Expression and nutritional regulation of lipogenic genes in the ruminant lactating mammary gland
Expression and nutritional regulation of lipogenic genes in the ruminant lactating mammary gland
复制标题
DOI：
10.1007/978-0-387-74087-4_2
复制
发表时间：
2008-01-01
期刊：
影响因子：
--
通讯作者：
Chilliard, Y.
中科院分区：
文献类型：
--
作者：
Bernard, L.;Leroux, C.;Chilliard, Y.
营养对奶牛和山羊乳脂产量和组成的影响已在很大程度上进行了研究，脂肪酸（FA）组成反应存在一定差异，乳脂产量反应存在明显的种属差异。最近，在反刍动物物种的脂肪生成基因的表征允许在体内研究集中在这些基因的乳腺表达的营养的影响，在奶牛（主要喂养牛奶脂肪抑制饮食）和山羊（喂养脂肪补充饮食）。这几项研究表明，两个物种之间的基因表达调控的一些相似之处，虽然反应并不总是一致的牛奶FA分泌的反应。反式-10 C18：1和反式-10，顺式-12共轭亚油酸作为乳脂合成的调节剂的核心作用已被提出。然而，反式-10 C18：1并不直接控制奶牛的乳脂合成，尽管事实上，它在很大程度上响应于饮食因素，其浓度与奶牛的乳脂产量反应呈负相关，在较小程度上，在山羊。牛奶反式-10，顺式-12共轭亚油酸通常与奶牛的乳脂抑制相关，但在山羊中不相关，并且在产后输注时，作为奶牛中关键脂肪生成基因表达的抑制剂。最近的证据也证明了反式-9，顺式-11共轭亚油酸异构体的抑制作用。营养素调节脂肪生成基因表达的分子机制尚未得到很好的确定，但SREBP-1的核心作用已被概述为FA效应的介导者，而PPARs和STAT 5的作用需要确定。预计体外脂质合成和分泌功能系统的开发将使未来的进展朝着（1）脂肪合成抑制剂和激活剂的鉴定，（2）细胞机制的知识，和（3）反刍动物物种之间的差异的理解。
The effect of nutrition on milk fat yield and composition has largely been investigated in cows and goats, with some differences for fatty acid (FA) composition responses and marked species differences in milk fat yield response. Recently, the characterization of lipogenic genes in ruminant species allowed in vivo studies focused on the effect of nutrition on mammary expression of these genes, in cows (mainly fed milk fat-depressing diets) and goats (fed lipid-supplemented diets). These few studies demonstrated some similarities in the regulation of gene expression between the two species, although the responses were not always in agreement with milk FA secretion responses. A central role for trans-10 C18:1 and trans-10, cis-12 CLA as regulators of milk fat synthesis has been proposed. However, trans-10 C18:1 does not directly control milk fat synthesis in cows, despite the fact that it largely responds to dietary factors, with its concentration being negatively correlated with milk fat yield response in cows and, to a lesser extent, in goats. Milk trans-10, cis-12 CLA is often correlated with milk fat depression in cows but not in goats and, when postruminally infused, acts as an inhibitor of the expression of key lipogenic genes in cows. Recent evidence has also proven the inhibitory effect of the trans-9, cis-11 CLA isomer. The molecular mechanisms by which nutrients regulate lipogenic gene expression have yet to be well identified, but a central role for SREBP-1 has been outlined as mediator of FA effects, whereas the roles of PPARs and STAT5 need to be determined. It is expected that the development of in vitro functional systems for lipid synthesis and secretion will allow future progress toward (1) the identification of the inhibitors and activators of fat synthesis, (2) the knowledge of cellular mechanisms, and (3) the understanding of differences between ruminant species.