coding region will be used to accomplish this aim. In Project IV we will initiate studies of the role of PKC* on cell proliferation and apoptosis in pregnancy, lactation and involution. This serine/threonine kinase is an upstream regulatory factor in epithelial cell apoptosis and we will use it to elucidate the pathways through which mammary epithelial cell survival can be compromised by milk stasis or hormone withdrawal. These studies will form a foundation on which to base an understanding of why lactation does not always proceed optimally and in the long run should help us increase the human milk supply for infants, particularly preterm infants, for whom human breast milk is a priority.