College of Biotechnology, Southwest University, Chongqing, 400715, China.
Biological Science Research Center, Southwest University, Chongqing, 400715, China.
Mol Genet Genomics. 2019 Dec;294(6):1375-1383. doi: 10.1007/s00438-019-01550-2. Epub 2019 Jun 18.
Forkhead box O (FoxO) is a downstream transcription factor of the insulin-signaling pathway, which plays vital roles in the growth and metabolism of organisms. In this study, BmFoxO was overexpressed in BmE cells, in which proliferation was inhibited and apoptosis was increased. The transgenic vector overexpressing BmFoxO was constructed, and the transgenic silkworm line A4FoxO was generated via embryonic microinjection. The body size of A4FoxO silkworm was smaller than that of non-transgenic silkworm (WT). The quantitative polymerase chain reaction results revealed that the insulin pathway was enhanced and the growth-related TOR pathway was suppressed. Furthermore, the translation of proteins in the fat body of A4FoxO silkworm was inhibited. The expression level of genes involved in the glucose synthesis and lipolysis pathways was increased, whereas that of genes involved in fat synthesis was decreased. Oil red O staining revealed that the amount of lipid droplets was reduced in A4FoxO silkworms compared with WT. Further analysis showed that the content of triglyceride and glycogen was significantly decreased in fat body, but the content of glucose and trehalose was increased in the hemolymph of A4FoxO silkworms. These results suggest that the enhanced expression of BmFoxO disturbs glycolipid metabolism and affects silkworm growth.
叉头框蛋白 O（FoxO）是胰岛素信号通路的下游转录因子，在生物的生长和代谢中发挥着重要作用。本研究在 BmE 细胞中转录激活 BmFoxO 表达，发现细胞增殖受到抑制而凋亡增加。构建了 BmFoxO 过表达的转基因载体，通过胚胎显微注射获得了转 BmFoxO 基因的家蚕品系 A4FoxO。与野生型（WT）相比，A4FoxO 家蚕的体型较小。定量聚合酶链反应结果显示胰岛素途径增强，与生长相关的 TOR 途径受到抑制。此外，A4FoxO 家蚕脂肪体中蛋白质的翻译受到抑制。参与葡萄糖合成和脂解途径的基因表达水平升高，而参与脂肪合成的基因表达水平降低。油红 O 染色显示 A4FoxO 家蚕脂肪体中的脂质滴数量减少。进一步分析表明，A4FoxO 家蚕脂肪体中的甘油三酯和糖原含量显著降低，而血液中的葡萄糖和海藻糖含量增加。这些结果表明，BmFoxO 的过度表达扰乱了糖脂代谢，影响了家蚕的生长。
