Differential expression and localization of lipid transporters in the bovine mammary gland during the pregnancy-lactation cycle
Differential expression and localization of lipid transporters in the bovine mammary gland during the pregnancy-lactation cycle
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DOI：
10.3168/jds.2009-2063
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发表时间：
2009-08-01
影响因子：
3.5
通讯作者：
Albrecht, C.
中科院分区：
文献类型：
--
作者：
Mani, O.;Sorensen, M. T.;Albrecht, C.
脂质在乳腺上皮细胞（MEC）中的转运决定了乳中脂质的含量和组成。我们研究了奶牛在泌乳期和干奶期（DP）的脂质转运蛋白及其调节剂的表达与血液代谢产物的比较。在妊娠-哺乳周期的7个阶段，从10只动物中采集重复的乳腺活检和血液样本。特异性mRNA的表达水平通过定量逆转录-PCR测定，而ABCA 1通过免疫组织化学定位。血清代谢物通过常见的酶化学测定。与哺乳期相比，DP期间ABCA 1和ABCA 7的mRNA表达水平升高，并且与血液胆固醇水平呈负相关。产后发现ABCG 2、NPC 1、SREBP 1、SREBP 2、LXR α和PPAR γ水平升高，而ABCG 1在乳腺功能阶段之间没有差异。ABCA 1蛋白定位于MEC中，并显示DP和哺乳期之间的差异活性，表明ABCA 1在DP期间从MEC中去除过量细胞胆固醇的作用。ABCA 7和NPC 1的表达谱可能分别反映了这些转运蛋白在凋亡细胞的清除和胆固醇的细胞内再分布中的作用。乳腺中脂质转运蛋白的调节部分与控制脂质稳态的转录因子有关。
The transport of lipids across mammary gland epithelial cells (MEC) determines milk lipid content and composition. We investigated the expression of lipid transporters and their regulators in comparison to blood metabolites during lactation and dry period (DP) in dairy cows. Repeated mammary gland biopsies and blood samples were taken from 10 animals at 7 stages of the pregnancy-lactation cycle. Expression levels of the specific mRNAs were determined by quantitative reverse transcription-PCR, whereas ABCA1 was localized by immunohistochemistry. Blood serum metabolites were determined by common enzymatic chemistries. Elevated mRNA profiles of ABCA1 and ABCA7 were found during DP as compared with lactation and were inversely associated with blood cholesterol levels. Elevated levels of ABCG2, NPC1, SREBP1, SREBP2, LXR alpha, and PPAR gamma were found postpartum, whereas ABCG1 did not differ between the functional stages of the mammary gland. The ABCA1 protein was localized in MEC and showed differential activity between DP and lactation suggesting a role of ABCA1 in the removal of excess cellular cholesterol from MEC during the DP. The expression profiles of ABCA7 and NPC1 may reflect a role of these transporters in the clearance of apoptotic cells and the intracellular redistribution of cholesterol, respectively. Regulation of lipid transporters in the mammary gland is partially associated with transcription factors that control lipid homeostasis.