Department of Nutrition, University of California, One Shields Ave., Davis, CA 95616, USA.
Int J Biochem Cell Biol. 2010 Aug;42(8):1363-9. doi: 10.1016/j.biocel.2009.07.019. Epub 2009 Aug 7.
MicroRNAs function as gene expression modulators that are critical for mammalian development. Lactoferrin receptor on the apical membrane of enterocytes has been suggested to play key roles in the absorption of lactoferrin-bound iron from breast milk. The objective of this study was to identify mechanisms of microRNA mediated post-transcriptional regulation of the lactoferrin receptor. Sequence analyses revealed that the miR-584 sequence is identical in human, mouse and rat, and there is a conserved region complementary to the seed region (5' nucleotides 2-8) of miR-584 within the lactoferrin receptor mRNA-3'-untranslated region. miR-584 was further found to co-localize with lactoferrin receptor mRNA in mouse small intestine. The 3'-untranslated region of human lactoferrin receptor mRNA was cloned into pGL3-control luciferase reporter vector. By luciferase reporter assays in HEK293 cells, miR-584 mimic specifically repressed the reporter activity in a dose-dependent manner. miR-584 mimic reduced endogenous lactoferrin receptor protein expression in Caco-2 cells, without significantly affecting the mRNA level. We also determined that miR-584 expression is inversely correlated with lactoferrin receptor mRNA and protein expression. Taken together, we propose that miR-584 contributes to the post-transcriptional expression of lactoferrin receptor during the perinatal period. These findings demonstrate a novel example of how microRNAs may be involved in regulation of nutrient metabolism in the newborn.
微小 RNA 作为基因表达调节剂，在哺乳动物发育中起着至关重要的作用。肠细胞顶膜上的乳铁蛋白受体被认为在从母乳中吸收乳铁蛋白结合铁方面发挥关键作用。本研究的目的是确定微小 RNA 介导的乳铁蛋白受体转录后调控的机制。序列分析表明，miR-584 在人类、小鼠和大鼠中的序列是相同的，并且在乳铁蛋白受体 mRNA 3'-非翻译区中有一个与 miR-584 的种子区（5'核苷酸 2-8）互补的保守区域。miR-584 进一步被发现在小鼠小肠中与乳铁蛋白受体 mRNA 共定位。将人乳铁蛋白受体 mRNA 的 3'-非翻译区克隆到 pGL3-control 荧光素酶报告载体中。通过在 HEK293 细胞中的荧光素酶报告基因检测，miR-584 模拟物特异性地以剂量依赖性方式抑制报告基因的活性。miR-584 模拟物在 Caco-2 细胞中减少内源性乳铁蛋白受体蛋白的表达，而对 mRNA 水平没有显著影响。我们还确定 miR-584 的表达与乳铁蛋白受体 mRNA 和蛋白的表达呈负相关。总之，我们提出 miR-584 有助于围产期乳铁蛋白受体的转录后表达。这些发现表明微小 RNA 可能参与新生儿营养代谢的调节。
