Ala-Gln通过mTOR/p38 MAPK信号通路介导细胞凋亡与自噬对仔猪肠道屏障功能的调控作用

Glutamine (Gln) is not only the main energy source of intestinal mucosal cells but also the nitrogen source for nucleic acid synthesis in cell division. In the condition of stress, Gln is usually regarded as a key factor for reparing the intestinal mucosal damage. Because of the low absorption rate and being easily transformed to pyroglutamic acid and ammonia, Gln is frequently substituted by Ala-Gln which is widely used in TPN of clinic medicine. However, few researches focus on regulatory effect of Ala-Gln on barrier function of intestinal mucosal in piglets. The cell line model, immunoblot assay, PCR, siRNA and confocal microscopy techniques are used in this project: (1) to research the regulatory effect of Ala-Gln on proliferation, apoptosis and Bcl-2 gene expression of the intestinal epithelia in piglets; (2) to define the interrelation between Ala-Gln and the intestinal epithelia autophagy in piglets; (3)to illustrate the mechanism of IPEC autophagy mediated by Ala-Gln through mTOR/p38 MAPK pathway. The results can provide a necessary theory evidence for revealing the mechanism of regulatory effect of Ala-Gln on intestinal barrier function in piglets, and play a potential role for maintaining the intestinal mucosal integrality in weaning piglets.

谷氨酰胺（Gln）是小肠粘膜细胞的主要能源及细胞分裂时核酸合成的氮源。在应激状态下，Gln是肠粘膜损伤修复的关键因子。但由于人工合成的Gln吸收率低且易转化为焦谷氨酸和氨，在人的全胃肠外营养中常用丙胺酰谷氨酰胺（Ala-Gln）代替Gln。目前，在仔猪研究中关于Ala-Gln调节肠道屏障功能的研究还很少。本项目拟在前期工作的基础上，运用细胞系模型、免疫印迹、PCR、RNA沉默、共聚焦显微定位等技术手段：（1）探讨Ala-Gln对仔猪小肠上皮细胞增殖、细胞凋亡及其关键基因Bcl-2表达的调节作用；（2）明确Ala-Gln与仔猪小肠上皮细胞自噬之间的内在关系；（3）阐明mTOR/p38 MAPK信号通路在仔猪小肠上皮细胞自噬过程中的介导作用。研究结果将为揭示Ala-Gln调控仔猪肠道屏障功能的作用机制提供理论依据，并为生产中维护断奶仔猪肠黏膜的完整性提供潜在的技术支持。

谷氨酰胺（Gln）是小肠粘膜细胞的主要能源及细胞分裂时核酸合成的氮源。在应激状态下，肠黏膜屏障功能的损伤主要依赖Gln来修复。但因Gln吸收率低且易转化为焦谷氨酸和氨，在临床医学全胃肠外营养中常用丙胺酰谷氨酰胺（Ala-Gln）代替Gln。目前，在仔猪研究中关于Ala-Gln对肠粘膜屏障功能的探讨还很少。本项目在前期工作的基础上，运用营养学、细胞系模型、免疫印迹、PCR、共聚焦显微定位等技术手段：（1）研究了Ala-Gln对断奶仔猪生长性能、小肠黏膜形态结构与功能的影响；（2）探明了Ala-Gln对肠上皮细胞增殖、细胞凋亡及其关键基因Bcl-2表达的调节作用；（3）探讨了Ala-Gln对断奶仔猪小肠上皮细胞紧密连接蛋白Occludin定位与表达的影响；（4）研究了Ala-Gln通过mTOR/p38MAPK信号通路介导仔猪小肠上皮细胞自噬的调控作用，揭示了Ala-Gln通过mTOR/p38 MAPK信号通路调控仔猪小肠屏障功能的作用机制。研究结果为系统阐明Ala-Gln调控仔猪肠黏膜屏障功能的作用机制提供了必要的理论依据，并为生产中减缓因断奶应激导致的仔猪肠黏膜损伤提供了潜在的技术支持。