LACTOFERRIN EXPRESSION IN TRANSGENIC MICE

乳铁蛋白是一种多功能、非血红素铁结合蛋白， 在乳汁、某些粘膜分泌物中浓度较高， 多形核白细胞颗粒。 我们知道很多关于 乳铁蛋白结构、铁结合、对病原体的作用以及 与各种类型的细胞结合。我们真正不明白的是 分子的生理作用，特别是在牛奶中， 乳腺 乳铁蛋白提供了母乳中25%的蛋白质， 然而，配方奶粉喂养的婴儿，他们的牛奶中没有乳铁蛋白， 似乎做得很好。 向婴儿添加乳铁蛋白的技术能力 公式正在迅速发展。 问题是，这是必要的，还是 在什么条件下有益？ 本方法使用小鼠作为 一个模型系统来研究这种优雅的 分子。 该模型系统具有优于膳食或配方的优点 补充，改变剂量的乳铁蛋白被递送至 新生儿从出生的时候，在自然，物种特定的牛奶。 我们的具体实验方法将在小鼠中使用转基因技术 提供双重假设的关键检验，即： (1)乳铁蛋白在人类新生儿发育中的主要作用 是i）通过去除体内多余的铁来调节铁平衡， 胃肠道，ii）刺激肠成熟，和 iii）减少潜在细菌病原体的生长。 (2)在乳腺本身乳铁蛋白保护免受感染 以及在分泌停滞期，例如妊娠晚期， 退化和乳腺炎。 为了验证这些假设，我们将首先检查 人乳铁蛋白在小鼠乳汁中过表达对新生儿发育的影响 和铁平衡的研究。 然后我们将 建立过表达同源乳铁蛋白的转基因小鼠， 了解这种分子的物种特异性效应。 最后我们 将开发技术，以获得乳腺特异性抑制， 乳铁蛋白在乳发生和退化过程中的合成。 在缺乏大量活性重组乳铁蛋白的情况下， 战略概述是唯一一个可以提供人力和 在新生动物中大量存在同源乳铁蛋白。 如果 抑制方法是成功的，我们将另外能够定义 乳铁蛋白缺乏对乳腺和 新生儿 所提出的转基因技术的力量在于， 它们是乳腺特异性的，并且解决了以下长期生理学问题： 乳铁蛋白对母亲和婴儿都有好处。

Lactoferrin is a multifunctional, non-heme iron-binding protein found in high concentration in milk, some mucosal secretions, and in specific granules of polymorphonuclear leukocytes. We know a great deal about lactoferrin structure, iron binding, effects on pathogenic agents and binding to various types of cells. What we really do not understand is the physiological role of the molecule, particularly in the milk and mammary gland. Lactoferrin provides 25% of the protein in human milk, yet formula-fed infants, who receive no lactoferrin in their milk, seemingly do well. The technical capacity to add lactoferrin to infant formula is rapidly being developed. The question is, is it necessary or beneficial and under what conditions? The present approach uses mice as a model system to investigate the physiological role of this elegant molecule. This model system has the advantage over dietary or formula supplementation that altered doses of lactoferrin are delivered to the neonate from the time of birth and in the natural, species specific milk. Our specific experimental approach will use transgenic technology in mice to provide critical tests of the dual hypotheses that: (1) The major roles of lactoferrin in neonatal development in the human are i) to regulate iron balance specifically by removing excess iron from the gastrointestinal tract, ii) to stimulate intestinal maturation and iii) to decrease growth of potential bacterial pathogens. (2) In the mammary gland itself lactoferrin protects against infection and inflammation during periods of secretory stasis, e.g. late pregnancy, involution and mastitis. To test these hypotheses we will first examine the effects of overexpression of human lactoferrin in mouse milk on neonatal development and iron balance using transgenic mice already available. We will then create transgenic mice overexpressing homologous lactoferrin in order to understand the species-specific effects of the molecule. Finally, we will develop technology to obtain mammary-specific inhibition of lactoferrin synthesis during lactogenesis and involution. In the absence of large supplies of active, recombinant lactoferrin the strategy outlined is the only one that can supply both human and homologous lactoferrin in large quantities to neonatal animals. If the inhibition approach is successful, we will in addition be able to define the effects of lactoferrin deficiency both in the mammary gland and in the neonate. The power of the transgenic techniques proposed are that they are mammary specific and address the long term physiology of lactoferrin n both mother and infant.