FoxOs-CDX2信号通路调控草鱼肠道PepT1转运小肽的分子机制研究

小肽转运载体1（PepT1）在鱼类肠道小肽转运过程中发挥关键的作用。前期研究发现，激活或抑制草鱼肠道FoxOs活性，CDX2及PepT1基因的表达有协同响应的关系，推测FoxOs-CDX2信号通路可能对草鱼肠道PepT1转运小肽具有调控作用。本项目以草鱼为研究对象，采用细胞生物学、分子生物学等技术方法，继续深入鉴定草鱼肠道FoxOs-CDX2信号通路，探究其对PepT1基因表达的影响；明确草鱼转录因子FoxOs对CDX2启动子活性的调控作用，以及草鱼肠道转录因子FoxOs和CDX2与PepT1转运小肽的响应关系及机理，最终阐明FoxOs-CDX2信号通路调控草鱼肠道PepT1转运小肽的分子机制，从而为促进鱼类肠道小肽转运吸收及改善饲料蛋白质利用效率提供理论依据和技术支撑。

The oligopeptide transporter 1 (PepT1) plays a crucial role in the transport and absorption of di-/tri-peptides in fish intestines. The preliminary studies have revealed that when the intestinal FoxOs activity of grass carp is activated or inhibited, the expression of CDX2 and PepT1 genes show significant synergistic changes. We speculate that FoxOs-CDX2 signaling pathway may have a regulatory effect on PepT1 transport di-/tri-peptides in the intestinal tract of grass carp. This project takes grass carps as the research object and uses cell biology, molecular biology and other technical methods to further identify the FoxOs-CDX2 signaling pathway in the intestinal of grass carp, and explore its regulatory effect on the expression of PepT1 gene. Then, we will clarify the regulation effect of grass carp transcription factor FoxOs on CDX2 promoter activity, as well as the response relationship and mechanism of grass carp FoxOs and CDX2 with intestinal PepT1 transit peptide. Eventually, the molecular mechanism of FoxOs-CDX2 signaling pathway regulating the intestinal PepT1 transport small peptides of grass carp was clarified, which provided theoretical basis and technical support for promoting the intestinal transport and absorption of di-/tri-peptides of fish and improving the feed protein utilization efficiency.