Zeng Y, Wang C, Niu Y, Chi D, Xu M, Si L, Qu X, Li J
College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China.
Reprod Domest Anim. 2017 Oct;52(5):842-850. doi: 10.1111/rda.12987. Epub 2017 Apr 29.
Proteins in the LIPIN family play key roles in lipid synthesis mainly on triacylglycerol (TAG) biosynthesis, and they also act as transcriptional coactivators to regulate the expression of genes involved in lipid metabolism with other nuclear factors. Hence, this study was designed to investigate LIPIN1 in pig oocytes and embryos by the delipidation. After delipidation, the content of lipids (LDs) and TAG in MII oocyte was significantly reduced; however, a similar increasing tendency of TAG was shown during embryos development. Subsequently, the expression of genes related to TAG biosynthesis including GPAT1, AGPAT1, AGPAT2, LIPIN1, DGAT and the nuclear factors interacted with LIPIN1 including PPARα and PPARγ was investigated. It is obvious that DGAT and GPAT1, and LIPIN1 increased significantly after delipidation at 1-cell and 4-cell stage, and the expression of PPARα and PPARγ also increased at 4-cell stage. By immunofluorescence staining and Western blots, LIPIN1 was found to exhibit a dynamic localization pattern and gradually increase with the development of delipated embryo. In the early developmental stages (1-, 2- and 4-cell stages), it was distributed over the cortical layer. But at the blastocyst stage, a homogeneous distribution of LIPIN1 was observed in cytoplasm. At 2-cell stage, the expression of PPARα decreased when LIPIN1 was interfered by small interfering RNA, but PPARγ has no significant difference. Therefore, in this study, we find after delipidation, the content of TAG and LIPIN1 will gradually increase during embryo development and nuclear factor PPARα and PPARγ can also be affected by delipidation. The interaction of LIPIN1 and PPARα exists in porcine embryo.
LIPIN家族中的蛋白质在脂质合成中发挥关键作用，主要参与三酰甘油（TAG）的生物合成，并且它们还作为转录共激活因子，与其他核因子一起调节参与脂质代谢的基因的表达。因此，本研究旨在通过去脂作用来研究猪卵母细胞和胚胎中的LIPIN1。去脂后，MII期卵母细胞中的脂质（LDs）和TAG含量显著降低；然而，在胚胎发育过程中TAG呈现出类似的增加趋势。随后，研究了与TAG生物合成相关的基因（包括GPAT1、AGPAT1、AGPAT2、LIPIN1、DGAT）以及与LIPIN1相互作用的核因子（包括PPARα和PPARγ）的表达。显然，DGAT、GPAT1和LIPIN1在1细胞和4细胞期去脂后显著增加，PPARα和PPARγ的表达在4细胞期也增加。通过免疫荧光染色和蛋白质印迹法，发现LIPIN1呈现出动态定位模式，并随着去脂胚胎的发育而逐渐增加。在早期发育阶段（1细胞、2细胞和4细胞期），它分布在皮质层。但在囊胚期，观察到LIPIN1在细胞质中均匀分布。在2细胞期，当LIPIN1受到小干扰RNA干扰时，PPARα的表达下降，但PPARγ没有显著差异。因此，在本研究中，我们发现去脂后，TAG和LIPIN1的含量在胚胎发育过程中会逐渐增加，核因子PPARα和PPARγ也会受到去脂的影响。LIPIN1与PPARα在猪胚胎中存在相互作用。
