Circ-Amotl1在母体能量水平调控猪胎盘养分转运和胎儿发育中的作用及分子机制

One mode of action found on some circRNAs is the sponging activity of this class of molecules to bind miRNAs, allowing them to arrest miRNAs activity and to regulate its target gene expression. A large number of studies showed that energy levels during pregnancy effecting progeny miRNA expression thereby affecting their fetal development in mice, but its precise mechanism is still unclear. Our previous study indicated that miR-17 retarded cell and tissue growth of mice, and overexpress circ-Amotl1 inhibited the expression of miR-17. We also found that maternal dietary energy levels could affect the placental nutrient transfer and fetal growth via the regulation of imprinted gene IGF-2 and H19 in mice. However, to the best of our knowledge, it was rarely reported in swine. Therefore, by using gilts as model, we anticipated that the present study could disclose a original regulatory pathway which is composed of circ-Amotl1, miR-17, and imprinted genes IGF-2 or H19. As well as this could act as a model for studying on the prevalence of maternal energy level and offspring growth and development. These would have an important theoretical significance at deeply understand the relationship between energy levels and placental nutrient transport and clarify its mechanism of fetal development, as well as have great practical significance at improving the modern swine industry.

环状RNAs可通过吸附miRNAs后抑制其活性，进而调控miRNAs靶基因的表达。鼠上的研究发现，母体能量水平可影响后代miRNAs表达进而影响其生长发育，但其精确机制不清楚。我们前期的结果表明，miR-17具有抑制小鼠细胞及组织生长的作用，而circ-Amotl1过表达可抑制miR-17的表达。我们还发现，母体能量水平可通过调节印迹基因 IGF-2/H19的表达影响小鼠胎盘养分转运及胎儿发育，在猪上未见报道。因此，本项目进一步以妊娠母猪为研究对象，探讨饲粮能量水平是否可通过调控胎盘-胎儿中circ-Amotl对miR-17的吸附作用影响 IGF-2/H19的表达，进而影响胎盘养分转运相关基因的表达，最终对胎儿生长发育产生影响，这对于深入认识母体营养与胎儿生长发育的机制具有重大的理论意义，也对提高我国养猪业生产水平具有重要的实践意义。

环状RNAs可通过吸附miRNAs后抑制其活性，进而调控miRNAs靶基因的表达。鼠上的研究发现，母体能量水平可影响后代miRNAs表达进而影响其生长发育，但其精确机制不清楚。我们前期的结果表明，miR-17具有抑制小鼠细胞及组织生长的作用，而circ-Amotl1过表达可抑制miR-17的表达。我们还发现，母体能量水平可通过调节印迹基因 IGF-2/H19的表达影响小鼠胎盘养分转运及胎儿发育，在猪上未见报道。因此，本项目进一步以妊娠母猪为研究对象，探讨饲粮能量水平是否可通过调控胎盘-胎儿中circ-Amotl对miR-17的吸附作用影响 IGF-2/H19的表达，进而影响胎盘养分转运相关基因的表达，最终对胎儿生长发育产生影响。主要研究内容及试验结果如下：.(1)完成母猪饲养试验，取得试验结果如下：.1）随着日粮能量水平的提高，妊娠110d（分娩）母猪体重、胎儿重、母猪血清中葡萄糖、甘油三酯、游离脂肪酸及瘦素含量升高 (P<0.05)，日粮处理对妊娠各阶段血清总胆固醇和糖皮质激素的影响差异均不显著 (P>0.05)；与其他组相比，妊娠90d (P<0.05)和110d (P<0.01)高能组胎盘重量显著增加。2）其他两组相比，高能量水平组分娩时胎盘组织中circ-Amotl1、IGF-2、STAT3、Slc2a3、Slc27a1的表达量显著提高 (P<0.05)，而H19、miR-17-5p的表达量显著下降(P>0.05)。.(2)通过体外细胞培养，取得试验结果如下：.1)高能量水平提高了细胞中circ-Amotl1的表达，并且促进了细胞的增殖、存活、粘附和迁移。2) circ-Amotl1通过提高STAT3的核转位能力来增强细胞活力。STAT3、IGF-2的表达量随着能量水平的的升高而增加，而miR-17-5p和H19的表达量显著降低。Circ-Amotl1和miR-17-5p之间的反馈调节共同调控细胞及动物的生长。.通过以上试验结果，初步探明了母猪饲粮能量水平与胎盘养分转运及胎儿宫内生长发育的关系，即母体营养水平对胎盘养分转运及宫内健康发育的影响可通过营养—激素—circRNAs—印迹基因（IGF-2/H19）修饰与表达—养分转运途径实现。以上结果，对于深入认识母体营养与胎儿生长发育的机制具有重大的理论意义，也对提高我国养猪业生产水平具有重要的实践意义。