酪氨酸氧化产物诱发机体氧化应激与组织损伤机制的研究

In the food process, high temperature, shear, dry can lead to the oxidation of protein. The oxidative modification of tyrosine residue side groups generate tyrosine oxidation products (TOP), wich induced changes of protein structure, functional and decreased antioxidant capacity of protein. TOP and some oxidized amino acid residues of protein provide with potential cytotoxicity. Although TOP accumulation inducing oxidative stress is known to be related chronic disease in human，it is not clear that intake of TOP affect the redox state of body and lead to the energy metabolism disorder. One composition，DT of TOP has double phenol hydroxyl is similar to Thyroxine in structure. In preliminary study showed that mice fed oxidated protein can cause oxidative stress in heart，liver and kidney and affect metabolism. Its mechanism remains to be elucidated. The objective of this project is to investigate that the intestinal absorption of oxidative protein product TOP, to explore the mechanism of DT effects on thyroid hormone synthesis, transport and inhibiting thyroid hormone receptor-mediated transcriptional activity and affect its celluar substance, energy metabolism and celluar proliferation and differentiation. The study will help to understand processing-induced changes in protein nutritional quality and the effect on health. It will provide guidance for the food protein processing technology.

食物加工过程中，各种理化、生物因素引起的组分间反应导致蛋白质的氨基酸残基侧链基团氧化，改变蛋白结构和功能、不仅降低抗氧化性，且研究发现摄食氧化蛋白可引起心、肝、肾组织氧化应激、纤维化，酪氨酸氧化产物（TOP）双酪氨酸（DT）、AOPP积累。体内蛋白DT、AOPP累积通常具有潜在细胞毒性作用，并与多种慢性疾病发生发展存在密切关系，但摄食TOP对机体REOXD与DT累积和组织损伤的机制目前尚不清楚。本课题研究TOP的组分吸收、并通过细胞模型和整体代谢，研究TOP诱导自由基及诱发氧化应激，干扰甲状腺素相关物质、能量代谢及其诱导细胞凋亡作用，运用分子生物学手段揭示其可能机制。为丰富食物蛋白质营养理论，合理加工技术提供指导，对提高人口健康素质具有重要的理论和实际意义。

食物蛋白质中酪氨酸极易被氧化修饰形成共价结合的双酪氨酸（DT），其对机体健康的危害和影响国内外尚无系统研究。项目通过细胞、动物学实验发现，高双酪氨酸摄入引起大小鼠多器官组织中DT积累，产生氧化还原状态失衡与炎症反应；DT上调肝、肾组织MAPK/P38/TGF-β和JNK/p38 / TGF-β1途径，促使肝、肾组织纤维化；造成心肌、胰腺组织损伤、线粒体功能紊乱，胰腺、肌细胞对葡萄糖敏感性下降，经Akt-mTOR途径引发糖代谢紊乱，且呈现时间和剂量的累积效应。DT导致幼龄及成年动物脑单胺类神经递质紊乱，线粒体凋亡、下调长时程学习记忆通路而出现学习记忆障碍。此外，DT还引起肠道微生物群变化、屏障功能受损，三甲胺及TMAO增高。分子模拟技术发现DT与甲状腺激素等激素结构相似，并竞争性干扰甲状腺等激素作用，造成糖、脂与能量代谢紊乱，影响心血管、肝、肾与神经系统功能障碍。建立不同温度喷雾干燥乳粉、不同热加工猪肉和添加双酪氨酸日粮动物模型，证实了加工中高温、高压条件下，可导致食源性酪氨酸氧化产物成倍增加，证实了蛋白质氧化形成的DT是加工红肉导致肥胖、血脂、血糖代谢紊乱与导致学习记忆能力障碍的重要原因。结论：蛋白质氧化产物DT是诱发人类代谢综合征的重要食源性因素。